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Shaking engine trouble 1995 Yukon.


gbelovskiy
04-25-2004, 08:51 AM
Dear GMC users.
Please advise me what to do in the following situation:
Recently discovered that two of my car's cilinders are not good -- obviously car was overheated b4. Could not find the problem for a month after tune up was done and oil changed engine started to shake...
Think the seller put heavy oil in the engine (or lucas stabilizer) to reduce oil spreading in the head... Two of my spark plugs got completely clogged with burned oil, so I have to take them out once a month now and replace -- otherwise car is shaking very badly... Checked the compression of each of the cilinders -- good about 150. Only the oil rings on two of them not good. Previous owner has guaranteed that engine is great and he never had any problems with it... Lier. :banghead: :banghead: :banghead:

Please advise if there are any special OIL BURNING spark plugs??? If so please advise where to buy them??? Is that more dangerous to drive like that?? or more dangerous to drive on the LUCAS oil stabilizer??? How long might the car work like that??? Do I have to replace the engine & if so what is the best and cheapest PLACE TO DO THAT??? Or I have to fix just these two cilinders??? Please advise A.S.A.P. Sincerely, Greg.
I am from East Brunswick NJ ZIP 08816

usscvr
04-25-2004, 09:51 AM
Sorry guy - it sounds like you're in quite a fix (no pun intended...).

If you have low compression on two cylinders, the obvious and most complete way to correct this problem is to re-ring those cylinders. That will solve the headaches of worrying, unnecessary replacement of plugs, oil additives, etc.

I don't know that you necessarily need to replace the entire engine, although that is an option. However, re-ringing only two cylinders can cause its own set of problems, like higher compression on those two cylinders than the other 6, which may cause vibrations. The best thing to do, as most good mechanics will tell you, is that if you're going to tear down the engine for this problem, you check and replace the rings on all 8, properly checking end-gap of the rings, and honing each cylinder for proper seating of the rings, to ensure even compression across the spectrum. Going this far into the engine will also give you the chance to check your main and rod bearings, rods, oil pump & pick-up screen, and have both cylinder heads re-worked and good-to-go. This is a lot of work if you are doing it yourself, and expensive if you're paying someone to do it, but in the long run, you'll be happy you did.

gbelovskiy
04-26-2004, 07:17 PM
Thanks a lot for your kind reply. I really appreciate it! The thing is that compression on these two bad cils is about 150 as other six, however oil rings on two of them are not so great and after about 15 min plugs are clogged with burning oil! What I have done for a while is added lucas oil stabilizer and put 4+ BOSH self cleaning (150,000 miles) plugs + drain a little oil to the lowest possible level. Right now it is about 85% better and engine is shaking very very light, almost like normal 8 cyl. Do not have much money now to do the job, so I kind of stuck now with it..... One more time thank you for advice and good luck to you, Sir! Regards, Greg.

usscvr
04-27-2004, 08:24 AM
I can certainly understand the money issue, not having enough, but some things you said caught my eye that I wanted to respond to. You spoke initially about a “shaking” in your engine (presumably regarding the two suspect cylinders), then said that the compression was about the same as the other six. If compression is the same, and you still have a shaking/vibration in the engine, this is potentially indicative of another problem like timing, fouled plugs, mis-fire(s), or a number of other potential problems. You ought to check those out.

This brings me to my next point – self-cleaning plugs. They are a wonderful idea, and they actually work well in “normal” operating engines, but if you have oil leaking into the cylinders, I’m afraid the efficiency of “self-cleaning” will be shot. Self-cleaning plugs do nothing more than create a better spark inside the cylinder, which burns all/most of the fuel more efficiently, which reduces the chance of any [carbon] buildup in the cylinder. Even with a small oil leak into the cylinder(s), a better burn will reduce the chances of any build-up, but if more oil is leaking into the cylinder than can be burned by these plugs, build-up/fouling of the plug can and will occur. So “self-cleaning” can be a bit of a misnomer. However, if these plugs are working for you, then there is no reason to stop using them.

Lastly, reducing your oil level to minimum levels can be more dangerous than what you are already facing. I somewhat understand your logic here, but you face the danger of “Oil Starvation” in your engine when you reduce your oil level like you have. Oil starvation on major components can result in premature failure of a number of crucial parts, which can severely damage or destroy your engine. I would not recommend this and be VERY careful doing this. You could face much larger repairs should something go wrong. With a minimum oil level, something as simple as a fast stop, or a quick turn (like evading a slow car in front of you – or whatever) can cause the oil in the sump to shift, thus starving the oil pump of a fluid supply, and dropping your oil pressure to ZERO. This provides the potential for causing severe damage. Now, this is a worse case scenario as an example, but it can happen. I’d be very careful reducing your oil level.

It sounds like, however, that you seem to have them under control. Good luck with your problems. Just be careful.

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