engine won't turn over

[Carolyn Phillip]

Please we need advice on starting our diesel engine on the powerboat we recently purchased. One of the 1986 8.2 liter Detroit diesels will not turn over when the starter is engaged. The starter turns fine and the bendix appears to operate as it should on a bench test. Our new batteries are good and start the second engine okay; and will occasionally start the problem engine. The engine ran really well when it did start and it only has 1300 hrs on it. The starter motor mostly now just free spins when installed on the non-starting engine and when energized. The flywheel teeth and the bendix teeth look good. The engine did start a few times since we bought the boat and ccasionally made a grinding noise. I do not know what the grinding noise was from but saw no indications of teeth chewed on the bendix or flywheel.
The bushing bearing on the shaft the bendix rides on is a little sloppy but does not appear to be causing the problem.
Thank you fellow-members! Any advice would be greatly appreciated.

 

[Xlantic]

Well, if the starter spins freely then the Bendix is clearly not engaging the flywheel for some reason. Lubrication of the Bendix tends to fix this problem but if it worked correctly during your bench test then it could be the "sloppines" you detected.

 

[Lepke]

Not every starter that bench tests ok is good. If the solenoid windings are weak or getting a bad connection, the gear may not pull all the way into the flywheel gear.
There are a couple way to trouble shoot in place. If you touch a small wire between the small terminal and the one where the battery cable attaches, you will bypass the key and entire ignition circuit. If that makes it work, then you have to search out the wiring to and from the key and any relays.
Or you can cross the two heavy terminals with something like a screw driver, and the starter will spin. That bypasses the solenoid but doesn't operate the Bendix drive. Doing the key or small wire at the same time should make the starter operate normally. If not you have a bad solenoid.
A new starter is about $325 and currently there is a used starter on ebay for about $150.

 

[Carolyn Phillip]

engine won't start

Not every starter that bench tests ok is good. If the solenoid windings are weak or getting a bad connection, the gear may not pull all the way into the flywheel gear.
There are a couple way to trouble shoot in place. If you touch a small wire between the small terminal and the one where the battery cable attaches, you will bypass the key and entire ignition circuit. If that makes it work, then you have to search out the wiring to and from the key and any relays.
Or you can cross the two heavy terminals with something like a screw driver, and the starter will spin. That bypasses the solenoid but doesn't operate the Bendix drive. Doing the key or small wire at the same time should make the starter operate normally. If not you have a bad solenoid.
A new starter is about $325 and currently there is a used starter on ebay for about $150.

Thank you Lepke for your kind, thoughtful & quick response...I did bypass the ignition wiring and went directly to the solenoid, and the solenoid engaged the same as it did with the ignition wire--no change. I did bypass the solenoid switch with a screwdriver snd connected the battery hot wire to the starter. The starter spun free without the bendix engaged. I put a spanner between the bendix and the bendix stop washer, and it appeared to have have plenty of force.
I am reluctant to order a new starter since we are in the Bahamas and communication, delivery, brokerage, taxes, etc. can be demanding.

 

[Lepke]

You should verify that the Bendix linkage moves thru the entire range without binding. Some lube on the shaft and pivot point might help.

There may be someone there that rebuilds starters.
I believe the engines turn in the same direction. If so you could swap starters and see if the other starter works on the balky engine.
In the past, I have started one engine, carefully remove the starter and use it to start the 2nd engine. You need to maintain power to the electronics on the first engine.

Good luck.

 

[SoWhat]

Switch starters. Quick and simple diagnosis.
If no joy, attempt to turn crankshaft pulley nut. You might need a 3' extension on your wrench. Should be stiff but should turn.

 

[plittle2005]

As described above, this is usually what happens when 2 adjacent teeth are missing on the flywheel ring gear.

Sometimes it will mesh, others not.. Bar it over and inspect all teeth thru starter opening.

 

[Carolyn Phillip]

yup...found the problem. wow. Thanks for all of your kind and wonderful help members. After dismantling the starter and shining a flashlight down the inside of the bendix, I saw the "worm gear" was stripped...not a problem with the starter shaft.