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Oil Leak

twiget

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About two weeks ago I was going to make a trip to the local drag strip. In preperation for the foray, I gave my GS a once over to make sure everything was good. I found she was about a quart low on oil, and that it looked like it was about 7k miles old. I changed the oil back in February, and have put maybe 2-2.5k miles on her since.

Today was my first chance to put her up on jack stands and do an oil change. That was pretty uneventfull, but I did find the leak. It appears to be comming from the front of the oil pan, as the crossmember right below it is caked in oil, as is the front of the pan.

According to my Chiltons manual, to get the oil pan off, I need to pull the left cat, the starter, and the flywheel cover. Is there anything else I should know? How hard is it to pull the cat? Are there gaskets I need to replace for that too?

And speaking of gaskets, what do you guys recommend for the oil pan? And what kind of sealant for the gaskets?

Now to the condition of the oil, would sitting in the car for 5 months cause it to degrade like that? Previous to February, I did an oil change in early October, right before I put her in storage. The February oil change was nice and clean. And now that I'm thinking about it, she did backfire on me about 6-8 weeks ago.

A lot of you guys have much more experience in this than I do, so what do you suggest I do to hunt down the problem?

Thanks
Jason
 
M

macz28cam

Guest
same oil leak problem

It seem that this is a common problem but no one has the balls to talk about it. I have the same situation with my CE LT-4. It seems to be a complicated matter on fixing this problem on the account of the engine having to be raised FROM THE TOP ONLY!!! After that, the problem is easy to fix....
 

Rob

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This is the first I've heard about it. Is this a common problem with LT4 engines?
 

twiget

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Rob, so far as I know, my GS is the only one I've heard of that has had a leak in this particular area. I've heard of leaks in other spots though.

Oh, and I forgot to mention, she was a little low on power steering fluid. Is there any prefered kind, or are they all pretty much the same?

Jason
 
M

macz28cam

Guest
oil leak

I would pull out my factory service manual to verify if the Chilton manual is correct if I were you just to safe. I've owned my CE for 2 yrs now and I have yet to find the correct service procedures in the engine bay to be anything but straight foward out of the Chilton manual. I have one and I will go thru it tomorrow. If you need any particular pages, I'll gladly fax them to you.

First things first, clean the area throughly of oil, then add some leak detector. I found out from several LT-4 owners and 2 local area dealers that there was a problem with the intake manifolds, the front engine cover and the oil pan leaking. Since the first two areas are a pain to work with, I will definitely try the leak detector first to find the leak. I'm heading to PEP Boys this weekend...keep me informed....
 
D

drdupa

Guest
How did you make out with your oil leak? Did you find out where it's coming from?
My LT-4 also leaks, I only have 16000 miles on it.
 
V

vettepilot

Guest
Before you go pulling everything apart, check for a few obvious things first... Check the torque on the oil pan screws, with time, the gasket material does compress and shrink slightly, this causes a loss in the torque of the screws, and a place for the oil to begin seeping. Over time it gets worse, but a "snug-up" of those screws will increase the life of the current seals around the oil pan considerably. AFTER you retorque those oil pan fasteners, then wash the underside to remove the buildup, and keep an eye on it for a few weeks. Don't high pressure it until you do the retorque, if they have lost their torque, you may push the dirt and water into the pan, that's why you should re-torque first.
The Chevrolet engines have always needed a retorque to the oil pan and rocker arm covers since cars had dirt floors. Most people don't bother because it doesn't show up for a couple of years, or about 20 - 30 K miles. It's very inexpensive preventative maintenance to check them at about the 5000 - 6000 mile mark when new. Don't overtighten though, this will cause a leak from overcompression of the gasket material.
The other known area prone to seepage/leaks is the intake manifold front and rear end seals. Occasionaly they are not seated correctly and of course we have that old enemy of time to deal with too.
One other area to check is the front seal in the timing chain cover, these can begin seeping and it moves down onto the front of the oil pan, dirt and grime builds up and it looks like it is coming from the oil pan.
Good luck!
vettepilot
 
Joined
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It is common .........very common for synthetic to turn black after a short time............I also have a rear main that's started drippin'....after I had some mods done........
ernaehrung001.gif
 

twiget

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I dont know about you guys, but I find it almost impossible to put my 'Vette in the garage for an extended period of time durring the summer. It's a good thing I didnt too, as I've only got 2 gears in my truck now (it's a TH350 tranny, went out of warranty about 15 years ago:(). That being the case, I have not permanately fixed the problem, yet. I've been nursing her though the summer. No heavy driving, just crusing around, maybe an occasional smoking tire incident:) but nothing extended. And I've payed close attention to the oil level, the leak is still there, but it's not getting any bigger.

I did put her up on jack stands to more closely locate the leak. I was able to determine that the leak is not comming from the oil pan as suspected. After talking to some other people, I think the leak is the teflon gasket at the hub of the crank shaft, under the timing cover. Or possibly the driveshaft that goes to the opti-spark.

I'll know more next month when I put her up for the winter. Would it be a good idea to change the opti-spark out while I'm in there? She's got a little under 84k on the clock, and has back-fired on me once all ready...

And any recomendations on an electric water pump? Hopefully I can free up some hp while I'm in there.:)

Jason
 

cntrhub

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Miss my '62 & '80 4- Sp. Vettes
Use a good grease cutter, like brake cleaner. I would spray right at the opti-spark area and let the cleaner wash down the oil that has accumulated. The seal on the opti-spark will begin leaking as soon as you pull out of the driveway. That's how fast these leak, and maybe why you lost all that oil so quickly? There is a special tapered seal installer for the opti-spark seal. They are a bear to install if you don't have the Kent-Moore tool.
Let's not jump ahead here. Clean the opti-spark area, light up the car and literally watch the oil leak out of that seal. This is just a guess on my part and I would chase this area before looking at the crank seal.
Remember, "the higher up you look" for a leak, the better chance you may find the real cause. Begin there.
 
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none right now :(
well, my LT4 leaks too... Oil is all over the bottom of the car, and of course, I can't tell where the heck it is coming from... I am going to try to degrease everything this weekend and go from there... Also, I can smell the oil burning off the exhaust... it is starting to stink... this problem sounds common, and a real PITA!!!
 
D

drdupa

Guest
oil leak

How are you able to get look at the cam seal while the engine is running. It seems to me that in order to get a good look at this seal one must remove the distributor. I am able to look at the crank seal as well as the water pump seal with a mirror. I can tell that there are no leaks coming from these areas. This leaves only the distributor seal, front cover seal, or intake manifold. I forgot to tell you guys that I did replace the oil pan gasket only to find oil still running down along side of the front cover and collecting on the bottom lip of the oil pan. This gives the appearance that the pan is leaking. This will be my winter project, however I am getting too old for this stuff. I don't mind paying to get this work done, but it seem that those that know what they are doing are far and few in between. I'll take my time and do it right. I can also screw it up same as the next guy.
 

cntrhub

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North Hollywood, Ca.
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Miss my '62 & '80 4- Sp. Vettes
Again, clean any oil from said areas. Go to the food or drug store and buy a small aerosol can of foot powder. Spray the questioned area at these mating areas. If there is a leak, you will see the oil over the white foot spray. If you spray an area across a wide part of the motor, you may catch the line of oil dripping down before it widens or is blown by moving air.
You are not really looking at the cam seal (in a disassembled mode) in a matter of speaking. What you are looking for, is the vertical direction of the leak. If you know that a seal is directly above the leak, (by design) there is a good chance this is it? Now, you have to determine if the seal housing is machined too wide and the oil leak has just enough pressure to leak out between the seal and the housing. Or, if the shaft that the seal contacts, is worn (tapered groove) and is seeping out of the shaft's seal?
If the exhaust pipe is burning oil caused by a leak, it's most likely the distributor gasket (older cars) or the intake manifold at the rear (most V8's). Take a wad of paper towels, wipe the rear manifold as low as you can go. If it comes up wet, it might be either of the two? If there is a distributor, wipe the area just below the Dist. housing. If it's wet there and dry at the intake sides....it's the paper gasket at the Dist. Or, take a mirror and look also. Sometimes there is hardly any room to angle the mirror or something is usually in the way. If there is no distributor at the manifold, it is most likely the intake manifold.
The best sealer for intake manifolds (in my opinion) is still Goodwrench RTV Silicone Rubber Sealant.
 
M

macz28cam

Guest
I think I fixed the oil leak..

Well, I finally had time to get under the car. The bottom of the car was covered with oil everywhere. I searched all over the car and found NO leak from the top portion of the engine. Since the majority of the oil was on the bottom, It must have been the oil pan gasket. I went to the dealer, bought the oil pan kit and 3 1/2 hours later.. 30min to r/r the pan and gasket and other accessories and 3hour of cleaning the bottom of the engine compartment and suspension crossmember (so I'm anal about a clean vette). I took an all day road trip to Palm Springs and a 160mph blast on a back road on the way home and so far no leaks. I'll keep checking in the future...
 
Joined
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290
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Michigan
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96' LT4
One thing you guys might want to consider ....................is to find out via ..........GM Bowling Green...........who is the Guru ...(the one guy corvette owners flock to for service)....chevrolet corvette specialist in your geographical area...............A friend of mine in Michigan is one of these guru types at about 5'1 and a 140#'s ..............works on everything from 53 to current.........funny thing .........the dealership couldn't sell a boat in a flood...........just the reverse of most........enough rant........
He knew about the various leaks.........multiple pages of them..............tech bulletins galore.........so the corvette specialist in or near your home town.........might actually be a good thing ... I've had the intake leak repaired on my 93 40th..............it was very common on the LT-1's.........The Lt-4 has been leaking just a wee bit...........for about 2 years.........at the rear (looks like a rear main). Unless.... you like to ..and have the means to........work on your car.............tracking down the leaks ought to start w/ the tech bulletins at the dealership......IMHO
ernaehrung001.gif
 

96CERon

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Sep 15, 2002
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CE 1996
I have the oil leak also in my CE--I can see that the crak position sensor is wet. With this info does any one think it is coming from the distributor seal--allready tightned the pan bolts.
 
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Could you try to be a little more descriptive........
 
J

jimhart

Guest
LT4 Oil Leak

I fixed the intake manifold leak in my 1996 LT4 about 6 months ago. It was leaking from the front and rear valley cover seals. The interesting thing was the manifold bolts were about hand tight. There was evidence that very little sealant was used on the bolts. The engine had about 28k miles and has never been apart. It was reassembled using the correct valley and bolt sealant. It remains tight as a drum.
 

CKA_Racing

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Jan 5, 2003
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Steve's Driveway in Manassas
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1996 CE LT4 Power Effects with stock resonator.
I have or had all the leaks described above. I fix the intake leak at 75,000 miles on my own. That cured the huge amounts of oil seen under there car, like on the oil pan, exhaust, front cross member. I still have small leaks coming from the very front of the oil pan. As mentioned above, it may be the oil pan seal, timing cover seal, crank shaft seal.

On the issue with the oil getting dirty quickly. I would check your spark plugs for sure. The little puck falls off the stock plugs often enough regardless of mileage. That changes the gap to .62 from the stock .50. Not good. You may not really notice the slightly less power at all or backfires.
 

96CERon

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Sep 15, 2002
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Phoenix
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CE 1996
My small oil leak is still there--obviously since I've done nothing other than keep it clean underneath every two weeks. It still appears to be coming from one of the seals above the front of the the pan. No leaks from the valley areas either front or rear.

I eventually found what I thought was the serpentine belt noise that I thougt was the culprit for the squacking noise I heard every time I turned. Changed the belt didn't help. Much to my embarrasement is was the positraction clutches. Changed the oil and put in the GM additive and presto no more noise.
 

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