Engine won't start

scurvy · #1 (**permalink**) 10-22-2007

This is probably part three by now, but this is the gist!

1973 Volvo-Penta MD6A (like Gummy's). Inboard diesel, 10hp, 2 cyl.

Turned key about three weeks ago an just got chatter from the voltage regulator,relay.

1. Charged batteries....."chatter"
2. Cleaned connections as best as I could..."chatter"
3. Replaced old regulator/relay with new"used" original bosch regulator/relay...."chatter"

4. Tried jumping the starter directly with jumper cables...."sparked and motor never turned a revolution"!
5. removed starter and had it bench tested.....ran like a charm once it was grounded. ???

Now what? Could it be a grounding issue? Could it go back to the ignition key? How exactly do I check for a bad ground and typically, what does one do to correct this?

Thanks for all your suggestions and know-how!
Chris

PS-just finished this little painting for my avitar...what do you think???

timebandit · #2 (**permalink**) 10-22-2007

Sounds like a bad ground. EZ way to check is to take jumper cable and conect from battery ground to starter. If this works check where the cable is bolted to the engine also be sure there is no paint at the engine, starter contact point. I would connect the ground cable to a bolt that mounts the starter to the engine, no paint please.

timebandit · #3 (**permalink**) 10-22-2007

There is a small chance that the engind may be Hydro Locked. You can check this by turning the engine over by hand in the direction of rotation it normally turns.
If you cant turn it by hand the starter wont turn it.

faisond · #4 (**permalink**) 10-22-2007

Certainly timebandit's suggestion is a good one. Quick and easy to check. If that fails, several other possibilities come to mind. Since you jumped directly to the starter, that eliminates the ignition switch or wiring as the no-crank cause. The fact that you had sparks present when you jumped to the starter could imply that your ground is OK but of course, it only takes a little resistance to make the starting circuit inoperative. Your original post mentioned you charged batteries and cleaned the connections. You should have a good 12.8 -13 v thirty minutes after you removed the charger. Measure it at the starter and at the batteries to be sure. Check tightness of the positive cable where it bolts to the starter solenoid. If voltage is good, connections are clean and tight and if timebandit's ground test doesn't produce results, I'd begin to suspect a weak starter solenoid, bad brushes, or a bad spot on the starter commutator, or high armature resistance. If the bench test didn't load the starter but simply ran the motor unloaded, it may not have proved anything. You could have one of these starter problems. Good luck.

scurvy · #5 (**permalink**) 10-22-2007

Quote:

Originally Posted by timebandit

There is a small chance that the engind may be Hydro Locked. You can check this by turning the engine over by hand in the direction of rotation it normally turns.
If you cant turn it by hand the starter wont turn it.

Hi timebandit!

The engine turns right over...no problems. I think it is the ground too...I have tried everything else, but still not sure how I check it from the starter motor back. There is the large cable that is attached tot he large post on the starter. Then, I have two other wires that lead to two posts and one lone wire that is attached by a bolt to the bottom of the starter. I imagine one of these goes back to the starter switch...and not sure about the others. The dynastart is a generator as well, so I thought that the other wires may lead back to the battery for recharge?

any suggestions? am I warm?
Chris

Gummy · #6 (**permalink**) 10-22-2007

The same thing happened to me. I could take the dynastart off and it would spin but once on the engine it would not spin. It drove me crazy. Somehow just the tension of the belts on the motor was enough to stop it. I took it off and indeed, I could stop the motor easily with my hand and a rag. That's when I decided to clean up the inside. That fixed mine. Now occasionally mine won't spin but I can just advance it a bit and it will spin again. I need to replacethe brushes.

I bypassed all the electical questions(relays etc) by touching a hot wire to the large post on the dynastart. I still do this when troubleshooting so I can be right next to the engine and see what's going on.

scurvy · #7 (**permalink**) 10-22-2007

Thanks Gummy and Faisond!

Gummy, I wish that I could be of more help with your situation...how are things coming with your MD6A?

Chris

Gummy · #8 (**permalink**) 10-22-2007

Very Very frustrating. I was so disappointed on Fri. but I am feeling inspired again. I am going to change all my fuel lines and have the injector pump rebuilt. I am thinking about pulling the head too to make sure there is nothing wrong where my injectors go in. We'll see about that. I may also see about changing the copper sleeves that my injectors go into as I get a bit of blowby between them and the injectors. Still thinking about it. I'll probably just go with the lines and rebuild first and see what happens.

scurvy · #9 (**permalink**) 10-22-2007

Gummy,

Well, you are waaaay ahead of me as far as your understanding of these engines is concerned. Too bad we didn't live closer...we could commiserate, exchange ideas, and keep the good micro-breweries in business!!!

scurvy · #10 (**permalink**) 10-24-2007

Would anyone suggest that I replace the brushes now while the starter is off, or wait until sring as the boat will be hauled in the next few weeks.

Chris