Melling Oil Pumps are BAD!

[rbryant]

I am finally mentally over my recent engine failure to where I can talk about it....

I finally got my engine together a few weeks back and was taking it for some breakin runs. I drove it maybe 10 miles and noticed my oil pressure light blip on. I looked at my VDO guage and it read fine so I thought "oh a bad sender that sucks." and continued on.

It happend again at idle and the light stayed on for a second. I didn't hear any lifter noise or anything so I still dismissed it as the sender.

Well I drove it a bit more, had oil pressure, etc and then all of a sudden it dropped while I was on it and I had a huge knock. It took out every bearing in the engine!

I primed the pump before install and had pleantly of oil pressure when I was idling so I honestly believe it was an oil pump issue. I have also heard of other such stories with Melling pumps so I really regret not getting a factory pump!

The machinist told me that I had waited too long on my rebuild since the engine sat around for a year and that all of the assembly lube dried up and I didn't prime it well enough. The oil pump was damaged but he felt it was due to lack of priming... IMO it was due to lack of the Melling pump holding its prime....

I had an oring in the pickup so it wasn't that common mistake, etc It just simply failed and cost me another $600 in machining, bearings, etc plus gaskets and a new oil pump.

So saving $30-40 on the oil pump cost me over $600, many weeks of down time and many hours of labor!

BTW my VDO guage didn't work because the sender for that was the one that was wrong... Yes I know the VDO gauges use a different sender but this one is their US ohm range not VDO. The thing I didn't realize was that there are about 10 different US ohm range pressure senders (stupid me). Always trust all warnings until you know better!!!!!

-Rich

[inmyshadow]

If you don't like melling pumps, don't buy a MOPAR pump then.

Mopar pumps are Melling pumps.

I I have also heard of other such stories with Melling pumps so I really regret not getting a factory pump!


-Rich

[turbovanman²]

Yep, Melling is an OEM supplier so thats not the problem. Its hard to figure out over the internet but its quite possible you had a bad pump. If so, get ahold of Melling and calmly describe your issue. They might have you send them the pump and if its at fault, you could get some money back. Usually, pump failures are due to crap in the pan, improper install. I haven't seen one fail due to lack of priming etc.

[Frank]

Not exactly. There are clear casting differences and the pumps are different because the MOPAR are high volume low pressure and the Mellings are high pressure. Yes you could have the same by changing the spring, but that isnt quite the case from what I could tell.... even in the maching tolerances.

I was pissed with my Mellings which tore my intermediate shaft up. My new MOPAR is clearly different and I have a touch higher spring kit for it to properly handle the heavy springs in my valve train.

The MOPAR's may have Mellings inside of them (which is probably what you meant to say), but they are not the same setup or same style.


Frank

[Frank]

Just because Mellings makes stuff doesnt mean it is the same Mellings unit that gives alot of us people grief.


Frank

[Tony Hanna]

On the other side of the coin, I had pretty good luck out of the Melling pump I ran in the Daytona. The only problem (if you could call it that) with it was that it had to be ground to fit properly. There was a paper with the pump which I didn't read that mentioned it. No oil pressure and the distributer moving around while cranking the engine had John and I confused until I finally read the paper and realized what had happened. It was a pretty simple fix after that.

[turbovanman²]

Just because Mellings makes stuff doesnt mean it is the same Mellings unit that gives alot of us people grief.


Frank

Didn't say it was an exact copy, just they make OEM pumps. My advice of calling them still holds true.

[Frank]

Ya but when people have problems, it confuses them as they aren't the same with problems, etc.

[Directconnection]

Sooo.... I have a mellings in my VNT Shadow. No problemo. I made sure that I did not get the high pressure version. I got a pump for a plain jane 2.2 N/A Shadow. Maybe it's the high pressure or high volume ones that are causing grief?

I do have a high pressure pump from FM that sits on the shelf as I am afraid to use it and blow the seals out on my turbo.

Got's me a tad worried though about pumps. How much is the Mopar pump?


I got to sell some of my stuff....

[Frank]

It has definently been the high pressure units... especially with fresh rebuilds. My Mellings was 90cold idle and 60hot idle. My new Mopar is at 25cold idle and 12hot idle. I ordered the spring to make it higher.

The new genuine Mopar ones can be ordered from ChrisW from TU for around $120????


Frank

[Directconnection]

It has definently been the high pressure units... especially with fresh rebuilds.
Frank

For sale: 1-new still in the box Mellings high pressure oil pump. Best offer...

I think I'll just use another stock N/A 2.2 application Mellings again for the new motor.

[turbovanman²]

Well, I just checked, I have a Melling in my van, no issues, I guess its not the HV one as my oil pressure is like Franks 2nd pump readings.

[Frank]

Well, I just checked, I have a Melling in my van, no issues, I guess its not the HV one as my oil pressure is like Franks 2nd pump readings.

That means it is the HV one. THe HP are the bad ones.

[turbovanman²]

That means it is the HV one. THe HP are the bad ones.

Whatever, I have a normal, regular, plane jane, joe blow oil pump.

[TurboJerry]

I've had no issues with either. I do wonder at times about the added strain that is put on the oil pump/aux shaft gears. If you spin it by hand you can feel the "drag" increase in the HV/HP pump when it builds pressure.

[Frank]

Thanks Jerry. I noticed the same thing between my HP Mellings pump and my new Mopar HV pump... alot different in feel and drag. I think the HP Mellings pump had too much load also at the high rpms and that is why is skipped on my intermediate shaft.


Frank

[Dave]

Okay some folks have had no problems with their pumps. I had just last night! Happened as soon as you got off the highway right? My light came on - same thought, sending unit. Nope, oil pressure DROPPED! Flew back on then dropped. I shut if off immediately.

Screw that. I'm going OEM soon.

[Frank]

Okay some folks have had no problems with their pumps. I had just last night! Happened as soon as you got off the highway right? My light came on - same thought, sending unit. Nope, oil pressure DROPPED! Flew back on then dropped. I shut if off immediately.

Screw that. I'm going OEM soon.

Call up TU get a genuine mopar unit from him, then call up Summit and order the upgraded spring for it.

Wait... off the highway, as in high speed, lots of braking, off ramp/turn? Did it do it again during the turn or after you got into the straight? If it was all during the turn, then that is normal.... only baffles help that.

Frank

[Dave]

Call up TU get a genuine mopar unit from him, then call up Summit and order the upgraded spring for it.

Wait... off the highway, as in high speed, lots of braking, off ramp/turn? Did it do it again during the turn or after you got into the straight? If it was all during the turn, then that is normal.... only baffles help that.

Frank

Frank, thanks for the tip. I'll get ahold of Chris. How do I replace the spring in there? Also, I turn the oil pump in a tightening motion (clockwise) with an impact gun, yah?

It happened when I got off the highway and at a dead stop when RPMs dropped to idle (800RPMs). If I lifted it just a hair off idle the oil light would go off.

[puppet]

You guys do know that Melling makes one .. (1) .. oil pump for our engines (P/N .. M118). ... and it isn't HV or HP, just a standard, OE, replacement pump.

Pressure is a product of the engine internal clearances .. or, resistance to flow. Flow goes up as the engine wears. Pressure goes down as a result. You can get a feel for what's going on inside the engine by paying attention to when and how much oil pressure varies w/RPM and or at idle.