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Old 01-01-2010, 06:34 PM
Dovetail Dovetail is offline
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Join Date: Mar 2008
Posts: 9
Compression interpretation/ bad exhaust smoke and blowby

Hello all:
I have a 1980 300SD with 210,000 on it. It was previously owned by my cousin (since 1982), and was his daily driver until about 10 years ago. He meticulously cared for it up until that point, however his mechanic, although a popular independent mechanic in the Pasadena, CA area, is not someone who I would take my car to. They used 20/50 wt Pennzoil, which was regularly changed. Over the last 10 years this has been his second car, and approximately 10,000 miles were put on it over that time period, as well as run on homemade biodiesel (made by his mechanic). The maintenance was benign neglect. His wife started it oneday and it went into runaway (not traveling, but while in park). She had to call the fire dept who stopped it by blocking the turbo intake. After that the car was gladly given to me. His mechanic thought it was the fuel injector pump (stuck fuel rail), and had it partially dismantled. I found a good used injector pump, swapped it out, and got the car running. 6 degrees of off timing was noted so I rolled a new chain in. It now runs very nicely, however has a loud knock when cold (always had this), and despite new injector nozzles, still has the knock which goes away when warm. However, the most obnoxious thing is that it smokes really bad, and has significant blow-by. It is a little slower than other turbo diesels I have had, but still has respectable off the line speed and power under load (when warm). Before I put any more effort into this I figured I should check the compression. The readings I got were:

27
23
27
27
27

So the question is, is the 4 bar difference significant? Could that be the origin of the smoking grayish exhaust? The blow-by? By the way, despite several tanks of diesel the exhaust still smells like McDonalds. Do you think more time and money should be invested? I am thinking I will see if new valve stem seals will help, but I hate to invest much in it if I can not get rid of the smokey exhaust. Any comments would be appreciated,
Will
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