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Old 04-10-2001, 09:55 AM
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Join Date: May 1999
Posts: 11
My mechanic checked the cylinder compression pressures in my '81 300D yesterday. The pressures were: #1=19, #2=23, #3=20, #4=20, #5=23. Pressures are in bars or kg/sq. cm. The pressure are reportedly supposed to be in the range of 24.4 to 30.6 bars. The mechanic said this will cause poor fuel efficiency and some oil burn. However, the car always gets 26-27 mpg, even with a lot of city driving. It does burn some oil but no more than the specs say it should burn normally. He says I need an overhaul ($4,000 so out of the question for me.) I haven't checked on rebuilt or salvage engines. Might do that or I might just continue as is. I haven't really had any problems accept smoke when I floor it and low acceleration which I thought was normal. It does seem to vibrate quite a bit which is what led us to the compression testing. The interior and body are in excellent condition. The odometer reads 93,000; I've had the car 3 years. Any thoughts or advice on what to do would be much appreciated.
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Old 04-10-2001, 11:45 AM
goldenbear's Avatar
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Join Date: Mar 2001
Location: NorCal
Posts: 442
What were the symptoms that lead you to having the compression checked? The car has very low miles to require an overhaul, and the fact that you state that the car runs well and still maintains good mileage would support that theory. I have heard others speak of experiences of faulty compression checks, so you may be interested in taking the vehicle someplace else for a second opinion. Or, just drive it and be happy.

'04 ML500 - 53k, Inspiration Edition, Desert Silver
'11 Audi A4 Avant - Brilliant Black
'87 300SDL sold
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Old 04-10-2001, 01:07 PM
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Join Date: May 1999
Posts: 11
I like the "don't worry, be happy" route. I wondered about a faulty pressure check, too. Originally I asked the mechanic to check out a vibration I have in 3rd gear. He came back and said the engine was sounding bad and worse than it had on previous visits so he was afraid I was in serious trouble. Thus, the compression tests. The fuel economy rating is 19 - 26 mpg, so it couldn't do much better than the 26-27 I'm getting now. If anyone else has any thoughts please let me know. It's an old car but I hope to keep it going as long as possible.
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Old 04-10-2001, 04:44 PM
Join Date: Aug 2000
Location: Holland, MI
Posts: 1,316
Check through previous threads. A common theme is that if a diesel has enough compression, it will start. If it doesn't it won't. Before considering a rebuild, or replacement, have the compression checked again AND be sure you can't live with the engine the way it runs now.

BCingU, Jim
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Old 04-10-2001, 07:39 PM
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Join Date: May 2000
Location: Soperton, Ga. USA
Posts: 11,877
du I would drive it and not

worry about a rebuild until about 400k miles (as long as you do what is right in regards to oil changes). I recently purchased a 1985 300D with 218k miles and it starts and runs great. I replaced the timing chain and the first thing I did after that was put it up to 95 on the interstate. The engine runs out great at around 4k rpm (I was scared to do this not knowing the history of the timing chain). Don't spend the $ on the rebuild and get another mechanic to give you a second opinion if you still have doubts. The key thing (I think) is to look at the differences between the cylinders) and not necessarily the numbers.
'85 300D
'95 E320
'97 CRV
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