Last spring I replaced all three seals in the timing cover of my LT4 with about 36000 miles on it. The crank seal had been leaking a little bit, and I decided to go ahead and fix it up. Everything went great, other than a few headaches associated with it being my first time pulling apart the front of the motor, and the leak was completely stopped. The garage floor stayed dry for about 2 months/1000 miles of driving, and then sure enough the puddle returned. Oil on top of the front crossmember dripping back and covering the oil pan. I wasn't happy but decided I didn't want to tear into again that summer, and the leak was rather wasn't that large. Well this past week, the puddles have gotten much larger (8 inches) and its dripping back onto my exhaust and burning, causing all sorts of stink and smoke. I can't stand driving it like this, so I am about to break back into the front of motor. I plan on re doing all the seals as well as timing cover gasket and oil pan gasket. Any suggestions or advice to help this repair last for than a couple months?

 

well that certainly sucks.

when you get the water pump off, try to determine exactly where the leak is and if it is from a seal, which of the seals is leaking. Depending on where the leak is from, some mechanical repair might also be called for.

let us know what you find.

 

I would put florescent dye in oil to be sure where oil is leaking from. It could be a new leak.

 

FWIW Lucas Oil's Stop Leak stopped a leak so bad in my L-98 I was going to name it "Valdez Special". 1 quart and a 275 mile trip stopped every bit of oil leaks and has for over 20K miles.

Rick

 

where was your car leaking from?

 

Waterpump drive is generally the culprit

did you use the tool to install it.

 

I agree. I tried making my own water pump seal tool...not! I finally bought one off eBay. It was the best $20 I spent. Also, you probably know this, but if you remove the timing cover, make sure to raise the engine and drop the oil pan. Ask me how I know this isn't a shortcut worth taking, no matter how careful you think you can be.

 

 

Somewhere from the bottom rear of the engine, I'm guessing rear seal or maybe pan gasket, the car pretty much sat for 13 years barely seeing the light of day. I was hesitant to put anything in the engine but I would have had to pull it to replace the seal, and might as well rebuild it while it's out was my thinking.

RH

 

You don't have to pull the engine to do the rear seal
just the transmission and clutch


also check the back of the manifold

 

rebuild a 36,000 mile LT4 ? You might have some peripheral issues with the engine, like leaks, deteriorated hoses from age, non use, seals, but almost certainly nothing to justify the expense of a rebuild. If the compression is good..and I bet it is...and it doesn't burn oil (not to be confused with leaking oil) then leave it be...you're asking for more potential problems than you're solving.

dropping the exhaust, removing the C beam, pulling the transmission, and removing the flywheel to gain access to the rear main seal ain't exactly fun... it is labor intensive, but if time is not a factor and you do it in incremental steps, it is a job that's very doable, even by one person (except for pulling that heavy ZF transmission, should have some help there) even without a lift. Of course at this point, it would be the sensible thing to replace the pan gasket if there was any evidence of it leaking.

But wait! even before you dive in, the LT4 engine have a Teflon rear seal that is an upgrade over the LT1 engines, closely check at the top rear of the engine...there are two oil sensor / sending units and associated fittings that very well could be the source of your oil leak. Since oil flows down, it could manifest itself as an oil leak "somewhere from the bottom rear of the engine".

good luck.

wish my LT4 had only 36,000 miles

 

I understand your frustrations. I changed two front seals until I realized the CRANK HUB was the culprit. Possibly not your problem. But it was mine. Only 31,000 miles on my supercharged '93.

 

x2 on the dye. Found my drive seal leak without question. And I was thinking it was the pan.

 

If you pull the hub off, be sure to check if it's grooved. If so, you either replace it or sleeve it. A groove typically results in annoying drips vs what you have, but if it's apart it should be checked.

 

I just had the dealer do the Opti, Waterpump, Timing Cover Seal, drive shaft seals, crank sensor, etc. A week later, my leak had returned. A big spot off the front of the trans and a little off the back. Silver Dollar and Nickel-sized. Blow back from the front. Had dealer go back in and they discovered the crank sensor was leaking/bad o-ring. Put another in. 10 days later, it's back again.


The tech told my service advisor that the leak could be because of my timing cover itself because they can become porous and saturate in oil. I'm still suspicious that they are using crank sensors with O-rings that are 20 years old and are failing. Has anyone ever heard about this porous/oil saturation issue? A big reason I take this to the dealer is because A) they have a guy that knows these cars B) access to resources/info C) when something goes awry they take care of it.


If this timing cover saturation thing exists, I have no problem paying for a new cover (I know, hard to find and limited options), but I am going to expect them to eat the labor because they should have mentioned it as a possibility before we did the job and I would have had them do it then. $300 versus $1,500? You betcha.

 

BUMP, Any help?

 

All of those look dry. My big question is if anybody has ever encountered a timing cover that has become porous and leaks?

 

This was common in older times, and AFAIK, more so on things like motor cycles (Harley, Norton are a couple I'm aware of)....but modern aluminum castings? I'm going to say that it is incredibly uncommon, to non existent.

 

I had an '87 Regal T-Type that developed a leak in the aluminum intake manifold that the dealer fixed under warranty. I don't know how common it was.

 

Have you verified the front and rear china walls are not the areas leaking? The only thing sealing that area is RTV. I pulled my intake off last winter and replaced the intake gasket, which was oil soaked, and reapplied new RTV.