Oil leak

[Nw2000]

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Hey guys for a while now I’ve had a pesky oil leak that I just can’t seem to pin down. It runs down the transmission bell housing and drips down a little nip on the transmission pan. When we installed the engine we replaced the oil pan gasket,rear main seal,timing cover gaskets,valve covers etc. also tightened down oil pressure pipe on the top of the block with thread sealant any advice would be appreciated thank you.

 

[10mm Nut]

Check oil pressure sending unit and the back of the intake. It's likely one or the other.

 

[Nw2000]

Check oil pressure sending unit and the back of the intake. It's likely one or the other.

I’ll check again. We did take off the intake and I thought we sealed it up pretty good but I’ve been suspicious of that.

 

[10mm Nut]

The two I listed are almost always the culprit when you have an oik leak up high on the back of the engine. Get a good strong light and check it close.

 

[Schurkey]

Power-wash all the accumulated dreck off the engine, especially where you suspect the leak is, and the path downward from there. Dry the engine as best you can with compressed air.

Drive it--or just run it--enough to generate a couple drips onto the garage floor. The engine heat dries the rest of the wash water.

Blow cornstarch or talc powder around the potential leakage areas. The talc sticks to the fresh oil trail.

Or do it the new way--flourescent dye in the oil, blacklight, special goggles to see the dye on the outside of the engine.

 

[Nw2000]

Power-wash all the accumulated dreck off the engine, especially where you suspect the leak is, and the path downward from there. Dry the engine as best you can with compressed air.

Drive it--or just run it--enough to generate a couple drips onto the garage floor. The engine heat dries the rest of the wash water.

Blow cornstarch or talc powder around the potential leakage areas. The talc sticks to the fresh oil trail.

Or do it the new way--flourescent dye in the oil, blacklight, special goggles to see the dye on the outside of the engine.

I’m gonna pick up some dye tomorrow and see if that’ll help me get to the bottom of this.

 

[Aparke4]

Just had my k2500 steam cleaned and holy smoke was it worth it! I am tracking down leaks and this made it simple! Add the UV dye after a good steam cleaning and its going to be very obvious. My truck had never been cleaned underneath and that 269k worth of miles!

 

[Frank Enstein]

Mine leaks like the Exxon Valdes. At least I save the cost of Fluid Film every year!
+1 on the clean and talc

 

[thinger2]

When you replaced the intake, did you use the gasket on the "china wall" or did you use rtv?
The gaskets are all junk.
I like ultra gray. seems to work pretty good.
The adapter fitting for the oil pressure switch is sealed with thread sealant so the factory didnt have to "clock" each adapter.
They are 1/8 npt pipe thread.
The factory ones are not brass.
They are chem coated steel so plan accordingly.
Get a 1/8 npt thread die and carefully rethread the end that goes into the block untill it clocks about 90 degrees short of where you want it to be.
Keep checking it and then put the thread sealant on.
The sealant when wet will lube up the threads and make it turn to far and then you cant get an oil pressure socket on it.
It really is a lot of futzing around but if you take your time you get an adapter that tightens up exactly where you want it.
It wont leak again and an op switch socket goes on with no clearence issues.
And try to give the sealant a good 24 hours to cure

 

[Nw2000]

When you replaced the intake, did you use the gasket on the "china wall" or did you use rtv?
The gaskets are all junk.
I like ultra gray. seems to work pretty good.
The adapter fitting for the oil pressure switch is sealed with thread sealant so the factory didnt have to "clock" each adapter.
They are 1/8 npt pipe thread.
The factory ones are not brass.
They are chem coated steel so plan accordingly.
Get a 1/8 npt thread die and carefully rethread the end that goes into the block untill it clocks about 90 degrees short of where you want it to be.
Keep checking it and then put the thread sealant on.
The sealant when wet will lube up the threads and make it turn to far and then you cant get an oil pressure socket on it.
It really is a lot of futzing around but if you take your time you get an adapter that tightens up exactly where you want it.
It wont leak again and an op switch socket goes on with no clearence issues.
And try to give the sealant a good 24 hours to cure

On the I take we used felpro gaskets and blue rtv to seal the front and back. What had happened is we first installed the intake off the 305 we took out but a bolt snapped on the thermostat housing so we used the intake that was on the 350 originally. I wasn’t as confident in its seal as it was much harder to clean due gunk and I was getting tired of filling with it at that point having to rebuy gaskets and all.