OK. Here's the deal. My new 85 300D's starter is bad. I had the old starter from my 81 still sitting here and rebuilt it. Took it over to Advance and had them test it and it tested fine.

When I removed the one from the from the 85 I noticed I had made a mistake and had the ground wire of the 81 starter on the wrong bolt. I had it on the long one, not the short on as the 85 has it. So I took the solenoid off again, turned it and put it on to match the one coming off the 85. Got the starter all put in and wired up but when I goto hook up the battery the starter spins!

It doesn't engage, just spins. This is with the key off in the dash, and with the little wire that runs to the starter removed, still spins. I have verified that the positive from the battery is correctly hooked up to the longer post.

Any ideas?

Did I hurt something having the solenoid hooked up backwards and having it tested? How did it pass the test hooded up backwards to begin with?

Not looking forward to having to remove it from the car again....

Have the starter already back out... MUCH easier the second time around lol. Heading into town to have both tested and see what the issue is

Well interestedly both starters tested fine... Even though the one I put back together didn,t actually engage... The one I took off would engage and work, so I'm guessing that it,s just too weak to actually turn over the engine any more. Guess I'll just go ahead and order a new one.

Taking the starter from the 85 apart right now. Nice that in the later years that they used philips to hold the solenoid, I was actually able to get all 3 out without issue, unlike the starter from the 81. On the 81 starter I had to drill out the screws, then increased the head of the whole to fit the new allen head bolts I put back in. Also had to drill them out a little since I could only find 30s instead of the original 40 length.

Since that cars already on stands and I have everything setup for doing the job, I'm going to go ahead and try to recondition the original starter. If it works, I save myself 140 bucks. To me thats worth doing.

On another note, I was able to use the hi/low switch and the expansion valve from this car in my 81 and got the A/C operational again. I know they are cheap parts (totaling about 30 bucks) But they where there and I have no idea when this car will actually be back on the road again.

How about a pic or a diagram of what you are talking about?
The starters I have worked on all have 2 large bolt terminals on the solenoid, bat wire goes on 1 & the other, that has a tab on it coming from the coil of the solenoid, connects to the heavy wire going into the starter brushes. There is also a small terminal for the starter control wire.
If you mix up the 2 main terminals you wont get the solenoid to do anything.
It takes a lot of effort to damage a starter by wrong connections.

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

Somethings'not right. There is no ground wire to the starter! If the starter spins but not engage, you hooked up the wire to the wrong terminal of the starter!

The starter solenoid engages a clutch and supplies power to the starter motor simultaneously.

The 3 solenoid screws have loctite on them. Tip: Heat (the solenoid body where the loctite on the threads are, not the head of the screws) with a propane torch to soften the loctite first- no drilling necessary

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

If your car has California bits, the starter is different. Don't remember exactly how, but it is different. Went through this on a wagon once, many moons ago.

Jay

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On the road, currently:
'83 300D (German spec.) 168k mi. - - Wolfgang (tucked snugly away for the winter!)
'87 300D 375k mi. - finally went over to "The Dark Side"
'87 300TD 225k mi.
Cannondale 66cm CAAD5 w/Campy/Jamis Aurora
Hujsak Custom Fixie/Landshark Track Shark Custom/Ahearne Custom 29'er

I must have miss explained this. Buy ground wire, I was talking about the heavy wire coming off the starter to the solenoid. On my other starters, this wire is attached to the shorter of the two posts on the solenoid. When I had it first tested I had it on the longer of the two posts.

Ah that explains it. Still, that is NOT a ground wire. It is the starter motor field coil wire that gets switched +12V when the solenoid engages. You can test the starter motor before installing it if you have the right ammeter and a phototach. Army posted a link to Bosch starter motor PDF with the test specs and maintenance procedures.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I cracked them both open again, the 81's to see what the issue with it just spinning and the 85's just because it didn't work. The 85's was totally burned up inside, wires melted etc... someone really cranked on it hard... In the 81 I noticed I didn't get the pushrod of the clutch on correctly, so I fixed that. I actually swapped the entire solinod from the 85's since it was working correctly, even with the starter motor itself being toast.

going out to put it on the car again and see what happens


Kind of trial by error, but learning a lot. This is the first starter I've ever repaired. Normally I just buy a cheap starter and replace.

Success!

Starter is strong and turning over the engine as good as the brand new one I have on the 81. Now, just have to finish a few adjustments and I should be able to test start the car tomorrow morning.