Melling Oil Pumps are BAD!

[rfb6435]

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

[Ken F]

My Melling is holding up great! 1 year for an engine to sit is a long time. Not doubting that is was the oil pumps fault, I'm just saying you were probably just unlucky.

[rfb6435]

Quote:

Originally Posted by Ken F My Melling is holding up great! 1 year for an engine to sit is a long time. Not doubting that is was the oil pumps fault, I'm just saying you were probably just unlucky.

I am being a little bold in my title but I want to draw attention to this... If the manufacturing tolerances are bad enough that this happend to me and I have heard of others with the same experience it just isn't worth the risk IMO.

Oil pumps are simple so I really didn't expect it to be a problem but I got burned!

The oil pump is just too critical to get anything but the best!

-Rich

[glhs727]

I have used melling pumps in about 20 different motors in the last 5 years with zero failures. I might have missed something but how exactly do you know the oil pump is bad, went bad, caused the issue, etc...? There seems to be several maybe's in there plus your machinist didn't think it was the pump failing that caused it, but rather lack of priming etc.. Did you take apart the pump, check tolerances? wear? find crap in there? or what? I think it's a pretty broad statement to say melling oil pumps are bad especially since melling is the OEM pump manufacturer for lots of car manufacturers and there are millions of cars running around with them, and we don't hear of recalls.
later,
Cindy

[Dodgeglht]

I agree with Cindy. As an employee of Advance Auto Parts, I can safely say I have sold many Melling oil pumps & have had zero complaints about them. Not one that was purchased has been returned due to failure. And she is correct that most manufacurers do use Melling pumps in their engines.

[mopar2ya]

I thought Melling was the OEM supplier also. Sounds like the machine shop screwed the pooch and blamed the pump mabey?

[cadmanspd]

Used to work for a very large engine remanufacturer. 250 or so engines a week. 90% used Melling pumps with no problems, the rest were Dynagear. Most warranty problems were related to other mechanical failures and the pump was a victim rather than a cause. The white goop assembly lube doesn't do well if it sits for a long time either. It hardens and clumps up bad. Disassembled a Ford FE that had sat for some time and it was almost glued together by the stuff!

[iTurbo]

I've intsalled melling oil pumps in three engines (all 2.2/2.5) and never had a problem. Sounds to me like your intermediate shaft teeth sheared. I've heard of that happening a few times.

[rfb6435]

The intermediate shaft was fine. The oil was primed and was clearly flowing to the head when I cranked the engine with the valve cover off. I really don't see how it was a priming issue or assembly lube issue.

The fact that the oil pressure was fine and then suddently dropped off and then was fine again makes me think oil pump all the way.

The pump was dissassembled and was all scuffed up. The car lost oil pressure and didn't have any leaks what else could have happend?

Ok well it is an opinion anyway so I guess your mileage may vary.

-Rich

[Dodgeglht]

The way it seems is you're blaming a part that probably was not at fault. I'm sure if a machinist said it was from the mentioned problems there is probably something to it. If you doubt that then you might want to go to a different machinist. If he's good, then he knows what he's talking about & can tell what happens when an engine fails like that.. besides that you prolly shoulda shut it off when the light kept coming on. That said something was going on right there, regardless what your gauge was saying.

[rfb6435]

Quote:

Originally Posted by Dodgeglht The way it seems is you're blaming a part that probably was not at fault. I'm sure if a machinist said it was from the mentioned problems there is probably something to it. If you doubt that then you might want to go to a different machinist. If he's good, then he knows what he's talking about & can tell what happens when an engine fails like that.. besides that you prolly shoulda shut it off when the light kept coming on. That said something was going on right there, regardless what your gauge was saying.

I definately should have shut it off. I didn't because I thought the aftermarket gauge was more reliable (my mistake) and I didn't hear any valve train noise. I would have expected all sorts of lifter noise with no oil pressure. I guess they still had plenty of oil in them though. I admit that it was a really dumb thing but either way if it dropped the pressure at full RPM it wouldn't matter anyway becaues it would be too late.

The engine will now have a spark cutout based on oil pressure.

The machinist is very respected and has built a lot of engines.

With that in mind I guess it is hard to prove anything.... If the engine failed it puts junk in the oil pump and the oil pump fails fails. If the pump fails then it makes the engine fail and puts junk in the oil pump and the oil pump fails...

The *********** thread gives more details about differences between the mopar and melling pumps. Melling might be the supplier to mopar but the pump is mopar spec and not all melling pumps meet that spec.

-Rich

[DustyR/T]

I as well work for advance and Melling is one of the only pumps offerred for most applications w/ not one return or complaint regarding the unit. We also offer HV and HP versions for some applications.

[DaytonaTurbo87]

I dunno, I thought I read that melling was and is the only supplier who makes oil pumps for the v8 mopar engines. They've been building these things for decades and I think they would know what they're doing by now.

[glhs727]

we only sell the high VOLUME melling, and have a had a great success rate with them. The *********** thread pretty much supports the same thing said here. that melling pumps are good, and as with most things about our cars, make sure you use the right parts for YOUR application ie the high volume not high pressure pump. Rich, sorry to hear about your bad luck. Like you said, it could have been the pump, could have been something that got into the pump, no way to tell for sure, but even products that have a great success rate 99%+ can still have a failure. Smart thinking on the fuel cut related to low oil pressure. I had a similar set-up on my VW bug. It wasn't a fuel cut, but an ignition cut when oil pressure went below 8 psi.
later,
Cindy

[puppet]

Rich ... you have to admit that it wouldn't make sense for Melling to produce two grades of oil pump for the same app. The box may differ but the spec has to match.

Let's just say that the pump wasn't the root cause. For the pressure to drop like you described would mean that the pump was either sucking air or not bolted to the block properly. Another alternative would be bearing clearance issues or a blocked oil gallery.