A "warped" oil pump???

[JeffWVR4]

Have any of you ever run into a problem where a brand new Mitsubishi oil pump was actually warped such that it would not seal flatly against the block? I just rebuilt an engine and after it warms up, oil seems to be seeping out from the top of the oil pump slightly to the right. The oil then drips down into the valley under the timing belt and drips from the bottom of the timing cover, and some of it runs down the side of the pump and drips off the pan.

I gooped a buch of RTV over the joint between the pump and the block, and that seemed to have slowed down the leak a little, as it stopped dripping off the pan, but it may have increased the flow of oil down into the valley. Hard to tell.

Next I removed the pump, checked the gasket for foreign matter, and mated the pump against the block without a gasket to check for trueness, and all seemed well. But I did notice a little of the RTV had forced it's way between the pump and the gasket slightly on the right hand side. I put the pump back on and the oil is still leaking the same way. Although it's difficult to see, it doesn't appear that the oil is running down from higher up, and the only thing above it anyway is the water pump, which should not be causing oil leaks as far as I can tell. I've removed, checked, and re-installed the rear valve cover twice. All bolts are torqued to spec.

I'm stumped here. The only thing that would make any sense is a warped oil pump, but I've never heard of that happening before. And as I said, this is a brand new pump with 0 miles on it, and about 30 minutes of engine idle time. Is it likely that once the engine has some miles on it that this will clear up, or just get worse?

Has anybody ever had this problem?

Edit: If it makes any difference, this is a 93VR4 engine.

[helmvr4]

sorry to change the subject but i noticed ur running 16 g's and dr heads , did u ever run the 16g's without dr heads ?? and did u notice a difference when u went with the heads , how much of a difference?, try taking the oil pump to a machine shop and have it machined flat LOL?

[JeffWVR4]

Originally Posted by helmvr4

sorry to change the subject but i noticed ur running 16 g's and dr heads , did u ever run the 16g's without dr heads ?? and did u notice a difference when u went with the heads , how much of a difference?, try taking the oil pump to a machine shop and have it machined flat LOL?

Yes, I did. I ran the 16G's before the heads and engine rebuild, which also included larger pistons. And I did notice a difference. It seems to pull harder, especially on the high end, and my traps improved a little, from 118 to 121mph, but due to other issues I haven't been able to reduce my ET's yet. But this year.... ;-)

[JeffWVR4]

Anybody?

[rrjohnso2000]

I have never heard of this. Have you checked the mating surfaces with a machinists straight edge? I know checking the block may be difficult/not possible but the new pump could be checked. I know you do a lot of work on our cars so take no offense but are you sure the mating surfaces were completely clean and free of debris. If you installed while still in the car something could have easily gotten in while you were installing it. good luck

[JeffWVR4]

Originally Posted by rrjohnso2000

I have never heard of this. Have you checked the mating surfaces with a machinists straight edge? I know checking the block may be difficult/not possible but the new pump could be checked. I know you do a lot of work on our cars so take no offense but are you sure the mating surfaces were completely clean and free of debris. If you installed while still in the car something could have easily gotten in while you were installing it. good luck

No offense taken at all. When I originally installed the pump, the engine was out of the car. After I reinstalled the engine and got it running, I noticed the leak once the engine warmed up. Then I removed the pump with the engine still in the car and checked the mating surfaces and gasket for any foreign matter or old gasket material, which I really expected and was hoping to find, but didn't. The block had been dipped and stripped, so it was very clean, as was the pump. With the gasket removed, I mated the pump back on the block to see if I could see any gaps or slop in the fitment. It looked good for as much as I could see. (I didn't think to use a straight-edge at that point. Wish I had now). When I re-installed the pump and got the engine running again, the leak was exactly the same as before.

A good friend of mine, and former Chrysler mechanic, suggested using some leak detection "dye" and a blacklight to be able to better pinpoint the origin of the leak. It's very difficult to see the oil on a freshly painted gloss-black block. So I may try this if I end up taking this thing apart again.

[Boostaddict]

Use a thin coat of TRS on both sides of the gasket... if it really is the pump this will fix it. I'd suspect the oil galley plug on the front of the block first though...

[MustGoFaster]

I've seen a warped 4G63 block causing the oil pump to not seal. Anything is possible.

[JeffWVR4]

Originally Posted by Boostaddict

Use a thin coat of TRS on both sides of the gasket... if it really is the pump this will fix it. I'd suspect the oil galley plug on the front of the block first though...

I know this was an older post, but I finally got the problem resoved and thought it was worth an update. Boosaddict was right. It turned out to be a leaking oil galley plug on the front of the block. The leak was impossible to see with the engine running, and the area around that plug seemed dry. But I discovered it because the engine I rebuilt right after this one had a bad leak from under the rear main seal, which turned out to be a leaking oil galley plug on the rear of the block, and the front one started leaking about 60 miles later. So it made sense that that would be the problem on the first one, and it was. The plugs were not really loose, but they weren't real tight either. So I put some sealer on all of them, tightened them good, and problem solved (after a combined total of 59 hours of work to find it and fix it)!!!