Greeting, occasionally the starter on my '97 850, 210,000 mile exhibits a spin/no engagement symptom.
After multiple attempts the starter will engage long enough to crank the motor.
This is an intermittent problem, started happening a couple of years ago, then fine for awhile (years) then started happening again the other day.

I'm thinking that it's not practical to try and rebuild the starter with a new solenoid.

Is a reman. Bosch the best option. ?
Are used ones worth the hassle ??

Thanks
Peter

Hi Peter,

When the starter refuses to spin with the key.
You can rule out a worn ignition switch segment and a set of alarm relay
points by trying to start with the service port in the engine bay.

Jump +12 volts from the battery to service port single female
spade connector (17/1 in the schematic)

There's a single green/red wire to the connector that breaks
out of the harness near the filler tube to the window washer tank
in back of the passenger side headlight.
Hook up the jumper to the positive terminal of the battery first.
Use a heavy wire terminated with a female spade lug and
do the jumping at the service connector which is far away from the battery
Don't make sparks near the battery, bad idea.

Then the only thing in the circuit will be the shift selector switch
to the starter solenoid. (assuming auto tranny)

With my old 740 the starter would quit dead with the key,
and It would start immediately by shorting the two solenoid lugs.
They were easy to get at with a long screwdriver.
Then the starter might work normally for months or quit immediately.
It was hard to troubleshoot when it was working.
I suspected the solenoid, but got rid of the car before trying.

Can you see the 850 starter solenoid lugs with the starter buried in there?
I never had an issue with my 850 starter so I don't know.

Strangely I've seen after market Volvo starters with the solenoid
for less money than I could find the solenoid alone, go figure.

Be sure to service your multiple Positive battery cable connections at the battery. Clean corroded terminal ends, check crimps especially on the smaller wires. Use Penetrox (zinc paste) or conductive grease on them: Nickel or Copper based anti-seize.

Good luck, Bill

Bill, the starter spins fine, it's just that the drive gear is NOT engaging with the flywheel.

The issue turned out to be a sticking solenoid.
Bought a used starter off FB marketplace, which also had a stuck solenoid, lol
Removed the solenoid to clean and lube it.
Also did this to the OE started so that I now have a spare starter if needed.

Sticking solenoid was the issue with my 95 850. Strange issue. Car would start fine cold. When warm, sometimes it would start and sometimes not. I’d let the starter cool for about 15 minutes then it would start. Grew tired of that BS and finally diagnosed the problem and repaired it.

--
Will I buy another Volvo??? We'll see....

Hi Peter,

I'm glad you could rehab those starters, thanks for following up.

Please elaborate as to what exactly was binding up the solenoid.
Was it wear and/or grunge in the works?
What did you decide to lube the solenoid with, and where exactly?

I'll look at my old 740 starter motor that was finicky, probably the solenoid.
It's rewarding to fix these things rather than to buy new.

Best regards, Bill

Hi Peter,

Please elaborate about what you found binding and what you lubed in your starter. I went down this road with Volvo starters in my 740 and had recurring no starts that would be solved for varying amounts of time by starting by shorting the solenoid terminals with a big screwdriver. This was with two starters.

I looked at one of those starters yesterday and found very little wrong and now I am starting to believe that the ignition switch may be unable to provide
enough current to run the starter solenoid ALL the time. I'm guessing you still
have that bug. The solenoid gags because not enough current from a worn ignition
switch contact #50.

I haven't done this yet, but it would be easy to see how much current the solenoid draws by starting with the service port with an ammeter in series.

It's notable that the starter circuit is unfused, and perhaps the ignition switch is the fuse?

The starter solenoid may need it's own relay to be more reliable?

Whatsay? Bill

Hi Peter,

Look here for new replacement option:

https://www.ebay.com/itm/373809258038

These low prices are putting the local alternator
starter motor re-builder shops out of business around here.

Good Luck, Bill