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View Full Version : 4.3 oil leak 1996 16 Classic



Cap't Ron
02-13-2010, 02:34 PM
:confused:I have a Classic 16. I have an oil leak that i cannot find, short of pulling the motor. I put on new heads. Installed new intake gaskets.cheked the oil filter mount for a forgotten gasket. Had a rear seal installed last year.
Any ideas?

silverghost
02-13-2010, 03:06 PM
I have always had good luck discovering hard to find leaks with a UV "Black-Light" and UV dye !
NAPA sells a small bottle of UV dye that you add to your engine oil. (they also sell UV dye for trans fluid, coolant, freon, hydraulics, brake fluid etc.
Each UV dye is specific.
Cost $ 6 per bottle.
Get a cheap UV "Black Light 110 volt or flashlight LED type from ebay etc.
Cost about $20 .
Run engine~
Shut down & check for leaks.
Check with UV "Black-Light" and the oil sorce will glow a bright neon color !
You can't miss this glowing dye !
Sounds like you already covered most potential oil leak areas.
What about the front timing gear cover & front balancer seal ?
Good Luck

mrfixxall
02-13-2010, 03:39 PM
i take it their was no leak before you did the heads? Did you install the distributor gasket? also did you use silicone on the intake to block on the front and rear of the intake? is this a vortec or a older 4.3? did you seal the intake bolts?

lot's of ? but we need to know the yera of the engine...

Rodger
02-14-2010, 09:43 AM
[QUOTE=mrfixxall;556157]i take it their was no leak before you did the heads? Did you install the distributor gasket? also did you use silicone on the intake to block on the front and rear of the intake? is this a vortec or a older 4.3? did you seal the intake bolts?

Pay close attention to fixall's statement. If you used the intake-manifold front & rear rail gaskets instead of silicone, it's very likely that is where your leak is.

Ron Vukonich
02-14-2010, 10:25 AM
Thanks All
I'm thinking the front timing cover.I really don't want to pull the motor but it might be the best way. just regasket all the lower stuff,pan timing cover etc,
Thanks

gcarter
02-14-2010, 12:02 PM
Just so you know, they make two piece and three piece timing covers so the pan doesn't have to be dropped to pull the timing cover.
They can be very useful.

BUIZILLA
02-14-2010, 12:21 PM
fixx may be right

rear corners of intake gasket

silverghost
02-14-2010, 12:35 PM
I have also seen many a steel sheet metal oil pan rust out or develop pin holes .
I cannot count the number of engines wrecked by leaking steel pans !

Ghost
02-14-2010, 01:13 PM
I have always had good luck discovering hard to find leaks with a UV "Black-Light" and UV dye !
NAPA sells a small bottle of UV dye that you add to your engine oil. (they also sell UV dye for trans fluid, coolant, freon, hydraulics, brake fluid etc.
Each UV dye is specific.
Cost $ 6 per bottle.
Get a cheap UV "Black Light 110 volt or flashlight LED type from ebay etc.
Cost about $20 .
Run engine~
Shut down & check for leaks.
Check with UV "Black-Light" and the oil sorce will glow a bright neon color !
You can't miss this glowing dye !
Sounds like you already covered most potential oil leak areas.
What about the front timing gear cover & front balancer seal ?
Good Luck

SG, this is great to know, very cool. -Mike

DC18
02-19-2010, 01:21 AM
I have always had good luck discovering hard to find leaks with a UV "Black-Light" and UV dye !
NAPA sells a small bottle of UV dye that you add to your engine oil. (they also sell UV dye for trans fluid, coolant, freon, hydraulics, brake fluid etc.
Each UV dye is specific.
Cost $ 6 per bottle.
Get a cheap UV "Black Light 110 volt or flashlight LED type from ebay etc.
Cost about $20 .
Run engine~
Shut down & check for leaks.
Check with UV "Black-Light" and the oil sorce will glow a bright neon color !
You can't miss this glowing dye !
Sounds like you already covered most potential oil leak areas.
What about the front timing gear cover & front balancer seal ?
Good Luck
Have used the tracer dyes for years now, they work.


i take it their was no leak before you did the heads? Did you install the distributor gasket? also did you use silicone on the intake to block on the front and rear of the intake? is this a vortec or a older 4.3? did you seal the intake bolts?

:yes: Sounds like the logical answer to me. Have seen people do this many times. I usually am the one to redo the repair. If you are using FelPro gaskets, I beleive that is mentioned on the box or if your parts guy is savvy, he will ask the right questions.

lot's of ? but we need to know the yera of the engine...

TheFees
02-21-2010, 06:34 PM
I don't know if this applies to your specific motor, but in my 1987 classic 350 Mag I had a tough time figuring out where an oil leak was coming from that would flood the bilge with oil. I finally found it, and it was the plug that went into the block on the side that was there to send a signal if the oil pressure got too low. It has a porcelin center that develops a leak. Seems kind of ironic but the thing that is installed to prevent oil problems from wasting the motor, winds up failing, causing an oil leak, and if not caught, wasting the motor.
Just start up your boat preferably on the trailer with the muffs hooked up for cooling with a hose, and look at the side of the block, that is if your boat has the emergency pressure sensor, and you will see a steady stream of oil flowing down the side from beneath the plug. It is an easy repair. Get a new plug, and install it.