300 SDL Stuck Starter - PeachParts Mercedes-Benz Forum

ccooper · #1 02-25-2008, 01:19 PM

I now have another issue to add to my litany of starting problems. My starter motor attempts to spin, but makes a loud "GA-CHUNK" sound and stops, almost as if the flywheel was frozen. I recently replaced the starter with a remanufactured Bosch, and it has started flawlessly until now.

I eliminated the NSS and starter switch as culprits as I shorted the terminals on the solenoid, getting the exact same result. It is definitely not a bad motor, evidenced by the loud klank that shakes the car versus the much quieter "click" a solenoid attempting to start a bad motor makes. The condition of the glowplugs seems irrelevent as the starter doesn't even spin (the GP light does come on).

There are two things it seems it could be to me. I do have a cracked head, leaking coolant. First is the cylinders could be rusted. The second is the water vapor has fouled and plugged the catalytic converter. However, aside from the coolant loss, the car has run flawlessly and with no lack of power.

I just want to note why I'm continuing to run it, even with the cracked head. I work from home and only need to drive a 45 mile roundtrip twice a week, plus sundry errands, so the car is used regularly, but lightly. Being self-employed and growing my business, I want to put off purchasing a full-time car as long as possible.

I'm also intending to replace the engine with a used one from another car. My compressor is bad, the injection pump has issues, and so forth. For me, while it's a calculated risk, the replacement cost of the ancillaries justify the $2500 plus install it would cost me. I didn't check my coolant and as a result, the car overheated, causing the #14 head to crack. How do I know? Before the hoses had flex in the morning, after they were hard as a rock. Even if I get a used engine but with a good #14 head, all I need to do is ensure the car doesn't overheat. Lesson learned.

Does this sound like a fixable issue? If so, what are your thoughts on it and what would it take. Or am I best advised to either replace the engine or to get a full-time car and put the SDL out to pasture as a hobby car?

Casey

LUVMBDiesels · #2 02-25-2008, 01:27 PM

Can you turn the engine over with a wrench on the crankshaft bolt? If so then the starter might not be installed correctly, if not then start saving that $2500...

JimSmith · #3 02-25-2008, 01:28 PM

Try turning the engine over by hand, meaning, put a socket on the hex head of the bolt holding the pulley on the crankshaft with the transmission in neutral. If the engine turns over by hand, the problem is more likely starter-related. It is possible if you don't have any grinding or other sounds, other than the "clunk" of the solenoid driving the pinion into the flywheel, that the starter is misaligned and pinion gear teeth don't engage. This will prevent the motor from being energized as the system functions by having the solenoid close the contacts for the starter motor at the end of its stroke. If it is not getting to the end of its stroke for some reason you have to address that. Check the bolts and that the starter is seated against the bell housing flange correctly. Good luck, Jim

kerry · #4 02-25-2008, 01:32 PM

Sounds to me as if your engine is seized. Like everyone else says, try turning the engine over with a socket and breaker bar on the crankshaft bolt. If it doesn't turn buy a lottery ticket.

Brian Carlton · #5 02-25-2008, 01:39 PM

Quote:

Originally Posted by ccooper

I now have another issue to add to my litany of starting problems. My starter motor attempts to spin, but makes a loud "GA-CHUNK" sound and stops, almost as if the flywheel was frozen.

There are two things it seems it could be to me. I do have a cracked head, leaking coolant. First is the cylinders could be rusted. The second is the water vapor has fouled and plugged the catalytic converter. However, aside from the coolant loss, the car has run flawlessly and with no lack of power.

Coolant is leaking into one cylinder while it's sitting. It doesn't take much coolant to stop rotation of the engine on the compression stroke..........there's not a lot of volume in there. The coolant will eventually drain through the ring end gaps if under compression..........and hence the reason that you can eventually start it.

I'd guess that you never see this problem unless the vehicle sits overnight..........correct?

If you had a starter problem, you'd see the issue on more frequent occasions.

babymog · #6 02-25-2008, 01:40 PM

Depending on the location and severity of the head gasket or crack problem, it could also be hydrolocked. Try turning the engine by hand backward a few degrees, if it turns backward but not forward from where it is, I'd guess hydrolock.

ccooper · #7 02-25-2008, 02:14 PM

Thank you all for the replies. I hadn't thought about hydrolock. Just a clarification and a question.

Brian Carlton:

Quote:

The coolant will eventually drain through the ring end gaps if under compression..........and hence the reason that you can eventually start it.

I'd guess that you never see this problem unless the vehicle sits overnight..........correct?

This is the first time this has happened. I tried to start it Friday, Saturday, Sunday and this morning, with temperatures ranging from 50 to 75 degrees, sunshine and clouds. Same result each time. However, the problem happened after the vehicle sat overnight.

babymog:

Quote:

Depending on the location and severity of the head gasket or crack problem, it could also be hydrolocked. Try turning the engine by hand backward a few degrees, if it turns backward but not forward from where it is, I'd guess hydrolock.

Silly question: which way is forward and which way is backward? I haven't had a chance to check it yet. I'm assuming a long handled torque wrench will get me there, but what size socket? I've feared to tread near the engine.

JimSmith · #8 02-25-2008, 02:38 PM

Forward is clockwise looking at the front of the engine (that would be counter clockwise if you were seated in the driver's seat). Don't recall the socket size - 19 mm or 22 mm? Someone else with better memory can chime in.

I would also check the condition of the starter and its fasteners. Jim

Brian Carlton · #9 02-25-2008, 02:39 PM

Quote:

Originally Posted by ccooper

Thank you all for the replies. I hadn't thought about hydrolock. Just a clarification and a question.

Brian Carlton:

This is the first time this has happened. I tried to start it Friday, Saturday, Sunday and this morning, with temperatures ranging from 50 to 75 degrees, sunshine and clouds. Same result each time. However, the problem happened after the vehicle sat overnight.

Well, the question that is now apparent is:

"Will the coolant drain down through the ring gaps"?

I would tend to think so.........but, others might have a different opinion?

Time to go back to the manual rotation of the crankshaft with a socket wrench. If there is coolant in the cylinder.......you won't be able to turn it a full turn.

kerry · #10 02-25-2008, 02:48 PM

27mm?? At least that is what I think it is on a 617.

pawoSD · #11 02-25-2008, 02:59 PM

Could pull the glowplugs and try cranking....if coolant shoots out of one or more of the holes and the engine is able to spin freely...then you've found your problem.

JimSmith · #12 02-25-2008, 03:09 PM

Quote:

Originally Posted by Brian Carlton

Well, the question that is now apparent is:

"Will the coolant drain down through the ring gaps"?

I would tend to think so.........but, others might have a different opinion?

Time to go back to the manual rotation of the crankshaft with a socket wrench. If there is coolant in the cylinder.......you won't be able to turn it a full turn.

If the liquid leaks in faster than it leaks out "just sitting there," it will just stay too full to allow the crank to rotate. If you apply torque to the crankshaft in the direction of pushing the piston up in the afflicted cylinder, it should stop leaking fluid in, and force the fluid in there to leak out faster, which may allow you to turn the crank very, very slowly. If that was the scenario I would not have expected to hear a "clunk" though. The "clunk" implies there was some significant relative motion that abruptly ended, making the "loud "GA-CHUNK" sound."

We won't know until the owner tries to turn the crank by hand. If it moves, it seems to me this is best explained by a starter that is either broken from abuse or is loose, and the pinion is being misaligned and hitting a hard stop before it engages the flywheel ring gear teeth or closes the electrical contacts that energize the starter motor.

I once ruined a starter by not changing engine mounts before they literally broke. Daughter was driving the car at college years ago and complained the car would not start unless she got it rolling in neutral, jumped in, put it in second and dropped the clutch (she called it "pop starting"). We were together with her and the car at a summer gathering so I checked the car out. I was kind of stunned by the way the car adapted to a broken left side (injection pump side) engine mount.

The starter lifted the engine and rocked it over towards the passenger side of the engine compartment when rotating the crank against the resistance of the compression stroke, then, abruptly let it crunch back down on the driver's side mount remnants, and then repeated the process. It was turning the crank so slowly on the compression stroke it wouldn't start on a hot summer day, even all all warmed up after a recent pop start and run around the area. Before seeing this dance under the hood, I thought the engine was shot, except for how strongly it climbed hills on the Northway from Albany, NY to exit 32. New mounts, and a new starter fixed it for another 4 years and about 50k miles.

The starter was really shot. When I removed the front support bracket, the front section just fell off. The screws inside that held it together were sheared off.

Anyway, my point is the starter can be either loose on its bolt circle and has become misaligned, or it can just have some broken fasteners inside that allow it to become misaligned. An attempt to roll it over by hand will be revealing. Jim

NJ300sdl · #13 02-25-2008, 03:28 PM

Believe the size of crank bolt is 27MM.

ccooper · #14 02-25-2008, 08:17 PM

I get the wrench in to the crankshaft bolt how? I haven't had the time to jack up my car to try to get to it from underneath. For grins, I turned the fan belt with some assistance from the power steering pump, with an interesting result.

I tried turning it the forward (clockwise) direction. No go. Which makes sense since my starter on 00 wire couldn't do it either. I tried the backward direction and was able to move a quarter turn. I actually could have done more, but I was curious to see if that impacted the starter.

The bad news is the car doesn't start. The good news is the engine turned slightly, before coming to a stop. I suspect Lary Bible's hypothesis about coolant in the cylinder applies. The starter motor is designed to be strong enough to compress air at 19:1. It is not strong enough to compress liquid, though. By turning the belt backwards, I effectively created an intake stroke, increasing the volume. The starter could turn until the liquid was compressed to the point it created too much resistance, causing it to stop. It's exactly the same as how the electric seat motor stops as soon as the seat has reached the end of the track (resistance). Needless to say, the next try gave me the "GA-CHUNK" again. Just like the seat motor would.

So what do I do next? I suspect I could rotate the crank backwards using my Mickey Mouse method. I would rather not have to lift the car and try it that way, especially since it looks like even from the bottom I'd need to remove the radiator. If that does resolve the issue, does your experience tell you it will keep recurring?

Again, thank you for your most helpful responses.

pawoSD · #15 02-25-2008, 08:21 PM

Rotating it backwards too much can cause the timing chain to skip time or get messed up....I'd not recommend that. I'd pull the glowplugs and try cranking it.

Also, "strong enough to compress liquid" Liquid cannot be compressed, at all. Thats why hydraulic things work so well.