Vovlo MD2B starting/wiring issue.

[Ramblingman]

The PO installed a new switch and starter on the Volvo MD2B. When I turn the switch there is a click and nothing more. Removed the starter and set it against the block. Then tried it, I heard the motor spin.

Back on the engine there is a click only.

New strong batteries.
New charger. (Mastervolt)

For those familiar with the engine - it appears to be a positive ground block. Is this true? The positive is currently (I got it that way) attached to the block at the alternator mount.

Also - the engine spins freely and easy by hand.

[gjordan]

I doubt very much that it is a positive ground system unless it is a very old English boat. Try finding a wiring diagram on line and trace things out. As far as testing the starter with it out of the block, just leaning it against the block wont give it a good enough connection to show if it is working. A diesel starter has so much torque that if you test with jumper cables ( a better way) you will have to put your foot on the starter to keep it from jumping half way across the room. If you do it with jumper cables, put the negative to the starter case, and touch the positive to the insulated stud that goes into the starter. If it spins up slowly , or not at all, then you have found the problem. If it jumps like hell, the starter is probably fine, and check the wiring again.____Good Luck with it._____Grant.

[gjordan]

I just reread your post, and after you get the starter sorted out, be prepared to test the alternator. You may have smoked it with the positive ground. I hope I am wrong, but dont be surprised. ____Grant.

[Ramblingman]

I keep thinking the PO had it hooked up wrong and cooked, the starter, the batteries, the charger, the alternator.

[Cheechako]

I dont remember my MD2B being positiive ground. You might look at the flywheel teeth. Or maybe the starter can spin unloaded but the brushes are too bad for it to turn the engine.

[Ramblingman]

So I am thinking this setup I inherited is wrong but in a nutshell this diagram shows that the positive goes from the batteries to the switch, to the block attached at the bracket that holds the alternator in place.

http://ramblingman.org/basicwiring.JPG

The cable from the battery switch (also installed by PO) to the engine is pretty stiff and runs pretty tight. It would reach the batteries if I made them face negative towards the engine.

[gjordan]

Get an actual Volvo diagram. That drawing is wrong._____Grant.

[Ramblingman]

Originally Posted by gjordan

Get an actual Volvo diagram. That drawing is wrong._____Grant.

I thought so too. I have removed the engine from wiring at this time and now have a Volvo workshop manual. The block should be negative according to the manual.

I figure a day of poking about and I should at least diagnose the issue.

Thanks all!!!