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240D 1982 (4-Speed), Diesel Jimmy 6.2L 1983, Diesel Suburban 6.2L 1988
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31 Posts
Discussion Starter #1 (Edited)
Hi folks,
I am considering looking at a 95 E300 diesel with 170k miles.
The owner indicates that the car is sluggish when going up a steep hill (max speed of 45mph).
The car supposedly has no power/speed issue on flat terrain.
What do you think the issue can be and how do I diagnose?
Transmission issue?
Blocked oxidation catalytic converter?
Resonance Flap?
Vacuum control flap?
Thanks,
-Kevin
 

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E320/E250 Bluetec Ford F350 6.7l
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36,707 Posts
Has to be 95 as 85 had no cats, flaps and other stuff.
Those NA engines are not famous for big power and their power comes close to 5000 rpm, so what % of incline we are talking about here?
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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17,372 Posts
Had identical on my '95 diesel. Very little power. Issue was neglected fuel system and clogged oxidation catalyst.

Bypassed catalyst and replaced all 3 fuel filters which restored full power & torque.
 

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240D 1982 (4-Speed), Diesel Jimmy 6.2L 1983, Diesel Suburban 6.2L 1988
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31 Posts
Discussion Starter #5
sbaert,

I have not gone to look at the car yet.
The car is about an hour’s drive from my location and owner has been reluctant to reply to my email questions.
I am looking for information on how to diagnose if the power issue is a major or minor repair?
Oil or coolant leaking from the side of the engine would indicate a head / head gasket issue.
White smoke pouring out the tail pipe indicates fuel is not being burned. (Compression or injector issue)

How did you know your 95 only needed 3 fuel filters and catalyst bypass?

Thanks,

-Kevin
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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17,372 Posts
Upon pre-purchase inspection, the service records indicated fuel filters had not been changed in just over 10K. Actuallly, the only filter that ever got changed was the main fuel filter element (canister type). The pre-filter and in-tank strainer had never been touched. Luckily, I had very little traces of algae buildup even though the car had been sitting for most of its life.

I pulled the tank and had it chemically cleaned and replaced all 3 filters. Some improvement, but not a whole lot. A diesel purge helped, but again only incrementally. The lack of performance remained.

With the engine running, I felt for pressure at the tailpipe and it was weaker than it should be. I cut out the oxidation catalyst and substituted 2 pieces of automotive grade stainless tube. My car is smog exempt, so I was not worried about running into registration issues.

Upon cutting the catalyst open, I found it to be 90%+ clogged with soot. I also had a exhaust rattle, which was caused by the element inside the cat having cracked, hence the reason for removing it and cutting it open for inspection. I must assume the cat cracked due to overheating caused by the obstruction.
 

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95 E300, 91 300TE, 84 190D
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782 Posts
Although max 134 hp is at 5000 rpm, max torque 155 ft/lb is at 2600 rpm. Adequate muscle for hills at mid range rpm.

Also, "White smoke pouring out the tail pipe indicates fuel is not being burned"- no, that's coolant being burned. For a diesel car, black smoke pouring out is WOT or excess fuel.

If you buy it, check the air filter too.
 

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240D 1982 (4-Speed), Diesel Jimmy 6.2L 1983, Diesel Suburban 6.2L 1988
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31 Posts
Discussion Starter #8
All,
Thank you for sharing the knowledge.
Unfortunately, this 95 300D sold before I had a chance to see it.
Thanks,
-Kevin
 
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