My water pump housing is very stuck on one of the ~4" long studs that are on the engine block. The stud/housing has corroded to the point that the stud is effectively pressed into the housing. So, I'm looking for ideas for what else to try before I spend the next 6 years of my life drilling through 3+ inches of stud. Here's what I've done so far:

- It started with an idler pulley install, which requires the removal of the left-most water pump housing stud to be replaced with a bolt. I attempted to double-nut the stud to remove it, but it wouldn't budge and I ended up breaking the threads off the end of the stud.

- I decided to remove the water pump housing so I could try to get the stud out. It took some effort to free the water pump itself from the stud, but I managed to get it off. Which leads me to where I am now: the housing is stuck on the left-most stud...

I've tried:
- Soaking it with PB blaster every chance I get
- Slide hammer hooked behind the housing
- Wiggling it side-to-side... a lot
- I removed the other studs. I can rotate the housing 5-10 degrees counter-clockwise, but the stuck stud rotates with the housing (I'm just screwing the stud slightly out of the engine block). This doesn't help my case since the stud is still completely fused to the housing and I obviously can't rotate the housing further since it hits other things on the engine.
- I made some pieces that thread into the two adjacent bolt holes on the housing so I can use a 2 jaw puller (see attached picture). The bolt holes aren't perfectly in line with the stud, so the puller wants to deflect to the side a bit, but I can still get a lot of force on it -- much more than I could ever imagine getting with any other method.
- Heat combined with all of the above. It's hard to get it very hot though since it's such a big chunk of aluminum.

All of this and it still hasn't budged. Literally, it hasn't moved a millimeter.

So, I'm out of ideas. I tried drilling the end of the stud to test how soft it was... it's very hard. A brand new drill bit took a long time to make a small dent. And even if I do attempt to drill through it, there's now way I can drill a straight hole all the way through the stud, so I'll just be left with a mess.

Ideas/opinions are desperately needed and appreciated.

 

Did you try heating the stud? A propane torch probably won't do it but you can try. Oxy acetylene would be better. If you can get the stud red hot you should be able to remove it.

 

You could run a die nut down the un-threaded part of the stud, to get a new thread, and try the double-nut trick again

 

Oxy acetylene sounds like a good next-step. I've tried propane quite a bit, but it doesn't seem to be working, as you suspected.

I've also been doing some research on using muriatic acid to dissolve the rust, but I'm worried about damaging surrounding parts. Seems like it could work though. Anyone have experience with that?

 

Think that stud goes through the water pump housing. To get heat (and/or lubricant) to the threads, you'll need to remove the housing. Also, you can't pull it out. It's a bolt that needs to turn counter-clockwise. Use a good stud puller close to the block after you liberally heat (and/or lubricate) it.

 

The threads aren't the issue, the stud is just corroded to the point where it's effectively fused to the water pump housing. As I mentioned, I can rotate the whole water pump housing and stud a few degrees, so the threads are turning. The stud is just frozen to the hole it passes through in the water pump housing.

 

Well that sucks. If there wasn't so much crap in the way you could unscrew the housing with stud and then deal with it off the car. You may want to try heating the housing near the stud (you'll have to move the turbo inlet) to expand the housing, then use a stud puller (put back another stud to keep the housing from rotating). If you can get a little gap between the housing and the block by rotating the housing, you can also try tapping the housing toward the block (with care). Best would be to put a pipe just larger than the stud to concentrate the tapping to that area.

Keep at it and hopefully you'll it will break free.

These cars are a real PITA, especially if they haven't been taken apart in 25 years.

Good luck

 

Alright, took the surgical route. I ended up using a die grinder with a cutoff wheel. I cut a slit into the side of the water pump housing, as close to the engine block as I could get (1/2" or so from the block), and went through the side of the stuck stud (cut until I quit seeing sparks). After that, I wiggled the housing for 10 minutes or so, and eventually it just fatigued the aluminum and broke off next to the slit I cut. Grabbed the small remaining chunk of the housing with a pair of vice grips and threaded it right out.

Now that I have the housing off, I'm convinced that it never would have slid off the stud. It's just too corroded into the through hole in the housing.

Anyway, I found a used water pump housing for $30, so I'll trash the old one and throw this one on there.

Thanks for the suggestions guys.

 

Note to self...maybe a little anti-seize on the shank of the stud next time I have it off.