lunaticinaZ

Sorry it's not a 3rd gen, but I am going to pick up a 1984 Chevy truck and the last time it was running oil was coming out from the back of the engine. The leak was heavy but the owner got the truck pulled over and cut off before it blew up. Said the oil would come out faster when they came to a stop vs driving but it was still coming out when driving.
I'm thinking it's a rear main seal but I would like some input from you guys if you think it could be anything else causing this.
It's a 84 c10 with a 87 350 carbed.

Kevman

Sounds like a bad rear main seal, not fun to change..

lunaticinaZ

Thats what i'm thinking, and I know they are not fun to change but it's one of those if you can fix it you can have it deals and the body alone on this truck is worth a pretty penny. no dents, no rust.

toomany

Rear mains can leak a lot of oil, I've never seen one that was so bad that you couldn't pour it in faster than it came out.

I'd be looking at the oil presure sender (near the distributor) and around the oil filter (either two gaskets or, if there is one, the port above the oil filer). I've also seen valve covers leak a bunch of oil too.

lunaticinaZ

ya know what....... i know the last 2 owners of this truck personally, and I remember the 1st of the 2 saying it was leaking oil from one of the valve covers. That may very well be the problem if the 2nd owner didn't fix that.
My big concern is could a crack in the block cause this?

Grumbles

It's possible. You'd be more likely to see coolant from a cracked block than oil though.

Checking for an oil leak is simple, as there are only a few gasket sealed locations to look for, and if it ain't a gasket you're pretty much boned. For the sheer volume you say you're leaking, I would look at these places first:

Timing chain cover (though that is at the front and probably not it)

Sender

Filter

Oil pan gasket

Less likely but still possible:

Valve covers

intake manifold front and rear seals

If all of those check out, grit your teeth and start looking at the RMS.


It's very possible your valve cover is leaking, but there's not a chance in hell you're dumping more oil than you can put in out of them. You'd have to have absolutely zero gasket sealing them to do something that drastic. Either way it's 30 minutes of work and like 20 bucks at autozone, so definitely worth your time to replace.


EDIT: If it's a truck, did it come with an oil cooler? I know my Vortec motor did, and I can imagine one of those lines breaking or the unit itself leaking if it managed to get punctured by a rock or stray socket or something.

five7kid

iTrader: (14)

Keep this discussion related to the engine only, which can be applied to 3rd gens, and we'll leave it open.

Start talking about things that are specific to an '84 truck, and it'll be closed.

toomany

I seriously doubt it'd be a cracked block. If the block were cracked and oil were leaking...it probably wouldn't be running anymore.

Also, the plugs at the rear of the block behind the camshaft. 3 for the oil gallies and one big one behind the cam.

Personaly I'd climb in there and have someone start the vehicle. There is plenty of room under the hood of that thing. If it's leaking that much it shouldn't be hard to spot.

Grumbles and OP: There shouldn't be any oil cooler on it, atleast not factory.

lunaticinaZ

HA HA well I went a looked at it yesteday. Turns out it's not leaking oil at all. It's leaking.... no... spraying trans fluid from the hole in the bottom of the tranny. the hole I think is supposed to be there(draing hole) it's at the bottom of the bell housing.
But when I start it up and let if run for a few.it starts squirting fuid out of that hole.
It's a 700 r4 tranny. Am I screwed?

lunaticinaZ

OK, I searched and found it's either the front seal or the torque converter is damaged. And the hole is the drain hole in the converter cover. Is it hard to change the front seal on a 700 r4? I'm going to fix this myself if I can, but if I can't my father in law said he would do it for me, but I would like to do this myself for the knowladge and know how.
So if I can swindle a guy at work out of his 92 third gen with a 700 r4 I'll know what to do if this happens to it