head install botch

[Froggx]

Tonight I attempted to install heads my second time (first time failed because one row of studs was too short). Well anyway I was following tq specs on the site 44lbs + 95 degrees, and using the torque order out of service man. Anyway, the 44 lbs went fine. Then I went back and added 95 degrees to the first stud. About 50 degees in I heard a loud pop and it became very easy to turn the stud. Long story short the stud lost its grip and started backing itself out. I undid the head and found 3 of my other studs were very close to doing the same thing. What am I doing wrong here and how can I fix it?

[geoffinbc]

Your studs are pulling out of the block? Or they are tightening themselves when you turn the nut?

Did you seal the stud in the block and use an assembly lube on the nut? Is there a washer under the nut?

[Froggx]

studs are coming loose and out of the block basically, not holding i.e. I get it nice and torque'd down then I can turn the whole thing by hand . I used rtv gasket sealant on the studs, going to retry with red loctite and rtv later, and give it more than one day to cure this time. There was a washer under the nut. There was no assembly lube on the nut, do I need some and what should I use if so?

[geoffinbc]

Ok it sounds like the studs are pulling out of the block. Are any of the threads being damaged? Did you use a tap to clean the threads versus a thread chaser? It sounds like there is too large of clearance between the threads and you have no holding power.

Hold a stud against an old head bolt and mesh the threads together. The threads size and pitch should be identical.

Yes you need assemby libe on the nut. You can buy some or use 30 weight oil not a multigrade.

[Guest]

Are you sure your studs are M11 thread (by 1.25 IIRC)? It sounds like they may be a smaller, possibly standard thread.

[Froggx]

I'll check my threads tommorrow, they did feel somewhat loose sitting in the block (I could wiggle them around when threaded all the way in). None of the threads appeared damaged. Also I'll make sure to use some oil or assembly lube this round. Another question, should I use standard nuts or lock nuts? My father told me to use lock nuts so it wouldn't have a chance to back out so that's what I tried this time around.

[geoffinbc]

There is no way they should wiggle in the block at all. Maybe a couple thou but that it. The threads should mesh very precisley. Do not use lock nuts. Hex nuts with washers are what you use. Where did the studs come from?

[Froggx]

Yeah these were like "wobble wobble" sitting in the block. It's a set of mcmaster-carr studs, don't think they are specifically designed for my motor in anyway, not even sure if they are meant for any motor, I wanted to go with ARP but I let my dad order them and this is what he decided on. Guess I might want to get some new studs (again). Looks like I need to invest in some hex nuts now too.

[geoffinbc]

Dude you gotta go ARP. Thoes studs are maybe grade 5 they will not withstand the abuse of an engine.

Get the ARP studs they will fit and never fail. Save the hastle.

[Froggx]

Alright, I'll see about ordering a set tommorrow. Anyone have part numbers or is it pretty easy to figure out?

[Froggx]

Looked up application guide, ARP pn# 233-4003 is for the 2.8L 60 deg V6, will this also work with my 3400?

[hamondale]

I'll check my threads tommorrow, they did feel somewhat loose sitting in the block (I could wiggle them around when threaded all the way in). None of the threads appeared damaged.

That sounds bad. If the threads on the studs weren't damaged, and at least one of them pulled loose, that leaves the threads on the block being the part that was damaged. It sounds like the block threads are getting shorn off or at leat severely distorted. Better inspect carefully, since even if you left some threads behind, they may not be very strong.

[Froggx]

Sounds like it needs a tap run through it then at least. They most likely felt loose because the studs were the wrong type pitch for the block. Don't get me wrong and think I could yank the studs straight out out of block, I still had to unscrew them all out one by one, they just lost the tension holding themselves in.

[firechiken]

If you thought you had them tight, and they became loose, you pulled threads. Always use fasteners that are made for the job. You can get away with using regular bolts/studs to mount your alternator and things like that, but not things like your heads or bottom end. And using lock nuts will give you false torque readings.

[Froggx]

Ok so I got home and started playing around in my garage some. First things first I meshed the threads on the studs I have against my old head bolts, great match there so the pitch has to be right. Then I got extra curious so I finger-tightened a few of my old head bolts into my block. They played around just as much as my studs. Now I somewhat doubt faulty design when using these studs, at least on the block end. I'd like to contribute my studs breaking free to use of locknuts + no lubrication on nuts/washers when installing, anyone care to agree or disagree?