1970 deville starter problem

[L Rossi]

Hey there,

If this is too long, my car keeps killing starters probably because im using the wrong starter or installing it wrong (or both). Please help.

I have a 70 sedan deville that has the worst starter problem I have ever encountered. I've owned the car for about a year now and in that time i've driven it approximately 400 miles and have replaced the starter 4 times. The starter it had on it when I bought it was an oriely's reman starter that I think is just a GM "one-size fits all deal" which is probably why it didn't last. It wound up breaking while the car was at an alignment shop and the alignment guys tried to replace it but couldn't and ultimately made me pick up the car with a tow truck because they couldn't get it working. Eventually I got another oriely's starter and it worked fine for a while... until it started grinding against the flywheel. At this point I called the previous owner and asked him if he'd had similar issues. He said he hadn't but that when he had installed the starter there had been a bracket on the rear to help hold it in place that was now missing. I ordered this bracket and installed it and again the starter worked fine for a while.. then it began grinding again. At this point I wound up replacing the starter as the housing had cracked and it was no longer useable. I installed a new made (not reman) american made powermaster starter that is supposed to be made for cadillac (but it looks identical to the oriely's ones) with the bracket and lots of locktite and no shims. It worked perfectly for about 6 months. Now it has begun binding in the flywheel and won't start the car (obviously). I have spent both of the last two days under the car trying two different starters with varying amounts of shims and have had two results: either the starter is too far away from the flywheel and it starter chipping the teeth or it's too close the flywheel binds the bendix. Im sure I'm doing something wrong but I have very little expirence beyond this car and I don't know what else to do. If anyone has any tips that could help me get this right I'd love to hear them. This car runs pretty dang good all thjngs considered and it's a shame to just let it sit in my garage.it may also be important to note that this car has recently had a timing chain and waterpump replacement but ran and drove fine afterward and started up several times.

[badpoints]

Your timing may be to far advanced making the engine hard to turn over. Get an after market high torque starter

[James Landi]

I've had a similar frustating experience with another car company's starter... have you noticed whether or not the bolt holes have changed shape and are not perfectly round?  Perhaps, without the necessary rear bracket that was left off, the previous starters wobbled sufficiently and created damage and wear space in the bolt holes, slightly distending them.  If that's the case, no manner of Locktite of wrenching will keep the starter in place as torque pushes the starter away from the proper placement. If you can take a pinch bar and move the starter even slightly sidewards after you've moderately tighten it in place, then that;s the problem.  I "permanently" fixed mine by creating shims that I put in the sides that were distended (that is stretched) --- it was a tedious process but it did work.   Hope this helps, James

[Dave Shepherd]

Also make sure the starter bolts aren't bent. Any binding  will eventually  crack the nose of the starter. Plenty of info on line and videos on how to properly  shim the starter and check tooth contact. Doesn't  have to be Cadillac specific, any GM car is about the same technique.

[L Rossi]

Your timing may be to far advanced making the engine hard to turn over. Get an after market high torque starter

thank you that's a good idea. It is definitely advanced pretty far

[L Rossi]

I've had a similar frustating experience with another car company's starter... have you noticed whether or not the bolt holes have changed shape and are not perfectly round?  Perhaps, without the necessary rear bracket that was left off, the previous starters wobbled sufficiently and created damage and wear space in the bolt holes, slightly distending them.  If that's the case, no manner of Locktite of wrenching will keep the starter in place as torque pushes the starter away from the proper placement. If you can take a pinch bar and move the starter even slightly sidewards after you've moderately tighten it in place, then that;s the problem.  I "permanently" fixed mine by creating shims that I put in the sides that were distended (that is stretched) --- it was a tedious process but it did work.   Hope this helps, James

I haven't checked the holes but I will now... yikes that sounds terrible. I have tightened the starter all the way on (12 times last night haha) and tried very hard to move it each time after tightening and it wouldnt budge so I suppose that's a good sign.

[L Rossi]

Also make sure the starter bolts aren't bent. Any binding  will eventually  crack the nose of the starter. Plenty of info on line and videos on how to properly  shim the starter and check tooth contact. Doesn't  have to be Cadillac specific, any GM car is about the same technique.

Good idea. Yeah I checked a few videos for chevys that had what looked like an identical starter and they were helpful but my engagment has consistently been either so good that the bendix gets stuck in the flywheel or so bad that it doesnt even mesh with the teeth depending on shimming

[L Rossi]

Follow up question, does anyone know how many teeth the 70 deville flywheel has? I saw one thing that said 166 and another that said 168 and another that said 153. I would personally prefer not to have to climb under there and count them if any of you guys know.

[TJ Hopland]

Number of teeth was what I was wondering about.  I kinda remember something about the Cads needing a different gear but these days the reman and builders just don't care and one size kinda fits all. 

What kind of shape are the teeth in?  Maybe you have the right starters now but the damage was done previously.

[bcroe]

My experience is, all the 68 up BOP engines used the same basic
geometry for the starter gearing, till they came out with the TH325
trans on the 79 Eldo/Riv/Toro. Might be 166 teeth, does it matter? 

Certainly that engine needs the heavy duty starter, but I doubt that
is the failure issue.  Make sure the mount is secure, sometimes a
shim is needed for gear clearance.  I would make sure the timing
chain is not sloppy, otherwise it could cause a problem bouncing
back and forth starting. 

Check the condition of the flex plate that mounts the starter ring
gear.  These have been known to crack.  Here I found that the flex
plate on the 68-78 FWD Toro came with deeper teeth for durability,
than the same engine on a RWD car.  I have managed to collect
enough of these mechanically interchangeable flex plates for all
my O engine cars, FWD or RWD.  Perhps the 68-78 Eldo did the
same, a flex plate from one of them might help.  Bruce Roe

[L Rossi]

Number of teeth was what I was wondering about.  I kinda remember something about the Cads needing a different gear but these days the reman and builders just don't care and one size kinda fits all. 

What kind of shape are the teeth in?  Maybe you have the right starters now but the damage was done previously.

The teeth are actually in perfect shape. The flywheel is a bit chipped but not in a way that would stop it from engaging and i think most of that was there. All the starters i have had have 9 teeth on the bendix but the high torque ones i see online have 10 usually. I called a couple of auto parts stores but they told me to try ebay...

[L Rossi]

My experience is, all the 68 up BOP engines used the same basic
geometry for the starter gearing, till they came out with the TH325
trans on the 79 Eldo/Riv/Toro. Might be 166 teeth, does it matter? 

Certainly that engine needs the heavy duty starter, but I doubt that
is the failure issue.  Make sure the mount is secure, sometimes a
shim is needed for gear clearance.  I would make sure the timing
chain is not sloppy, otherwise it could cause a problem bouncing
back and forth starting. 

Check the condition of the flex plate that mounts the starter ring
gear.  These have been known to crack.  Here I found that the flex
plate on the 68-78 FWD Toro came with deeper teeth for durability,
than the same engine on a RWD car.  I have managed to collect
enough of these mechanically interchangeable flex plates for all
my O engine cars, FWD or RWD.  Perhps the 68-78 Eldo did the
same, a flex plate from one of them might help.  Bruce Roe

Yeah the timing chain is definitely not sloppy it's brand new. I have tried mounting the starter in a lot of different ways with lots of different shim combinations. Definitely the best results have come with less shims and even none at all. I think badpoints' idea of the stock starters not being strong enough to turn it makes sense as i have seen them get perfect engagement and turn the motor for a second before getting bound up. Could also be as James Landi pointed out that the bolts might be messed up or even the holes.

Also, wouldn't the number of teeth matter quite a bit? Don't you need to have the right number of teeth on the bendix so that they match up with the flywheel? I measured both of them and they're the same so I guess that's right then... but if my starter has 9 teeth can I just use a starter with 10 and expect it to work?

[James Landi]

I'd check on Bruce's suggestion--- I owned a 61 Cadillac that I managed to crack the bolt "ears" on all by two places of contact (I was young and really stupid). I experienced starter engagement problems, as well as vibration when the pressing on the gas and driving in gear.  In my situation, I found a mechanic who expertly wielded the flex plate to the flywheel.    It's sometimes hard to discern those cracks as they generally appear nearly under the bolts. Keep us in the loop with your findings.  I know this is tedious, tiresome and frustrating work.James

[bcroe]

All my TH400 or TH425 trans cars have the same
numbers of teeth, never heard of another option. 
Diesel is different.
Bruce

[L Rossi]

All my TH400 or TH425 trans cars have the same
numbers of teeth, never heard of another option. 
Diesel is different.
Bruce

Ok that's good to know, thank you

[L Rossi]

I'd check on Bruce's suggestion--- I owned a 61 Cadillac that I managed to crack the bolt "ears" on all by two places of contact (I was young and really stupid). I experienced starter engagement problems, as well as vibration when the pressing on the gas and driving in gear.  In my situation, I found a mechanic who expertly wielded the flex plate to the flywheel.    It's sometimes hard to discern those cracks as they generally appear nearly under the bolts. Keep us in the loop with your findings.  I know this is tedious, tiresome and frustrating work.James

Dang yeah I really hope it isnt that. Thanks, yeah I have to fix it one way or another.

[badpoints]

I had a high compression engine in my corvette that I ran with maximum advance. I ate starters until I installed a permanent magnet gear reduction starter. You might have carbon build up in your cylinders. A cylinder can ignite on the compression stroke and fight the starter.

[TJ Hopland]

Since it sounds like this is a stock car that should work with a stock starter I would be inclined to try and figure out why its not working before resorting to a different style starter but if that is the route you wanted to go they do exist.

https://www.robbmcperformance.com/products/cad_starter.html

[badpoints]

The PMGR starters sound cool when you start the car.