Strange starter issues

[rt3500]

Hi guys , I bought this 1991 1 ton (454) last fall and had just driven it lightly around town until early summer this year when I did the first long haul towing about 6000 pounds partially through mountains . It was hot and the truck was working . When I got home truck wouldnt start , photo shows what happened . I replaced the starter , but the same thing happened again but this time no heavy towing . The plug wire boots were also fairly cooked , so I'm thinking overheated exhaust manifolds maybe cooking the starters . I checked the timing and it was in fact about 10 or 12 degrees retarded (after un plugging single wire at junction block) . My question to those with more experience with these 454s is , do you think manifold temp caused this or is there something else going on electrically ? Advice greatly appreciated .

 

[GoToGuy]

Does your starter have the heat shield ? Towing , working hard cooling does it's job. But the other externals get affected by the higher heat under hood. If it doesn't have the heat shield that's what happens. That 1000° plus heat in the manifolds isn't cooled enough by under hood airflow. That's why the shield is there. People change the starter , " I don't need that " , and this happens. Or you get why won't my truck start when it's really hot. The starter gets too hot build high internal resistance, no start. Install heat shield and new starter, that's damaged, I believe unserviceable. Good luck.

 

[Schurkey]

Retarded timing makes exhaust temp higher. I bet the truck really perked-up when you poked the distributor to advance the timing.

Lack of heat shield makes starter temp higher.

I think you found the end result. But just to be sure, I'd be looking for a cracked exhaust manifold or failed exhaust gasket blowing exhaust gas directly on the starter.

 

[rt3500]

Does your starter have the heat shield ? Towing , working hard cooling does it's job. But the other externals get affected by the higher heat under hood. If it doesn't have the heat shield that's what happens. That 1000° plus heat in the manifolds isn't cooled enough by under hood airflow. That's why the shield is there. People change the starter , " I don't need that " , and this happens. Or you get why won't my truck start when it's really hot. The starter gets too hot build high internal resistance, no start. Install heat shield and new starter, that's damaged, I believe unserviceable. Good luck.

Thanks for your input . Correct , there is no heat shield on the starter side , I didn't realize it should have one . I checked and there looks to be one on the steering side . Hopefully these are available , I'll get one coming .

 

[rt3500]

Retarded timing makes exhaust temp higher. I bet the truck really perked-up when you poked the distributor to advance the timing.

Lack of heat shield makes starter temp higher.

I think you found the end result. But just to be sure, I'd be looking for a cracked exhaust manifold or failed exhaust gasket blowing exhaust gas directly on the starter.

Until the starter failures , the truck always did start and run very well , but after advancing the timing yesterday it seems significantly better . I always calculate mpg , every fill up , and I've put about 4,000 miles on it since I got it . When hauling it was getting 7.5 - 8.0 depending on terrain . Not hauling 8.5 - 9.0 . I'm hauling this weekend and am looking forward to see if mpg improves with this timing change .

I will look carefully for cracked manifold. Keeping my fingers crossed on that one .

Thanks for your help!

 

[Road Trip]

My question to those with more experience with these 454s is , do you think manifold temp caused this or is there something else going on electrically ? Advice greatly appreciated .

Greetings rt3500,

GoToGuy & Schurkey are pointing you in the right direction. To give you a general idea of
what the GM engineers came up with to help reject the radiant heat from the exhaust manifolds
from cooking the starters, here's a pointer to a recent thread that ended up going into detail
on starter motor factory heat shields: (Shields up!)

Important note: I think this previous thread was mostly about small block heat shields, so
just take the gist of that thread and use it to help justify the time & effort to look up the
big block specific heat shield part numbers & get them on their way to your engine bay.

(If it helps any, my '99 454 C2500 still has the factory heat shields, and so far so good,
the starter is cranking great and no signs of radiant heat damage from the exhaust manifolds.)

May the next starter be the last starter. Best of luck --

 

[rebelyell]

OP rt3500:
The starter experiencing failures is the older style "10MT" direct-drive.
Many later model trucks began delivering using a newer OE design known as "PG-260" ... it's smaller in diameter (effectively farther away from heat source), is much lighter, has Permanent Magnets (instead of heat-sensitive field coils), has an internal planetary Gear Reduction (instead of direct-drive) and requires-uses considerably less current. Those PG-260 aka PMGR starters eventually superseded old 10MT. Suggest upgrade to PG-260 but it does Require a new pair of bolts because they ARE different. Your old bolts will seem to fit But they cannot properly align starter & it cannot remain tightened. Correct bolts truly matter !

 

[Road Trip]

OP rt3500:
...Suggest upgrade to PG-260 but it does Require a new pair of bolts because they ARE different. Your old bolts will seem to fit But they cannot properly align starter & it cannot remain tightened. Correct bolts truly matter !

OP,

rebelyell's suggestion of a starter upgrade is a sound one, along with his caution
about the importance of the exact starter bolts that sort out all the metric/standand/alignment
issues simultaneously. Here's a link to what Schurkey shared in a recent post about these:
(Magic bolts allowing PMGR starter upgrade)

Looks like a heat-shielded PMGR starter would be the cat's meow, bringing you up to the
GMT400 BBC starter state of the art. (All cranking w/no cooking)

Best of luck. Let us know what you end up solving your problem with.

 

[GoToGuy]

The heat shield the starter needs is specific to the starter. I said nothing about shielding the manifolds. The shield is for the starter.

You must be registered for see images attach

 

[rt3500]

thanks to everyone for all the input . The diagram showing the heat shield is very helpful , and I also like the idea of permanent magnet starter for sure , I will look into but can't do much of anything before I pull out this week .

While on the subject of buying good parts , I have been frustrated with what I'm getting . I asked for the best starter they can provide yet I have a feeling its substandard , and I ordered OEM plug wires and got something that is kind of close but certainly not exact . What is the go - to supplier for only the best parts ?
Thanks.