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Old 02-01-2002, 12:54 AM
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'89 300TE-- Replace or Repair?

Recently got the wagon off E-bay. (seller goes by name of viorea-- watch out). When the engine warms up, there is a TON of blue smoke on acceleration. Took MB tech 2 seconds to say "valve job and/or seals and rings". Independent mech. says it'd be better all the way around to replace the engine.

Is it possible at all that it could just be old seals?

If not, used engines from that year seem to average around 100,000 miles. Wouldn't it still need a valve job in another 20 or 30 thousand?

This is my first MB purchase (I am fighting the urge to make it my last) and any advice or info whatsoever would be most greatly appreciated.

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Old 02-01-2002, 08:49 AM
Michael's Avatar
Join Date: Jul 1999
Location: CT, USA
Posts: 2,699
Your M103 motor is fairly bulletproof-your symptoms surprise me. It certainly sounds like piston ring problems, but I suppose a top end (ie bad valve guide) could cause these symptoms.

Do you have the service history? Has the head ever been off?

I think the first thing I'd do is a compression test to see where you are, or perhaps better diagnose what ails your car

When properly maintained, you now own one helluva car-I hope you get it right and keep it that way!
"If everything seems under control, you're simply not going fast enough" --Mario Andretti

1995 E500 street car
1986 Porsche 944 Turbo S track car
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Old 02-01-2002, 09:39 AM
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Join Date: Jul 2001
Location: Los Angeles
Posts: 262
My most trusted engine tech of all is my brother. He specializes in motorcycle racing engines, however, and he is on the right coast whilst I'm on the left. Anyway, he does do car engines as well, and he mentioned that certain MB models are notorious for soft valve seals that wear out quickly. I haven't explored the issue yet because I don't have that problem. But I would most certainly check the valve seals before committing to something more major. From the clouds of smoke you describe, however, I suspect you will be doing more than that.
Mark Stetson
1995 E320 Wagon Moonstone Grey/Parchment 106K mi.
2007 E63 AMG Graphite/designo 75K mi
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Old 02-01-2002, 04:08 PM
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I've seen many 103's that used a lot of oil 1qt. in 200 miles and they don't smoke that much as long as the catalyst is working however if there is a hole in the modulator valve you will get a smoke cloud.
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Old 02-02-2002, 12:21 AM
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Thanks for the replies. I have been going through the service records (fortunately, they were saved; of course, there could be a few "key" records missing) but

1) there are a LOT of service records, and
2) I am not a mechanic.

But, Michael, as far as I can tell, the head has never been off.

Here is what I HAVE found:

1) Techs have been noting an oil leak at oil level sensor and at rear main seal since early '98, about 50,000 miles ago.
2) Oil has been changed often.
3) Spark plugs seem to be replaced about every 3 months.
4) In '98, car came in with fluid leak R/F. Tech comments: "Due to over-heat condition". Oil leaks already present. R/F leak exists to this day, as my driveway will attest.
5) Splash guard under engine is missing.

Mike, please tell me more about the modulator valve.

Michael, I wonder why the MB tech didn't do the compression test? He did a cooling system pressure test, and R/R spark plugs to see if coolant was leaking into combustion chamber, and that's all. I know from driving it to the shop that there is a big gap between pressing the accelerator and the car actually moving, but I assumed it was mainly because of the 4000lb weight. (Remember, this is my first MB-- I really don't know how this wagon is supposed to take off).

The last service record I have is from 9-14-01. Think I'll call the tech, and see if he remembers anything.

Lastly, what about just replacing the engine? Any thoughts on that?

Thanks again guys,

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Old 02-02-2002, 07:27 AM
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Location: CT, USA
Posts: 2,699
The thing is, Scott, that those M103 motors just don't go bad...well, they all need head work eventually, but the bottom end of those motors are known to last forever! Then again, if you overheat it, that could change things I suppose.

My wagon has 176k miles, and it runs as-new; my bro-in-law has an '88 too, and his has something like 250k miles on it-his runs perfect too.

I'm thinking what you really need is an experienced tech that can tell you what's up-we're all merely taking stabs at this in the dark.

As to the rear main, I had mine replaced 3 weeks ago, for the second time! It's not an unheard-of problem-I suggest if you do have this seal replaced, be advised that Mercedes has available an offset rear main seal, which means that the seal lip rides on a different place on the crankshaft (I think it's a 2mm offset).
"If everything seems under control, you're simply not going fast enough" --Mario Andretti

1995 E500 street car
1986 Porsche 944 Turbo S track car
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Old 02-02-2002, 07:46 AM
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Location: San Jose, CA
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If smoke occurs while idling, or after the engine starts, but not while on the freeway, it is more likely to be the cheap valve seals.

If it smokes when you get on it, then it sounds like it may be rings.
Do a leak down test to determine which.
1981 300CD (Benzina)
1968 250 S (Gina) 266,000 miles!
1983 Alfa Romeo GTV6 (Guido)
1976 Jaguar XJS-saved a V-12 from the chevy curse, what a great engine!
1988 Cadillac Eldorado (better car than you might think!)
1988 Yamaha Venture (better than a Wing!)
1977 Suzuki GS750B
1976 Yamaha XS 650 (sold)
1991 Suzuki GSX1100G (Shafty Gixser)
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Old 02-02-2002, 02:27 PM
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Location: Evansville, Indiana
Posts: 8,150

There are two sources for oil in the engine -- bad vacuum modulator on the transmission and blowby or valve seals in the engine.

Check in the air cleaner for oil -- the blowby is routed into the center (clean side) of the air filter by the big molded hose from the valve cover. If there is considerable oil in there, you have a blowby problem and will need a replacement engine or overhaul.

If there is little or no oil in the air filter housing, check the vacuum modulator on the transmission -- an incredible amount of transmission oil can get sucked up that little vacuum line, and will make blue or white smoke.

Quite a bit of oil can go down the valve guide seals. This is usually most evident at idle and on startup.

My 88 TE respondes very nicely to throttle input. I suspect that if you have serious throttle lag most of the vacuum lines in the engine compartment are bad and leaking. Throttle lag and rough running are an indication of a vacuum leak.

Empty, your TE weighs about 2500 lbs. Gross vehicle weight is 4500 lbs, I think. It's geared rather low, should go like a scalded cat!

1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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Old 02-02-2002, 03:58 PM
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Join Date: Jul 1999
Location: CT, USA
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A TE, unladen, is closer to 3,500 lbs (a '92 weighs 3,590, but was a little heavier than an '89). GVWR is 4,700 for my '88 TE.

Absolutely great cars when running right-good luck sorting things out
"If everything seems under control, you're simply not going fast enough" --Mario Andretti

1995 E500 street car
1986 Porsche 944 Turbo S track car
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Old 02-02-2002, 09:19 PM
Mr. BILL's Avatar
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Join Date: Aug 2000
Location: Austin, TX
Posts: 576
Take a deep breath and count to 10.

You already have a problem (maybe) from jumping to conclusions. Read the posts here, no one has said you need a new engine. If you have the cars history and it does not indicate the valve guide seals replaced with the updated ones, it could be as simple as that, (about $400). You should have a dry and wet compression test and a leak down test as well as a pressure test of the cooling system.

It also sounds like you need the opinion of another tech. Look under the section that lists good techs in your area. If one isn't listed, this is the place to ask.

Since your records indicate frequent oil changes, that should weigh in your favor as far as the rings and valves go. TAke your time, go to another shop, ask questions here and usethe search feature to learn more. This is the best forum anywhere to get good,useful information.

Good luck,


91 300E 120K
90 300SE 275K (sold)
92 BMW 525iM 120K
90 BMW 525iA 175K
85 300D 175K (sold)
84 300SD 245K (sold)
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