dacfan

Just picked up an '86 and it has a BAD oil leak. It's been leaking so long and is such a mess underneath it's really tough to locate. When I drive it a short distance and it reaches operating temp, oil starts burning off of the passenger side manifold/exhaust and a steady cloud of smoke rises up. This led me to believe oil sensor behind distributor or china wall but when I got it up on ramps and looked underneath, it is a steady constant drip from the center of the front crossmember. Looks like it must be pouring from the front of the engine and then blowing back on everything else. Everything around the cross member is filthy and I can't seem to see exactly where it is coming from but it is really pouring.
I know I need to get some uv die but thought I would ask what seal on the front would be most likely to fail and allow that much oil to leak? And primarily all over the crossmember?
Valve cover seals replaced and it doesn't look like it's the problem. Upper engine is visually dry at least down past the water pump as far as I can visually inspect.
This thing is almost loosing too much oil to drive.

John A. Marker

Since it is an 86....NO OPTI to worry about. Spray the under side of the engine with a good degreaser and perhaps a pressure washer and clean it off so you can see where the oil is coming from.

It could be leaking around the timing chain cover or the crank seal.

Greg Gore

Valve Covers
Intake Manifold end seals (china rail)
Groove worn in damper from front seal (needs new one or install wear sleeve)

1991Z07

I've had a confusing leak I can't locate on mine...broke down and bought a UV testing kit with the fluids for oil, water and A/C...for something like $65.

Have not used it yet...hope to have some time this week to troubleshoot where it's coming from. The UV kits make it so easy to see where the trail starts...

Tom400CFI

1. Drive it to a car wash and POWER WASH the begeezus out of the engine bay, crossmember, front of engine, and underside. Get it clean. A "can of degreaser" ain't going to cut it here, I'm guessing. Working on dirty cars sucks and ya want the thing clean anyway, don't you? Go clean it FIRST.

2. NOW look for the leak. No UV dye needed. It will be obvious once clean. My GUESS based on what you wrote above? Harmonic balancer outer has slipped back and cut through your timing chain cover.


Go clean the thing and the leak won't be so confusing. It will become self evident.

dacfan

Thanks guys! I appreciate the help. My last C4 had the opti and I didn't want water anywhere near it but you are right, I can spray the bottom clean on an old L98 with no real problems. It is so nasty and dripping everywhere I get oil all over me just looking up at it. Balancer cutting through the timing chain cover makes a lot of sense considering how much oil I'm losing. I just can't image the front seal or even the intake leaking that much oil. I would expect a smaller leak from the china wall or valve cover gasket. Time to clean it up! Anyone else that has lost a LOT of oil up front is welcome to chime in. It will be a few days and a quart or two before I can get it into a car wash booth.

Cliff Harris

I was thinking the same thing. It happened to me. I used JB Weld to seal up the hole 10 years ago and it's still holding strong. I didn't want to drop the pan to get the timing chain cover off.

That said, there's a new timing chain cover sitting on my workbench. I need to replace the oil pan gasket and figured since it's apart...

Just BOB

Don't get too agressive with the pressure washer until you confirm that there is not a gaping hole in the timing cover. You don't want to wash a bunch of water, grit and hell knows what else into the oil pan.

dacfan

Looks like the balancer knocking a hole in the timing cover is more than a random occurance. And to hear this just as I find that the harmonic balancer in my C5 is starting to wobble makes me second guess my bowtie allegiance. I'm now convinced the same engineer that decided where to put a C4 heater core is the same guy that decided the front crossmember and steering rack should be an inch from the balancer on a C5. Same guy that decided to go to one piece rear seal.

LongBeachC4

Think it the timing cover crank seal. Mine is doing it and the oil is dripping all under the engine and trans. I could just knock it out but I plan a refit this summer. Doing gaskets, timing chain, balancer, water pump, hoses, power steering hoses, valve springs, valve seals, rockers, fuel reg, egr, and injection system. Should take about 2 days.