starter problems

[demcheson]

I have a 2002 lb7 Duramax with the Allison transmission, for the past several years I have had a problem with the starter not engaging. I replaced 2 starters with no luck. The problem had been getting worse so I had the flywheel replaced and another new starter installed. During the recent cold weather the starter did not engage on the first try so it seems that the problem has not been solved. Any suggestions?

[DmaxMaverick]

Welcome to the Forums!

What do you mean by "not engaging"? Is it doing anything? Spinning, grinding, clicking, thumping or clanging? The starter motor system includes not only the starter motor (and attached solenoid), but the ignition switch, wire harness(es), and a relay in the power distribution box under the hood. If it does nothing when the key is turned, it could be the ign. switch, the relay, or any number of connectors in the system. A failed battery or poor terminal connection (most common) will usually cause clicking or buzzing when the key is turned to start.

[demcheson]

It makes a grinding noise as if the gear is not engaging. When it finally does engage the starter turns the engine over well. The ring gear and starter gear were both rounded off when they were removed. I swapped the circuit breaker for the starter today so I will see if that will make a difference.

[demcheson]

When I installed the second starter I cleaned the surface on the block and also checked the mounting surface on the starter with a straight edge to make sure it was flat and that the starter was seating properly.

[DmaxMaverick]

The starter doesn't (normally) require a shim for clearance, but you may consider it in you case. If the gear teeth are rounded off, and you have issues with engagement, there may be a need for it. This is unusual, and may call for unusual recourse. The shim you may need is a standard GM starter shim for previous (gas) Vortech engines (common item at any parts store). Start with the smallest thickness.If it engages sometimes, it won't require much adjustment.

[demcheson]

I am wondering about adding a shim, to me it seems that the starter gear is not extending far enough to engage the ring gear. Would the shim go on the starter gear shaft to move the gear forward?

[DmaxMaverick]

Thinking on it further, DO NOT use a shim. I was thinking of a different starter, and this one mounts differently.

Still, this should not be happening. If it was fine for years and hundreds of starts, something is really wrong. You've replaced the starter and flex plate, so the only thing left is the mounting surface. Look for damage there, or something interfering with a true install. I'm wondering if the tranny adapter plate has been damaged (warped, bent, cracked), preventing a parallel gear engagement. The starter mounting surface is not part of the block.

[ginger743]

I haven't had a starter apart for some years but in the old starters didn't the solenoid engage the starter motor gear a few milliseconds before the , " disc" made contact with the terminals to apply power to the motor ? Is it sounding like the starter gear is spinning against the flywheel gear , " grinding " and can't engage ? Be nice if you had the , " original starter to compare it to . Why did you replace the starter the first time ? I guess from what you said earlier the starter motor gear isn't moving far enough to engage the ring gear . Maybe applying power to the starter when it's off of the Engine to see if the gear is being moved to the max toward the end of the starter shaft. Is the starter motor just running free and not making any , " grinding " noise like it would if it's running against the ring gear and can't engage ?

Normally the starter gear is not spinning when the gear is , " slammed " home by the solenoid to engage the flywheel gear, if it was spinning we would hear it , " grinding " each time we start our engine if it would engage at all while it's spinning .

The Gear teeth are manufactured , " rounded " to facilitate engagement . Were the starters that you've had fail rebuilt starters ?


Just kicking some ideas around here :>)

Jerry

[DmaxMaverick]

.......Just kicking some ideas around here :>)

Jerry

That's how problems get solved. Keep on!

[BigRabbitMan]

At this point I would check, clean ALL connections from the battery to ground and from the battery to the starter. I fought a starter issue on a Dodge 440 for a couple of years and finally determined that it was a bad connection on the end of the ground cable. It was the cable to end lug that was the problem so test, clean and retighten everything as it may not be getting that full jolt of volts when the connection is made.

Just a thought.

[CareyK]

I have a 2002 lb7 Duramax with the Allison transmission, for the past several years I have had a problem with the starter not engaging. I replaced 2 starters with no luck. The problem had been getting worse so I had the flywheel replaced and another new starter installed. During the recent cold weather the starter did not engage on the first try so it seems that the problem has not been solved. Any suggestions?

Can't offer any suggestions...but I too have a 2002 LB7 Duramax. I have the exact same situation as you. I bought my truck in 2002 with a 118,000 Km on it. It now has 273,000 Kms. My starter "occasionally" will not engage. It sounds like the starter doesn't fully engage. When I attempt a start I am always aware that this might happen. It may happen twice in one day or once in five months! But on a second try it always engages! I have a remote starter and in cold weather ( -30 degrees C in Saskatchewan) the situation happens a bit more frequently at times and the starter spins for about 5 seconds before the cycle stops. Therefore 99% of the time I don't use the remote starter in cold weather. But at times I will try the remote....just to see!
I have not replaced the starter and don't plan to unless the situation becomes much much more frequent. It is a difficult problem to solve, especially when it's intermittent. I wonder if GM has a service bulletin on this. You're not alone.

[DmaxMaverick]

Can't offer any suggestions...but I too have a 2002 LB7 Duramax. I have the exact same situation as you. I bought my truck in 2002 with a 118,000 Km on it. It now has 273,000 Kms. My starter "occasionally" will not engage. It sounds like the starter doesn't fully engage. When I attempt a start I am always aware that this might happen. It may happen twice in one day or once in five months! But on a second try it always engages! I have a remote starter and in cold weather ( -30 degrees C in Saskatchewan) the situation happens a bit more frequently at times and the starter spins for about 5 seconds before the cycle stops. Therefore 99% of the time I don't use the remote starter in cold weather. But at times I will try the remote....just to see!
I have not replaced the starter and don't plan to unless the situation becomes much much more frequent. It is a difficult problem to solve, especially when it's intermittent. I wonder if GM has a service bulletin on this. You're not alone.

No TSB (bulletin). I checked.

Yours may be entirely different, not having replaced any parts yet. It could be a worn flex plate, specifically worn teeth at a specific location. When an engine stops, it will (normally) stop at a specific rotation index (3 or 4 locations on V8's). This means, if your engine is biased to fewer, starting will be at a more common location on the ring gear. This location will wear the teeth more during start. This can be overcome most of the time if the engine is "bumped" slightly after shutdown. Easy to do on LB7's, as they won't start quickly when bumped with the starter, or nearly 100% effective if turned by hand (wrench on the alternator nut). 1/8th of a turn is all. This allows the starter drive gear a shot at "fresh" ring gear teeth. If you want to use remote start, this will improve confidence it won't grind. It's a choice: open the hood when it's warm, or go out in the cold to start it.

[Kennedy]

We had a 2005 here that we did an out of chassis head gasket job on. Customer reported intermittent starter grind issues so we replaced it while we were at it. I seem to recall my starter/alt guy commenting about the starter model in question having a characteristic that contributed to this issue. We used a brand new aftermarket unit from one of his known and trusted companies and it's been fine ever since.

[demcheson]

The first 2 starters were Hatachi new units from NAPA, I am not sure the brand of the last one but the shop said it was also new. I think I will start looking for an electrical problem to see if that solves it. Thanks for the suggestions.