The rear crank main seal on my IROC leaks really bad. I lose a quart of oil in 10 days due to it. Since i don't have the money to get it fixed right now, what's the best stop leak additive on the market for leaks like this? The leak is bad enough to coat the rear end of the car with oil on the highway.

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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

 

With a leak that bad, I would safe to say you'll need to pull the motor and fix it. Which I know isn't the easies thing, but a quart ever 10 days is alot of oil.

Sorry for the bad news....

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350 4 bolt main, Speed-O-Motive 383 stroker kit, re-sized rods ground for clearance,Hypereutectic pistons,9.8:1 compression,HPC Coated RPM intake, Speed Demon 750 cfm carb,World Products Sportsman II heads,2.02/1.60 valves, K-Motion springs, Comp Cam 1.6 roller rockers, Lunati adv.292/230@.050 with .512 lift,Crane pushrods,Proform HEI and MSD6A box,HPC coated 1 5/8 headers, 2.5" exhaust with 40 series mufflers,TH350 with B&M 3000 stall, Powertrax NoSlip Locker, 4.11 gears.

 

I know this doesn't answer your question, but you don't need to pull the motor to do it. You do have to drop the trans to get to it, but that's somewhat easier than pulling the engine. The oil pan also has to be dropped slightly, but if you're careful you can get lucky and not have to change the oil pan gasket.

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88 firebird formula
350 Vortec TBI
214int/224exh, .471int/.491exh
Edelbrock headers
SIX-speed
Eats LS1's with a 2.73 open rear and 2 1/4 stock catback

My Formula

 

i know i got the same thing goin on with my lg4 iroc.. rear main leaks so bad its killing clutches, leaking back on them and making them slip.. one of theese days i need to pull that tranny, fix the 5th gear synchro, put a new clutch in, and replace that rear main seal...

 

You don't need to drop the oil pan slightly to replace the seal. (At least I never have )

just don't replace the paper gasket they give you, they never leak anyway.

Use a seal puller or thin screwdriver to pry the seal out...BE CAREFUL Do not pry against the crank seal surface, this will cause the new one to leak worse than the old one.

Lube the inner lip of the new seal and press it on with your hands until the seal lip is all the way on the crank, then tap it lightly til its flush.

Install it DRY. (no sealer)

I make it sound more complicated than it is.



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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

GO #3

 

I agree u dont need to do anything but pull the tranny and gently pull out the seal. My friend who is an experienced tranny tech had my unit out of the car in no more than 30min .I would just find someone u trust and fix it right

 

How tough is it to get the tranny out? That sucker is HEAVY so how do I lower it and reinstall it after I'm done?

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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

 

well, u gotta use a jack to lower the tranny, but you definately dont have to pull the motor, just yank the trans and take your time.. you can get it done

Steve

 

How high should I lift the car for this?

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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

 

As high as you need to in order to wheel the tranny out from underneath with it perched on the jack and with a block of wood between the jack and the trans pan.

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The IROC Homepage
<A HREF="http://www.rit.edu/~jli4307/camaro" TARGET=_blank>
View the restoration of an 85 IROC</A>
"I didn't know a bored out Ford could go so slow" -Shenandoah

 

its really not that bad of a job, the worst thing for me is, i dont have a garage i can use, and i have a gravel driveway, so i gotta get a friend or two and get the tranny out by hand.. heheh you really dont need to drop the oil pan? hrmm never paid that much attention..

 

I think my rear main must be leaking too, then. It drips overnight, and after I stop the car after driving for a while, there is a white smoke rising from underneath the engine, and it smells like burning oil. Could the oil be leaking out of the rear main, and onto the exhaust? Thanks guys.

 

83Z28: The oil can drip on the ex. pipe from the rear main seal, alot of times it will spread on the pipe while driving.

If yours is the original engine (1983) you would have to pull the motor to do your rear main seal. (its not a one piece seal)

Some people do it in chassis but to me its just easier to pull the motor.

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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

GO #3

 

what about a 1958 chevy car, would i need to pull the motor to replace the seal???

 

Hell yeah!

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92 Z28 L98 350
---------------
Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires...

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

 

I think it might not be the rear main seal after all. I checked for oil spots under the car and it turned out that the only spot was under the oil filter. I have checked the filter and it is tight, so I think it could be the filter body or something.

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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

 

Are you sure its the rear main? I had a bad leak myself and the oil pressure was wishy washy, it ended up being a 35 dollar oil pressure sensor. 1/2 hour labour no leak, good pressure.

hopefully this is your problem, if not good luck man

 

Dude, I'm keeping my fingers crossed - let's hope it's not the rear main seal. getting under this gaddamed car is such a major hassle I swear. Did your car go through oil the same way mine's going. I guess my oil is completely replaced every month or so.

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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

 

engineboy, centerbolt valve covers = one peice main seal, right? i forget centerbolts came out in late 86 with the new heads didnt they?

 

That SHOULD apply.

Run your casting numbers to make sure that someone didn't swap short blocks before you had it.
www.mortec.com

You can look up behind the flexplate at the rear of the crankshaft, if you see the aluminum piece that the seal is in then its a one piece. If all you see is rear main bearing cap, its a 2 piece.
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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

GO #3

[This message has been edited by Engineboy (edited October 03, 2000).]

 

YES!!! It is the oil pressure sending unit that's been leaking. I pulled off the plastic inspection cover for the bellhousing yesterday to check if the there was any oil on the TC or the engine backplate - absolutely dry, not a trace of oil. Looked up at the oil pressure sending unit and there's oil all over the place. I'll have to get the underbody steamed cleaned or something to remove the oil buildup from it. I can't touch anything on it without getting up to my elbows in oil.

A couple of questions about the sending unit: Does it actually go bad and start leaking or could it be just loose? If it has gone bad, how much will a replacement cost and what size wrench do I need to pull the sucker off?

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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

 

The sending unit is like 20-25 bucks or from Pep Boys (Borg-Warner unit). To get it off you can either buy a oil sending unit socket... OR use a pair of vice grips to grip it and unscrew it. Also a Crescent wrench with a wide gap will work.

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92 Z28 L98 350
---------------
Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires...

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

 

I got the sending unit but I'm a bit confused about this . The unit that was on my car is the same thing that Autozone has listed as a sending unit for the oil warning light. But my sending unit worked fine with my gauge. The sending unit for an oil pressure gauge looked like a small fuel filter. The threads weren't the right size to fit on my motor, and the connector was a single slip on style tab, not the weatherpak connector in my wiring harness. Naturally I didn't get that one. Instead I got an exact replacement for the unit that came off my car. It cost $8.99, compared to the other one, which was for $15.99.

This one that I have now looks like most other temperature sensors on our cars except that it has small hole at the threaded end for the oil. Tell me its the right one. I don't want to have a pressure gauge giving me readings from a stupid idiot light sending unit, especially since the other won't fit anyway.

Another thing - There was oil all over the areas of the block surrounding the sending unit. If I discover later that it wasn't infact the sending unit that was leaking then what other places should I look for? The oil filter for one, although I know it doesn't leak. It possibly couldn't be oil leaking from the head gasket. If there was a leak there wouldn't it cause typical head gasket failure problems like water in the oil, and oily coolant? What about the AIR system plumbing - does it carry any oil?

The reason I'm thinking it might not be the sending unit is because I noticed a lot of oil on the wiring harness that passes over the sending unit. It could be oil sprayed out of the sending unit, but that sounds kind of far fetched to me. Whadya guys think?
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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

[This message has been edited by 88irocz28 (edited October 07, 2000).]

 

if it isnt the oil sending unit it is most likely your intake gasket which is a pain to change...i just went thru the exact same problem and it was my intake gasket leaking..and to answer your question about the air tubes they Do Not carry oil through them....hope this helps

 

Alot of times the oil leaks through the electrical plug end of the sending unit.

This will cause the oil to "creep" up the wires. Sometimes it will go up/in the harness for a couple of inches.

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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

GO #3

 

there are two sending units.. one is for the gauge (big canister) the other is a switch (what you need to replace), next time your in, if they dont know what your talking about (typical autozone or pepboys), just teel them cornballs you need the switch for a light.. its the same part.. the wrench head on it isnt a standard hex so you will need a oil pressure sending unit socket or good vise grips, or even a small pipe wrench will work..

 

I think the leak is finally gone . I drove about 200 miles this weekend, and the oil is exactly where it should be - at the full mark. There was some oil coating the rear bumper but i think that's from the residual crap left on the underbody. I guess it'll take some time to get the stuff off. Thanks for all the help guys . Where would I be without this site?

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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

 

I own an 87 camaro sport coupe with the 305-4bbl (LG4 - I think) I've got an oil leak and I suspect it's the oil pressure sensor, but can't seam to locate it. Can describe where it's located?

 

When I want to see where a leak comes from, I thoroughly clean the area with a hot pressure washer. A "coin-op" pressure washer will work too, it'll just take longer (not as hot, less pressure). When I'm done, the engine and all wires will be completely free from oil.

Be careful not to get the distributor wet or carburator (if you have a carb). If you're not sure if something will get wet, just wrap it in plastic.

Then just keep an eye on it to see where the oil starts to form.

 

gbledsoe,

The oil pressure switch is on the oil filter mounting flange, while the oil pressure sending unit is mounted right behind the distributor cap at an angle. The switch has a waterproof weatherpak connector, and the sending unit has a single blade type connector. This is on a LB9 305 TPI but it should be the same on your LG4 too.

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'88 IROC 305 TPI
Crappy 700R4 slushbox
Gutted airboxes
180 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel (gotta luv it)
Ram-air setup coming soon
Flowmaster muffler (puke)
Taylor SpiroPro wires
Accel cap and rotor
Ported plenum
Throttle body bypass
Kills: '94 Z28, Olds Aurora V8, bunch of Mustangs, T-birds, ricers, and others who assumed a 12 year-old car would be too slow.

 

Just did this today on my 1987 5.7l while the trans was out. I didnt touch the oil pan nor did I take the aluminum housing that the seal sits in, off. I drilled a small hole in the center of the seal, screwed in a drywall screw, used the claw of a hammer to pull it out with ease. I Lubed up the new seal insides, started it in the housing at an angle to be sure the inner lip was not folded over and seated on the crank properly, then worked the inner lip over the rest of the crank by hand. It took very little force to just guide the lip over the crank while you push gently. Once the seal was all the way over the crank I used the old seal and the hammer to tap it into place. Took like 15 minutes total and that was because I was going slow, being very careful.