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Discussion Starter · #1 ·
I have a 2000 Hyundai GS with 180K miles that I had to replace the head on. I used new bolts, all new gaskets and I am having an issue where the head bolts are lossening even after tightened to the proper torque. I replaced the gasket again and still having the same issue. This happens about every 5K miles. Has anybody experienced this and have a fix?
 

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maybe a bit more info here? how did you discover the bolts were loosening? is it causing issues or were you just checking? losing compression at all?

was the new head and block checked for flatness within spec?

torque angle guide used? proper tightening pattern? proper lubricant used on the threads during original install?

if there is no issues and you're just tightening, this is not a good idea. those bolts are 'torque to yield'. simply put, when a metal is stretched under its yield point it will spring back to its original shape. after the yield point, the metal will stay in that deformed shape. your bolts are designed to be torqued to the yield point. this removes the spring in the metal and provides better clamping force.

that being said, its very normal for the torque on the bolts to change a bit over time with heat cycles. this is part of the design.

the downside to this is TTY (torque to yield) bolts CANNOT be reused and should not be retightened! you'd be causing further deformation in the bolts and the ultimate failure of a head bolt snapping down the road.
 

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He say he's used new bolts on the rebuild. I question the accuracy of the torque wrench setting. Hopefully, he installed the new ones in the proper sequence as he tightened them. Usually a 3-step process. Once to snug them down. Twice to further repeat the tightening. (Just think lug nuts on a wheel!) And a 3rd, and final, check in the same sequence to confirm the click on each bolt.

Going in and retightening them, later, is not normal. I've never had to do this on any head gasket or head replacement. Once on, done!
 
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Maybe the wrench was dropped at some point etc and its no longer accurate?
I threw mine out, still have to buy another...
It be just as cheap to replace it as to find an independent calibration lab somewhere to run it through the paces to check against a torque standard. However, if he knew someone that works in a nearby factory that might have the ear of the technician in the in-house calibration lab. Hmm...
 

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Discussion Starter · #7 ·
The head had to be replaced because the timing belt broke and a couple of the valves went thru the head. I tested the block for flatness and was in tolerance. The head was purchased from a reputable head remanufacturer. What happens is I will get a check engine light with cylinder 1 misfire. if I wait too long than it will include more cylinders. The engine loses compression and will not accelerate smoothly or idle correctly. I hate to keep buying new bolts as I had the first ones warrantied and replaced them. Same issue. Is there a head gsket available to help fix this problem? BTW, torque was checked with 2 differnt torque wrnches, both brand new.
 

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something is being missed here....sounds like you know what you're doing which is always a big plus :)

was the head a used one? sounds new, but if not it may have been machined already a few times and that could cause issues with the combustion chamber volume being reduced....thinking higher compression and possibly more heat produced.

having trouble finding the minimum value here myself, maybe someone can lend a hand?

i'd say this is a heat cycling problem though. the heat cycling is causing your bolts to loosen....which shouldn't really happen with TTY, that's why manufacturers went with them years ago.

another possibility could be a blocked or partially blocked coolant passageway causing localized overheating. sounds like its around your cyl. 1 being the worst, so i'd start there.

if all else fails....i could suggest studs instead of the bolts, but that seems more like a band-aid fix. its not solving the root problem.

do remember, if you pull the head you'll need a new HG unfortunately.
 

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I just changed the head gasket in a beta 1 and it ran good for about 8 minutes then the aluminum got all chewed up on what would be the cam bearing, on the front exhaust cam bearing at the timing belt pulley. The valve cover and cams were soaked with water/oil mix. I had reused my head bolts.
 

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If the bolts are too long (new bolts) then it may be bottoming out
This would give a false torque reading and the bolts would loosen after a short while.
Best is to add a couple of washers to the top of the bolts
If they are too close to the edge and no washers will fit
Maybe using a bench grinder to shorten the bolts a little will help???

The other thing is that the bolts could be too short
This would not ive the bolts and threads enough to catch and hold tight (given the amount of torque necessary)

Either way, question, did you check the old parts with the new ones before using the new parts??
If I am wrong then sorry I could not help

Good luck
 

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I like to run tap down all the head bolt holes at deck to cut the previous edition' coke and crap out of the holes all way to bottom,, then flood hole with carb or brake kleen, and blow out holes of crap so they nice and clean and bolts spin in freely

Use the Hyundai part numbered bolts, and make sure the washer is in place.. most of product call for "X" torque as 1st step, then so many degree additional in 1 or 2 steps
 
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