Starter Bolt maintenance

[The Daver]

Hi All,

New user, 1st post. I recently had a broken starter bolt on a Mercruiser 4.3 LX. It was the bolt closest to the engine block, of course. My local marine dealer/service dept was able to extract the remaining part of the bolt and put it all back together. Good to go! My question is, should I make checking the starter bolts a part of maintenance? Does anyone else do this as a part of engine maintenance? I do not ever want this to happen again.

Background information. The motor was a new rebuilt Jasper. It has been in the boat 3 seasons, here in Minnesota. I do not have very many hours on the motor. Probably less than 20.

 

[Bondo]

Ayuh,..... Welcome Aboard,........ The only maintenance I do on starter bolts, is coat the threads with #3 form a gasket, 'n snug 'em in good, 'n tight when I change a starter,.....

Cleanin', 'n sealin' the electrical connections is something to keep an eye on,.....

 

[Scott Danforth]

bolt broke because the starter bolt was loose. follow bondo's advice

 

[burtonrider11]

bolt broke because the starter bolt was loose. follow bondo's advice

Yup, had the same thing happen to me a few years ago on the 5.7. Had to do the extraction myself (scared me to death!). Bought new ARP bolts, oiled the threads and bolt shoulders per the tech at ARP and torqued them down real snug. Never had a problem since....

 

[The Daver]

Thanks guys!!!

 

[RaceCarRich]

Not sure which engines have the bracket on the rear of the starter but it often goes missing. IIRC I had one on my last boat with a 3.0L and had to modify the bracket for an aftermarket starter. If your engine came from the factory with a bracket, I’d make sure it’s there.

 

[Lou C]

Agreed and if you can't get one from Merc, it is actually a GM part that you can get from a GM parts dealer or places like summit racing or jegs.

 

[The Daver]

Thanks for all the advice guys. The shop was able to get the broken bolt piece out and put back together. Great news, right? Now, I told them to go ahead and winterize it. After draining the oil, water, about a quart or so was found in the oil. Turns out, my timing was off. One burnt piston and cylinder and whatever else went along with it. Turns out the orginal shop that did my rebuilt engine swap didn't do a very good job. So, I had my engine rebuilt again. I was hoping to maybe trade this one in a year or two, but I'll probably never get my money invested in it back. But it's good to go for now. knock on wood.

 

[Lou C]

1) did they find the source of the water? Blown HG? Or cracked cyl head? The exhaust system should be checked carefully in cases of water intrusion. In Minnesota I doubt you'd have a rusted through elbow or manifold like we can have but the old style wet exhaust gaskets between the 2 certainly can leak if not installed right or of cheap aftermarket gaskets are used.
2) broken starter bolt...was the original starter replaced with a smaller PMGR starter? If so these may use different bolts with a knurled surface to keep them from loosening, and it’s important to make sure the bolts are not too long. If so they can bottom out and not clamp the starter hard enough and that’s what caused the bolts to break.

otherwise you can have a recurrence of both problems !

 

[tank1949]

Hi All,

New user, 1st post. I recently had a broken starter bolt on a Mercruiser 4.3 LX. It was the bolt closest to the engine block, of course. My local marine dealer/service dept was able to extract the remaining part of the bolt and put it all back together. Good to go! My question is, should I make checking the starter bolts a part of maintenance? Does anyone else do this as a part of engine maintenance? I do not ever want this to happen again.

Background information. The motor was a new rebuilt Jasper. It has been in the boat 3 seasons, here in Minnesota. I do not have very many hours on the motor. Probably less than 20.

Water over damn now, but modern Chevy V8s, and I assume V6s, have tapered bolts specific for starters. The tapering helps center starter to block/flywheel. Their hex heads are a bit longer too. I hope shop went back with starter specific bolts. You may want to use mirror to look under starter at bolts installed. If bolt heads are longer than traditional 3/8" common hex bolts, that is a good indicator that they used correct bolts for starter. I learned the hard way decades ago!!!! Its a possibility that whoever put parts back on Jasper motor grabbed what was available (regular hex head 3/8" bolt) and starter eventually vibrated lose. Thank God you didn't eat flywheel ring gear. Good luck!