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supercrackerbox
01-18-2006, 05:16 PM
I run an 86 GLHT radiator in my Shelby Z. As you may know, the L-body radiators have an extra nipple on the driver's side in lieu of a nipple on the water pump housing. Currently I have a rubber cap over the nipple. Would this be a good source of coolant for the cylinder head mod?

Frank
01-18-2006, 05:34 PM
It could work. I would definently monitor your coolant temps after the install. The reason for this is that you would be bypassing the thermostat. You may wind up with a cold spot depending on the way the fluid would move about in the system. I would say build it... if you have adverse effects, tap the water pump.


Frank

supercrackerbox
01-18-2006, 05:38 PM
Hmmm, good point, didn't think of that. I do have a temperature gauge, just haven't installed it yet. The sensor for it however is in the top of the thermostat box.

What direction does the coolant flow in these cars anyway?

slasky
01-18-2006, 05:56 PM
the coolant flows from the block to the head.

Frank
01-18-2006, 06:16 PM
correct. the main reason for tapping off of the water pump into the side of the head is that the positive pressure will create some circulation. Then when the thermostat opens up, you get full circulation/disipation of coolant out of the head.

With your idea, it would help to keep from having a hot spot in the head, however it would constantly be flowing out of the head into the radiator even with the thermostat closed. Could it work? Sure... how well? Dunno. You may even need to try different restictors in the line to keep it from flowing to quickly and causing the engine to run cooler then anticipated.


Frank

supercrackerbox
01-18-2006, 07:37 PM
How about this: Perhaps another option could be to run the heater hoses to the nipple on the radiator like an L-body, and then run from the nipple on the water pump to the head, I'm guessing with a restrictor to cut down the volume.

I'm really just going over ideas at the moment, I probably won't be doing any engine work for at least several more months until I finish the body work.

Frank
01-19-2006, 10:34 AM
For the work, I would just do the common mod of running from water pump to the side of the head. Its a sure thing and takes the same about of time IMHO.


Frank

John B
01-20-2006, 02:08 PM
When I did the mod I screwed up and drilled into the inlet side of the pump housing. Still seems to work fine. The flow to #4 is reversed but it's still moving.:nod:

cordes
01-20-2006, 02:20 PM
When I did the mod I screwed up and drilled into the inlet side of the pump housing. Still seems to work fine. The flow to #4 is reversed but it's still moving.:nod:


It will be interesting to see what comes of your method.

Has anyone else done it this way?

John B
01-20-2006, 02:36 PM
It seems to work fine; even though it's returning heated coolant back to the pump bypassing the radiator it's still runs as cool as before. At first I used a restrictor in the 3/8" line to slow the flow but took it out recently and noticed no change in engine temp. It eliminates the stagnation at #4 for sure. I doubt that many others have done this-most TDers are less bewildered than I am...

TeddyZ
01-25-2006, 11:18 PM
dumb --- question.... what about running a line from the side of the head to the hex nut on top of the thermostat? or T in with the turbo???

johnl
01-25-2006, 11:32 PM
dumb --- question.... what about running a line from the side of the head to the hex nut on top of the thermostat? or T in with the turbo???

If you mean a T in from the coolant line that runs from the turbo to the T-stat box, then that coolant would have just been heated by the turbo - likely the hottest coolant anywhere in the system. As for a short line from the air evac hex/allen head on the topp of the T-stat - OK to relieve the dead spot behind #4 but will not deliver the much cooler coolant provided by a take off tap at the high side of the water pump.

Frank
01-25-2006, 11:33 PM
well you still have stagnation until the thermostat opens.


frank

pooky
01-25-2006, 11:54 PM
correct. the main reason for tapping off of the water pump into the side of the head is that the positive pressure will create some circulation. Then when the thermostat opens up, you get full circulation/disipation of coolant out of the head.

With your idea, it would help to keep from having a hot spot in the head, however it would constantly be flowing out of the head into the radiator even with the thermostat closed. Could it work? Sure... how well? Dunno. You may even need to try different restictors in the line to keep it from flowing to quickly and causing the engine to run cooler then anticipated.


Frank Tried this a couple years ago. Engine would never reach180*, even on a 95* day.

johnl
01-26-2006, 02:41 AM
well you still have stagnation until the thermostat opens.


frank

OK but is there any real heat before the T stat opens? If we are talking about a possible drag racing scenario where heat builds to the point of damage to #4 piston before the T stat can open, then leave the T stat out.

rbryant
01-27-2006, 12:02 PM
correct. the main reason for tapping off of the water pump into the side of the head is that the positive pressure will create some circulation. Then when the thermostat opens up, you get full circulation/disipation of coolant out of the head.

With your idea, it would help to keep from having a hot spot in the head, however it would constantly be flowing out of the head into the radiator even with the thermostat closed. Could it work? Sure... how well? Dunno. You may even need to try different restictors in the line to keep it from flowing to quickly and causing the engine to run cooler then anticipated.


Frank

I disagree. Correct me if I am missing something but:

The engine is actually setup that way stock... The stock tube that goes out of the waterbox to the heater core is before the thermostat!

It then goes through the heater core switch and then to the suction side of the water pump either on the pump its self, the outlet of the rad, or even a tee into the bottom rad line on some cars. That means that it is always sucking some of the coolant out of the waterbox without going through the thermostat.

I don't see how it is any different to plug the tube from the waterbox and run the line from the side of the head instead. Other than the fact that you are solving the #4 stagnation problem rather than taking the water from the waterbox.

-Rich

Frank
01-27-2006, 12:48 PM
Apples and oranges here...

On OUR cars, the heater core is not removing enough heat to worry about because it is indeed going from head back to inlet of the pump. Not that big of heat loss. All of it is staying before the thermostat. To dump fluid into the nice and large radiator could upset the balance of heat in the engine. Too cold and you have bad gas mileage and increase wear internally.


Frank

rbryant
01-27-2006, 02:16 PM
Apples and oranges here...

On OUR cars, the heater core is not removing enough heat to worry about because it is indeed going from head back to inlet of the pump. Not that big of heat loss. All of it is staying before the thermostat. To dump fluid into the nice and large radiator could upset the balance of heat in the engine. Too cold and you have bad gas mileage and increase wear internally.


Frank

I would agree if the nipple was on the inlet side of the rad but it isn't. That nipple is on the outlet side and goes directly to the water pump.

It is the same thing as having it on the suction side of the water pump like it is with the stock heater core setup.

One thing to note is that it is a terrible source for coolant to the head... It is a destination for coolant from the head because the nipple will actually suck water from the head bypassing the radiator. :)

-Rich

rbryant
11-05-2006, 05:52 AM
I found something interesting in the junkyard today on the number 4 cooling mod!

VW apparently was more worried about this problem on their 1.8l engine than ChryCo was because they actually did a #4 cooling mod!

Their 1.8/2.0 head actually is layed out much like the 2.2 (the 1.8 and 2.0VW engines share the same block with the 1.7 but Chryco made their own 1.7l head rather than using VWs)

Here is the head showing the similarity in location of the water outlet:

http://rbryant.freeshell.org/images/cooling_mod/VW%201.8-2.0.jpg

The forward connection goes to the radiator and the side goes back to the water pump pressure side. Note that the thermostat is actually in the water pump's radiator return line.

The interesting thing is that it also has a freeze plug in the side but is tapped for two holes so you can put one of these on it:

http://rbryant.freeshell.org/images/cooling_mod/VW%20cooling%201.JPG

The VW part number is: 026-121-145 in case it is hard to read. It is for a 3/4" line rather than 5/8 but that isn't a big deal. The common block water pump has a 3/4" inlet on it anyway so we are used to dealing with this and already know what to order or use when we have 5/8" hose with a 3/4" connection...

http://rbryant.freeshell.org/images/cooling_mod/VW%20cooling2.JPG

http://rbryant.freeshell.org/images/cooling_mod/VW%20cooling3.jpg

The oring means all we have to do is drill and tap two little holes in the side of our head for 10mm headed bolts. Or even some 1/4" bolts if you happen to have that tap handy!

The line then simply goes through the heater core and back to the water pump post thermostat (no thermostat control, no passing through the radiator, no collecting $200).

The bigger thing is that this shows that VW felt that the proper way to do the number four cooling mod was to simply return the water to the suction side of the pump. I have felt this all along and feel that we should plug the old heater core feed line and feed the heater core from a #4 mod. If it makes you feel better you can tee it with the #4 mod and feed the water to the heater core but either way the heater core normally takes water from the engine and returns it to the water pump without going through the thermostat or the radiator.

The one thing I haven't wrapped my head around is that VW actually sends a 3/4" line back from the pressure side of the water pump to the #3/#4 cooling outlet... I have to think about this a bit more but I believe it isn't a major difference... The coolant will not pass through the radiator when the stat is closed because the outlet of the rad will be plugged. that means the water will go through the engine both through 1-2-3 as normal and through the 3-4 outlet and back out the #4. Most of the flow should however go through the entire engine.

When it is open the pressure side line will force water to return directly through the radiator for a second pass along with the normal water from #3/#4 and some percentage of water will go directly from the #4 to the suction side of the water pump to circulate again. Hose sizes play a big part here and I haven't done the math or thought about the radiator as a restriction....

In my setup the water will go through the entire engine when the stat is closed but not the radiator. When the stat opens it will go mostly through the radiator but some percentage will go directly from the added #4 outlet to water pump and circulate again..

I believe the only difference is that more water flows accross the #4 with the pressure side connection to the #3/#4 in/outlet. But either way more flow gets out of the #4 even without it.

If you pick up one of these you will be amazed at how nicely it fits on the 2.2 8V head. It looks like it was made to be there and Chryco just forgot to drill and tap the holes for it....

-Rich

cordes
11-05-2006, 02:36 PM
That is very cool. No pun intended. THanks for the tip.

turbovanmanČ
11-05-2006, 05:42 PM
I am going to move this to the FAQ section so it sticks around, awesome find. Funny thing is, I see those engines all the time, doh!

johnl
11-14-2006, 07:25 PM
RBRYANT wrote -

"The stock tube that goes out of the waterbox to the heater core is before the thermostat!"

"It then goes through the heater core switch and then to the suction side of the water pump either on the pump its self, the outlet of the rad, or even a tee into the bottom rad line on some cars. That means that it is always sucking some of the coolant out of the waterbox without going through the thermostat."

Rich - Of all the people that have posted on the #4 mod, why the heck didn't anyone else see/say this!?!?! The T-stat is always bypassed!

Great stuff.

Then, months later, you top your own insight - the VW factory did a #4 mod.

My car seems to take too much time to get up to temperature. I wonder if the lag in temp rise is because of the routing of my #4 mod. I have a 3/8 hose tapped into the high pressure side of my L-body water pump casting. That is, my set up does NOT suck water out at the the #4 corner, instead it pushes water in there. Being an L body, my heater hose connects to cold side (driver's side) of the radiator. I wonder if the heater circuit's T-stat bypass of coolant to the driver's side (low side) of the radiator, as in the early cars, actually cools more (too much) as compared to the later model's routing of the heater hose to the low side of the water pump? That is, the factory took the radiator completely, as opposed to partly, out of the heater hose T-stat bypass route.

I'll pinch off my #4 mod 3/8 inch hose and see if I get a quicker temp rise.

WVRampage
11-14-2006, 08:09 PM
on some replacement L-Body rads the coolant line in the rad is pluged with a pipe plug so you could get a pipe bushing and the threat the AN adapter in to the rad with no problems I would assume right.And wasnt there something on the Dodge garage about puting thr outlet on the end od the head were the freeze plug is.

rbryant
11-14-2006, 08:39 PM
If you are running a heater core then just plug the normal line that feeds the heater core (I used an NPT plug) and connect #4 freeze plug line to the heater core instead. With no heater core you should be connecting that line directly to the radiator or water pump nipple so you just swap that line with the #4 freeze plug line that you just added...

Basically the only thing we are changing here is to have water leave the #4 cyl rather than smaller line that exits the bottom of the water box before the

turbo Scamp
11-21-2006, 10:43 PM
The VW part number is: 026-121-145 in case it is hard to read. It is for a 3/4" line rather than 5/8 but that isn't a big deal. The common block water pump has a 3/4" inlet on it anyway so we are used to dealing with this and already know what to order or use when we have 5/8" hose with a 3/4" connection...

A couple of questions...

What year and model of VW came with these engines? I gave that part # to the counter guy at the local VW dealer today and he gave me the "blank parts guy stare". Said he needed to know a year and a model :mad:

Also, I don't have a common block so i am not used to dealing with the 5/8" hose to the 3/4" fitting thing. What do you use? :confused:

I am gonna pull the head shortly to replact the turbo coolant and oil lines. I want to do this mod while the head is off. Super cool find!

- Bill

cordes
11-21-2006, 10:45 PM
The VW part number is: 026-121-145 in case it is hard to read. It is for a 3/4" line rather than 5/8 but that isn't a big deal. The common block water pump has a 3/4" inlet on it anyway so we are used to dealing with this and already know what to order or use when we have 5/8" hose with a 3/4" connection...

A couple of questions...

What year and model of VW came with these engines? I gave that part # to the counter guy at the local VW dealer today and he gave me the "blank parts guy stare". Said he needed to know a year and a model :mad:

Also, I don't have a common block so i am not used to dealing with the 5/8" hose to the 3/4" fitting thing. What do you use? :confused:

I am gonna pull the head shortly to replact the turbo coolant and oil lines. I want to do this mod while the head is off. Super cool find!

- Bill



You can pick up the coupler at any parts store. It is very common, and only costs a couple of bucks. The water outlet came on the VW 1.7L motors if I recall this thread correctly. That would be late 70s early 80s.

turbo Scamp
11-21-2006, 10:53 PM
That's kinda what i figured on the coupler.

I may just look in the bone yards for the fitting. The VW guys act like they don't want my money anyway.

Thanks.

- Bill

rbryant
11-22-2006, 05:04 AM
Hmm..

I got this one from what I think was a MK2 Golf. I think I have also seen them on MK1 Rabbits aswell. It should be pretty much any of the 8v non cross flow 1.7/1.8l gas engines.

Besides a coupler you can go in the back and find a 5/8" hose that has a 3/4" end on it. I know I have seen them. The hose that goes to the smaller water pump inlet is supposed to be this type of hose. They will be more expensive but you can get them. If you buy good quality hose you can also just streach the 5/8 hose over the 3/4 fitting in most cases. Just be careful that you do it slow (using a heat gun helps).

-Rich

rbryant
01-18-2007, 09:44 PM
The only thing that I would add to that is that you really should have coolant leave from both the waterbox and the #4 freeze plug for this mod rather than simply plugging the waterbox line.

The reason is because you can get some stagnation inside of the waterbox if there isn't constantly coolant flowing by the thermostat. I now recognize that this is why the VW engine has coolant leaving from both places. This is easy to accomplish with a tee in the line that goes to the heater core. My setup is working fine but I have see the temperature gauge move a little bit more drastically than I would like on initial warmup. This makes me think there is some stagnation there since my temp sender is also in the waterbox.

-Rich

johnl
01-19-2007, 04:25 AM
Taking coolant from #4 and running it to a Tee in the heater bypass hose eliminates the need for drilling and tapping the water pump housing.

rbryant
01-19-2007, 01:07 PM
Taking coolant from #4 and running it to a Tee in the heater bypass hose eliminates the need for drilling and tapping the water pump housing.

Exactly, it is a shorter line. The mod that puts cold water in the #4 also doesn't seem clean to me. It really should be into the block not the head if ran to the head it will never help the cooling to the #4 area of the block.

The size of the line also seems somewhat critical with that setup where it isn't with teeing into the heater bypass.

-Rich