Mercruiser 496 - starter bolt hole threads gone !!

[89PartyHut]

So I figure this needs a helicoil.. But I am curious does anyone know if the 04 496 block threads go deeper than the factory start bolt is long? We just got our boat back a few weeks ago from the shop. It had a loose starter and the flywheel was all chewed up. It was under warranty through extended warranty (bought used) so it was no big deal.. Just took a few weeks to get her back. Well 3 weeks later same thing.. Went to go start her and grind the flywheel.. Checked the starter and it was wiggling by hand.. Took it back to the shop they tried to tighten it up and it just spun out all the threads..

​As we all know this is the week of the 4th and we have 15 people coming from all over. Family we haven't seen in years. This boat was the toy for the week.. So does anyone know if a longer bolt will be a tempoary fix for the next few days? Then she will go back and have her motor pulled out AGAIN..

 

[RicardoMarine]

I'm not quite sure if this is what happened in your scenario.....

Not all starter motor nose housings are the same today. With the difference in these, they require the correct length bolts and with the correct knurling. Bolts that are too long will bottom out prior to fully clamping the nose housing against the block!
My guess would be that a new starter motor was used, and perhaps the original bolts were used.

Point being..... what ever mearsures are taking to correct the threads, don't create a repeat of this by not double-checking the bolts against the nose housing.

If a thread insert is used..... don't forget that there needs to be an un-threaded section for the bolt's knurled area "dowell affect" for alignment.

 

[Villain lll]

To Rick's point,

inspect the bolt holes first. Run a tap into both holes and try to clean them out first. Spray generously with a penetrating oil to clean out and remove particles.

if the bolts were too short originally, they might have strip out but there still might be enough threads behind, once cleaned, to firmly attach without issue.

It's pretty difficult to strip out both of these holes in the block unless the bolts are too short to begin with.

measure the starter flange and the depth of the hole and ensure the bolts are within an 1/8-3/16 from the hole end when tight.

i have feeling that if you do the above. You will be able to secure the starter and enjoy the 4th.

 

[89PartyHut]

Starter is now bolted back up and engine starts normally again. Looks like the previous bolt was only using half of the available threads..

 

[Villain lll]

Glad to hear. I hope you followed our advice and cleaned up those threads and holes before just inserting longer bolts.

Surely wouldn't want to get in there again.

 

[89PartyHut]

The shop that should of found this mistake did it for us. They milled a bolt to spec.