• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Merry Xmas Me!

Bad news. I'm back to my 28MT starter. :rage:

Unfortunately the Powermaster did a pretty gnarly job at stripping half the teeth off my ring gear within only a couple months of occasional use. I have been in touch with their tech support but I'm unwilling to eat the cost of shipping the starter back to them on something that isn't my bad. I have two 28MT starters and spent some time under the truck making measurements to try to figure out what went wrong before replacing the ring gear. I measured how far the pinion was engaging with the ring gear - only biting into it by 0.235", which is less than half the width of the ring gear teeth (0.500"). At first I thought that the issue was the starter having too much pinion clearance. It does - measured about 0.085" where they say it should be around 0.045". The 28MT, which was begrudgingly starting the truck for the past 2 years, was at 0.060". This is a bit past the far side of the spec but definitely closer. The glaring difference here is that the 28MT starter extends its pinion gear clear past the rear face of the ring gear, using the entire face of the teeth to distribute the pretty lame force it applies to the ring gear while trying to start the truck. As far as I can tell the Powermaster was off both axially and radially, and it really made a mess of things. Shame on me for not checking, but I thought these engines were not supposed to have starter shims so I assumed it would be right. Even if they were supposed to be shimmed, usually if you take shims out you put them back. From what I see here to make this starter fit correctly the mounting bolt holes would have to be plugged and re-drilled in the correct location, but doesn't look like fun since the casing isn't solid.

I put one of the factory starters back on about a month ago to buy time and replace the flexplate once the weather warmed up a bit, but it was too far gone and started to make some pretty bad sounds a week and a half ago so I stopped using it to avoid getting stuck somewhere.

Last night, I finished changing my flex plate in God's garage, flat on my back with little cooperation from the weather, and I'm not very pleased to have had to do it. I put the other 28MT on it since the pinion gear didn't look very good on the other one after running over that gnarly ring gear. At least I don't have a 24' long 4-ton blockade in my driveway anymore, and I really needed to have use of my junk schlepper again.

I am working up another e-mail to their tech support with all of the details of what I measured and what I found, as I didn't have enough information before to be sure what happened. Hopefully they will respond favorably - this has been pretty disappointing thus far.
 
I called and talked to them about the other 2 that a heard that were out spec. They took my input from before and are moving the positive post to better spot he said on newer ones coming out really soon.
But he said they haven’t got back any yet with the mounting position issues. But they would like to get one back to see whats up. I know the one guy just sent his back to summit and got AC Delco instead. The other guy is still decideding if he will rebuild his 6.5.
 
I have done this occasionally with uncooperative suppliers.
Buy another one, return the old one for refund as if it's the new one. I'm talking about new starters. Did this 3 times during one month on lifetime warranty parts less than a month old. Without hesitation they FINALLY gave me a beefier one, same warranty. I got REAL good at swapping them out. Replacing all power wiring only helped delay replacement. Needs new glows now.
 
I hate to hear that. Hopefully they will make it right.

Take some pictures of the damage and send them in the email. I agree with Will, ask them to email you a sipping label.
 
@reddtekk I spoke to Thompson there by the way. Please keep us informed on this.
They have been top notch service to all I have heard from. I would think they will get you squared away, and make sure if problems for everyone else pops up.

He mentioned they have had to do some custom stuff for guys with sbc and bbc gassers that the block castings weren’t in spec. He said he didn’t onow of the. 6.2/6.5 having a similar issue but it is possible. I agree, GM was not good about getting that block ear in spec.
While you have starter off, maybe take measurements of hole placement and gap from back of block to flywheel and a few of us can give comparisons. I have a GM 506 in my garage I can get to. Be a while yet before I could measure my optimizer.

If several people that have accesable garage engines could measure all the different casting models, that may teach us all something about starter placement and things to do for better starter and flywheel life.

Maybe a different thread if you do t want to muddy this one up with it? Lmk I will get measurements today.
 
New starter geometry thread started HERE. Any and all input welcome.

Dave from Powermaster just called me back a little while ago. Really nice folks to talk to, and they are going to e-mail a label to get it back and see what went wrong. They took quick action once I had enough data on the situation. They have plenty of 28MT starters around as they also rebuild them, so they have plenty to compare this to and I'm sure they'll promptly determine what went wrong.
 
...I thought these engines were not supposed to have starter shims...

GM went as far as stamping "NO Shim" on the starters for this exact reason. At least the gear reduction rebuild I am looking at on my shelf has that on it.

Sounds like the PM wasn't getting the pinion kicked out all the way before starting it's motor? Perhaps from the measurements you took. Thanks for doing that and hopefully PowerMaster will get to the bottom of it.

I have been told stories about bad engine thrust bearings letting things move way forward during cranking.

Only other thought I have is to make sure the flexplate isn't backwards and I am not sure it would actually bolt on backwards.
 
@WarWagon I also have that on the casting of my starter, as well as factory manual NATP-9431 on page 6D2-7 only listing shimming instructions for gas engines. They interestingly don't make a "Do not shim" statement, they just don't say anything about it.

Flexplate was on the correct way and I was careful to get the replacement on correctly. I have read about this in other threads here and elsewhere when looking for pointers before embarking on replacement. I don't think that the problem is a thrust bearing or block issue - both of my 28MTs fit fine, pinion clearance is acceptable, and the teeth fully engage with the ring gear. Powermaster mentioned that they suspect something with the bendix drive. I have it boxed up and the label printed, so I'll drop it off at the UPS store next change I get.

Thanks everyone for the input. I will let you all know what PM finds when they receive it.
 
There are some starters made like the 8 million pound Prestolite starter for 6.2&6.5 that require shimming. Most starters for this engine dont. That being said, small block chevy gas originally did not. Then after years of production runs and casting changes, found enough issue that it became the standard to test for what shims are required, even though many never needed one shim.
Casting errors happen in blocks and starters. Always good to take a quick look at clearance.
 
Back
Top