Coraphix

so after a series of problems with my water pump i finally get it all together, then i go to put my thermostat back together. Put the new thermo in, with new gasket, then started working in the bolts. i switched back and forth to make sure it was even, finally snugged down the top, then went to the bottom to snug it and it slipped. at first i pulled out the bolt then went to a parts store got exact replacement. it stripped. so we then looked into the fact that the threads in the head were stripped. so i rented a rethreader from O'Riellys and tried to rethread it. failed. every bolt i put in will just start to get harder then slip, and the rethreader is hitting the back of the hole without getting that hard.

now i need ideas for what i should do next. i REALLY dont want to have to replace my head because i'm totally broke and dont have the time for that long of a job. (and i'm supposed to go wheeling tomorrow night) Anyone know what i could do? Any ideas can help, thank you.

Xjman101

Hate to break it to you man but your head is aluminum so you can't tap it heili coil it or jb weld it the same thing happened to me and the only thing I could do was replace it it cost 250 for a new one at any good head shop

trans_am7935

please do your research before posting!

all 4.0 Jeep engines came with an iron block and iron cylinder head. all you have to do is drill out the hole (removing all old threads) then get a tap and tap the new hole (with a bigger size of coarse) and get a bigger bolt to match it. drill out the hole in the thermostat housing if necessary to fit a bigger bolt. make sure you cover the water passageway so no shavings get in there because that would be devastating to your cooling system.

when re-drilling the hole, ensure you make the new hole strait and not lopsided or you will be doing it all over again. you can rent all these tools from autozone.

good luck with your repair.

waltermitty

I've used helicoils in aluminum with good success.

trans_am7935

yes this is also possible, it is just not recommended when you strip bolt holes in an aluminum block that bolt cylinder heads on. let say you strip a head bolt trying to bolt the cylinder head on to an aluminum block, then you are screwed as it is not recommended for that kind of constant pressure that takes that kind of abuse, every where else should be just fine.

djb383

.....and even if the head was aluminum, which it's not, the repair is the same. Look up the chart to find the correct drill bit size for a given size hole and use the correct tap to cut the new threads.

Gorillaxj

x2, don't unserstand the second post....

but i agree with trans_am7935. drill it one step bigger to remove threads only, (might not need to do this step as it sounds like you have pulled all of them out already) and then tap it for a bigger bolt, or heli-coil it to use the same bolt. both good options but the bigger bolt is probably easyer.

*edit* its not really a good idea to helicoil any head bolt, but is done.

djb383

There are special sized drill bits for hole drilling/thread tapping. Some bits have a "letter" designation instead of a number. Need to look at chart for the correct bit/hole size.

jronald

I have been out of racing more than 30 years, and even then it was with small block Chevy's. That said, all of our aluminum blocks were Heli-Coiled. Everything that was torqued to more than 15ftlbs was tapped and coiled. That may NOT be done these days, but for lower torque applications, hell I would do it an a skinny minute!

All of this is mute if you can drill it oversize and use a larger bolt


Ron

Lyon

Sounds like the guy with the failed heli coil trick on his aluminum head didn't know what he was doing and his mechanic ripped him off as well.

I agree with retapping the hole. You have to be very careful drilling out that housing. What I would do is drill and tap the hole in the block and install a stud set up with a reduced thread the same size as the original bolt to go through the hole in the housing so you don't comprimise strength. Just my .02

mrfajita

I did the same thing with the bottom bolt on my water pump
Never retapped it, and I am always super paranoid about it. Whenever I smell coolant (which for some reason is really often even though none leaks), I get out and pop the hood, look at the bottom of the pump. I'll retap it when I need a new pump or it starts leaking.

cubsin2079

Torque spec on those bolts is only 13 ft-lbs.

Coraphix

1st, if it was my water pump i would, there are enough other bolts to hold it tight enough, mine is on my thermostat housing which only has 2 bolts, if i loose one of those there is only 1 left. doesnt work as well.

2nd, i did get the idea from a friend to drill and retap, (worse case i still have to replace the head) so i tried, and it broke, not the tap, the hole. the bottom left section (only about 1/8 of an inch thick) broke off as i was trying to tap it. now i only have 1 hole for the top bolt. i cant do anything with unless i glue or epoxy it on somehow.

any other ideas to try and fix or should i just give up and get a new head?
and if i get a new head is it worth searching through a JY or should i get a new one?

freegdr

can you put up a pic

N20jeep

where can i get one of these fancy aluminum heads?