Logo

Baffling starter heat soak

TitanTn

New member
New: battery cables, alternator, 10 month old starter, coil, plugs, 2 year old plug wires, rebuilt 7.4L.

I rebuilt my 454 over the winter. Bored .30 over, new pistons, lifters, head job, oil pump, cam, etc. I did nothing to the transmission other than paint it. I went through the break-in for the cam and then the rings. Timing is set to 10 degrees. It seems to be running great.

I've never been excited about how fast (it's slow) the engine turns over. But the batteries are both 1000 CCA and both have been tested to be within expected performance. My issue is that after running for 15 - 20 minutes - on the lake - it will not restart. It won't turn over. It tries to crank, but won't. The starter is very hot to the touch, and the transmission bell housing is also very hot. On several different lake tests I have cooled the starter with cold lake water and within a few minutes it will turn over again - albeit slowly. I've bench tested the starter and it seems to work as it should. I really think the bell housing is getting hot for some reason and the starter is getting heat soak. I don't know.

Now for the strange part. When I get the engine started after one of these non-crank situations, it is a pill to keep idling. It just stumbles all over itself. Anything over 1,200 rpms runs great. I can seemingly go as long as I want until I slow down and try to idle (sucks because now I'm trying to load on the trailer).

I can confirm that the starter is letting go of the flywheel after starting the engine. I'm confused about why things are heating up. I can't reproduce the issue on the trailer. It seems that I have to be in gear and running on the lake. Transmission oil is fresh, smells fine, and shows no sign of water.

I'll take any and all advice. Thanks so much.
 
Your over-bore of .30 (if we were to use "thousanths of an inch") , would be .300", or roughly just over 1/8 of 1 inch.
I think that you meant to say .030" over bore! :D:eek::)

OK... I'm just ribbing you! :cool:


******************

Your ignition timing...... you say 10 degrees.
Have you verified this to be correct?
Are you by chance "bucking" against spark lead while trying to crank???

Which style starter motor??
Today's HTGR/PMGR..... or an older style motor????
Old School Bendix Drive by chance????

How are the battery cables.... both Positive and Negative????
How are the cable ends???

How is the MBSS???? (MBSS = main battery selector switch)
Is it by chance a 90* sweep Perko????? :mad: :mad: :rolleyes: (not a good choice)


.
 
Just pertaining to this big block engine: Check for crossed plug wires, if #6, & #8, are crossed, the engine will run, and not balk, you'd never know?,, But, it will not have full power! IMO, with the cylinders out of phase, the hot exhaust at the wrong time on #8 maybe causing your starter heat sink issue! I don't know how long it might have been running like this, but you may have other damage?

I had this happen on a big block street car due to vandalism, that's why I'm suggesting it! ;)
 
Last edited:
Cylinder order: Engine Front Right side 1-3-5-7, Engine Front Left side 2-4-6-8, Engine firing order, Clockwise on Dizzy: 1-8-4-3-6-5-7-2 for normal rotation.
 
Your over-bore of .30 (if we were to use "thousanths of an inch") , would be .300", or roughly just over 1/8 of 1 inch.
I think that you meant to say .030" over bore! :D:eek::)

OK... I'm just ribbing you! :cool:


******************

Your ignition timing...... you say 10 degrees.
Have you verified this to be correct?
Are you by chance "bucking" against spark lead while trying to crank???

Which style starter motor??
Today's HTGR/PMGR..... or an older style motor????
Old School Bendix Drive by chance????

How are the battery cables.... both Positive and Negative????
How are the cable ends???

How is the MBSS???? (MBSS = main battery selector switch)
Is it by chance a 90* sweep Perko????? :mad: :mad: :rolleyes: (not a good choice)


.

You got me. I forgot a zero.

Timing is correct and apparently you can rule out the timing by removing the coil plug when the hard cranking issue is happening and see if it persists. It did persist and I'm very sure that the timing is correct and is not causing the problem.

Here is the starter I bought last year: http://www.dbelectrical.com/p-11469-new-starter-mercruiser-inboard-stern-drive-crusader.aspx

Battery cables are only about a year old as well as the connectors. I've checked them all and they check out good.

MBSS. I'm not sure what a 90* sweep is, but yes, it's a Perko. It's a two battery switch where I have 1/2/ALL/OFF options.
 
Just pertaining to this big block engine: Check for crossed plug wires, if #6, & #8, are crossed, the engine will run, and not balk, you'd never know?,, But, it will not have full power! IMO, with the cylinders out of phase, the hot exhaust at the wrong time on #8 maybe causing your starter heat sink issue! I don't know how long it might have been running like this, but you may have other damage?

I had this happen on a big block street car due to vandalism, that's why I'm suggesting it! ;)


This is an interesting thought. I'm pretty sure I doubled checked this when I assembling the engine, but it certainly doesn't hurt to check again.
 
Well, the plugs are all wired correctly.

I had the issue on the lake tonight and the bell housing temp was 127 and the starter was 117. That doesn't seem very hot to me. I'm wondering if the temp is actually within spec, but the starter just can't handle it for some reason?
 
Is the ignition switch sticking in the start position? If it has the bendix style starter the flywheel will disenguage the pinion when it starts and it is possible the starter is still running. Just a thought just start it like normal and check to see if you have voltage at the starter when the engine is running. Do you need to turn the key back manually into the run position or is there posative spring pressure?


Thanks for the suggestion, but I have checked voltage while running and there's nothing. The starter is not turning with the flywheel. The switch is your typical, spring type that automatically comes back from the start position into the run position.

I ran the boat yesterday on the lake and when the no crank situation happened the bell housing temp was 127 and the starter temp was 117. That doesn't really seem that high to me. I'm wondering if the starter or the integral solenoid are flaky and just can't take what is normal heat. The starter bench tested just fine, but that's under cold conditions.
 
Back
Top