1969 L36 Starter Grinding Noise

[Steve Nelson]

Once last weekend when I attempted to start my 69 390HP 4-spd the starter made a nasty grinding noise. I thought it may have been a one time thing since it had never happened before. However, it's happened twice now this weekend. All other times the starter has functioned normally when starting the vehicle.

I believe the starter is original, and nothing related to the starter, or starting mechanism has been altered or modified for at least the last 20 years, if ever. So I don't think it would be a shimming issue.

My question is is it likely that the starter itself is beginning to fail, or is it likely that something else in the starting mechanism (like the flywheel teeth) is getting worn or starting to fail? Should I replace/rebuild the starter? What's the best way to diagnose the actual root cause of the grinding noise?

Thanks,

Steve Nelson

[John O.]

Re: 1969 L36 Starter Grinding Noise

Hi Steve.

Just for the heck of it, check to see if the starter is loose. Maybe the bolts got loose.Grag hold of the starter and see if it moves. That can cause the mis-aliagment of the teeth. And it might only happen now and then.You might even have a bad solenoid.When trying to start the engine it might not be retracting fast enough and getting caught against the flywheel.If the starter is tight. Take it out and check the starter gear for fresh wear.Also check the flywheel teeth for wear.There is always the possibility of the flywheel coming loose. Then do a bench test.Use your battery and jumper cables to see if the solenoid extends the starter gear and the starter rotates ok.

Other than that,buy a new one. There not that much. Unless this is a numbers matching judged car.....Good luck..John

[Joe L.]

Re: 1969 L36 Starter Grinding Noise

Steve-----

My guess would be that you may be experiencing the beginnings of a starter drive problem. I'd do the following:

1) remove the starter and replace the starter drive. It's not very difficult to do. It might also be a good time to rebuild the complete starter motor. This is not too difficult, either, and there are not really very many parts that normally get replaced in the process. The starter drive is normally not one of the items that get's replaced. However, I always replace them and, especially in your case, I'd say it's critical to replace it. The starter drive is available from GM under GM #10470757 or Delco D-2051 for a current GM list of $31.90 (less through Delco);

2) with the starter off the engine, inspect the ring gear teeth on the flywheel. Some wear is normal and acceptable. Severe wear or missing teeth mean you need to replace the ring gear;

3) rebuild the solenoid. Replace or, at least, "reverse" the solenoid contacts under the "Bakelite" cover.

[Terry F.]

Re: 1969 L36 Starter Grinding Noise

I was wondering what help it is to reverse the leads under the bakelite cap of the solinoid? I believe they are soldered to the terminals. Just wondering, I am sure you have a good reason.

The other problem could be a starter misalignment. I have two shims under the end of my starter housing. They were present when I pulled the starter to rebuild on my 390 hp.

I agree, I would pull the starter and rebuild it. Chances are it needs a freshy fresh. Easy to rebuild, especially if you have the overhaul manual. Later, Terry

[David D.]

Re: 1969 L36 Starter Grinding Noise

Steve, If the starter is original, with the cast iron nose and open end, check if the bushing is still intact, after starter removal, of course. It used to be common for the bushing to walk out of the end of the nose cone, from use. The fix, if the bushing is still useable, is to tap it back in and stake it in place. Dave

[Jim T.]

Re: 1969 L36 Starter Grinding Noise

What Joe may be referencing by reversing is the terminal that the battery cable connects to. The contact point inside the cap of the battery cable terminal makes electrical contact with only half of its contact area as manufacutred. With the battery cable removed from this terminal, them remove or loosen the retaining nut, twist the terminal 180 and secure. You will now have placed an unused and unworn contact area for electrical contact with the solenoid plunger. This can be done with the starter in the car.

[Terry F.]

Re: 1969 L36 Starter Grinding Noise

I know what you are talking about now. Makes sense. Terry

[Terry M.]

Re: 1969 L36 Starter Grinding Noise

The washer (I have forgotten what the official GM term is for this part, but it is the part that moves when the solenoid is energized.) that contacts the battery terminal, if the solenoid is old enough, can also be reversed to provide a fresh contact surface to the battery terminal. The newer construction stakes the washer in place and makes it impossible to reverse. A new washer is called for, in that case. At the minimum, disassembly of the solenoid will allow inspection of these parts and replacement or re-positioning as necessary.
Back in the day we used to teach this as part of Auto Shop 101, but no more. Newer starters and alternators are often not field rebuildable. Another nice thing about old-school cars.

[Rod Wagner]

Re: 1969 L36 Starter Grinding Noise

There is also a brass/copper bushing in the back end of the starter. If it has significant wear, the armature can rub against the starter case itself, causing noise. While you are at it, check the brushes and the commentator (the section of the armature the brushes touch)for wear. Clean the commentator so there are distinct "lines" of copper and bakelite. This can be done with some emory cloth, but the bast way is to chuck the armature in a lathe and use a fine file.