A buddy of mine has an 89 formula 350. A couple of days ago, he was at my house, and when he left, he got about half way home(about a block and a half from my house), and the car started to drop oil( although he didn't notice till he got home) but anyways, he droped a lot of oil from there till his house and it came from between the bellhousing and the oil pan. So immediatly I thought rear main seal.

Are there any other possiblilties or is that it. And remember he dropped a lot of oil. Maybe 3 or 4 quarts in a block and a half.

 

china wall gasket, oil sender, oil filter, oil plug would all be more likely than the main seal

 

Sounds like maybe the freeze-plug type plug behind the cam...

 

not the filter or the oil plug. The oil sending unit is suspect number one now, and what is the china wall gasket?

and second question is where is the oil sending unit? I was told it is on the back of the engine on the drivers side by the distributor but i can't find it? Any hints?

 

I do believe the china wall seal is the seal between the block and the intake. Thats where mine leaked for along time until I got off my lazy *** and fixed it. I would look really close around the intake because when mine was leaking it leaked bewteen the bellhousing and motor like your talking about. Also check and see if its the distributer gasket.

 

The oil pressure sending unit is exactly where you stated, it screws into a "T" which comes off the oil tube. It should have a thick tan wire plugged into it, at least my IROC did. Also its a little cylinder about 1.5 inces long. I had an oil leak forever, till I replaced this exact same thing. No more leaky.

Hope this helps.

 

On my 92 the sender is above the oil filter on the driver's side of the block. I think the sender is different if you don't have the factory gauge package. I know on the older ones it's by the distruibutor.
Just replaced mine too...leaking like a b*tch.
-Rich-

 

The oil pressure sender would have to be entirely missing to produce a leak that would lose "3 or 4 quarts driving a block and a half"... yes, those leak, and yes, they can leak alot, but not that much...

There's something wrong besides that, unless it just fell completely apart or came completely off.

 

I'm guessing he's had the leak for a while and/or burns oil and didn't notice any oil missing until now because he doesn't bother checking the level. He probably didn't lose an entire quart between your house and his house, if so the oil would be pouring, not dripping.

 

it was pouring, not dripping. I wish i had a way to show how much it is crazy. You can picture it like this for about 100 feet it is a path of oil about 1 foot wide then it slims down to what appears to be where a garbage truck drove by and left that trail that they do. that goes on for the rest of the trip. not to mention what is splatered all under the car. ( sorry about the garbage truck symbolism it's all i had).

 

I would clean all the oil off underneath the car, fill it back up, start it and just lay under the car and pinpoint where it came from.


:hail:IROC-Z

 

This may be a stupid question, but did you check his oil filter? Have you looked at it yet? It's good to eliminate easy things before jumping into the more difficult/expensive stuff. Do what rocky383 says if you can't figure it out, but you may want to lay sometime down so you don't spill four quarts of oil on the ground.

 

A leak that bad ought to be easy enough to find. It has to be the filter or the drain plug. Thats alot of oil even for the intake or valve covers...Maybe a hole in the pan its self. As mentioned get under the car and pour in some new. Easy find I would guess...

 

beat by seconds, Rezzin

 

it's not the pan or the filter, and it is hard to see where it is coming from. All the tune port crap is in the way on top and the only thing you can see from the bottom is that it is coming out between the bellhousing and the oil pan. But oil is also on top of the engine? We should know what it is tonight

 

I had to get under it with the motor running to find my last leak.
It's the best method.
Wear eye protection.
-Rich-

 

my guess is the oil pressure sender blew off, and the initial pressure caused a lot of oil to come out at once. It's the only thing I can think of besides the main seal. If you can't find it, it must be gone.

 

ok, here is one to toss in to the mix.

sorry if i'm hijacking someone's post, but here goes.

my 84 is leaking oil, but here's the funny thing. i can start the car, let it idle for 15-20 minutes, and it doesn't leak.

however, once i put the car in gear and start driving, is when it starts leaking. then once i park the car, i get a drip from the front of the engine.

i'd say it's a decent leak, as i drove the car to work 2 days in a row (approx 100 miles), and the car ate 5 quarts of oil.

any hints?

 

This is in response to the original post. The 89 with a 350. Does the car have an oil cooler between the block & oil filter? If so, remove the filter & tighten the hollow bolt that the filter screws onto. From repeated filter removals, this bolt lossens up & the cooler to block o-ring leaks.

 

Sounds like blow-by when the engine is under load is forcing oil out from around the seals (or?). Have you done a compression check and/or a leakdown test recently?

 

Keven,

Are you the pro basketball player from the Suns?

:hail:IROC-Z

 

robertg:

Is this a new motor? or have you recently removed anything from the front of the motor?

 

"Keven,

Are you the pro basketball player from the Suns?"




Way off topic...

Everywhere I go, there are a bunch of "me."

When I lived in Santa Cruz, ummm, let's see... There was the late night phone calls from "Kevin's" girlfriends ... my wife loved that. There was the trucker who had a set of tires for "Kevin"...
There was the "Kevin" who owed everybody money...

I once received a warrant for my arrest in the mail (?!?!). Seems that another "Kevin" had skipped his court date in Ohio. Same physical description, same DOB --- last thing people heard he was "moving to California." Bingo, I pop up on the radar screen.

It goes on and on.

 

Damn.

:hail:IROC-Z

 

rb:

no, this is my first rebuild, an 81 305 with 87 416 heads.

the only thing i've replaced recently was the harmonic dampener, and the oil seal in the timing cover.

i'm wondering if i missed a bolt hole somewhere that i was supposed to plug? i have a mechanical oil pressure gauge plumbed into the fitting near the distributor at the back of the block.

i'm presuming it's coming from the front of the engine, but i can't pinpoint where, because the oil is hitting my flex fan, which flings it everywhere. i have oil on my strut towers, my hood, my wires, etc. let's just say that i shouldn't have any chassis lube problems due to this slight oil problem i'm having.

 

Sure sounds like it might be that seal you replaced in the timing cover.

You could buy that fluorescent dye kit and put some in the motor oil (it's safe). Wash down the front of the motor really well with some engine cleaner or Dawn-type dishwash liquid. Start it up and let it run a little. Check for the source of the leak with the black light (UV).

Just a thought here -- I am not very familiar with the Chevy motor per se but this seems like a possibility.

When you rebuilt your motor, what was the clearance on the crank thrust bearings? What I am thinking is that (using the 'right-hand rule' from physics -- I think the engine rotates clockwise when looking dead on at the flywheel) when you put it in gear and some torque builds up, the crank pushes forward in the block. If the thrust bearings are ok that doesn't result in much actual movement. If the clearance is wrong, the crank would actually move forward and I am thinking that might remove the sealing area on the harmonic balancer from the lip of the seal. When you stop or idle the car in neutral (or with the clutch in) the crank would probably move back and create the mystery.

Maybe some brave soul is willing to stand and look at the harmonic balancer while you torque load the engine. The movement is probably plainly visible if thats the problem.

Or maybe you didn't fully seat the harmonic balancer; maybe the seal popped out? Etc.

Hope that helps!

Kevin

 

robertg,
Look at your timing cover and see if the leak is coming from there. Sometimes it's difficult to seal well. Other than that the only probably thing I see leaking is the front intake/block gasket or sealant(front china wall). I don't see how the fan is blowing it everywhere, as it should just blow it backwards. It's got to be squirting out under some pressure to hit the fan.

Stroked,
Oil is ontop of the engine and dripping down the back? That's sort of odd. I'm wondering if he's got a lot of things leaking. Any word yet?

 

RobertG:

It is very easy to mess up the timing cover/oil pan seal when/if you take off the timing chain cover. Did you pull the cover to replace the seal?

Another thought, did the replacement balancer have a smooth machined surface where it slides into the new seal? If not, that is a good place for a leak. There are sleeves to slide over old, scored balancers that let the seal on the timing cover do its job properly.

Another place to check---on most small-block Chevys, on the passenger side, lower front of the block are two bolt holes, one just above the other (originally used for the '55-'57s engine mounts), just to the left of the harmonic balancer.

The top hole HAS to have a bolt in it as it goes directly to a passage that has oil in it (the fuel pump pushrod slides up and down in this passage). MANY, people have had a mysterious leak only to discover they left out an "unnecessary" bolt.

jms

 

jms:

i do have that bolt hole plugged, the one near the fuel pump. also, the balancer i installed was a fresh summit unit (nice smooth surface).

no, i did not pull the timing cover to change the oil seal.

i'm almost considering yanking the engine right now and tearing it down, but i still want to do some cruises and what not. missed a whole bunch this summer because of this.

rez: i wonder how i would have oil all over the underside of the hood then if it isn't getting slung around by the fan? i have oil everywhere. i'd take a picture, but my camera has been recalled, it gets shipped out tuesday.

kevin: i tried the balancer and the oil seal, because i thought it was leaking from there. no change. still no leaks at idle, pressure is ~50 psi on the gauge until the engine hits operating temp, then it lowers to ~30 psi. i'm almost wondering if maybe i forgot to set the thrust? i don't recall my rebuild manual mentioning that. that's what has me mystified, as the rear main seal would leak even at idle.

this is truely weird.

 

The thing jms mentioned is what I was thinking. That's a real favorite mystery high-speed oil leak. Oh well...

 

bump back to the top for anyone else to suggest.

 

Im curious to know whats up. When you figure it out let us know heres a bump ttt

 

If the leak is this mysterious and large, maybe a UV leak detection kit would save you a lot of time, effort, and money. Here is a 'cheap' do-it-yourself version of the kit:

JC Whitney lists Multipurpose Dye for $3.99 a bottle (one application): stock number 81XD8280B [Page 171 in Catalog 663J-06]

You should be able to pick up an incandescent UV (black light) bulb locally for not too much money. But if you cannot find one try these people:

http://www.abclights.com/chanbul.html


They have them on sale right now for $2.29 (from $2.49).

I'm thinking even with freight, you're probably under $20 total for both items.

Good luck!

Kevin

 

Sorry to keep you all wondering. My PC went down. But anyways I'm almost too embarrased to tell you all what was wrong.

We sprayed the bottom of the car off and started it up. And black stuff that was thick like oil, had the same texture started shooting all over the place.........from the front of the tranny. Stupid *** up thought it was oil, but it was severly used tranny fluid. Now doesnt' the make us look dumb


thanks for all the advice though