1990 3.0 OMC Cobra

[josh08]

Just recently purchased my first boat. It's a 1990 Sunbird Corsair 185. I had the muffs on and started the motor, the throttle accidentally got hit to run wide open and I quickly got it back to neutral, then the motor died and wouldn't crank. I used a multimeter and determined the slave solenoid above the starter on the block had went bad, I replaced it and now it's cranking, but none of the pulleys on the front or the crank is turning. I tried using a screwdriver in a spark plug wire to see if it would arc over to the block and got nothing. The bottom flywheel cover was removed when I bought the boat, the flywheel is spinning when I crank it but the crank pulley isn't turning on the front of the motor. I did look and find what looks to be 3 flywheel studs laying under the motor. The motor is 302BMRPWS. I thought maybe the flywheel studs could have sheared, the crank could have broke, or the keyway on the crank might have sheared. Any help would be greatly appreciated.

 

[alldodge]

The bolts either sheared or came off, or the flywheel is busted. In any case sounds like the motor has to come out

 

[josh08]

The 3 studs I found have most definitely been sheared, but I was thinking since their should be 6 on the flywheel the motor should still turn over. I did try turning the motor over by hand at the belt but the belt was slipping. Every mechanic I've talked to said they've never never the flywheel studs shear off.

 

[alldodge]

If I understand correctly, the starter is turning the fly wheel but the crankshaft is not turning (pulleys are not turning)

If this is correct, then the motor has to come out to determine what the problem is

 

[wrench 3]

You may have found three bolts but three more are probably stuck up inside somewhere. If three bolts sheered most likely all six did. The only way I can see that happening is if the flywheel had been loose for a while.
Like AllDodge said, whatever is going on the engine has to come out to fix.

 

[devildogae]

If your seeing studs, them it's highly likely the flywheel isn't connected to the crank anymore and it's just free spinning. Doubt the crankshaft would snap because of high revs. Pull engine and pull flywheel. Shouldn't be to hard to remove what's left of the bolts. Get you some left hand drill bits, shouldn't have problems getting them out.

 

[josh08]

I pulled the motor today and all 6 flywheel studs were sheared off. Has anyone seen this happen or know what could have caused it?

 

[alldodge]

Probably incorrectly torqued. If to tight one shears, then the cascade effect with the others. Either that or flywheel is out or balance

 

[josh08]

I've been able to get some out with left handed drill bits and ez outs. I have a couple being very stubborn. Does anyone have any other suggestions?

 

[Scott Danforth]

Is there enough sticking out to weld a nut on to?

Post a pic

 

[josh08]

Unfortunately their isn't enough to weld a nut on .
This was prior to me trying to remove any. I'm using the largest ez out I can at the moment, and I've even used a breaker bar on the ez out, but the whole crankshaft ends up turning with it.

 

[wrench 3]

You don't need the bolt sticking out to weld a nut to it. Get a smaller nut, hold it centered over the hole, start on the bolt with a MIG welder and build up to the nut.
From the marks on the crank it looks like I was correct that the flywheel was loose. Is there wear marks on the broken bolts?

Can you put a couple of new bolts in and place a bar across them to stop the crank from turning?

 

[josh08]

The one I'm having the most trouble with I've drilled out with the left hand bits and used a ez out almost to the point of getting really close to the threads on the crankshaft. The bolts that were broke have some of the threads smashed flat, it looks like they have flattened some threads on the crankshaft, but I'm going to try to use a tap to cut the threads back in.

 

[wrench 3]

Are you using a straight easy-out or one that screws in. The screw in ones have a tendency of expanding the bolt and jamming it in the hole.
As a last resort you can grind down a hacksaw blade, cut four slots in the bolt down to the threads and pick the pieces out. It's a PITA job but I've had success with it a few times.
Tapping the first piece with a screwdriver and hammer is enough to break the bolt threads that you haven't cut through.

 

[josh08]

It's a tapered ez out. A few of the others came out no problem.

 

[wrench 3]

If you don't think there's enough left to weld to, you're left with the hacksaw option.
Good luck


You could try a heat and cool. Heat it and it tries to expand but has no room so it compresses. Cool it and it shrinks in. Propane torch probably won't do it. You'll need Oxy/Acetylene.

 

[Scott Danforth]

Unfortunately their isn't enough to weld a nut on .
This was prior to me trying to remove any. I'm using the largest ez out I can at the moment, and I've even used a breaker bar on the ez out, but the whole crankshaft ends up turning with it.

pull a spark plug, feed some rope into the cylinder to act as a piston stop.

then try it.

however you may break off the easy out, then in that case, you need a new crank

 

[alldodge]

It needs heat to break free, and easiest way to add heat fast is with a welder. To help protect the crankshaft, place a washer over the stud and weld stud to center of washer, then weld a nut to the washer

 

[wrench 3]

A couple of points that I forgot to mention: For the hacksaw method you need to have the bolt drilled all the way through. Also for the heat and cool it works better if it's drilled all the way through.

 

[josh08]

I've got all but 2 out. I have drilled both all the way through and almost to the threads on the crank and still cannot get them out. I've tried everything suggested. I do have another motor that came with the boat (302AMRGDP) which is a 88 model I believe. I was told it was a good motor but, I was also told the boat was water ready. Does anyone know if I could swap the crankshaft out? I also noticed today the dowel pins are missing on both motors on the crankshaft.