A little back ground first. I purcahsed this car with a spun rod bearing beacause it looked like a good deal on a nice car with a problem I could fix, with in the, worst case a replacement engine. After removing the engine from the car and opening up the bottom end I decided to repair the enginer by rebuilding the bottom end. Thus I replaced the damaged rod had the crank ground installed new rod and main bearings and a new oil pump. I had to remove one head to replace the rod but other than this left the top end of the engine alone with the exception of inspecting a couple of the cam bearings on the head I didn't remove to see if there was damage to the the cams or bearings.

Now the engine is back in the car but after idling for a minute or two the oil pressure begins to drop as the engine warms up. I suspected a lack of oil pressure because of the way the engine sounded as it warmed up and the oil light started to flicker a bit. So I pulled off the oil pressure switch and connected a temporary mechanical oil pressure gauge to monitor the pressure.

When I start the car cold the oil pressure starts at 50+ psi and drops to about 30 psi by the time the fast idle ends. From there the pressure drops slowly over the next 5 + minutes to about 5 psi where I shut it down. I didn't have my watch when I ran this test so I'm guessing at the time involved.

I plasticgauged all the rod bearings so I'm confident in their bearing clearance. I didn't mic or plasticgauge the main bearings but don't have any reason to believe there is a clearance problem. So I'm stuck wondering where all my oil is going as the engine warms up. Any ideas would be greatly appreciated.

Thanks

 

36 views but no comments. Any ideas?

 

I really don't want to own up to what the problem was but in the interest of following up on this thread here it goes.

Pulled the engine again and started tearing it back down. This time I checked the main bearings and found there was too much clearance. Turns out they turned the main journals on my crank 0.50 mm but only gave me 0.25 mm oversized main bearings. Got the correct bearings and put everything back together again. Runs good now and drove it for a few weeks before the water pump started leaking. Should have the new water pump Monday and then it will be back on the road. Surprisingly the water pump is one of the few things I found that is easy to access on this car.

 

Well good job dude. This is the first ive seen the post. And yes, thank god they went easy on us for the water pump. lol

I believe you had the question on the transfer case. After all ive seen with the experience on here no one has had a problem with overfilling. Really it will just come out of the vent, if anything its just stinky. It will level itslef thru the vent.

 

Plastigauge is NOT a reliable measuring tool, FWIW. What clearances do you think you have?

 

Way to keep your cool while having to do it again, my hat is off to you for even attempting the big job to begin with, since they didn't engineer these things for the faint of heart to work on.

 

Don't know what the clearance was with the wrong bearigs. As I recall (was over a month ago) had 2 thousandth give or take a half when it went back together.

Plastigauge is not a great measurment tool but is good for go no-go.

 

I agree on the plastigauge. It's not the go part that brings trouble. It's the no-go part.

 

Hello there where did you find the oversize bearings for your car ?? I have the same problem and cannot locate the bearings thanks

 

Just out of curiosity, how many miles are on this engine? Oh and hats off to you for having the fortitude and talent to take this project on.

 

A little bit over a 100k previous owner ran it low on oil

 

Check Rockauto.com <-- link They have under and oversize options.