OMC head bolt thread repair

[lbhsbz]

I have what I believe to be a 87ish 200XP. New to me engine that was sitting a while. I pulled a head to check the cylinders out and going back on pulled the threads in the block for the first 3 bolts I tightened. Double checked torque spec and I screwed up and looked at the next line over on the chart...no worries. Yank the head back off and grab some time serts. I've installed hundreds of time serts and never had one fail.

First thing I noticed was how gummy/soft the block casting was while tapping for the insert. Inserts went in as planned...but when I went to torque the bolts, all 2 inserts pulled out of the block at less than 15 ft / lbs of torque. This block is likely junk now...but what am I missing here? I repair threads all the time as part of my business and have never seen some **** like this.

[FUJIMO]

...never used these, but would like to try them sometime. "alumaweld" aluminum welding rods. they are low temperature aluminum rods which you use a torch to apply. harbor freight by you, sells them. after you drill & tap those holes to new, you might consider studing them, instead of a headbolt. just ideas, never have had this issue...

[THP]

Ibhsbz
This is car engine stuff but it might be helpful. I have got my asskicked repairing aluminum big block chevy cylinder heads that have broken off the exhaust rocker stands. The weld repair is always softer than the casting. Which sounds like what your dealing with. The standard heli coil and timeserts have limited engagement for this type of repair in the soft material.
Jesel valvetrain Lakewood NJ makes 1 piece steel inserts that are much longer than the others for more thread engagement. They use standard course tap sizes for threading the casting. The one down side is they are thicker than time serts so you might not have room.
They have worked great for me
Good luck
Troy

[lbhsbz]

...never used these, but would like to try them sometime. "alumaweld" aluminum welding rods. they are low temperature aluminum rods which you use a torch to apply. harbor freight by you, sells them. after you drill & tap those holes to new, you might consider studing them, instead of a headbolt. just ideas, never have had this issue...

That stuff is basically zinc. It melts with a torch, but it's pot metal...no real strength to it.

[lbhsbz]

Ibhsbz
This is car engine stuff but it might be helpful. I have got my asskicked repairing aluminum big block chevy cylinder heads that have broken off the exhaust rocker stands. The weld repair is always softer than the casting. Which sounds like what your dealing with. The standard heli coil and timeserts have limited engagement for this type of repair in the soft material.
Jesel valvetrain Lakewood NJ makes 1 piece steel inserts that are much longer than the others for more thread engagement. They use standard course tap sizes for threading the casting. The one down side is they are thicker than time serts so you might not have room.
They have worked great for me
Good luck
Troy

I've fixed a couple BBF rocker studs in aluminum heads with Time-serts...but that was a 7/16-14 thread...kinda substantial.

I realize that the standard time serts have limited engagement. The rule of thumb was 1 diameter of threads for steel threads (that why nuts are the same height as the bolt diameter) and aluminum is generally 2 diameters of thread engagement. If we look at the larger OD thread on the insert, that's effectively 2 diameters of engagement of the original size...and it's worked plenty of other aluminum castings without any issues over the past 20 years.

It didn't even try to work here. It pulled out like there weren't even any threads in the hole (until the insert pulled through the gasket and hit the cylinder head lol). Like the block was cast from cheese.

I have a lathe and I can make whatever insert I want I guess...maybe I'll try going up another diameter and do the full depth of the hole, although that should be unnecessary.

[skialot2]

...never used these, but would like to try them sometime. "alumaweld" aluminum welding rods. they are low temperature aluminum rods which you use a torch to apply. harbor freight by you, sells them. after you drill & tap those holes to new, you might consider studing them, instead of a headbolt. just ideas, never have had this issue...

I used that stuff 20+ years ago when I was rebuilding my Bridgeport. The threads came out with a few main bolts and a couple head bolts. I cleaned everything with soap and water. Then i drilled all the stripped holes a little more with a clean dry drill bit so I would have fresh clean aluminum to bond to. It took about 20 minutes to heat up the block with an oxy-acetylene torch. Filled up the hole completely. Drilled and tapped without an insert. It worked great! I had the motor for 5 years after. I never had a problem. I even still have the stuff I had leftover from 20 years ago. It was called HTS-2000

[skialot2]

That stuff is basically zinc. It melts with a torch, but it's pot metal...no real strength to it.

I disagree. According to the instructions, it will be stronger than the base material. Up to 45900 psi. I used it on me Bridgeport 20+ years ago. The repair worked perfect! Made the block like new. I used the motor for 5 years before I sold it. Never had a problem. Here is some pics. This stuff is over 20 years old.

[AlliStan]

There is a product named Belzona that you might be able to use to fill the holes before redrilling and tapping. It is used in industry every day, and I have a friend who has used it to repair a cracked cast iron engine block on a tractor. It is very expensive to buy, but if you could get your hands on some it is nothing short of amazing. A call to the company would get you the info on which one of their compounds would be best suited for your purpose, but I believe the Belzona 1111 is the right one for your situation.

A few people use it to put nosecones on lowers but very few, because of it's cost. I recently had one put on a Tohatsu lower with Belzona.

https://www.belzona.com/en/products/1000.aspx

[FUJIMO]

...never used these, but would like to try them sometime. "alumaweld" aluminum welding rods. they are low temperature aluminum rods which you use a torch to apply. harbor freight by you, sells them. after you drill & tap those holes to new, you might consider studing them, instead of a headbolt. just ideas, never have had this issue...

...i mispelled the name. its "alumiweld". this is, i believe, the originator of the product... www.alumiweld.com ... don't know about the knockoffs of it. harbor freights product very well could be theyr'e version of it & not exactly the same. you can source it now from e-bay, amazon, etc...

[perfmarine1]

I would not try those alum weld rods. Just put helicoils in them. Have done many and never had one fail.

[lbhsbz]

I would not try those alum weld rods. Just put helicoils in them. Have done many and never had one fail.

Well, that's sorta the topic of this thread...I stripped a couple holes and installed time-serts (superior to heli-coils, but similar concept...it's a solid thread insert) and the inserts pulled out like butter.

Edit: I may have found the smoking gun...pulled the powerhead and the lower unit apart today to make it easier to deal with in storage...about 1" of sand/gravel sitting in front of the water pump as soon as the lower started to separate, and the water tube was packed full of sand too. I imagine that it got real hot real fast and hurt changed the temper on the aluminum maybe?

[perfmarine1]

Well, that's sorta the topic of this thread...I stripped a couple holes and installed time-serts (superior to heli-coils, but similar concept...it's a solid thread insert) and the inserts pulled out like butter.

Edit: I may have found the smoking gun...pulled the powerhead and the lower unit apart today to make it easier to deal with in storage...about 1" of sand/gravel sitting in front of the water pump as soon as the lower started to separate, and the water tube was packed full of sand too. I imagine that it got real hot real fast and hurt changed the temper on the aluminum maybe?

I'm just telling you my experience from working on outboards and modifying OMC and mercury outboards for 40 years, I've used nothin, but helicoils and always work good.