240D Solenoid diagnosis - Page 2 - PeachParts Mercedes-Benz Forum

frictionshifter · #16 05-20-2018, 05:39 PM

Ok - Battery is charged, now showing 13v. But I still think the rebuilt starter is not working; it has never worked since I got it back from the shop. I get no crank or even a click at the starter. Tried to jump the starter too, with no luck. I plan on pulling it tomorrow morning and bench testing, and likely returning it to the shop.

I 'think' the ground problem is solved. The block-chassis ground contact points looked clean and solid, but I tied the speedo cable so it is not rubbing the ground. Maybe that was it? After putting the recharged battery back in, I tested the starter with the jumper cable between the Battery-neg and block. When the engine still didn't start, I removed the jumper cable, and then tested the GP voltage during pre-glow. It read 1.5-1.8v between Battery-Neg and each GP, and 10.8 between GP and block. That the GPs were actually warming up was a sign of some progress. But should they only be pulling 1.5v each (under load)?

Diseasel300 · #17 05-20-2018, 06:09 PM

The speedo cable rubbing shouldn't affect anything electrically. It's just not a good idea to have them rubbing, eventually you'll damage something.

The battery negative should be common with the engine block. If you measure 10.8V to the block, you should measure 10.8V to the battery negative.

I think at this point we need a picture of how your glow plugs are connected to troubleshoot that problem further.

If you suspect the starter is not working, you should be able to take it to somewhere like Auto-Zone and have it tested. If it works on the bench, you know it isn't the motor.

ROLLGUY · #18 05-20-2018, 06:24 PM

As a rule, I always test a starter (new or used) before I install it on the engine. It is worth the effort. I don't like putting in a starter, only to find that it does not work AFTER I remove it.

frictionshifter · #19 05-20-2018, 09:01 PM

My previous measure of the GP voltage was wrong; I am getting a steady 10.8 between GP and block, GP and batt-neg.

Rollguy - I like your rule. I should have asked the shop to test it for me before leaving. Hoping I can work that starter out tomorrow and get back on the road.

funola · #20 05-20-2018, 10:11 PM

If you had a local shop rebuild your starter, I am sure they tested it before they handed it back to you. Check that the cables to the starter are connected correctly and connections are snug (do not over tighten or you can crack the plastic on the solenoid), mounting bolts are tight (that's how the starter is grounded), ground strap is clean and snug. You can jumper the small terminal on the starter to bypass the key switch and it should crank.

ROLLGUY · #21 05-20-2018, 10:27 PM

Quote:

Originally Posted by frictionshifter

My previous measure of the GP voltage was wrong; I am getting a steady 10.8 between GP and block, GP and batt-neg.

Rollguy - I like your rule. I should have asked the shop to test it for me before leaving. Hoping I can work that starter out tomorrow and get back on the road.

Even if the shop tested it (and I assume they did), It would have been nice to know for yourself before installing it. I learned the hard way years ago. I put a starter in that I assumed was good (came out of a running car). After installing it, it would not crank. I pulled it out and tested it. It did in fact work, and I found out the no start problem was elsewhere. If I would have tested it first, I would have not removed the starter, but looked elsewhere first.....Rich

frictionshifter · #22 05-21-2018, 11:03 AM

Morning update - STILL NOT STARTING

The starter was faulty - there were two solder points in the starter motor that needed to be re-soldered. The shop fixed it, and I watched them re-test.

Installed the starter. Check all the voltage:
12.8v in the battery
At pre-glow, 11.5v Battery Neg to Starter positive, 10.8 Battery Neg to Glow Plugs, 11 Battery Neg to GP fuse.

Attempt to start - just a clunk. I assume the starter is engaging but not turning the flywheel. With that voltage, shouldn't the starter turn the flywheel? I tried 5 times and stopped. I also tried with jumper cables to another car.

What am I missing here? I'm in Florida, so its not cold. Fuel supply and compression have never been an issue. It was running strong a week ago when the starter went.

ROLLGUY · #23 05-21-2018, 11:37 AM

The only thing left is the neutral safety switch and the ignition switch. I would check the NSS first, that is usually the culprit.

frictionshifter · #24 05-21-2018, 11:58 AM

No NSS as it is a manual.

Even with all that voltage running to the GPs, could the Ignition Switch still be at fault? I thought the GPs and starter solenoid were on the same circuit from Ignition.

Edit: One issue this car has always had is that pre-glow relay/light stays on for its full cycle (~90 secs). Not sure if that helps confirm Ignition switch or not.

strelnik · #25 05-21-2018, 12:05 PM

Quote:

Originally Posted by frictionshifter

Had the starter rebuilt at a local shop. Installed it this afternoon. NO GO! Despite my glow plug issues (chronicled elsewhere), the starter barely clicks. Even when I attempt to jump it from the battery, or use the screwdriver trick. I get a click from the ignition area when jumping it (a click that is louder in the car than outside; and which lights the pre-glow lamp).

If the starter were rebuilt properly, shouldn't it at least try to crank the engine? Guess I know where I'll be Monday morning.

Many Benzes originally had two ground cables: a short one from the (-) terminal of the battery to the body; and another one underneath, usually mesh, from the chassis/body to the transmission body.

I often replace the little cable with a marine battery clamp and a 25-30" battery cable with a eyelet at each end. There's a spot on the block to attach the cable, right at the passenger-rear side of the valve cover. 12mm bolt. The other end goes to the battery clamp.

The original battery cable arrangement was ok but now you need something better, more reliable.

frictionshifter · #26 05-21-2018, 12:06 PM

Is it possible for the engine to just seize? I tried turning the crank with the PS bolt. The PS belt just slides instead of turning the crankshaft.

Diseasel300 · #27 05-21-2018, 12:37 PM

The engine could potentially be seized, turning the PS pulley isn't a reliable way to spin the engine. You want a 27mm hex on the crankshaft nut. If you can turn the engine over with a wrench, it isn't seized.

Does the manual have a safety switch on the clutch pedal?

Glow plugs are initiated by the keyswitch, but they have no bearing on whether or not the starter motor will crank. Glow light malfunctioning is a common issue with the series style controller running parallel glow plugs, the light will basically stay on until the relay times out. Turn the key, count to 5 and you should probably be glowed long enough to start for the most part. About the time it takes you to put your seatbelt on after turning the key to preglow.

Find a helper and have them attempt to crank the engine while you measure voltage between the engine block and battery negative. You should see no voltage, or if you do, extremely low (<1V). If you see voltage present, or worse - battery voltage when the starter is "engaged" you have definitively confirmed you have grounding issues between block and battery.

frictionshifter · #28 05-21-2018, 05:23 PM

Alright. I'm convinced the engine is seized. Which would explain why the starter pinion gear spun out. All the electrical is working fine, as far as I can tell.

Went to the crank bolt with a 27mm socket and could not get it to budge. Fan shroud and fan were taken off, plenty of room, pulling clockwise, and nothing.

The car sat for 2 days before any start problems. There was no indication of any running issues before. Where does it go from here?

Cut the AC belt?
Pull the GPs and check for fuel in the cylinders?
Tow it to a professional?
Part it out?
Burn it?

Diseasel300 · #29 05-21-2018, 09:18 PM

Pull the accessory drive belts off and see if it makes any difference in your ability to turn the engine by hand. You really need at least an 18" handle on your socket to turn the engine, with the high compression it's very hard to turn.

If still no go, pull the GP's and see if you're hydrolocked with fuel, oil, or coolant. With the GP's still out, try to turn it over by hand.

If still not turning, you may have some sort of mechanical failure.