CAR: 1985 300TDT, 149,000 miles, California model, synthethic oil, old (7-8 years) but seemingly good battery

PROBLEM: When starting cold I get a fraction of a second hesitation after turning the key before the starter motor actually cranks. Doesn't usually happen when the car is hot. Delay is very short but a new thing for this car. It has always cranked up immediately until recently. The starter seems to turn the engine over normally once going without a noticable lugging or slowing. There is no "click" when I first turn the key, just silence then 1/2-1 second later the starter motor engages.

THEORY: The windings on my starter are getting old and it is having trouble turning over the engine when it is cold. This is the original starter so the timing of (sounds like) future failure seems about right. Alternatively, it may be that the grease in the bendix gear is old and dried out so it has trouble engaging except when it is hot.

QUESTIONS: Anyone experience this symptom before their starter motor failed? If so any idea how much time I have before it dies totally? (I'm not anxious to spend the $$ on a new starter until I have to) Could the battery really be the problem even though it appears to be still strong. Any and all opinions and/or experience with this is appreciated.

LRG

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

Irg,

Had a problem very recently where my starter wouldn't start, then would and I finally realized that the key didn't turn all the way over to the start position. I removed the starter key lock and found it very stiff. I was just about to go to the dealer to get a new one when I decided to wash out the lock with some grease and silicone remover (solvent). After I washed it, the lock worked beautifully. Later I had to shoot a little graphite into the reinstalled key lock but it's been working great ever since.

Did you see my thread on the Intercooled 300DT?
Good Luck!!

Ben
www.reproduce100s.com

"The starter seems to turn over normally" .. since you said this.. it sounds more like a sticky solinoid... this is just a big relay to handle the large amount of electricity which you would not want to route through the key switch.. you might clean or replace it...

I would agree with Ridge. That sounds like bad contacts in the ignition switch. Clean it out and see how it works before doing anything with the starter.

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Orland Park, IL
1985 300SD 215,000 miles

Thanks for the ideas. I'm not sure about the key switch because it only seems to happen when the engine is cold, never when it is hot. Just the same, I'll check it out. I think the solenoid idea makes sense. Not sure if it's possible to remove and clean/oil it though. Has anyone tried this?

Ridge: I love the intercooler, really nice, clean job. Did you tinker with the IP to get more fuel in too? Seems that's the way to really get the full HP boost.

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

At 8 yrs., get a new battery (you'll need one soon enough anyway). Probably lacks the "juice" when cold to get the momentum going as quickly as when it was young. The hotter it is (up to a point) the more amps. it puts out and the less friction it has to overcome. The switch, solenoid, starter are all possibilities also, BUT....an eight year old battery? On a diesel? I'd go for the statisically probable here.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Irg,

After looking at jba's comment about the battery, I'd vote for that. Missed that in your original post. When in doubt, always assume it's the non-Mercedes parts.

Haven't tried anything with adjusting the IP on the intercooled 300DT, since we've plenty of power as it is and want to proceed conservatively.

Ben
www.reproduce100s.c0m

As you describe this, I fully expect that the problem is the starter solenoid. These are available as a Bosch repair item. I have had mixed results replacing only the solenoid.

If you were working on a 240D I would recommend replacing only the solenoid because you can remove and replace the starter in a 240D in a matter of minutes with no frustration at all. On the five cylinder, however, removing and replacing the starter is a challenging operation. I would replace the entire starter, and I would probably wait until it laid down for good.

If the problem were the battery, the starter would turn slower, not delay in its engagement.

Good luck,

I like that!


thebern

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1982 240D 313,000 (4 speed)
1984 300CD 172,483
1985 German Shepherd Dog -Lacey- R.I.P.11/04/05

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