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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: nativetexan on September 03, 2010, 10:59:03 pm

Title: Oil leak
Post by: nativetexan on September 03, 2010, 10:59:03 pm
Okay, so as I have let it run and drove it around the block a couple of times, I noticed that it has a few oil spots. I can see oil around the starter [dripping slow] and the flywheel cover plate. Where could this be coming from beside the obvious, rear main? Any ideas?
Title: Oil leak
Post by: Lt.Del on September 03, 2010, 11:42:53 pm
remove flywheel dust cover.  take a rag and clean off all oil.   Let idle and see exactly where it comes from.  It could be oil pan gasket, but, if it is coming from flywheel/rear pan area, I bet it is the rear main. 
Title: Oil leak
Post by: nativetexan on September 04, 2010, 01:38:38 am
Dang it ! say it aint so!!! I'll check it.
Title: Oil leak
Post by: Irish_Alley on September 04, 2010, 03:23:46 am
Dang it ! say it aint so!!! I'll check it.
it aint so  ;)
Title: Oil leak
Post by: bobcooter on September 04, 2010, 09:11:11 pm
If the starter is getting wet, it could be the valve cover leaking at the rear near the fire wall where it's hard to see. I already had the same problem, changed out the rear seal and it still leaked. I recently put new valve cover gaskets on and no leak now.
Title: Oil leak
Post by: nativetexan on September 08, 2010, 10:45:39 pm
If the starter is getting wet, it could be the valve cover leaking at the rear near the fire wall where it's hard to see. I already had the same problem, changed out the rear seal and it still leaked. I recently put new valve cover gaskets on and no leak now.

I think it is the covers, because I got under there and saw that it was puddling up near the base of the heads at the rear of the motor. But they are new covers with new gaskets... I think I might need to torque em down a bit more. Will post my results..
Title: Oil leak
Post by: Grim 82 on September 08, 2010, 10:56:01 pm
Also it wouldn't hurt to check the back of the intake and the oil pressure sending unit back there to see if they might be leaking.
Title: Oil leak
Post by: Irish_Alley on September 08, 2010, 11:06:14 pm
If the starter is getting wet, it could be the valve cover leaking at the rear near the fire wall where it's hard to see. I already had the same problem, changed out the rear seal and it still leaked. I recently put new valve cover gaskets on and no leak now.

I think it is the covers, because I got under there and saw that it was puddling up near the base of the heads at the rear of the motor. But they are new covers with new gaskets... I think I might need to torque em down a bit more. Will post my results..
You can over tighten them
Also it wouldn't hurt to check the back of the intake and the oil pressure sending unit back there to see if they might be leaking.
I once changed my intake gaskets like 3 or 4 times couldn't fix a leak coming from the rear of my motor. Come to find out I pinched the plastic tube from the oil sending unit and put a small hole in it
Title: Oil leak
Post by: nativetexan on October 06, 2010, 02:57:30 pm
okay, update! I took my truck in for the oil leak. Twice. First they told me that the pcv was clogged causing the engine to over pressurize and push the oil out. Didnt make sense to me, but, it wasnt leaking at the time so I drove off. Took the truck back to get the exhaust redone. Picked it up took it home. Oil leaking pretty bad. (once or twice per second.) A different guy told me that it seemed to be coming from the top rear where the oil sending unit is. He didnt think it was the rear of the intake because it doesnt leak everytime the engine is on. So he said the sunding unit was leaking and I needed to replace it. Didnt make sense but, I went and got a new one. Put it in and it didnt leak...yet. Drove it around the block and it started leaking!!! I have climbed up and down this truck. Below is a picture where I can see oil puddles but not the leak. any other ideas??? Im taking it back to the shop on saturday and am going to tell the guys not to call me until they know for sure it isnt leaking. I wonder; are therre any external screws or bolts that I may have left off the heads or the block that would cause oil to leak out??

(http://img80.imageshack.us/img80/7805/cimg5481.jpg) (http://img80.imageshack.us/i/cimg5481.jpg/)

Uploaded with ImageShack.us (http://imageshack.us)
Title: Re: Oil leak
Post by: Grim 82 on October 06, 2010, 03:27:09 pm
I can't find it at the moment but there is a thread on this site somewhere where a guy had a mystery oil leak in the back and he said it turned out to be a bellhousing bolt. I think he said he filled it with RTV and put a longer bolt in. Never heard of it before or after but it's worth looking at.

Found it: http://forum.73-87chevytrucks.com/smforum/index.php?topic=9169.15
Title: Re: Oil leak
Post by: nativetexan on October 06, 2010, 07:20:15 pm
But I thought the bell housing stays dry... Right  ???

What about the distributor? It is in the area I am seeing the oil. And, I used the original and never changed the o-ring that is on the shaft. Any input on that suspicion??
Title: Re: Oil leak
Post by: Captkaos on October 07, 2010, 03:17:21 pm
have you checked the oil fitting, rear intake seal, valve covers etc?

A clogged PCV will push oil out of bad seals if you don't have a vent.
Title: Re: Oil leak
Post by: nativetexan on October 07, 2010, 06:19:32 pm
oil fitting? What is that? Is there any screw holes back there by or on the head that I might not have plugged that could cause the problem. I took the distributor out and replaced the gasket. Still leaking. Should I pursue the bellhousing bolts? That makes no sense to me... But should I? Whatever it is it is happening on both sides. I see oil coming down both sides of the motor. I don't get it! This is a remanufactured motor!?  >:( I am super frustrated right now... 
Title: Re: Oil leak
Post by: screamin86 on October 07, 2010, 07:37:41 pm
I'm having similar issues! Once we get moved into our new house I'm going to pull the truck in the garage and start investigating why mines leaking. Mine is leaking in the same areas :/
Title: Re: Oil leak
Post by: nativetexan on October 09, 2010, 09:00:16 pm
I decided to check my intake bolt torque.. Book calls it at 30lbs. I found it to be 15-20lbs. I also actually found some oil on the back right corner of the intake. These two things are prompting me to redo the intake... What do you guys think? Step in the right direction?

Also, I am wondering if it is the PCV. It is a breather with a PCV nipple on it. Similar to this one

http://www.summitracing.com/parts/SUM-G3408/ (http://www.summitracing.com/parts/SUM-G3408/)

Is this okay? I only have the PCV breather on the right front hole and a regular breather on the left back hole (behind the oil fill)



Title: Re: Oil leak
Post by: VileZambonie on October 09, 2010, 10:23:02 pm
degrease it and put dye tracer in it. Use a UZ light and yellow glasses and you'll find it. Typical leak spots are

Intake, valve covers, distributor, oil sending unit, oil pan, rear mian seal.
Title: Re: Oil leak
Post by: Irish_Alley on October 10, 2010, 12:08:56 am
The pcv is ok. most time they blow out at the rear of the intake I just redid mine two days ago cause it was leaking out faster than I could put it in and I was leaving a smoke screen behind me ::) but it seams to have fixed the problem be for I used the high temp gasket sealer(red stuff) and I did this time but when I took my intake off back passengers side didn’t have any resistance at coming off and the sealant that was on the intake was not stuck to anything just sitting there so that seams to be where mine was leaking from. Just clean it good a razor blade then with a rag with some brake cleaner on it
Title: Re: Oil leak
Post by: zimcocomp on October 20, 2010, 01:17:43 pm
Hi. I am new to the forum and I have a question about the rear main seal. I have a 1986 silverado with a 350 and it appears to need a rear seal. The problem is, when I try to get an estimate for the job it seems no one is quite sure if it is a one piece or two piece. The one piece is very expensive to replace and the two piece is much less. Anyone know of a sure fire way of telling which it may be?

Thanks
Title: Re: Oil leak
Post by: beastie_3 on October 21, 2010, 12:19:56 pm
run the block casting number.
Title: Re: Oil leak
Post by: Lt.Del on October 21, 2010, 12:42:37 pm
driver's side oil dipsitck or passenger side dipstick?
I 'believe' that the two piece rear main seals, which do not require removing the transmission, has the dipstick on driver's side.  My '79 is that way.  The 86 and up, dipstick on passenger side, has the expensive-changing one piece. 
Someone please correct me if I am wrong, but I think this is the case generally.
Title: Re: Oil leak
Post by: TexasRed on October 21, 2010, 01:42:09 pm
I think the 80's started the passenger side dipstick. My '84 two piece is like that and so are the later model ones.
Title: Re: Oil leak
Post by: beastie_3 on October 22, 2010, 01:39:39 pm
Correct on the dipstick year, 79/80, but I think the main seal changed later on.
Title: Re: Oil leak
Post by: screamin86 on October 22, 2010, 01:59:16 pm
I believe the 1pc rm started in 86 maybe 85
Title: Re: Oil leak
Post by: Lt.Del on October 22, 2010, 04:10:53 pm
86 and up one piece.
I thought the dipstick changed sides then too, but, i guess consensus shows that changed in '80.
Title: Re: Oil leak
Post by: nativetexan on November 06, 2010, 06:41:34 pm
So I re-did the intake seals, and replaced the nipple for the oil sender with one from the salvage yard and it held for a few weeks. I was under there today and, it is still leaking. oil in all the same spots. I will say it slowed down as it is not dripping, but the oil is there nonetheless. What to do. Not to mention, my current tranny issues, kinda making me wanna throw in the towel and find another one...
Title: Re: Oil leak
Post by: VileZambonie on November 06, 2010, 07:47:08 pm
Quote
degrease it and put dye tracer in it. Use a UV light and yellow glasses and you'll find it. Typical leak spots are

Intake, valve covers, distributor, oil sending unit, oil pan, rear mian seal.
Title: Re: Oil leak
Post by: nativetexan on November 06, 2010, 08:33:03 pm
Alright, Alright...  :D ;D