Replaced T-stat, one stud won't stay in...

[stealthES13]

Replaced the t-stat on my 2001 T4R (319k)- the top stud and the PS bottom stud came out when I loosened the nuts. I tried to hand thread them back in then place the housing back over them... the top nut tightens to 14 ft lb, but as soon as the PS bottom nut starts to get tight the stud loosens up. I took both out to compare and they are the same length so I'm not sure why one will seat properly and the other won't. I had it all buttoned up and started adding coolant when it began to leak pretty bad, jumped under to ensure everything was snug when I noticed the issue with the PS bottom stud "floating".

Any ideas as to why this last stud won't seat and let me snug the nut against the housing so I can finish this job?

 

[phattyduck]

Sounds like you got some stripped threads in the aluminum...

-Charlie

 

[stealthES13]

That's my concern... does that mean a new water pump in addition to the thermostat?

A buddy of mine suggested epoxying the stud in place... not sure how I feel about that and admit I'm out of my depth on that one.

Would a helicoil repair kit be a good solution?

 

[2TH4IST]

The 3 studs in the pic correct? If so they go into steel not aluminum, thread into the block itself. Helicoil is best option at this point. It would suck but it would be best to remove the water pump to do the work.

ETA - make sure the stud threads are ok, I've seen the threads on studs strip too.

 

[stealthES13]

The 3 studs in the pic correct? If so they go into steel not aluminum, thread into the block itself. Helicoil is best option at this point. It would suck but it would be best to remove the water pump to do the work.

ETA - make sure the stud threads are ok, I've seen the threads on studs strip too.

Correct, per your picture it's the left-most stud. Thank you... grabbed an M8 - 1.25 UNC (based on some other threads I found while searching for answers) thread repair kit. Going to grab replacement studs and nuts, try them first as it couldn't hurt.

 

[2TH4IST]

Clean the holes with brake cleaner first. Use the spray straw to get all the way back to where the threads are at. Blow it out with air if you have it available.

 

[rdruss]

Use some JB Weld on the stud if you don't want to heli coil. I used it on a front swaybar stud sever years ago and it's still holding.

 

[stealthES13]

Awesome- thanks for the responses. Going to try the least to the most invasive solutions- cleaning + new stud and nut, thread chaser (AZ has one I can borrow), helicoil. Will followup once I've got it up and running.

 

[stealthES13]

New stud and nut won't be in until tomorrow... cleaned all three nuts with the restore kit from AZ. Unfortunately, it seems the end that goes to the block is m9 x 1.25, which isn't in the kit. Additionally, because there is a couple inch space between the threads that go to the block and the threads for the nut, the chase wouldn't even get to the threads I want to clean up. Looking like JB weld may be the fix for me.

 

[2TH4IST]

I would stay away from jbwelding the stud into place. As you might jbweld it to the water pump as well. I would highly suggest fixing it the correct way, though it's a royal PITA.

I don't think the stud is m9, that is an extremely rare thread size. But I might have to eat some crow later.....

 

[stealthES13]

I would stay away from jbwelding the stud into place. As you might jbweld it to the water pump as well. I would highly suggest fixing it the correct way, though it's a royal PITA.

I don't think the stud is m9, that is an extremely rare thread size. But I might have to eat some crow later.....

Yeah- talked myself out of it. Also noticed the housing had a crack at the same location of the stripped threads... imagine the guy that replaced the wp for me a couple of years ago didn't pay attention to torque specs. :crybaby:

 

[stealthES13]

Replaced the housing + the original stud, I can now torque it down!! However, there is still a slow leak...steady trickle. Gasket not sealing? Dirty mating surface?

Link to video: Dropbox

 

[AuSeeker]

Replaced the housing + the original stud, I can now torque it down!! However, there is still a slow leak...steady trickle. Gasket not sealing? Dirty mating surface?

Link to video: Dropbox

Is there just a gasket or gasket with some type of gasket sealer?

If just a gasket you might want to add some gasket sealer on both sides of the gasket.

 

[2TH4IST]

You have 2 gaskets in that specific area unfortunately. One is the split o-ring that goes around the thermostat. Then the water pump gasket that goes between the water pump and block. If it was over torqued enough to crack the outlet, I'd guess the water pump gasket is smashed to much. The water pump gasket is metal with a rubber overlay on the inside to seal things up.

Happy you were able to fix the stud issue! Was it bad threads or a bad stud?

 

[stealthES13]

You have 2 gaskets in that specific area unfortunately. One is the split o-ring that goes around the thermostat. Then the water pump gasket that goes between the water pump and block. If it was over torqued enough to crack the outlet, I'd guess the water pump gasket is smashed to much. The water pump gasket is metal with a rubber overlay on the inside to seal things up.

Happy you were able to fix the stud issue! Was it bad threads or a bad stud?

Copy that! The leak ended up being my fault as I had the ground between the t-stat housing and the block... leak was resolved after I relocated it between the housing and nut, where it should have been. :frusty:

Bad stud! The original would only thread in about a turn and a half... when I tried the new one it kept going and going and going- huge relief there.

Thank you (and all that commented) for your help! This forum was certainly the reason I was able to get my T4R back up and running!

 

[2TH4IST]

Glad to hear it's up and running. As I say many times crap happens! Luckily the leak was fixable. And your very welcome.