[B&kML350]

Earlier this July stopped at the store and the ML would not restart (even when jumped) had the car towed home and called Mercedes to come get it and fix it since I did not have the time to do it.
They determined it a frozen starter motor and replaced it with Mercedes reman. ( not to happy about that thought I was getting a new one) Everything was fine. until last week drove home from work (30 min drive ) stopped for gas and ML would restart. Towed home again. Thought it was the battery ( new 2 month old ) so put the charge on it and took a 10amp and quickly dropped to 5. Waited a couple of hours and the ML started right up.
Tried an experiment to see if it would start if I left it overnight did so for 5 days in a row started each time last day stated 10 times in a row with out issue. Took it for a short drive parked it in drive and again restarted, took
it for a longer drive 30min or so back in drive a it would not restart. So recharge it again and started do so measurements rest voltage 12.5 to 12.7 running voltage from alt 14.1 to 14.4
starting voltage 11.5 dropping 9.9 (started) engine cold after driving it to temp 80C and trying to restart, car cranks slowly and voltage drops to 7 then nothing. I've removed the serpentine belt and all pulleys run freely.
So my question is, is there a way to test the starter to see if it is defective once it gets to engine temp( does anyone think I got a bad starter from get go) or what else should I look for ?

Thank You

 

[bobby735]

That 7v to zero..is not right... Where are you taking the voltage readings?.. battery POST to POST?.. Battery post (+) to engine block? Starter terminal (+) to engine block ?... I'm thinking you've got a bad connection or cable..

 

[43sqd]

Tried an experiment to see if it would start if I left it overnight did so for 5 days in a row started each time last day stated 10 times in a row with out issue.

So if my math is correct, you started the eng. 14 times in 5 days, 10 of which was in a row. Do you have any idea how many volts were drained from the battery without recharging it?

Remove battery cables and clean the battery posts and the insides of the terminals with extra fine sand paper (do not over do it). Then recharge the battery as you did before. Please read the PDF.

 

[B&kML350]

Thankyou for your comments
Bobby voltages taken directly from battery terminals lowest voltage was 7V no start
43 sqd thanks for the PDF I have already cleaned the battery posts to a shine also the neg cable to the fire wall I recharged the battery went for a drive and same issue no start hot. thinking I have issue with reman starter. I noticed in the pdf the positive terminal pictured has 3 cables to mine only has two is that something ?
The querry is why the car starts fine cold and will not after running for 30 min or more battery getting 14 plus volt charge from alt.

 

[bobby735]

It almost sounds like your alt. is dropping out after it gets hot.. That 7 volts is a problem, If a FULLY changed battery is being dropped down to 7v.. It would be putting out MAX amps, (700-800 cca).. the cables would be smoke'n hot.. Anyway to get an amp clamp on it when it won't start? If your putting out 700/800 cca, it's the starter.. if your putting out something far less, it's the battery/alt..

 

[bobby735]

Ps.. run car 30 min.. Don't turn car off.. what's the alt. putting out ? Don't turn car off, dribble a little water on the starter with a hose to cool it down, try to restart ?

 

[bobby735]

Just re-read your first post.. You said "you put a changer on it.. 10 amp then down to 5 amp.. THEN WAITED A COUPLE OF HOURS BEFORE RE-START.. My guess.. "battery cells are shorting out when it's hot".. Do you have another battery to swap with it when it's hot?..

 

[B&kML350]

Bobby thankyou for your comments Yes tried it with a second battery same results. will need to purchase a clamp on amp meter to try your test

 

[B&kML350]

Problem solved it was the 3mo old M/B reman starter replaced all good so far we'll see in another 3 mo's