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Old 10-29-2000, 10:15 AM
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I'm contemplating the purchase of a rust-free 175,000 mile 300D. (Turbodiesel, automatic) For a variety of reasons, it isn't practical to get the car to a shop for a compression test. I seem to recall an anecdotal test i.e. the car should accelerate from 30-50 mph within a x seconds. Does anyone have any experience or specs for this?

Question #2 After test-driving the car, I opened the hood with the engine running and found that there was some exhaust apparently coming out somwhere under the aircleaner assembly. Is this be indicative of a known problem? The exhaust system is quiet, leak free and amazingly smoke free (for a diesel.) Normally, I'd remove the air cleaner and have a look around, but the elderly owner is very protective of her old car etc. Any insights would be appreciated. Thanks.
John J.

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Old 10-29-2000, 09:15 PM
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Location: Austin, TX
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The "exhaust fumes" may be from oil leaking from the oil return line onto the exhaust. The tube attatches to a coming out of the bottom of the air cleaner housing. There are three little rubber mounts that hold on the air cleaner housing. It's pretty common for those to break, causing the housing to shake and the tube jump off the connection.

If that's all it is, $10.00 and you're good to go. Also, the bracket that the rubber mounts attatch to might be broken,($50-$60). This can also be an indication of worn motor mounts ($40-$50 DIY or $150-$200).

However, if the turbo is leaking, pony up $1000.00++!

I wouldn't recommend buying any diesel without a PPI and compression check unless I was buying a parts car, because that's what you could end up with.

Low miles mean NOTHING if the oil hasn't been changed.

Good luck!


90 300SE
85 300D
84 300SD (sold)
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Old 10-29-2000, 09:39 PM
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What year? I'll assume it's a 123 (77-85).

The smoke you are seeing may be the result of oil from the oil return tube leaking on the exhaust. This is pretty common. There are three little bushings that the air cleaner housing mounts onto and they break. There is a under the housing that the tube fits into. With the broken bushings, the housing can jump off the tube allowing oil to hit the exhaust. If that's all it is,$10.00 and you are good to go. Sometimes the bracket holding the bushings breaks that's another $60.00 (DIY).

Worn motor mounts usually are the root cause of the above ($50 DIY or $150-$200 tech).

Howver, if the turbo is leaking oil, you could be looking at $1000.00 plus.

I wouldn't buy any MB without a thourough PPI. Unless I was buying a parts car, because that's what you could end up with.

Protective or not, ask the seller if they would give you $5K for you wallet and everything in it. I bet they'd say no because they don't know what's in it. You should think the same way.

Low miles mean nothing if the oil hasn't been changed frequently.

Good luck,


90 300SE
85 300D
84 300SD (sold)
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Old 10-30-2000, 07:40 AM
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Hi Mr. Bill,
Thanks for your sage advice. Just to clarify, the under-hood "smoke" is clearly diesel exhaust. The engine is quiet at both idle and under load (hot and cold), so I don't think it's a cracked exhaust manifold. If it were a gas engine, I'd say it's more like an egr issue.
Re: the PPI, the car is so cheap as to be almost free, so I can take the risk on a rust-free chassis, clean interior, tight running gear, new rubber etc. The known problems are vacuum issues... central locking and engine cut-off. I'm going to give it a cold start tomorrow and if it handles that well, I'll probably buy it. BTW, I had a Volvo (VW) 6 cyl td previously and this MB sounds much better than the Volvo ever did.
Thanks for your insights.
Mr. Wheelman

'88 Volvo 745 255,000 mi.
'90 Volvo 744T 176,000 mi.
MB coming soon....
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Old 10-30-2000, 07:40 AM
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Make sure you get cold air on AC an hot air on heat!

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Old 10-30-2000, 07:44 AM
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Clarification, the car is a 1982 300D / 123
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Old 10-30-2000, 11:36 AM
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Join Date: Aug 2000
Location: Canada
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Wheelman, here is a thought about the leaking exhaust: Have an assistant hold a rag over the tailpipe, partially (not totally) restricting the exhaust. This will pressurise the exhaust enough to accentuate any leak sounds.

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Old 10-30-2000, 12:58 PM
Join Date: Aug 2000
Location: Holland, MI
Posts: 1,316
I've heard that if a diesel has enough compression to start, you're ahead of the game

For an inexpensive car, you can decide spend lots of $$ to repair/replace every little item, or DIY and "run what ya' brung" until it's time to donate it to the local charity motors lot. It might surprise you and everyone else by lasting a lot longer than you'd have thought.

If the car price is REALLY low, you've got very little to lose, except state license fees, etc. so it could be a real cheap date.

Good luck in either case.

BCingU, JIm

'96 E300D 60k mi (wife's daily ride)
'95 Audi 90 120k mi
'92 GMC Suburban 139k mi
'85 300SD 234k mi (my daily ride)
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