If the starter gets too hot, will it not engage? - Page 3 - PeachParts Mercedes-Benz Forum

Brian Carlton · #31 05-29-2006, 10:35 PM

Quote:

Originally Posted by Craig

I agree, they would spin much too slowly at 9V. I've spent to much time trying to troubleshoot what turned out to be bad batteries. I just put a new battery in the 300D, after it went dead at some point during the vacuum pump saga. The shop recharged it, but it just wouldn't hold a charge very long. It doesn't take much to kill one.

Absolutely. One complete discharge due to a dome light being left on by mistake and the battery is on it's way out.

The diesel needs a battery in very good condition, whereby it never has been fully discharged.........otherwise it's going to give problems.

Furthermore, I'm of the opinion that any battery over 48 months is on borrowed time in these vehicles.........unless you can start them very quickly even in very cold temperatures. I'm fortunate in this regard with the SD, but, most 617's need some cranking time at temperatures below 10°F.

Brian Carlton · #32 05-29-2006, 10:41 PM

Quote:

Originally Posted by 1985 300SD Sady

Also, would it be possible that my battery is just low from too much usage of my audio system? is 12.4v ok? Would it help to put the trickle charger on it for the night?

Nope. 12.4V is fine. The problem is under a load. A trickle charge won't help this situation.

1985 300SD Sady · #33 05-29-2006, 10:53 PM

alright, thanks.

vstech · #34 05-30-2006, 09:37 AM

Quote:

Originally Posted by Craig

I agree, they would spin much too slowly at 9V. I've spent to much time trying to troubleshoot what turned out to be bad batteries. I just put a new battery in the 300D, after it went dead at some point during the vacuum pump saga. The shop recharged it, but it just wouldn't hold a charge very long. It doesn't take much to kill one.

a battery that shows above 9 volts under a HEAVY load can still be good. but if it falls to or below 9 forget it. now if a starter is NOT cranking or even trying to crank, and the voltage is showing above or near 9, I would focus on the starter, because if the starter is not cranking it is not going to be drawing much juice, it is because it has a short or a bad winding.

Andy, I mentioned rebuilding the selanoid, because you said you had another starter with a known good winding, but a bad selanoid. I would not pull the starter until I knew for sure I had a fully tested good one to put back in.
John

#35 05-30-2006, 09:51 AM

It could be the starter drawing too much current, but I would still bet on the battery. I guess we'll have to wait for the results of his battery test.

1985 300SD Sady · #36 05-30-2006, 10:12 AM

Just got back from Autozoo...

The guy first just tested my battery, which was shown to be good but a little low on charge. At rest with his tester, the battery read 12.56 volts. Then I started the car while monitoring the voltage. With the glow plugs voltage dipped down to 11.9v and I never saw it go below 11v with the starter engaged today. This was with the car up to operating temperature and with it just being shut off 5 minuted before.

Then he checked to make sure that the alternator was charging fully, which it was. He had me keep it steady at 2000rpm's while the tester did its thing. He told me that it was charging fine and all the system needed was a light charge. I did not have a chance to see acually how many amps the alternator was putting out.

Seems like everything in this region is good? Maybe I will add another grounding strap.

opinions? suggestions?

#37 05-30-2006, 10:26 AM

Well, based in that info, it sounds like the battery/alternator are OK. That pretty much leaves the starter and the electrical connections. I would recheck all the connections, ground strap, etc. and see what happens. It may well be a problem with the solenoid or starter, but I would hate to start replacing stuff without knowing for sure. Can you live with the possibility of it occasionally not starting until you get to the bottom of this?

Brian Carlton · #38 05-30-2006, 10:26 AM

The fact that it held 11V while cranking is decent evidence that the battery is OK.

Therefore, if the problem returns, the solenoid/starter will have to be the culprit.......surprisingly.

1985 300SD Sady · #39 05-30-2006, 10:30 AM

I can live with it occasionaly not starting until I can get to the bottom of it.

I will try to get out there tonight (when it cools off) to check all the connections once again.

If I do need to remove the starter, where can I get a solenoid? should I just have the starter rebuilt? again?

As I asked before, could I get an aftermarket solenoid that could handle the amperage surges?

mplafleur · #40 05-30-2006, 01:07 PM

Andy,

It does look like you may have a hot soak issue with the starter.

You also stated that during your crank test that you saw 9 volts on one occasion. This was also done during a one second crank. If you look at cranking current, you will have the largest draw during the first second as the engine is getting to speed. It is easier to get the pistons through the compression stroke once it is turning. I am not suprised to see 9 volts on that first revolution.

84300DT · #41 05-30-2006, 02:03 PM

Quote:

Originally Posted by 1985 300SD Sady

The other day, I took a trip downtown (approx. 20 miles) to drop off some paperwork for my job. I had the stereo on loud (which has never made my car not start, even though it draws more than stock)

The car got up to about 100*C by the time I was there (which has been happening sparatically) Even on the hottest days sometimes it will never go past 90*C and just stick right between the two lines where it is supposed to be. Other days, it will ride at 100*C.

Anyway, when I parked, the temp. gauge read 100*C by this time the radio had been off for quite a while and I am sure that there was enough juice to restart the car.

After maybe 15 minutes I came back and the car would not start. The temp gauge still read just under 100*C. Glow light went, everything is normal until I bump the starter which makes the solenoid click, but the starter will not turn. I thought it could be the NSS but I dont think the solenoid would even click if that were the case. I put it in neutral just to see, and it still would not start.

I stopped and thought... I knew from previous endevours into electronics that the resistance of a wire (or any electric device ie. a starter) increases with temperature. This means that it takes more amperage to turn the engine over. I thought that was the reason it would not start. I opened the hood in a attempt to cool it off. After 10 minutes or so I tryed to start it again but all I heard was the click of the solenoid.

A man in a SUV drove by and I asked for a jump. He was willing and helped me jumpstart my car. This worked, turned over and started first time. What gives?

On my way home I stopped to return something at the store. When I was about to shut down the car, the temp gauge was showing 100*C again. I turned on the heat and kept the hood open and the engine idling until the temp gauge read 90*C (normal). I checked the voltage with a DMM and at idle it read 13.1VDC. I then shut the car down. I thought I should try to start it, and again this time it would not start.

I returned my item at the store and came back to the car, and it started right up.

I have not had any touble since this (but have only gone out on short trips) and my temp gauge has not been that high again yet.

Is it possible that the starter is just getting so hot it will not start without a jump?

this is a 1985 300SD with just over 200k miles. The starter is a Bosch rebuilt unit, the battery is less than 1 year old, and the voltage regulator has been replaced within the last year also. The alternator charges fine and this is the first time (since fixing my car) that it has not started. Also, I checked the grounding strap, and it is making good contact.

Any help is appreciated.

mine's been doing this for years.. i just cycle the key and it eventually starts.

BobK · #42 05-30-2006, 02:31 PM

Andy, for what it is worth.. here in Cincy, with our crazy weather/temps, the problem you desrcibed can be caused by the weather itself. May be another problem, but first look into this: With the wild temerature swings we have had lately (40 degree swing) you can get some funny corrison problems. I usually see these problems in hte spring and fall when the temp change is most pronounced. Battery connectors do not seem to expand and contract at same rate of speed. What you wind up with is a scale on the post and the inside of the cable terminal. This kills ya two ways. First, it is a high resistance to charging. Your battery may not get a full (or even partial) charge. Then, when you try to pull some serious current thru the connection, a la diesel starter, the voltage drop becomnes too large and ya caan't spin the starter. Common symptom is that the car was running but won't start now. Plus the headlights seem to come on fine (they are probably a bit dim, but too little to notice). Solution is to clean the connection really well and reconnect battery. Then put your charger on the battery and bring it all the way up to a full charge. BTW, 12.4 volts @ 70 degrees F. is about a 25% dischared battery. I've got a chart somewhere showing 0 to 100 % charge for a normal battery. I'll have to dig it up. There are other places you can have trouble charging your car. There is a connectin block I'll show you sometime that can completely stop you from charging (guess how I know!).
Clean your connections (if you haven't already), charge the battery (make sure you keep the water level up-distilled water only), and use your voltmeter to get good readings on what's going on. Gotta be able to get to work on time every day (or are you working down the street?)

vstech · #43 05-30-2006, 02:47 PM

Quote:

Originally Posted by BobK

BTW, 12.4 volts @ 70 degrees F. is about a 25% dischared battery. I've got a chart somewhere showing 0 to 100 % charge for a normal battery. I'll have to dig it up.

http://www.repairfaq.org/ELE/F_Car_Battery.html

vstech · #44 05-30-2006, 03:56 PM

Quote:

Originally Posted by vstech

http://www.repairfaq.org/ELE/F_Car_Battery.html

that is a good set of points to follow
also #4 is important...
John

1985 300SD Sady · #45 05-30-2006, 04:29 PM

Quote:

Originally Posted by mplafleur

Andy,

It does look like you may have a hot soak issue with the starter.

You also stated that during your crank test that you saw 9 volts on one occasion. This was also done during a one second crank. If you look at cranking current, you will have the largest draw during the first second as the engine is getting to speed. It is easier to get the pistons through the compression stroke once it is turning. I am not suprised to see 9 volts on that first revolution.

No, someone else mentioned that it should be ok down to 9v.

The lowest reading I have had during cranking is 10.2v. As you said, this was right as the starter engaged because that is when it takes more energy to get started. Once momentum builds it is easier to turn over the engine.