Oil Leak

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OZ67CUDA

OZ67CUDA

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I have a pretty big oil leak from the rear of my freshly installed 340. It appears to only leak when the engine is running, when you arrive home a small pool of oil about 2 inches in diameter arrives on the garage floor. The engine is new, I just installed it & have done 200 miles. I removed the transmission to access the back of the block because it seemed to be coming from the back right hand side. Thinking it was the plug located there I removed the plug ( & the other 2 ) resealed them with thread sealant, sealed over the top of the cam plug with red silicone & thought the leak would surely be fixed. Well its not, I just started the car after reinstalling everything & lo and behold it still leaks the same amount. Could there be a crack in the back of the block through the casting of the oil feed gallery going to the oil pump?
 

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Check the oil sending unit fittings. That is a very common area that leaks and fools people into thinking the leak is elsewhere. Also check your valve covers, oil filter assembly and the back of the intake at the rear rail.
 
Did you remove the distributor and oil pump drive and drill the oil pressure up before you reinstalled the trans to see where it came from under pressure? I did that on a 440 once and found it was my rear oil galley plug was cracked. Just cleaned everything real good and had someone run the oil pressure up and tada there the leak was!
 
Thanks Mad Dart I did those checks many times hoping it was so simple.
 
The oil sending unit will leak like a beeeaaatch - if bad - leaks quarts of oil on a drive.

Check it when running at speed. - It won't leak much at idle - not enough to notice. Just FYI.

Been there done that .

Bcudamatt
 
Thanks dragondan64 that is an excellent idea, I am waiting for a borescope to arrive so I can run the engine & search behind the flex plate, if that doesn't work it will be the drill. I wonder if the drill test would yield enough pressure to make it leak.
 
Check rear of intake they often leak if not enough silicone was used when you installed it.
 
On my current set up, I had a hard time getting the oil filter plate to stop leaking. I kept messing with it to no avail..... I ended up putting tbe canton billet filter plate on and that stopped the leak.... Just FYI

Oil leaks are weird. Most of the time they seem to be coming from a different place than they actually are.
 
Mad Dart said:
On my current set up, I had a hard time getting the oil filter plate to stop leaking. I kept messing with it to no avail..... I ended up putting tbe canton billet filter plate on and that stopped the leak.... Just FYI

Oil leaks are weird. Most of the time they seem to be coming from a different place than they actually are.
Click to expand...

I had that happen on a 360 once. The leak ran down the block so perfectly it made it look like it was coming from the back of the engine when it was really the oil filter plate. With clean oil it's harder to see it running down the block.

OZ67, yes the drill should make plenty pressure to see a leak
 
They sell a luminous dye for oil, its yellow or green. Use a cheap UV flashlight. lights up pretty good. Trouble is the stuff is everythere if the leak is up front.
Did you seat that cam galley plug correctly, ie, put it in bowed out and strike it with a ball peen hammer ?
 
When I removed the trans to fix the leak, none of the plugs looked like they had been leaking but I resealed them all anyway, The cam plug I used was a later model one but again it didn't seem to be leaking. The trans is coming out again & I'll bring the pressure up with a drill then I will definitely know where its coming from. I have a drag race / car show on in a couple of weekends so gotta hurry
 
Ok bad news. After resealing the plugs & doing the drill test everything was fine. Got everything back together, run the engine to operating temp, everything fine. Take her out for a spirited drive & when I arrive back home its leaking again. I replaced all plugs with larger taper items, totally sealed them with permatex # 2 sealant & did them up nice & tight. Please any ideas!!!
 
If any one is interested I have fixed the leak. I used a high performance thread sealant with the original tapered plugs.
 
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