Starter? 300TDT - PeachParts Mercedes-Benz Forum

shear2001 · #1 03-11-2003, 10:34 PM

Attempted to start the other day -10. Unable to start after about 5 minutes of cranking. Recharged the battery and now I only hear a click when I turn the key. I'm assuming I burned out the starter. Is there any way of telling?

Brian
300tdt 366k

diesel don · #2 03-11-2003, 10:47 PM

I'm not so sure. Clicks usually sound battery related to me. Was the starter still cranking when you called it quits?

Don

P.E.Haiges · #3 03-11-2003, 10:52 PM

It could be that you burned the contacts on the starter solonoid.

Try rapping solonoid with hammer while someone turns the key to start position. If this doesn't work try next step.

Short across the solonoid terminals with a wrench or screw driver with key not in start position and see if starter spins. It probably won't jump into the ring gear using this test. That's OK. If starter spins, it is probably OK and solonoid contacts are bad.

Try key starting again.

P E H

shear2001 · #4 03-11-2003, 11:12 PM

All I hear is a faint click, I'll try testing it tomorrow. How difficult is it to replace the starter?

shear2001 · #5 03-11-2003, 11:14 PM

I should also add that the battery is less than a year, and I had it recharging all day...

jfikentscher · #6 03-13-2003, 10:05 AM

This just happened to me!!. After a new battery, $75.00, I checked the solenoid. Found that the rubber wire protector was almost desintegrated and the contacts were all rusty. Disconnected the battery, got a wrench on the terminals and loosend them, sprayed them with WD40, waited a while for the oil to work, the retightened them. Car started like a dream!! I guess that the contacts were so corroded that there was no current flowing. I will replace the solenoid in warmer weather.

Joe.

SirMatt · #7 03-13-2003, 11:06 AM

Same thing has happened (and occassionally does happen) to me. Replaced the battery, the starter and the battery cables. Still happens now and then.

However, I have become convinced that my GP's have something to do with the problem. I have noticed that if I let my GP relay go ALL OF THE WAY through the GP cycle until the relay clicks before I try to crank the starter it will almost always start. My only thought is that one or more of the GP's or the relay itself may be drawing a lot of amps away from the starter circuit if I try to crank before the relay clicks.

Capt Kirk · #8 03-13-2003, 04:19 PM

click is starter related.

no click is electrical circuit related (ignition, alternator, battery)

SirMatt · #9 03-14-2003, 10:47 AM

Your mileage may vary, but the click I occassionally hear when I attempt to engage the starter circuit is most definitely coming from the GP relay on the driver's side of the engine compartment, not the starter which is under the engine on the passenger's side.

I am not saying that the starter may not be an issue, what I am saying is that in my case I replaced the starter, replaced the battery, and replaced the cables. I have one GP that I am almost certain is bad, #2, which the idiot who owned the car before me managed to crank down so tight that I have almost rounded it off trying to get it out (also cranked the oil filter canister down so hard I actually broke the wall of a socket trying to get it off, and cranked the trans pan down so hard that the gasket is well, less than a gasket, I cuss him ofter). Replaced 3 GP's. As long as let the GP relay go ALL OF THE WAY through the GP cycle and wait to hear the "click" when the relay shuts off (about 30-40 seconds AFTER the GP light goes OUT) before I crank, the car will almost always start without issue. THUS, my theory, correct or not, that the #2 GP or something in the GP circuit is drawing more amps than it should during the GP cycle thus drawing the battery down enough so that the starter wont engage unless I give it time to refresh itself.

Either way my "click" IS from the GP relay. No doubt about that.

Try warming the GP's and let the light go out, count 30-45 and you should hear a faint click from the left firewall. That's the GP timer relay. I assume that the ignition circuit is designed to shut off the GP's whenever the starter circuit is to be energized, thus the click when I try to crank. Again, I theorize that if I try to start before the GP timer shuts the relay on its own I am trying to start with vastly lowered amps (from some malfunctioning component; GP or relay itself?) and thus the starter will not engage. However, letting the relay cycle on its own gives the battery time to refresh just enough to crank the starter.

Anyway, my two cents. But Cpt. Kirk, I beg to differ Sir. My click can and does come directly from the GP relay.

Motorhead · #10 03-14-2003, 12:37 PM

The starter removal is somewhat of a job on the TDT. It comes out through the bottom side and the steering has to be turned a certain way to get it out. I went through this TWICE untill I found that I had a bad armature in the starter. Rebuilt the starter myself and she starts good. IT better start good because it's my wifes car.

Capt Kirk · #11 03-14-2003, 12:40 PM

well yeah, of course theres a click from over there.

But when your actually trying to turn the engine over (as in turn the key that last extra bit) and all you hear is a click instead of the starter trying to do its thing, then its starter related.

the GPs run before you even start the car, they have no effect on if the starter will turn or not. If you tryed long enough the engine would start up with out the glow plugs.

the click from the start should be pretty obvious, but have some one stand in front of the cara with the hood up when you try starting the car and tell you where all the various "startup" noises are coming from.

P.E.Haiges · #12 03-14-2003, 01:07 PM

Sir Matt,

Its the amperes flowing thru the glow plug that decreases the battery voltage and causes a voltage drop in the wires that tend to make you starter solonoid not work. It sounds like you have a starter solonoid that is just on the edge of working and when the voltage is slightly lowered, the pick coil in the solonoid doesn't pull enough to engage the starter.

If any of your GP were shorted, the fuse in the relay would burn out. In 30+ years of MB Diesels, I only had one GP short and that was the old series loop type. It was #2 and shorted to ground and pulled so much current, the starter would barely crank the engine. There wasn't any fuse in the old series GP systems. I had to remove the connections to the shorted GP and jumper to the other GP to start engine.

P E H

SirMatt · #13 03-14-2003, 05:32 PM

It is altogether possible that my solenoid is borderline, thus requiring more than the usual amps to fire off and engage the starter. That is entirely possible and even quite likely.

My main point is this however, the click I hear IS, get that IS from the GP relay. No doubt about it. In fact I can make the damned thing "click" over and over again if I just slightly tap the key back and forth in and out of the "I" position without making a full key cycle. I NEVER, get that, NEVER, get a click from the solenoid. The "click" noise is ALWAYS from the GP relay.

I fully understand that the GP's are merely an aid to starting a cold diesel engine and bear no bearing on the starter circuit itself. In fact, the idiot before me installed Champion GP's which happened to go out last week in a Texas Blue Norther which dropped temps in the Panhandle from 65 to 15 in the span of 5 hours. Without the GP's the only way I was able to start the engine was to tow the car home and plug in the block heater. Started on the second after a good block warming. My point is this, the GP's and the GP timer relay have to take amps from somewhere...the battery. If they take too much from the battery in their preignition cycle or if the starter or solenoid is borderline and needs a full 900CCA or so to fire off then the GP's and the GP circuit WILL most definitely affect the starter circuit in that there are simply not enough amps to accomplish the task placed on the battery by the starter circuit. Second, though I'm certainly not an expert, I suspect the "click" from the GP timer relay is in response to the ignition switch being engaged. As Cpt. Kirk explained the engine does not NEED the GP's to run and it's the timer relay's jpb to turn them off. Therefore, I suspect that when you engage the ignition switch a signal is sent to the timer relay to shut off the GP's in anticipation of the engine firing off. I strongly suspect that is the "click" that I hear. The GP relay shuts the GP's off anticipating a crank of the starter and a firing of the engine which never comes because not enough amps (for whatever reason) are getting to the starter.

It very well may be that my starter or at the least my solenoid are suspect. All I know FOR SURE is that the "click" when I turn the key to "I" and get no crank from the starter IS from the GP relay box. PERIOD. It'll click on its own if you let it time out and if the starter or solenoid don't fire I can hear it click when engage the ignition switch.

P.E.Haiges · #14 03-14-2003, 07:49 PM

SirMatt,

When the solonoid engages the starter, there is always a click. Only you might not hear it because of the noise of cranking the engine.

When the starter and solonoid do not work, there is no click. I understand what you mean about the clicking of the GP relay.

However, from a retired electrical engineer, its the voltage drop in the battery and wires that causes a weak solonoid not to work not that there are not amperes available from the battery. Before the solonoid engages, there are plenty of amperes available because the starter has not yet stared to draw its high current (ampere) load.

If the starter cranks the engine relatively easy when cold, the starter, battery, wires, connections contact points in the solonoid are OK because they all handleing the high current necessary to crank the cold engine. But if magnet in the solonoid is getting weak, sometimes it doesn't function to connect them all together.

It could also be that there is dirt, grease or rust or a combination of these on the solonoid plunger that puts a drag on it making it harder for the magnet to move the plunger and engage the starter.

P E H

Motorhead · #15 03-14-2003, 07:54 PM

With aged wiring, worn contacts in the ign switch and solenoids not as new as they once were, you can install a hard start relay on the starter solenoid. We did this all of the time on VWs...6volt and 12volt systems. You use a Ford starter solenoid which draws less that 2 amps to switch the key side of the MBZ starter solenoid. I have put these on MBZ diesels with good success.

Directions... Buy a 12volt grounded base Ford Starter relay.
1)Take a good sized guage wire,#8,#10 and hook it to the MBZ starter where the + battery cable hooks.
2)Hook that wire to one of the big terminals on the Ford relay.
3)Run another big wire from the other large terminal of the Ford starter relay to the small "Start" terminal on the MBZ starter.
4)Take the wire that comes from the key switch, the one that went to the small terminal on the MBZ solenoid "start" connection and hook it to the "S" terminal on the Ford relay.
5)Connect the Ford relay close to the starter with the base of the solenoid well grounded.

Basically you end up with the KEY closing the Ford relay which inturn takes Battery voltage right from the Starter through the Ford relay and hits the MBZ solenoid with a strong current supply.
Any questions, PM ME