On rare occasions starter keeps running afer engine starts and contionues running even after turning ignition off. The only way to stop starter is to disconnect battery cable. Could this be due to bad starter, ignition switch or somewhere upstream of the starter? All opinions apreciated. Otherwise starter works fine. This is on a 99 U320
Possibly a stuck/pitted starter solenoid?
Felix,
This is a story that you might find interesting. It happened to a buddy of mine:
He has a '95 U320 Cumminis M-11. He took off one day and drove a good distance until he lost power and pulled off to the side of the road. When he walked to the rear of the coach he smell something burning (electrical like) and saw his starter smoking - it was very very hot -paint on it was charred and discolored. What he discovered was that the primary solenoid (mounted next to battery isolator - looks just like a boost solenoid) had locked in the ON position and was engaging the starter the whole time he was driving. The teeth on the starter were gone but the teeth on flywheel were OK. He's not sure why the engine stopped (no shut down light). He thinks it might be vapor lock in the fuel line that runs close to the starter. He believes his starter didn't fail, the $20 solenoid did.
I had changed the auxillary start solenoid on the panel of the engine box a while back and thought that was the problem but the problem just again recurred. Am now thinking it is a starter problem. This is scarry because I cannot hear the starter running with the engine noise. H ard to dx an intermittent problem like this. I dissected the old solenoid It looked good. Connected to a 12 volt supply and functioned properly. I was under the impression that there is a solenoid on the starter.
Well ---- Power has to be getting to the starter thru that solenoid for it to keep running. I would look for a stuck solenoid or a shorted power supply to it. Check to see if you have power to the solenoid when you return the ignition sw. back to run after starting. Your ignition sw may be faulty or some other way there is power getting to that solenoid, or the solenoid has contacts that are stuck together and not opening when power is turned off to it. On your rig, is there some other connection that would put power to the starter? Some times there may be a feed to some other component from the starter or solenoid and if so, could be there. You may need to hook up a volt meter and monitor voltage at the starter if this is intermittent. Have a great day ---- Fritz
If your coach is similar to ours, you may find the attached circuit diagram helpful.
When you turn ignition from start position, many solenoids, relays should be not powered. With a meter you may find something stuck on, like the start solenoid which powers starter's solenoid.
After you disconnect battery and starter stops, will it start back up after immediately reconnecting battery?
After I reconnect battery terminals starter does not restart. It works normally with the ignition switch until problem occurs again which may not be for several months. This is a very intermittent problem. It has occured four or five times in the last several years.
I would connect a volt meter to the starter and just leave it there to monitor starter voltage. Leave it connected and located where you can monitor it during start up and if voltage still exists when ig sw is returned to run, shut down and check other key points that you have determined ahead of time. Have a great day ---- Fritz
Intermittent problems are sometimes very hard to track down. Rather than risk a starter and the possibility of being stuck somewhere, I would look at replacing ignition switch (where the key is) and any solenoid in the starting loop. They total much less $$ than the starter and only a tiny fraction of a service call plus starter.
You only get so many stuck starter incidents before it fails. Not as likely but replacing the ring gear on the torque converter would be super expensive.
Pierce
The solenoid is the relay switch for the starter. You have a sticking solenoid. It is like a relay for the headlight - handles the current that the wiring from the on / off switch, and the switch itself, can't handle. The solenoid is the only device between the batteries and the starter.
The only starter relay on my coach beside the one on the starter is an accessory start relay which is a black plastic box on the back wall of the engine made by bosch and rated for 75 amps. I have changed this relay twice and the problem still ocurs on rare occasions. James T. thinks it is the relay on the starter that is hanging up. He recomended replacing the starter with the cummins starter that they are using on the new coaches that has a built in acessory relay. It would take some minor wiring changes. I am thinking of having this done at the factory since some wiring changes will be needed. Besides I have taken two of these relays apart and tested them with a 12 volt supply and they worked and looked pristine. Thanks for all the replys.
Starter problem solved. When local cummins dealer removed old starter they found cap on end of solenoid on starter was missing exposing it to moisture. Flywheel gears were good. New starter smaller and lighter than old one. I did not want a rebuilt starter.