Loose Mercruiser Starter Bolts

I recently bought a 2000 Firsher deck boat with a 4.3L Mercruiser. The boat started and ran fine before I trailered it home. Once I got it home, I tried to start in in the driveway and the I heard the starter whining and the motor was not turning over so I went and bought a new starter.

Upon removing the old one, I was surprised to find that it was not very tight and the bolts were very easy to loosen. I inspected the old starter and some of the teeth were chipped and grooved. I pulled the spark plugs and inspected the flywheel all the way around...looked to be in good condition with no missing or chipped teeth (big relief).

I installed the new starter and when tightening the bolts back up, I was not able to get them tight at all. One bolt gets somewhat tight but the other will start to get tight and then slip. I was able to get them tight enough that the starter would not move. At this point, I cranked the boat up with no problems and launched it for a test run.

The boat ran great on the water until I turned it off and tried to start it again. Apparently the bolts had loosened themselves up and the starter was loose again, and no longer able to crank the boat. Once I got home, I tightened the bolts again and the boat cranked right up.

So, the problem is that I can't get the bolts tight enough when installing the starter and they become even looser when the boat is running in the water. My new starter did not come with new bolts so I had to reuse the old ones. I thought maybe new bolts with loctite would solve the problem but the old starter seems to have had the same problem before I ever removed the bolts.

My next fear is that the threaded holes in the engine could be stripped. If this is the case, what are my options? I thought about using a tap to enlarge the holes to the next largest bolt size? I also thought about using Helicoil inserts? Has anyone ever tried either of the above methods or any other for that matter?

Sorry for the long post...just wanted to give all the details. Thanks in advance for any suggestions or input!

Kyle

Re: Loose Mercruiser Starter Bolts

What condition are the bolts?You can get new bolts and compare.Try a couple of lock washers under the bolt head and see if that helps.Those bolts have been streched and probably need to be replaced.Temp fix is the hard cure locktite. Then if you have room drill and re-tap for the next larger size. Jerry

Re: Loose Mercruiser Starter Bolts

You need the proper bolts for your starter. Mercrusier used to send new bolts (2 sets, I metric, one sae) with each starter. If the previous owner tried to use the wrong bolts, they won't work.
Find your local Merc dealer and get the right bolts.
I have also run into a number of aftermarket starters with the wrong bolts in it.

Re: Loose Mercruiser Starter Bolts

I would remove the starter and thread the bolts in by hand. You can check the depth of the holes as compared to how far the bolts go in with the starter attached. You will also be able to feel if the threads are comprimise in the block although it is hard to imagine.

It should be obvious enough what shape the bolt threads are in. Maybe longer bolts will do the trick. I'm not sure how much meat there is, both thru the starter and on the block but the next size up would be noticably bigger.

It may be a bit tough to drill and retap considering the location of the holes.

Re: Loose Mercruiser Starter Bolts

The correct bolts are knurled, up by the head of the bolt, to take up any slop.

Re: Loose Mercruiser Starter Bolts

Thanks for the tips guys.

Does anyone know the part number for the bolts? The engine is a '99 or '00 4.3L with EFI. Also, is the manual online anywhere? I believe it is #25.

Kyle

Re: Loose Mercruiser Starter Bolts

Any GM dealer will have them