Fixing damn oil leaks

[orange72350]

I seem 2 have an oil leak or 2 in the rebuilt engine. One leak seems 2 be coming from where the timing chain cover snugs up to the oil pan. just to be sure, im gonna change the whole timing chain cover seal and pan gasket. The other leak seems to be coming from the back of the engine somehwere, but i cant seem 2 locate it. im gonna pull the intake, valve covers, and anything esle i can think off and re-seal everything. any suggestions before i get things torn apart? what about gasket and seal brands? can the pan be dropped without removing the engine from the chassis? second, can anyone maybe suggest where the oil is coming from at the back of the enigne? seems to be coming down from above the bellhousing because the oil is building up on the bottom of the pan on the tranny. i cant imagine what it is. i really hope it istn the rear seal. but anyway, any thoughts/suggestions are definetly appreciated.
thanx in advance
dale

[rays68]

just riding along I have the same two oil leaks

[orange72350]

What a couple crappy spots 2 have leaks. gets the whole under carriage of the truck just covered. it sucks, plus u gotta take half the damn engine apart to fix it. grrrrrrrrrrr.

[orange72350]

anyone??????

[hgs_notes]

The front cover leak is very common. I can not fix mine, it's a crappy design. Anyway, my local mechanic said to fix that, pull the oil pan, you'll have to unbolt the motor mounts and jsck up the engine to drop the pan. Once you have the old gaskets out clean the gasket surface areas with brake cleaner. Put a silicone sealant on the rubber gasket that fits into the groove on the timing chain cover, top and bottom of the gasket. Also make sure that the front oil pan bolt holes are not pulled in from over tightening. Hammer them flat before reinstall.

That might fix it.

On the back end, hope its not a rear main seal. But if it is coming from the top end, look on the back of the block. There is a place to screw in an oil pressure sending unit that may be leaking. Older engines, like from the 60's, had a vent back there also.

Have fun, I don't envy you.

HG

[Fred T]

On your leaky rear look at the rear of the intake manifold with an inspection mirror. Check the oil pressure line fitting and the intake to block seal. The intake to block seal is famous for leaks. Also check all around your valve covers for leaks. If you don't find the leak in those places, check the rear main seal by removing the flywheel cover before you pull the crank pan.

[keenee]

I thought that old chevys dripped to scare away the blue ovals and pentstars, like marking their turf.

[COBALT]

I have the exact same leak in the back of the engine. Turns out it's two things: the intake manifold rear deck seal, and the distributor! Some aluminum intakes are a little thinner here, and may require a spacer. I got a spacer from Mr. Gasket that I'm going to install, and I'm going to use Fel Pro intake gaskets with copper RTV this go around and see if I can stop it.

I'm "consuming" about 1/2 quart of oil every 3 weeks. I know its just running down the bell housing and ending up on the transmission pan. Arg!

[busterwivell]

If it's the intake leaking, the way to stop it is to use silicone instead of the gaskets you get in the kit. That's worked for me.

[Fred T]

Originally posted by busterwivell
If it's the intake leaking, the way to stop it is to use silicone instead of the gaskets you get in the kit. That's worked for me.

That's what's recommended, leak or not. Throw away the rubber end gaskets and lay down a 1/4" bead of silicon. Carefully set the intake so that it drops straight down. Then inspect to be sure the gaps are filled and bolt the intake in place. Remove the excess in the distributor hole before it cures, the rest can be smoothed with your finger, or wait and trim after it's cured.

[orange72350]

thanx guys. i cant wait to tear this engine apart. sarcasm. thanx fer tha tips
dale

[Woody]

On the rear of the intake leak, I have fixed a few by cleaning the area real good with brake cleaner or gas on a rag. then after it has dried, using High-Temp RTV (USE THE HIGH TEMP RTV it works a lot better) covered the ouside of the rubber gasket from the intake to the block (about 1/2" wide) and let it set up real good. Now it isn't a show engine by any means, but I didn't have to remove and reinstall the intake. And the Red HT RTV is the same color as the engine so it blends in well. I did this to an intake that was leaking on both frt & rear and it sealed them up great. That oil pan is a pain....Good Luck

[Orion 762]

Not sure if this is related to your leaks, but my '95 Tahoe (with 350 sbc) started leaking all over the backside of the engine (from the area of the rear intake manifold) BECAUSE I had closed off the breather line from the valve cover to the air breather. (I must have had a brain-fart doing this in the 1st place . . . something about not wanting to suck-in all that crankcase crap into my throttle-body.)

I still had a functioning PCV setup so I (wrongly) assumed that the crankcase would be vented. This setup (with the breather vent tube closed) blew out about 3 quarts of motor oil during a 2 hr drive! What a Mess!

I did a LOT of web surfing on this topic, and found that "many" engine oil leaks are due to improperly operating "crankcase vent" systems (includes the breather setup and the PCV valve). Any leaks in this system can cause either weird vacuum or weird pressure on the oil distribution system. At higher rpm, this "pressure" gets relieved through the "weakest link" in the engine gasket system. This usually starts at the rear of the intake manifold, dumping oil all over the bell housing and the back/underside of the engine and tx.

I feel somewhat stupid even posting this, but someone else might be able to learn from my mistake. Bottom line: keep that PCV and breather system in good shape, and many leaks can be minimized.

Orion 762