MM rebuilt starter seems dead

[skhorleb]

I have a late model A4. I rebuilt the engine 2 years ago and it has worked great ever since. Electronic ignition, new coil, gaskets, electric fuel pump, complete engine rewiring, resurfaced head, new engine studs, rebuilt the carburetor, flushed the fresh water cooling system...Lots of TLC! The rebuilt starter I purchased from MM 2 years ago has suddenly stopped working--no crank, no clicking, no sound. The starter does not function intermittently. The waterproof ignition switch I just purchased is good. There are no loose wires. I shorted the two posts on the solenoid with the ole' screwdriver trick and while it sparked, it failed to energize the starter.

I have plenty of juice--5 batteries (4 and 1) split between 2 banks. All fuses are good for every circuit including the 40 AMP fuse on the ignition circuit. The lights for the gauges work, cabin lights, and everything else off the main switch panel is fine - nav lights, steaming lights, radio, bilge pump, etc...

Next, I pulled the starter out and took it to the local O'Reilly's Auto Parts store. They took it in the back, tested it, and told me the starter was "good." I reinstalled it just in case of some fluke but no change.

Finally, I took it home, removed the back plate and observed no bad wiring or brushes. After reinstalling the starter's back plate, I turned to desperate measures. Using auto jumper cables, I tested it with my car battery (12 V system) which is brand new--negative to the flange on starter housing and positive to the lug directly behind the solenoid that disappears into the starter motor case. This test failed to energize the starter too.

Does all of this rule out the solenoid? How long is the warranty on MM's starters? Other than trying to find a reputable starter repair shop, is there anything else I can try to fix it? Thanks. Steve H.

[Don Moyer]

Steve,

You've done a great job of trouble shooting but I'm wondering how O'Reilly's Auto Parts store checked out your starter. Did you (or could you) check back with them to see what they did to get the starter to work? The only thing I can think of in addition to the things you're already mentioning is the possibility of a weak grounding path between the starter and engine block. Do you connect the grounding cable from the battery directly to one of the starter mounting bolts? The fact that the starter would not work even when you connected your jumper cable directly to the motor lug behind the solenoid is particularly suggestive of a major grounding issue.

Don

[skhorleb]

Hi Don,

I hope things are going well for you. As usual, I believe you are right.

I am not sure what the folks at the O'Reilly's Auto Parts store did, but I had to look up the Delco model number for them before they could run their test. 'No idea if they had to configure parameters on some test gizmo first, but they had it in the back only about 5 minutes before they concluded the starter was fine.

My engine grounding cable runs from the main ground terminal block to the rear of the engine block. When the starter is installed, I do not have any wiring going to either of the starter mounting bolts. The sea water pump mounting bracket shares the same upper bolt with my starter. (Fresh water cooling system is installed.)

My multimeter showed a strong connection, but just in case of restricted current that I could not detect, I replaced the lugs on both ends of the ground cable. This modification was completed after I had taken the starter to O'Rielly's and reinstalled it. No change.

After a few days of staring at the starter with the hopes something would come to mind, staring became unflattering glares at my starter. I broke down and took it to a reputable starter shop I found. He took it to the back of his shop and tested it. He told me it worked for about one second and then nothing. His diagnosis: internal ground wiring. His recommendation: either repair whatever wiring is bad or complete another rebuild, whichever I feel more comfortable with.

[Don Moyer]

Steve,

I can't promise that our starter rebuilding vendor will consider any warranty coverage after 2 years, but I would definitely like to be kept in the loop to learn more about this second shop's finding of a faulty "internal ground wiring". Assuming their diagnosis is correct, it should be an easy fix for them. I'm not sure why they would suggest another complete rebuild.

Don