1986 Mercury 2.2 - broken head bolts

[fastcat14]

I picked up a 1986 Merc 2.2HP today for cheap. It started first pull, and compression felt and sounded great. The only problem was that there was no telltale stream. I let it idle for 10 minutes, and the head didn't get hot at all. I read that sometimes the telltale port coming from the cylinder jacket on these models can get plugged. And it was, completely. I decided to take the head off, since I figured that would give me a good look at just how much corrosion and crud was in there. I am both glad I did, and wish I didn't.

The water passage in the head was completely blocked. I should have taken a photo before I cleaned it out (photo below is after) but there was no water flowing. It might have kept cool enough when at idle, but I dont think it would have been OK at full bore. The cylinder jacket also had a lot of crud in it, which I cleaned out. I guess this is what happens when you run motors in the saltwater and dont flush them after. The major problem is that I snapped two of the head bolts. I've tried vice grips but they wont budge.

My plan is to keep hitting them with PB Blaster and some heat and see if they free up. If not I the next step will be to weld a nut on the end of each "stud" and try again with a wrench, or just cut them off flush and drill so I can use an EZ out or something similar. Final resort would be to drill out the bolt completely and then re-tap to a larger size. Hopefully I can fix this, because this appears to be a low run-time motor and I would love to get it running again.

 

[Maxz695]

Re: 1986 Mercury 2.2 - broken head bolts

If you can spay the underside as well it may help alot I broke 2 water jacket cover bolt and had the loose the next day. Being you have a head cover there I doubt you can get under them but you can drill a smaller hole through the bolt and then spay oil in it and let soak. This beats re drilling and tapping the original threading. after looking at the pics a bit closer it looks as if you can soak the underside of the bolt so keep spaying and be patient they should work loose but go back and forth once they start to give to get oil in the threads. Keep working them back and forth as long as necessary to get them all the way out

 

[fastcat14]

Re: 1986 Mercury 2.2 - broken head bolts

Yeah, the other ends are open and I have soaking both sides generously with PB Blaster. I will keep that going for a few days and grab the ends with vice grips to see if they start to move. At this point they are frozen completely and wont budge. I might grind a couple of flat spots on each bolt to get a better grip, or grind a rough hex shape to the tips and then hammer on a small 1/4" drive socket. That has worked for me in the past with broken bolts. Patience is the hard part, I wanted to get the motor on my boat this weekend. But I'll kick myself if I rush and end up ruining it for good.

 

[Maxz695]

Re: 1986 Mercury 2.2 - broken head bolts

well when I had trouble with this kind of thing I would hollow out the bolt with a drill (undersize it) O to o the heat form the bit helped out alot and it also weakened the structure of the bolt witch made it easier to remove with an easy out. Before you drill though try tapping the bolt with pressure on the shaft like an impact wrench to try to shock it a bit free to get the ball rolling be careful not to strike to hard and crack the aluminum

 

[fastcat14]

Re: 1986 Mercury 2.2 - broken head bolts

well, things went from bad to worse........... then back to OK...... I think!

I kept soaking the bolts with liquid wrench and PB blaster, attempting to back them out, but no luck. A friend of mine lent me a tool made by IRWIN that is used to bite onto and back out studs and headless bolts, but they still would NOT budge. After 5 days of trying, I gave up. I took a dremel cutting wheel, cut the bolts off flush, then carefully drilled out them out. I should have just kept drilling and tapped, but instead I decided to try a screw extractor/EZ out type thing. Torque, torque.....SNAP!!! Yes, it broke off in one of the bolts.

I figured that was it, but I thought things over and came up with an idea. I used the cutting wheel to cut the extractor flush with the bolt/cylinder, then used a glass/tile carbide tipped drill bit (and lots of time), followed with a couple of regular cobalt bits, and managed to get through it, and through the rest of the bolt. Next I drilled through the other bolt, and so I am sort of back where I started. The next step is to drill and tap the holes, and put the head back on with a new head gasket. Below is a photo of how it looks now. Not perfect, but at this point, I am going keep going and see if I can get this motor running again.

 

[fastcat14]

Re: 1986 Mercury 2.2 - broken head bolts (Fixed)

Re: 1986 Mercury 2.2 - broken head bolts (Fixed)

I drilled and tapped the head bolt holes. Every thing went fine, the only issue was that I had to go down a size on one bolt. The broken screw extractor forced me to drill it out slightly off-center, and I was worried the 6mm drill/tap would take too much material away and possibly crack the water jacket. So 3 bolts are are 6mm, and the other is 5mm. Hopefully this will be OK.

I put in a new head gasket, torqued the head down, and checked the compression. It was 110 psi after 5 pulls of the rope. Maybe thats a bit low, or maybe its normal. I dont have a leak down tester. So I put the motor in the bucket and it fired right up. It seems to rev and run OK, and I didn't see any leaks on the outside. I can only give it quick bursts of throttle in the bucket, so next step is to take it out on the boat and see how it does on the water. =)