explain? (number 4 mod)

[TurboII]

what is the purpose of the number four mod again? is it effective? is it needed? and when will you need it?

Just wondering what its purpose is..well i Know its method but for Y?


Joey

[Bardo]

under higher boost, the number 4 piston gets hotter then the other 3 causing it to be the first one to melt. all the mod does is help keep it under control

[TurboII]

under higher boost, the number 4 piston gets hotter then the other 3 causing it to be the first one to melt. all the mod does is help keep it under control

is it a good thing to have even under stock formation? cause i am thinking about doing it while my engine is all apart.

[R/Tony]

Well I was having issues with the 4th piston, the last time it was almost melted due to detonation and heat, when the piston its too hot its more easy to detonate and the result its a melted piston, im running a holset turbo @ 20 psi.
Now after the 4th piston mod im running more cooler. :thumb:

[TurboII]

Well I was having issues with the 4th piston, the last time it was almost melted due to detonation and heat, when the piston its too hot its more easy to detonate and the result its a melted piston, im running a holset turbo @ 20 psi.
Now after the 4th piston mod im running more cooler. :thumb:

Dang. im at 15 now. i guess i'll do it too:thumb: just for insurance

[t3rse]

i ran 27# with nitrous with no cooling mod

[Bardo]

i ran 20 on a stock shelbyz (stock fuel, spark, turbo and ic) with no mod but im looking to build a lebaron and run 25 and im going to mod it

[turbovanman²]

It works, its cheap and simple to do so you might as well do it. The problem lies in the head design, the thermostat is in between cylinders 3 and 4, causing the water to stop moving in the #4 cylinder, this mod keeps the water flowing. Just drill and tap 1/8 pipe thread at the end of the head and around the lower rad hose area at the waterpump, run a hose and thats it.

[TurboII]

It works, its cheap and simple to do so you might as well do it. The problem lies in the head design, the thermostat is in between cylinders 3 and 4, causing the water to stop moving in the #4 cylinder, this mod keeps the water flowing. Just drill and tap 1/8 pipe thread at the end of the head and around the lower rad hose area at the waterpump, run a hose and thats it.

Ya i was going do that. i was going use earls an fitting.

Joey

[Shadow]

i ran 27# with nitrous with no cooling mod

Nitrous IS a type of cooling mod! :D

[t3rse]

without nitrous too :D

[black86glhs]

It works, its cheap and simple to do so you might as well do it. The problem lies in the head design, the thermostat is in between cylinders 3 and 4, causing the water to stop moving in the #4 cylinder, this mod keeps the water flowing. Just drill and tap 1/8 pipe thread at the end of the head and around the lower rad hose area at the waterpump, run a hose and thats it.Don't you need threaded fittings too? :eyebrows:

[moparzrule]

I used 1/4'' pipe thread fittings, and used 3/8'' fuel injection line-

http://i105.photobucket.com/albums/m216/87wagon/4coolantmod.jpg


This mod is only needed over 300 WHP or so.

[MiniMopar]

Is everyone putting the barb or the output side of the water pump housing? Seems like it might work better on the input side near where the heater core return is?

[moparzrule]

Some people ''T'' it into the upper radiator hose, that should work good too.

[johnl]

http://www.turbo-mopar.com/forums/showthread.php?t=1117&highlight=coolant

Read that thread, particularly what rbryant has to say.

[turbovanman²]

Is everyone putting the barb or the output side of the water pump housing? Seems like it might work better on the input side near where the heater core return is?

I think anywhere in that area will work.

[MiniMopar]

I think anywhere in that area will work.

I was just curious. If you put it on the outlet side, I would expect coolant to flow into the head by #4. If you put it on the inlet side, I would expect coolant to flow out of the head. Not sure if the difference in pressure between the pump and the head in those two scenarios is better one way or the other. Probably not by much. Perhaps having it on the inlet side might reduce the efficiency of the heater core on a DD.

Anyway, just rambling....

[johnl]

Right, a connection at a Tee on the low side/inlet hose of the pump sucks/relieves hot coolant from the #4 corner and by passes the radiator, while a connection via a barb on the high side of the pump presumably pushes coolant that has gone through the radiator to the #4 corner.

Don't forget that before the thermostat opens, the turbo coolant line and heater line are both bypassing the thermostat. And that means . . . . what? as to the two methods . . .

[MiniMopar]

Well, running it to the pump inlet effectively puts in parallel with the heater core. So it may reduce flow through the core somewhat since it acts sort of like a bypass. I dunno, the amount of water flowing through there is probably so little that it doesn't matter.

As far as the turbo lines...well they don't really bypass anything. The inlet is from the back of the block and the outlet is at the water box. Both are on the same side of the thermostat. I don't imagine there is much pressure difference between those two points at any point. That water line is more about allowing a convection current through the housing after the motor is off.

[cordes]

Well, running it to the pump inlet effectively puts in parallel with the heater core. So it may reduce flow through the core somewhat since it acts sort of like a bypass. I dunno, the amount of water flowing through there is probably so little that it doesn't matter.

As far as the turbo lines...well they don't really bypass anything. The inlet is from the back of the block and the outlet is at the water box. Both are on the same side of the thermostat. I don't imagine there is much pressure difference between those two points at any point. That water line is more about allowing a convection current through the housing after the motor is off.

Russ, your original post on the matter has really made me think. It is the first time that I have seen anyone question the validity of this idea in such a way.

I wonder what the pressure differential is between the top of the pump housing where most put it and that spot in the head. I wouldn't be surprised if there was a negligible difference. Has anyone put a gauge in both spots to see in which direction it actually flows?

[amoparacer]

It means that when your engine is cold the number 4 piston cant burn anyway. Sorry John just had to make the point:eyebrows::eyebrows:. So what are the top secret mods to your car hum????

Lynn

[johnl]

Thanks Russ, I always make the mistake of thinking that the coolant flow through the turbo housing runs from the Tstat housing to the block. NO. It the other way; it goes from the block to the Tstat housing. Before the Tstat opens, that same flow from the turbo then goes to the Tstat housing and then likely down and through the heater core by-pass and then back to the 5/8" barb on the radiator (L body) or the lower hose Tee (all others).

[black86glhs]

Has anyone run the #4 mod to the top of the thermostat housing? Not theory wise, but actually done it.

[moparzrule]

Has anyone run the #4 mod to the top of the thermostat housing? Not theory wise, but actually done it.

What? How would that even help? Coolant wouldn't circulate until the thermostat opened, unless you didn't have a thermostat in there.

[TurboJerry]

It's all about delta pressure. The pressure is higher where the coolant enters the block from the water pump. That is how the turbo coolant lines circulate coolant well. The #4 mod should be done so that it experiences the same delta that the heater core / thermostat bypass experiences. The coolant is always flowing through the thermostat box on the head when the T-stat is closed and the engine is running, otherwise you'd have steam pockets like crazy because of stagnate coolant until the thermostat opens, Then the coolant will "burp" all the steam / air out. I guess the best place to get the coolant from for the #4 mod would be the same place the heater core gets it from on the water pump, so the engine doesn't run ice cold from "pre-circulation" through the radiator. I had corrected this for a few people in the past and they said the engine(s) actually warm up after the correction... Sorry for the long post, but I studied the coolant flow through these engines so I knew what I was up against....

[black86glhs]

What? How would that even help? Coolant wouldn't circulate until the thermostat opened, unless you didn't have a thermostat in there.#1 I'm not too worried about it waiting until the t-stat opening. #2 IMHO it would still flow out the bottom of the t-stat housing thru the heater core pipe.

[cordes]

It's all about delta pressure. The pressure is higher where the coolant enters the block from the water pump. That is how the turbo coolant lines circulate coolant well. The #4 mod should be done so that it experiences the same delta that the heater core / thermostat bypass experiences. The coolant is always flowing through the thermostat box on the head when the T-stat is closed and the engine is running, otherwise you'd have steam pockets like crazy because of stagnate coolant until the thermostat opens, Then the coolant will "burp" all the steam / air out. I guess the best place to get the coolant from for the #4 mod would be the same place the heater core gets it from on the water pump, so the engine doesn't run ice cold from "pre-circulation" through the radiator. I had corrected this for a few people in the past and they said the engine(s) actually warm up after the correction... Sorry for the long post, but I studied the coolant flow through these engines so I knew what I was up against....

I've had a frustrating day and my brain hurts. Could you draw a picture for us visual folks with what you would recommend? If not I will come back later and reread your post.

[johnl]

Doesn't the heater core get hot coolant from the tstat housing? and send it back to the low side of the pump?

[Shadow]

Doesn't the heater core get hot coolant from the tstat housing? and send it back to the low side of the pump?

Exactly, that's why I plugged that hole and ran a 5/8 fitting right out of the end of the head (in the frost plug) and ran that to my H/C. :thumb:

[black86glhs]

Exactly, that's why I plugged that hole and ran a 5/8 fitting right out of the end of the head (in the frost plug) and ran that to my H/C. :thumb:I was kicking around this idea on the head that I just got done porting. Now I know it works. Thank Robert!

[Shadow]

I was kicking around this idea on the head that I just got done porting. Now I know it works. Thank Robert!

I've been using that mod for over 10 years with great results up to 350whp. For higher HP applications I go 1 step further and run a 5/8 barb out of the top of the pump and right into the #4 frost plug (front of the block). I truly believe this is 1 of the reasons I've had such good success with the mtr in the Charger.......even cooling = less stress = no HG problems. Tested too 480whp and 134mph traps! ;)

[black86glhs]

I've been using that mod for over 10 years with great results up to 350whp. For higher HP applications I go 1 step further and run a 5/8 barb out of the top of the pump and right into the #4 frost plug (front of the block). I truly believe this is 1 of the reasons I've had such good success with the mtr in the Charger.......even cooling = less stress = no HG problems. Tested too 480whp and 134mph traps! ;)Beautiful! I know what I will be doing. I'm not running that kind of HP, but I like the idea.:thumb:

[TurboII]

I've been using that mod for over 10 years with great results up to 350whp. For higher HP applications I go 1 step further and run a 5/8 barb out of the top of the pump and right into the #4 frost plug (front of the block). I truly believe this is 1 of the reasons I've had such good success with the mtr in the Charger.......even cooling = less stress = no HG problems. Tested too 480whp and 134mph traps! ;)

Pictures

[Shadow]

Pictures

Search "#4 cooling done differently" in this section. I posted some pics there a while back, they weren't great, but if you look close I think you can see everything. (I should have taken pic's before it went into the car)

[TurboII]

I used 1/4'' pipe thread fittings, and used 3/8'' fuel injection line-

http://i105.photobucket.com/albums/m216/87wagon/4coolantmod.jpg


This mod is only needed over 300 WHP or so.

is this mod effeicent. looks clean and simple. I was going to have it drilled and tapped with -AN fitting to give it a super clean look

[cordes]

is this mod effeicent. looks clean and simple. I was going to have it drilled and tapped with -AN fitting to give it a super clean look

It would appear as though that setup is not considered ideal any longer. You could still use AN fittings and line with the "new way" but for the cost I would just go with hardware store fittings.

[turbovanman²]

Exactly, that's why I plugged that hole and ran a 5/8 fitting right out of the end of the head (in the frost plug) and ran that to my H/C. :thumb:

What does that do, an easier way of doing the #4 mod? I don't suppose the heater heats up any faster does it?

[Shadow]

What does that do, an easier way of doing the #4 mod? I don't suppose the heater heats up any faster does it?

Don't know if it heats up any faster, but the head is getting coolant running straight through it even when the T-stat is closed. :thumb:

[turbovanman²]

Don't know if it heats up any faster, but the head is getting coolant running straight through it even when the T-stat is closed. :thumb:

True and ironically, the TIII head has the thermostat on the end and so is the heater hose nipple!! :nod:

[badandy]

Can someone post some links or part numbers for the plug at the thermostat box and the fitting needed after knocking the cylinder head frost plug out and tapping it with a 1" npt bit?

[cordes]

Can someone post some links or part numbers for the plug at the thermostat box and the fitting needed after knocking the cylinder head frost plug out and tapping it with a 1" npt bit?

It's 3/8ths NPT for the smaller holes at the water box and 3/4NPT on the bottom. http://www.jegs.com/p/JEGS/752570/10002/-1

I would get a 1" NPT to 5/8ths barb fitting at the hardware store and go from there coming out of the head.

[turbovanman²]

Can someone post some links or part numbers for the plug at the thermostat box and the fitting needed after knocking the cylinder head frost plug out and tapping it with a 1" npt bit?

I wouldn't use the frost plug for any type of fitting, they are not designed for that and could work loose due to more loading. Just drill and tap the head, plenty of room.

[Shadow]

True and ironically, the TIII head has the thermostat on the end and so is the heater hose nipple!! :nod:

EGGsactly! ;)

[TurboII]

okay, what about tapping a fitting into the top radiator hose instead of the water pump housing? would that work? wouldnt it be better off that way because its cooler temps going into the Num 4 cylinder.

my idea was to tap from the side of the head and using the top raditor hose and using one of these to do it.

http://www.d1specusa.com/catalog/D1%20tee%20joint%20for%20heat%20indicator.jpg

whatcha think?

[chilort]

I really like Shadow's idea of running water from the top of the water pump housing into the #4 frost plug. I, however, also agree with Simon that frost plugs aren't made to do this.

As for running anything purposefully through the heater core, that works as long as you aren't running Max A/C. Then the line to the heater core is closed off. For all the purpose built or no A/C cars, that's not a problem. But for those of us looking for better head cooling, who drive their cars daily, and who live in hell.... er Atlanta, that doesn't work.

[TurboII]

ya but what about my idea

[chilort]

Top radiator hose is the hot side.

[TurboII]

but isnt it after the radiator?

[85daytona]

Waters flows from top to bottom of the rad on these cars-if I read through these post right...So ya the top hose is the hot side and the pump sucks out of the lower/ pushes water into the block then up through the head etc?

Anyway I think that would still work as long as there's a pressure difference great enough to get the water moving out of that side of the head. From what I've read the whole point of the mod is to just get the water flowing from around the #4 piston

[turbovanman²]

I really like Shadow's idea of running water from the top of the water pump housing into the #4 frost plug. I, however, also agree with Simon that frost plugs aren't made to do this.

As for running anything purposefully through the heater core, that works as long as you aren't running Max A/C. Then the line to the heater core is closed off. For all the purpose built or no A/C cars, that's not a problem. But for those of us looking for better head cooling, who drive their cars daily, and who live in hell.... er Atlanta, that doesn't work.

Remember the bypass valve is just that, even when Max A/C is selected, the valve lets coolant still flow, just not thru the heater core, :D


okay, what about tapping a fitting into the top radiator hose instead of the water pump housing? would that work? wouldnt it be better off that way because its cooler temps going into the Num 4 cylinder.

my idea was to tap from the side of the head and using the top raditor hose and using one of these to do it.

http://www.d1specusa.com/catalog/D1%20tee%20joint%20for%20heat%20indicator.jpg

whatcha think?

There is more suction at the waterpump inlet AND the coolant is cooler so it would help remove a bit of heat and I think also speed up the warming up of coolant. Remember, when the thermsotat is closed, not much flow going thru the upper rad hose.

[Shadow]

I really like Shadow's idea of running water from the top of the water pump housing into the #4 frost plug. I, however, also agree with Simon that frost plugs aren't made to do this.

Been running a welded fitting into the frost plug like that for 4 years now.....not a drop, not a problem. I thought about tapping it for a fitting but decided that the frost plug is a tight enough friction fit to work, so I gave it a try. I do not, however, drive my car in the winter and in all kinds of crap weather. If someone wanted to tap the F/P hole for a more perminant fitting, go for it. But that's a pretty big hole! keep in mind that this level of "evenly distributed cooling" only becomes an issue at 400+WHP. From my perspective, anyway. (I would imagine it could be a benifit at any power level though.)

[johnl]

Remember the bypass valve is just that, even when Max A/C is selected, the valve lets coolant still flow, just not thru the heater core, :D



There is more suction at the waterpump inlet AND the coolant is cooler so it would help remove a bit of heat and I think also speed up the warming up of coolant. Remember, when the thermsotat is closed, not much flow going thru the upper rad hose.

All correct, and to which, for clarification, I would add - when the Tstat is closed, coolant IS going through the block/head/turbo and returning to the radiator (L body) or pump (all non-L body) from the bottom of the Tstat box and then by way of the heater hose assembly, whether it is in by-pass mode or not.

[rbryant]

okay, what about tapping a fitting into the top radiator hose instead of the water pump housing? would that work? wouldnt it be better off that way because its cooler temps going into the Num 4 cylinder.

my idea was to tap from the side of the head and using the top raditor hose and using one of these to do it.

http://www.d1specusa.com/catalog/D1%20tee%20joint%20for%20heat%20indicator.jpg

whatcha think?

It is the same thing as putting a tee inline with the waterbox except you need 1.25 to 5/8 tee.

BTW some of the lebarons came with these... You could run that line into the bottom radiator hose and leave the heater core lines as is. It might actually work better that way because you aren't splitting the t-stat bypass line and probably get more flow.

It could also be too much and slow down the warmup process though.

-Rich

[rbryant]

Remember, when the thermsotat is closed, not much flow going thru the upper rad hose.

Only because the t-stat is closed. If you tee into it the upper hose would then suck through the small line because it then has a path for coolant to go to the water pump through the teed line.

-Rich

[rbryant]

Can someone post some links or part numbers for the plug at the thermostat box and the fitting needed after knocking the cylinder head frost plug out and tapping it with a 1" npt bit?

I wouldn't do it with the NPT tap again.

The 1" NPT is too big to get square, the hole is too big for proper thread depth, and it bottoms out...

Mine had to be JB welded in after I did it. It doesn't leak and will actually be a PITA to remove so I left it.

Either drill a new smaller hole or get the VW 1.7l oringed outlet and drill two M8 holes to hold the outlet in place.

If the head is at the machine shop you could also weld in a 1" plug and then tap that.


-Rich

[Khajjathefang]

Thread bump from the dead. Couldn't you use the lower drain port on the radiator?

[turbovanman²]

Thread bump from the dead. Couldn't you use the lower drain port on the radiator?

For what? Draining the rad? ;)

[Khajjathefang]

I was thinking feeding the plug at #4.

[turbovanman²]

I was thinking feeding the plug at #4.

It could I guess.

[BadFastGTC]

While I find the discussion and theory to this interesting, I have never run the number 4 coolant mod on any of my cars. I focused on a better radiator and have run stock headbolts and gaskets with no problems.


It could I guess.

[Shadow]

While I find the discussion and theory to this interesting, I have never run the number 4 coolant mod on any of my cars. I focused on a better radiator and have run stock headbolts and gaskets with no problems.

Better rad/cooling is definately going to help + you don't really run into HG issues till 400+WHP, so maybe your just under the radar?

[BadFastGTC]

Better rad/cooling is definately going to help + you don't really run into HG issues till 400+WHP, so maybe your just under the radar?

3,000 lb raceweight ran 120.21mph. back at SDAC-13 worked out to 405whp. I have also done a lot of high mph, long highway runs for 10+ miles well above 150mph.

[turbovanman²]

While I find the discussion and theory to this interesting, I have never run the number 4 coolant mod on any of my cars. I focused on a better radiator and have run stock headbolts and gaskets with no problems.

Your special Steve, :eyebrows:

[Shadow]

3,000 lb raceweight ran 120.21mph. back at SDAC-13 worked out to 405whp. I have also done a lot of high mph, long highway runs for 10+ miles well above 150mph.

Sorry if that came across wrong, I wasn't trying to say you weren't near 400WHP :( (if that's how it sounded?)

As you say, 405WHP + efficient rad + put together and tuned right and you might be at the edge of not needing a more efficient and evenly distributed cooling mod.

The other side is I may not need all the cooling mods I have now that I'm also running a high efficiency rad ect! Guess I'll never know though as where I'm going I'm not about to take a chance at Less and de-modding to see what's right.

You could always crank yours up to 450WHP and see what happens :)

[BadFastGTC]

I'll find out when the 2.0 is complete as the goal is 500whp. The same top end, same radiator, and a stock head gasket are going back on. I beleive as you stated, the calibration will have a big impact. What I found interesting was when I pointed an infrared temp gun at my motor cylinders 2 & 3 were hotter than 1 & 4! Time will tell if I need to make other considerations when complete.



Sorry if that came across wrong, I wasn't trying to say you weren't near 400WHP :( (if that's how it sounded?)

As you say, 405WHP + efficient rad + put together and tuned right and you might be at the edge of not needing a more efficient and evenly distributed cooling mod.

The other side is I may not need all the cooling mods I have now that I'm also running a high efficiency rad ect! Guess I'll never know though as where I'm going I'm not about to take a chance at Less and de-modding to see what's right.

You could always crank yours up to 450WHP and see what happens :)

[phoebegoesvroom]

I'm curious about what you guys feel about this mod as far as improving day-to-day reliability. My GLHS will be my daily driver when I'm done, and I'm all for anything that will improve its reliability. It will be in situations where it's not moving a lot antifreeze, like stop n go traffic and city driving...which is totally different from having to endure a flat-out quarter mile run. Thoughts?

PS: I think I can get one of those VW water outlets that Rich mentions in another thread from a friend of a friend who has a collection of VW and races, so he probably has a few of these laying around. If I were to do this, I'd go that route.

[turbovanman²]

I would do it, the mod itself makes complete sense if you think about it.

[Shadowv4l]

Bigger and better radiator always helps, my car runs nice and cool no matter what i'm doing with no mod. If you are having heat issues with cylinder 4 you have bigger problems.

[cordes]

I'm curious about what you guys feel about this mod as far as improving day-to-day reliability. My GLHS will be my daily driver when I'm done, and I'm all for anything that will improve its reliability. It will be in situations where it's not moving a lot antifreeze, like stop n go traffic and city driving...which is totally different from having to endure a flat-out quarter mile run. Thoughts?

PS: I think I can get one of those VW water outlets that Rich mentions in another thread from a friend of a friend who has a collection of VW and races, so he probably has a few of these laying around. If I were to do this, I'd go that route.

It's one more thing to fail IMO. If you have your rad shrouded like it is from the factory it should be a non-issue.

[phoebegoesvroom]

It's one more thing to fail IMO. If you have your rad shrouded like it is from the factory it should be a non-issue.

Normally I'd agree, but it is just a flange and a short length of hose in place of the frost plug. There isn't much to fail. And I agree with Turbovanman, which is why I bring it up for DDs.

[turbovanman²]

Bigger and better radiator always helps, my car runs nice and cool no matter what i'm doing with no mod. If you are having heat issues with cylinder 4 you have bigger problems.

That's not the issue, the issue is the dead/stagnant coolant around #4, bigger rads etc don't solve that.

[trannybuster]

Been running a welded fitting into the frost plug like that for 4 years now.....not a drop, not a problem. I thought about tapping it for a fitting but decided that the frost plug is a tight enough friction fit to work, so I gave it a try. I do not, however, drive my car in the winter and in all kinds of crap weather. If someone wanted to tap the F/P hole for a more perminant fitting, go for it. But that's a pretty big hole! keep in mind that this level of "evenly distributed cooling" only becomes an issue at 400+WHP. From my perspective, anyway. (I would imagine it could be a benifit at any power level though.)

Also could use some Loctite Slip Fit Retaining compound, trust me, once that stuff sets the freeze plug wont budge, you will have to show it some love to remove it! http://au.iloctite.com/en/loctite-641-660-635-638-680-620-668-603-609-648-retaining/10 freeze plug it!

[phoebegoesvroom]

Here's a link to a page that shows the part that Rich was talking about in the other thread (his photos are missing for me, I assume they're missing for everyone?):

http://corradog60project.blogspot.com/2011/01/another-necessary-modification-coolant.html

A friend of a friend is a VW racer and he said he will give me one if he has a spare. Of course, I want the aluminum version. You can buy the plastic version brand new for only $2-3.

[rbryant]

Here's a link to a page that shows the part that Rich was talking about in the other thread (his photos are missing for me, I assume they're missing for everyone?):

http://corradog60project.blogspot.com/2011/01/another-necessary-modification-coolant.html

A friend of a friend is a VW racer and he said he will give me one if he has a spare. Of course, I want the aluminum version. You can buy the plastic version brand new for only $2-3.

I can't seem to find the pictures where I drilled and tapped the head for the VW housing. I sold the head with the housing so I don't have it anymore.

I really liked the oring in the VW housing. As long as the side of the head is flat and smooth there is no need for an additional gasket. It would probably be best to use M6 or 1/4" studs with threadlocker holding them in and sealing them to the head (they do go into the water jacket in most positions) that way removing the adapter is just a matter of loosening the nuts. No need for sealant, gaskets, etc.

The housing should also have enough meat on the boss section to take a 1/8" NPT temp probe.

Just make sure that there is a coolant line from the stock waterbox back to the water pump. If you have the VW outlet on the #4 freeze plug even if your t-stat is drilled it won't provide enough flow through the waterbox to allow the t-stat to work properly on initial warmup due to stagnation of the water in the box... The head will get well above the t-stat rating before the t-stat opens and then it will open and flood the ending with cold coolant quickly cooling the engine far below the t-stat rating (rapid heating and cooling is not good for head gaskets).

-Rich

[phoebegoesvroom]

Just make sure that there is a coolant line from the stock waterbox back to the water pump. If you have the VW outlet on the #4 freeze plug even if your t-stat is drilled it won't provide enough flow through the waterbox to allow the t-stat to work properly on initial warmup due to stagnation of the water in the box... The head will get well above the t-stat rating before the t-stat opens and then it will open and flood the ending with cold coolant quickly cooling the engine far below the t-stat rating (rapid heating and cooling is not good for head gaskets).

Thanks, Rich. IIRC, in the other thread you said to hook up the VW outlet to the heater return hose, right? Would this solve the problem?

[rbryant]

Thanks, Rich. IIRC, in the other thread you said to hook up the VW outlet to the heater return hose, right? Would this solve the problem?

It should Tee into the heater core inlet (with the factory hose from the waterbox) or return to the hot side of the radiator. If you run both the factory waterbox line and the line from the freeze plug into the heater core all will be good.

The important thing is that you SHOULD NOT plug the factory heater core feed hose or it will prevent the t-stat from working properly due to lack of water flow through the waterbox. I know that I experienced it as did tryingbe.

-Rich

[phoebegoesvroom]

Gotcha. Thanks for the tip, Rich! I plan on doing this mod on the new motor for my GLHS.

[tryingbe]

Waterpump to side of the head was easy enough to drill and tap when the engine is out. I had to machine the back of the a/c bracket to clear the barb.


http://www.thelostartof.net/tryingbe/dodge/omniproject/newpics/4.jpg

http://www.thelostartof.net/tryingbe/dodge/omniproject/newpics/5.jpg

http://www.thelostartof.net/tryingbe/dodge/omniproject/newpics/6.jpg