C4 members question. I bought an 85 two years ago in Florida on vacation with 30K miles on it in excellent condition. The gentleman I purchased it from disclosed several engine oil leaks which were not severe at that time along with some other minor issues (gas gauge always shows full, oil pressure gauge stuck at 80 lbs).

Now when I drive the car I notice a burned oil smell when I return and park it in my garage. I was hoping it was the valve cover gaskets but upon closer inspection I discovered that the head gasket on the driver's side is leaking oil. There is another oil leak on the front of the block near the water pump which appears to be blowing back and dripping off of the oil drain plug.

Since this engine has such low miles is it wiser to replace the head gaskets as it sits or pull the motor and replace all the gaskets and check for other issues or wear at that time?

thanks,
Fred

 

I have replaced L98 head gaskets while in car. Not difficult to do. Be sure to get the felpro gaskets that address the head scrubbing problem on OEM gaskets.

 

SouthernSon - I didn't really want to pull the engine and lose the whole driving season up north where I live.

thanks for your help!

 

are you sure it's head gaskets, and not intake manifold gaskets? without seeing your car, that would be my guess. valve cover gaskets, or on iron head L98's, RTV silicone, are the usual areas for leaks. the burning oil you smell, most likely is caused by valve cover leaks - oil running down on the exhaust manifolds. front and rear china walls is another area where leaks may develop - they are part of the manifold gaskets. the rear china wall leak may rundown on the front y-pipe - again, burning oil smell. my advice - spend some time and identify the areas leaking, bite the bullet, and spend a couple weekends and sort thing out. don't panic - most likely, they're minor issues. no need here to even think you need to pull the engine at this point. worst case, I'm guessing, VC's and intake manifold. don't forget the oil pressure sending unit on the block, behind the distributor. since your gauge is stuck on 80, there may be an issue here. BTW, half the fun of owning and driving a corvette is wrenching on a corvette. one final thing, don't skimp on gaskets - buy quality stuff. just about everyone here, and my gaskets of choice - felpro - quality stuff, available just about everywhere, and probably, the best bang for the buck.

 

Much obliged for your response and advice. As you can tell I am not a mechanic but do enjoy fixing some simple things on my Vette. Last summer I replaced the brake master cylinder with great success but engines are out of my league. Luckily for me my brother in law next door was a mechanic before becoming a computer programmer so he helps when I get into trouble. Just before I bought the car two years ago the previous owner replaced the oil sending unit because it was leaking. I see it is also leaking again and pressure is stuck on 80 so I just ordered a new one to put on next week. I will double check the heads but the oil leaks appear to be originating between the head and the engine block. Two spark plugs are also wet so maybe they aren't as tight as needed. Will check those as well. The section between the valve cover and head is dry so it's not coming from there. The front of the engine is very wet with oil so that is an area needing attention. These leaks were present when I bought the car and have driven it 2000 miles since then so they don't worry me but now I can smell them so they should to be addressed. thank you again and happy cruising!

 

FWIW:

I had an oil leak on my low mileage 89, either real seal or oil pan gasket. I was very hesitant but I bought a bottle of Lucas Oil's oil stop leak, put it in the engine, made a 250 mile trip and presto, the oil leak has stopped or slowed to a point that I don't see or smell it. This was a leak that would boil blue smoke out from under the car at stop lights.

Rick

 

Rick,

thanks and I thought about that but didn't want to experiment with my Vette. I am going to take the car to my mechanic who has had several corvettes and put it up on a lift to see where the leaks are then decide what if anything I'm going to do.

thanks for you help

 

I've never seen a SBC leak oil from the head gaskets.
I'd check to be sure it's the original engine, doesn't sound like a 30,000 mile engine.

 

I have to agree with Joe C. It sure seems likely that the intake manifold is leaking at the corners (China wall) rather than the head gasket leaking oil.

 

Head gaskets very rarely leak externally. When they fail, it is internally. Dollars to donuts you've got a valve cover leak and possibly an intake leak.

 

I have a 95' and had that burning oil smell after driving it. It turned out to be a leaky driveshaft seal at the transmission. The transmission fluid was leaking on the exhaust pipes which ran directly under the driveshaft. After replacing the seal, the smell went away completely.

 

Don't laugh...But where is the China Wall on the engine?

 

Front and rear where the intake is closest the block. Usually sealed with a bead of rtv/silicone.
Random google picture, the guys index fingers are on this area.

 

Now that I see that it makes sense...Thanks

 

I don’t want to put in a horror story here but changing the intake gaskets can be game changing. Your intake is held on by hex head bolts. If you have to go this far make sure you can loosen each bolt. I had the rear driver side hex head bolt seize up on me that stripped the hex pattern and I had to cut and chisel the head off. After all work was done, it would have been just as easy to pull the engine.
All ended well as I had my heads reworked which is where I was burning oil.

 

unless the intake hardware has been change, in stock form, the intake hardware is button-head TORX.

 

Maybe a stupid question but hi temp silicone is used on the flat area of the block from one side to the other?

 

this variety of RTV silicone is hi-temp/oil resistant, and usually what I use --



some guys like "the right stuff" -- similar, but much faster curing times. I tend not to use it. from what I understand, it starts setting up in 5 minutes. I usually don't work fast, and the slower times of plain old RTV, for me is just fine.

note, if using the rtv/silicone gasket maker, you must let it cure 24 hours before starting the engine. engine heat does not fast cure this stuff. also, make sure all surfaces are squeaky clean - I mean SQUEAKY clean!!! run the bead of RTV up on both sides of the manifold gaskets approximately 1/2 inch for proper sealing. this is covered in the FSM.

 

Steve,
It's also a good idea to centerpunch the china walls from head-to-head about every 1/4". It helps to retain the RTV or the neoprene gasket there.

Mick

 

I use the ultra black too. Clean it all with brake cleaner. If you ever find yourself working on an older block with factory holes in the block to hold the old rubber gaskets, clean those out too.

Once you've cleaned gasket material off a properly prepped surface you'll realize dimpling this surface is not necessary.