I recently purchased a retired police car - a 1995 Chevrolet Caprice with 109,000 miles. Oil pressure is good at all times, vacuum is a steady 18" at idle. Oil loss (consumption) is about 1 qt/1400 miles. I recently had a bad engine miss which got steadily worse. I changed the plugs and wires and found that the #8 cylinder (passenger side near the firewall) spark plug electrode was a blob of oily goo. All of the other plugs were fine. Changing the plugs solved the miss, but I obviously have a problem in that cylinder. That cylinder is near the breather in the valve cover, and I've noticed a fair amount of oil on the valve cover and the breather. I am beginning to think that the oil return in that cylinder head has sludged up, restricting the return flow of oil from the head which is then getting sucked into the cylinder. Before I pull the valve cover, I was wondering if there is anything else I could do to pinpoint my diagnosis, and if it holds, what I could do, like auto-rx, to clean up the oil return without pulling off the valve cover.
Oil fouled plug, '95 LT1 Caprice
- Thread starter raftel
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If the heads could not drain then you would have more than one problem cylinder.
I suggest a new valve seal on the affected cyl at the least. I'd do them all since I had the cover off anyway. They are easy to change with a good aircompressor and a hand held spring compressor.
I suggest a new valve seal on the affected cyl at the least. I'd do them all since I had the cover off anyway. They are easy to change with a good aircompressor and a hand held spring compressor.
You are on the wrong board for this try impalassforum.com . Basically you have acommon problem, the intake manifold got loose and you have an into the lifter valley vacuum leak. I have a bigger cam in my 96 Caprice and still pull 17+ inches, yours should pull more like 21". Time for a new inake manifold gasket. The reason it goes bad there is the heat from the EGR.
Oh and on the LT1 you do not need compressed air, if you bring the cylinder to TDC the valves only fall a short distance before hitting the piston, leaves plenty of room to get the locks in and out, but I wouldn't bother with the seals at this time. They were a good guess, but this is a particular LT1 issue with the gasket.
On that other forum I linked to I go by 96capriceMGR, see you there.
On that other forum I linked to I go by 96capriceMGR, see you there.
This is very, very interesting. I had a '79 Caprice with the 305 with the EXACT SAME symptoms. It eventually got so bad that the car was more like a fogging machine and I junked it. Could that have been the same problem? I thought the rings were failing.
Man, the things I did to that car. I was definitely young and stupid back then. I might still be driving it, knowing then what I do now. The one thing about that car, though, it started first time, every time, usually in under a second until the bitter end.
Man, the things I did to that car. I was definitely young and stupid back then. I might still be driving it, knowing then what I do now. The one thing about that car, though, it started first time, every time, usually in under a second until the bitter end.
yep 20+" of vaccuum in an Lt-1 would be normal (non-vibrating needle), these motors have continuous Intake manifold gasket leaks, a good DITY 1/2 day job to remove/clean up/replace...your plug change will probably take longer!
Come on the plugs aren't that bad.
Seriously though raftel, even if you do not join that forum and just read there it is a wonderful resource for 94-96 Caprice/Impala/Roadmaster/Fleetwood, and much of it even applies further back. There are a lot of fast cars there and I have talked to a few newbies that found some of the hardcore tech hard to wade through, but we have tried to put together a few comprehensive threads on all the basic repair parts complete with sources for GM parts at often half of dealer list. Anything model specific you need is there and if you are not that mechanically inclined I bet there is even someone who could recommend a shop near you that is "gearhead approved".
Seriously though raftel, even if you do not join that forum and just read there it is a wonderful resource for 94-96 Caprice/Impala/Roadmaster/Fleetwood, and much of it even applies further back. There are a lot of fast cars there and I have talked to a few newbies that found some of the hardcore tech hard to wade through, but we have tried to put together a few comprehensive threads on all the basic repair parts complete with sources for GM parts at often half of dealer list. Anything model specific you need is there and if you are not that mechanically inclined I bet there is even someone who could recommend a shop near you that is "gearhead approved".
Thanks everyone, and especially DJ. I already go through the Impala SS forums, and have posted there before, but I thought I'd pose this question here.
I think I was led down the clogged oil drain path by an experience I had with my previous car - a '83 Olds Custom Cruiser with a 307 V8. I got it for next to nothing because it smoked heavily and got 300 miles to the quart of oil. After replacing the valve seals, I found that oil was pooling up in the cylinder heads because the returns were blocked. After I cleaned them out with a pipe brush, oil consumption went down to nothing.
Looking at my Chevy more closely, I'd have to say the rear of the engine is fairly dirty (not too bad for the age/mileage tho), concentrating more on the passenger side rear - right where the EGR pipe goes in. I've gone to the Impala forums and found some good links on the repair procedure, but I still have some questions. Given a consumption rate of 1qt/1400 miles, how much time to I have, and how much damage am I doing? Could I try simply retorquing the manifold bolts, as some have suggested as a stopgap measure? And finally, I've already done the throttle body coolant bypass - does any coolant flow through the intake that I will have to worry about by draining off some coolant? Finally, as long as the intake is going to come off, what other maintainance/modifications should I look into? Thanks!
DJ, I'll look you up on the Impala forum - thanks again.
I think I was led down the clogged oil drain path by an experience I had with my previous car - a '83 Olds Custom Cruiser with a 307 V8. I got it for next to nothing because it smoked heavily and got 300 miles to the quart of oil. After replacing the valve seals, I found that oil was pooling up in the cylinder heads because the returns were blocked. After I cleaned them out with a pipe brush, oil consumption went down to nothing.
Looking at my Chevy more closely, I'd have to say the rear of the engine is fairly dirty (not too bad for the age/mileage tho), concentrating more on the passenger side rear - right where the EGR pipe goes in. I've gone to the Impala forums and found some good links on the repair procedure, but I still have some questions. Given a consumption rate of 1qt/1400 miles, how much time to I have, and how much damage am I doing? Could I try simply retorquing the manifold bolts, as some have suggested as a stopgap measure? And finally, I've already done the throttle body coolant bypass - does any coolant flow through the intake that I will have to worry about by draining off some coolant? Finally, as long as the intake is going to come off, what other maintainance/modifications should I look into? Thanks!
DJ, I'll look you up on the Impala forum - thanks again.
You can try retorqueing it can't hurt anything and might just help.
There is no coolant in the intake, the only place you would have had to worry about it was the TB.
Burning oil like that will obviously foul that plug and will also foul that side O2 sensor and ruin the cat if left long enough, couldn't guess on a timeframe.
Given the lack of coolant up there the intake is a fairly easy job, I couldn't take a guess at the time because the only time I pulled it was for a cam swap so I was going in a tad further, Jeff's guess would probably be a little on the long side if anything and it is always better to budget more time than you think you really need.
On the related part question, a new EGR valve would be a good idea, might check yours first but they are somewhat failure prone, don't forget a TB gasket. You could get by without but consider getting a fuel line disconnect tool, that way you can get the fuel rail out of the way, otherwise you could tie it up somehow. Depending on how well maintained the car was and your budget/willingness to spend money on an old car you might consider injector cleaning, while the car is apart you could drop the injectors off for disassembly and cleaning(if there is a local place) or better yet but more expensive have a Motorvac service performed after that would clean more than just the injectors.
There is no coolant in the intake, the only place you would have had to worry about it was the TB.
Burning oil like that will obviously foul that plug and will also foul that side O2 sensor and ruin the cat if left long enough, couldn't guess on a timeframe.
Given the lack of coolant up there the intake is a fairly easy job, I couldn't take a guess at the time because the only time I pulled it was for a cam swap so I was going in a tad further, Jeff's guess would probably be a little on the long side if anything and it is always better to budget more time than you think you really need.
On the related part question, a new EGR valve would be a good idea, might check yours first but they are somewhat failure prone, don't forget a TB gasket. You could get by without but consider getting a fuel line disconnect tool, that way you can get the fuel rail out of the way, otherwise you could tie it up somehow. Depending on how well maintained the car was and your budget/willingness to spend money on an old car you might consider injector cleaning, while the car is apart you could drop the injectors off for disassembly and cleaning(if there is a local place) or better yet but more expensive have a Motorvac service performed after that would clean more than just the injectors.
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