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Old 09-07-2014, 11:05 PM
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Join Date: Sep 2014
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617.912 compression results, any input ?

So i did a compression test on my 1978 300d. Cold engine.
Results on psi

Done thru the injectors. I would like to know if this is good or bad.
Before it i did change the transmission filter, the person who did it before marked the filter. As 8/1993 lol, so it wasn't change for 21 years.... Idk how many miles the car has because it resets every 99,999 miles.....

I guess i can check the valves next. Anyone can help with their cold engine results ?

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Old 09-08-2014, 12:36 AM
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Those are on the low end of required compression. Time to begin thinking about a rebuild or engine change.
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
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Old 09-08-2014, 02:30 AM
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Not horrible, but not exactly great either. If valve adjustment hasn't been done on time you may see improvement from that. Depending on the results of a compression test after a valve adjustment, this engine may be anywhere from "healthy" to "run it until it won't start and rebuild/replace".
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 367,xxx miles
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Old 09-08-2014, 03:15 AM
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If it hasn't been used much recently I'd change the engine oil and drive it for a bit. A re-test might give you some more comforting numbers...

...but if it is working just service it and use it - don't look for trouble 'cos if you do it usually finds you!
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
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I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior

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Old 09-08-2014, 08:41 AM
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Location: Matthews, NC
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If you go in to adjust the valves, also check the cam timing. That can also lower all the readings.

Paul M

84 500 SEL (307,xxx miles)
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