Still have engine oil leak..help!

[leadlobber7]

I just got my rear main seal changed. Drove my truck around for a couple hours and then let it sit for a couple days. Looked underneath it and I have very small amount of oil leaking down from where the bottom of the inspection cover flanges up to th400 transmission. But no oil coming out of the small hole in the bottom of the inspection cover that  the mechanic drilled to see if rear main seal is leaking.

Any ideas??

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[VileZambonie]

What are we working on? The inspection cover has a weep hole in it, he drilled another hole? Assuming you have a two piece rear main seal, it an easy job to screw up if you are not particular to steps that need to be followed when installing the new seal. Most experienced guys stagger the seal ends from the main cap and cylinder block as well as use a small dab of high quality RTV (like the right Stuff) on the back corners of the cap. Additionally the pan gasket can be a 4 piece gasket which in itself has similar little tricks that need to be followed or you will have leaks. Before we go any further, you need to tell us more about your truck and what exactly was done to it.

[blazer74]

Check your oil pressure Transmitter on the back of the block and/or above the oil filter.

Otherwise valve covers or back of manifold.

[leadlobber7]

My bad sorry guys. 86 Chevrolet k30 Sikverado 4x4 th400 454 BBC. I'm not very mechanically inclined as far as being able to diagnose issues with my truck, but I am learning so please understand. All I know is  I noticed a 5/16 or so hole in the inspection cover when I climbed underneath their following the rear main seal repair. I know that they replaced the rear main bearing cap? Because they replaced the rear main seal once and it still leaked so they went a step further and replace the cap, staggered the end seals used RTV replace the oil pan gasket and now there is no oil coming out of the hole in bottom of the inspection cover like it was following their first rear main seal repair. Just some oil on the bottom of it what are the flanges up to the transmission as well as a little bit of oil on the botton passenger side bolt for the bellhousing.

Also, today I talked to the mechanic that worked on it and he told me that they power washed and degreased  the underneath of the truck and engine  transmission area. they cleaned around the top of the engine the best they could and then they put dye in the engine oil and ran on a lift until they could find that the rear main seal was bad. Then following  the second repair to ensure  that they had made  the correct repair , they drove the truck about a hundred miles or so. Truck was idling when I drove to pick it up and I took it for a ride and then parked it.

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[leadlobber7]

Check your oil pressure Transmitter on the back of the block and/or above the oil filter.

Otherwise valve covers or back of manifold.

Yes it's above the oil filter and not leaking. Bone dry

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[VileZambonie]

So your next step is to check for oil leaks again with dye tracer.

I know that they replaced the rear main bearing cap? Because they replaced the rear main seal once

I have never in my life heard of a legit business changing the rear bearing cap for this without rebuilding the engine and quite frankly that is precision machined and alignment bored so unless they removed the engine, disassembled it and had it line bored i am interested to learn the trick they used to do this with the crankshaft in place.

My advice is to retrieve your original main bearing cap ASAP and explain to them that this is still an issue. Also ask them how the ensured the new bearing cap formed a perfect circle without having it machined. Who is the mechanic, how long have he been working on Mark IV BBC's?