oil consumption
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2nd Gear
Joined: Sep 2005
Posts: 2
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oil consumption
I recently bought an 85 with 72K on it, and soon after it started to consume A LOT of oil. Once in a while there will be a puff of smoke out of the tail pipes when I turn it over, but it's not anything major and it doesn't happen each time I start it. I did a compression check and everything seems to be fine. I do have some minor leaks under the vehicle around the master seal, but again, nothing major. Given the amount of oil I'm going through I'd expect to see a huge puddle, but that is not the case. The radiator does seem to have a bit of sludge, but I can't tell if it's oil, and again, I'd expect to see a lot of oil in there. I'm really a novice when it comes to these things, so if anyone can advise me on where to go from here I'd really appreciate the help. Oh, and can anyone tell me if they know of a good service center in the SF Bay area? Someone who really knows vettes?
Thanks
Thanks
Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
You say it's using a "lot of oil". How much are we talking about? ie...how many quarts in how many miles?
When you pulled the spark plugs out to do the compression test what did they look like? Any signs of oil fouling? If you have an oil consumption problem but the plugs are clean, it's got a leak somewhere.
Lack of blue smoke doesn't mean oil isn't being burned. An engine can burn a lot of oil and produce very little smoke.
The smoking on start up is usually valve seals and is a common problem on old SBC's.
72K is low mileage, but it all comes down to how the car has been maintained (or not maintained). At 146K, my 84 loses less than a quart between oil changes (3K intervals), and it has a slight leak. But the oil has been religiously changed since it was new. The previous owner(s) on your 85 may not have been as diligent.
Oil loss can only be attributed to 2 things.....leaks, or burning. Leaks can be internal or external. I would start by investigating the sludge in the radiator a little further, and if it turns out to be oil, then it's a matter of determining where it's coming from. Pull the radiator on your car (good time to clean the muck out from the front of it) and take it to a radiator shop to be flushed. See what comes out of it.
Good luck, let us know what you find out.
When you pulled the spark plugs out to do the compression test what did they look like? Any signs of oil fouling? If you have an oil consumption problem but the plugs are clean, it's got a leak somewhere.
Lack of blue smoke doesn't mean oil isn't being burned. An engine can burn a lot of oil and produce very little smoke.
The smoking on start up is usually valve seals and is a common problem on old SBC's.
72K is low mileage, but it all comes down to how the car has been maintained (or not maintained). At 146K, my 84 loses less than a quart between oil changes (3K intervals), and it has a slight leak. But the oil has been religiously changed since it was new. The previous owner(s) on your 85 may not have been as diligent.
Oil loss can only be attributed to 2 things.....leaks, or burning. Leaks can be internal or external. I would start by investigating the sludge in the radiator a little further, and if it turns out to be oil, then it's a matter of determining where it's coming from. Pull the radiator on your car (good time to clean the muck out from the front of it) and take it to a radiator shop to be flushed. See what comes out of it.
Good luck, let us know what you find out.
