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Old 03-03-2021, 12:06 AM
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Join Date: Feb 2019
Location: CA
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Starter Motor Service

It is engine rebuild time for my poor 300CD with 250k miles. While the engine is out I was wondering if there was something intelligent that I should do to the valuable California edition starter to help it live the good life when the engine returns. Is there some recommended service for it?

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Old 03-03-2021, 09:34 AM
psaboic's Avatar
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Curious......why does the engine need a rebuild at 250K? That is not a lot of miles for a decent OM617 engine.
2012 Mercedes ML350 Bluetec 70K (hers)
2002 VW Jetta TDI 217K (mine)
1998 Volvo S70 T5 Turbo 171K (kids)
1994 Ford F150 4WD 244K (wood getter)
1983 Mercedes 300D 360K (diesel commuter)
2005 Corvette 52K (fun car)
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Old 03-03-2021, 12:30 PM
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Possibly find a really good other used engine. The cost of doing a reasonably good rebuild is not in the chev 350 engine cost range.

You perhaps are in the best area of north America to find one. For example I think pistons are over five hundred each if needed. The non turbo engines pistons are a lot cheaper though.

You have several really good rebuilding shops in California. To have them take your starter apart and deal with any wear issues if any. Yours may not even be the original starter.

Two that may still advertise on ebay have good reputations. They also do not use junk parts for repairs.
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Old 03-03-2021, 09:48 PM
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The engine is getting rebuilt because when I installed the new No. 3 exhaust valve stem seal I could easily move the valve stem sideways way more than was proper. The compression on No. 3 cylinder was about 70 lower than the other cylinders. So reasonably good indications that a valve job is due. It turns out that if you are going to have to do a valve job, it is not that much more money to simply do everything else while you are at it. It will also cure the rest of the minor leaks. Once I made the decision that I was going to keep this car for the next 15-20 years I figured I may as well go "all in" with the engine rebuild while I can still find parts and services for this car. It won't get easier 10 years from now.
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Old 03-04-2021, 01:47 AM
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Join Date: Feb 2019
Location: CA
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Oh, I forgot to mention that the engine recently developed a coolant leak at the right rear head gasket. It is a fairly severe leak, so the head has to be removed. The valve job was just something I knew I should do if the head gasket ever had to be replaced.

And by the way, two of my Mercedes club buddies have 617 turbo diesels with head gasket leaks and simply cleaning up the head and replacing the head gasket failed to cure the leak. So there is a fair amount of wrenching involved to cure head gasket leaks on these cars.
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Old 03-04-2021, 09:30 AM
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Location: Redwood City, CA
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There's a lot I don't know but my general impression has been that if a diesel has good compression, messing with pistons and rings can bring grief. The logic I've heard is that most shops can't do the same quality work as the factory. In your case you're pretty sure the poor compression is not from pistons/rings.

All of what you mention can be done w/o pulling the engine ... I think.

1986 300SDL, 362K - restored to glory
1984 300D, 138K
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Old 03-04-2021, 04:11 PM
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Location: Sacramento, CA
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Before you pull the heads, check compression. If >350 psig in all cylinders, I wouldn't touch the block and just have the head redone to fix the loose valves. Unlike gasoline cars, most diesel owners don't fuss about leaky valve stems. For one thing, there is no intake vacuum to suck oil past, and what little does get past just burns in the engine since not much different than the fuel.

If you do have the lower end restored, most affordable would be to just re-ring the pistons. There are no over-sized pistons for a rebore. Indeed, even regular new pistons are "not available" and cost >$500 each if you can find one. If the cylinders are worn, the only solution is to remove the liners and install new cast-iron liners. I did that long ago in my 1985 300D, but haven't taken the block to a machine shop yet to deck and hone. When I do, I will fit used pistons (have a set) as most of mine had chunks missing.
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans
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Old 03-04-2021, 07:42 PM
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Location: Long Beach,CA
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Back to the Starter. Take it apart and look at the Brushes.

See post number 2 pic an Bosch part number on the brushes. Pic a brush set that has the metal tabs because if it has never been rebuilt the Brush Wires are welded to the Brush Holder.

Other pic in 36 and 37
84 300D, 82 Volvo 244Gl Diesel
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Old 03-08-2021, 04:04 PM
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Originally Posted by psaboic View Post
Curious......why does the engine need a rebuild at 250K? That is not a lot of miles for a decent OM617 engine.
My engine was rebuilt/replaced at about 203k miles.

Not because it wore out! There can be "other" reasons!

My turbo disintegrated and blew bits into cylinders. Likely because oil change jockey dropped air cleaner nut into intake.

Cost $$$ even back then in 2001 (about C$7k). But good part was that I then had an almost new engine. Rebuilt by an excellent mechanic. 20 years(but only 75k miles) later still going strong.

85 300D,72 350SL, 98 E320, Outback 2.5
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