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  #1  
Old 12-05-2009, 04:12 PM
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Compression test results, OM602.962 (300D 2,5 Turbo) 1992

Car has near 400k mi. I took a compression test through the injector ports. Engine was real cold, like 30F, so I plugged in the block heater for 1h inside garage before doing the test.

I have obtained 265-280 psi after 5 strokes on all 5 cylinders.

The car had problems to start with dropping temperatures recently (glow plugs are Ok). I sent all injectors to a shop and had them tested. Two of them were in bad shape (leaking and poor spray pattern).

They are now fitted with new nozzles (Bosch) and have been properly calibrated.

I'll post how the engine behaves when I get the car back next week.

Bye,

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'98 E300 Turbodiesel 244 000km
RIP '92 300D 2,5 Turbo 632 859,4km due to engine failure
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Old 12-06-2009, 12:14 AM
92 300D 2.5L OBK #59
 
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According to my data minimum compression pressure is 261 psi (18 bar). Normal is 377-464 psi (26-32 bar). Max variation between cylinders is 44 psi (3 Bar)
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Old 12-06-2009, 12:38 AM
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The FSM outlines the procedure for obtaining accurate cylinder compression data, the first line of the procedure states:

1. Warm engine up to operating temperature (approx. 80 C) Note Check compression only with engine at operating temperature.

Additionally:

6. Crank engine a number of times with starter with transmission in neutral and shutoff lever on the injection pump pressed to "stop" to remove combustion residues in the precombustion chamber of the cylinder.

8. Crank engine at least 8 revolutions to test compression.

You may want to conduct another test according to the recommended procedures before drawing any mistaken conclusions on data which is the result of incorrect testing procedures. Good luck!
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Old 12-06-2009, 03:45 AM
compress ignite's Avatar
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Not Enough (Hot) Revolutions

X2

Ben , I think your engine is MUCH healthier than you think!
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Old 12-06-2009, 11:41 AM
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Quote:
Originally Posted by compress ignite View Post
X2

Ben , I think your engine is MUCH healthier than you think!
I'm not too worried about the values I obtained. I stated the exact conditions I had (temperature, No. of cranks, etc.) because I knew it was not optimal nor as per FSM procedures. But I was afraid that if I had reinstalled the new injectors, started the engine to warm it up and found out it ran perfectly, I would not have removed them just to take compression readings. I'm always a little squeezed with time!

I am nevertheless quite happy with the little variation between cylinders. We'll see how it goes when I fire it up!

Thanks,
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'98 E300 Turbodiesel 244 000km
RIP '92 300D 2,5 Turbo 632 859,4km due to engine failure
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Old 12-18-2009, 12:03 AM
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The engine starts really well now. Has been sitting outside, unplugged by -20C (0F) today and still started really well. I am impressed!

But I still have an issue about sudden loss of power (boost drops suddenly), and bad idle.

I have done the modification to use a pressure actuated wastegate instead of the original vacuum type.

I suspect the used wastegate I installed may be the problem, or I have an issue with the ALDA, which I never removed myself.

And just thinking about it now: could be a good time to check injection timing and get an idea about timing chain stretch and wear...

I need to look into these issues.

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'98 E300 Turbodiesel 244 000km
RIP '92 300D 2,5 Turbo 632 859,4km due to engine failure
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