Is this common (t-stat replacement)?

[TonyB66]

I loosened two of the 12 mm nuts with no issue, but the bottom one was a bear. It eventually rounded; and I saw that coming. Spent the better part of the day trying to get that bugger out. When I got access to a car I was able to buy a 12 mm extractor socket that did the trick, finally.

Is it normal for the studs to come-out too?

If so, have folks simply used bolts (M8 x 1.25) instead?

Today's plan was to remove the t-stat, flush the coolant with it out through the old radiator, install a new t-stat, with the jiggle valve in the correct orientation (6 o'clock), and install a new radiator.

None of that got done. Off to The Home Depot before it closes...

Thanks for any input you might have.

 

[theesotericone]

Is it normal for the studs to come-out too?.

Not normal. Don't use a bolt. Just soak the studs in a penetrating oil until you can remove the nuts and re-use them. A bolt could work but you'd better make sure it is shorter then the end of stud to nut length.

 

[TonyB66]

Not normal. Don't use a bolt. Just soak the studs in a penetrating oil until you can remove the nuts and re-use them. A bolt could work but you'd better make sure it is shorter then the end of stud to nut length.

That was my thinking too so I'm bringing those with me. Think I might get two bolts for now so I can re-assemble and continue with my flush, sans the t-stat.

I'll then soak those two studs overnight.

After cleaning them up, should I Loctite them in?

Again, thanks.

 

[theesotericone]

That was my thinking too so I'm bringing those with me. Think I might get two bolts for now so I can re-assemble and continue with my flush, sans the t-stat.

I'll then soak those two studs overnight.

After cleaning them up, should I Loctite them in?

Again, thanks.

Loctite may not be a bad idea. I've replaced a few tsats over the years and I've never run into this problem. I'm sure loctite would be fine though. I'd also get two nuts that fit the studs. When you re-seat the studs first put the two nuts on. Then tighten them against each other making a lock nut to tighten the stud. There's probably a torque spec for the studs as well.

 

[TonyB66]

Loctite may not be a bad idea. I've replaced a few tsats over the years and I've never run into this problem. I'm sure loctite would be fine though. I'd also get two nuts that fit the studs. When you re-seat the studs first put the two nuts on. Then tighten them against each other making a lock nut to tighten the stud. There's probably a torque spec for the studs as well.

Just used double-nutting to get those frozen nuts off the studs.

Indeed, I am planning the same approach to torque the studs tomorrow. I too was wondering the torque spec for those! If anyone knows, please share. I didn't have my glasses on, by it seems that there might have been some sealant like material on those threads...

I purchased a couple M8 x 1.25 nuts, and while they fit perfect, they require a 13 mm or 1/2" wrench or socket, as opposed to 12 mm (stock). So, as it stands, one nut 12 mm and two are 13. I'll either buy one more 13 mm, or make a trip to the dealership to get two more OEM ones.

Thanks again for the help. Speaking of which, [MENTION=120071]mtbtim[/MENTION] availed himself a few times over PM today. Thanks!

 

[4Runner4Leon]

In the photo, it looks like the nuts are rusted to the studs, which is probably why the studs came out with the nuts.

Be careful with Home Depot nuts. Unless they are high strength, you may end up with something that fits, but will strip the threads when you try to torque it to factory specs. I'd rummage around to see if you can find another automotive M8 nut, or make sure you are buying grade 5 or 8 nuts, or whatever the metric equivalent is.

When installing studs, you don't really torque them hard (unless they have a shoulder, which these don't). You just want to insert them fully and cinch them just a bit past that. I would use some red loctite on the studs and let them cure before installing and torquing the nuts.

I hate having to run to hardware stores in the middle of a project, that was me this weekend running to OSH in the middle of a timing belt project, ugh.

Where are you in So Bay?

 

[4Runner4Leon]

I'd look for something like this, strength-wise. https://www.boltdepot.com/Product-Details.aspx?product=17692. Or better yet, go to the dealer and get the right ones, like you suggested.

 

[Twan]

I just had almost this exact issue recently. I ended up replacing all three studs and nuts since they were pretty cheap at the dealer. Used a dab of Loctite on the studs when I put it all back together. Made sure to torque the nuts on to proper spec when I put it all back together.

 

[Twan]

Nuts - 90179-08183
Studs - 90116-08270

 

[TonyB66]

Twan, looks like I am not alone. Thanks for the part numbers!

While I really need the nuts, I might get the studs too.

I plan to Loctite the studs, possibly red, and anti-seize the threads where the nuts go...

4Runner4Leon - On one of the studs, rust was indeed evident. Even the other one I'd say so too, just not as much. The nuts I got at THD are grade 8 or 8.8, I forgot. I'll get OEM ones tomorrow, assuming the dealership has them...

It takes up to 24 hours for Loctite to cure. I'm losing some serious time...

Oh, I'm in Morgan Hill. Thanks for the help.

 

[4Runner4Leon]

It takes up to 24 hours for Loctite to cure. I'm losing some serious time...

If you're pressed for time, you don't need to wait for the Loctite to cure. You can thread in the studs, then install the thermostat and housing, and torque the nuts to spec. The Loctite will cure on its own and hopefully the studs will stay in place next time you take the nuts off.

Careful with the anti seize on the nuts - if you use it, then reduce the torque a bit from spec, since you're seriously reducing the friction coefficient in the threads.

Oh, I'm in Morgan Hill. Thanks for the help.

Ah, I see, you mean the Bay Area South Bay. We have one here in LA too, which is where I am .

 

[octanejunkie]

Sorry for your woes, Tony

SS studs would be nice, and in a pinch SS lock nuts from OSH will work on the old studs assuming you can clean them up and thread them back in

I see no reason for Grade 8 or better here, it's not a high strength/shear application, but SS would be nice on any part that sees water or coolant over long periods of time

Good luck with the truck, and the boss :fro:

 

[TonyB66]

I'm a native Californian and have been to the LA area a fair amount over the years and I did not know of a Bay Area down there! I will modify my Location....

I will Loctite this morning, possibly two new studs and apply some heat to the area, to expedite the curing process. Honestly, with the plan to drive this truck for 3-5 family outings a year (Tahoe runs in the winter and camping in the summer), this might be the last t-stat it ever sees...

Mike SS would be nice alright. These got nearly 200k miles and could easily get re-used, and I might, but I imagine the price for new studs is not all that much. Less cleaning for me... I need to clean the female threads too. Trying to think what I have for that application, besides the old studs. Open to ideas...

Thanks.

 

[octanejunkie]

I'm a native Californian and have been to the LA area a fair amount over the years and I did not know of a Bay Area down there! I will modify my Location....

I will Loctite this morning, possibly two new studs and apply some heat to the area, to expedite the curing process. Honestly, with the plan to drive this truck for 3-5 family outings a year (Tahoe runs in the winter and camping in the summer), this might be the last t-stat it ever sees...

Mike SS would be nice alright. These got nearly 200k miles and could easily get re-used, and I might, but I imagine the price for new studs is not all that much. Less cleaning for me... I need to clean the female threads too. Trying to think what I have for that application, besides the old studs. Open to ideas...

Thanks.

Run a bottoming tap through the threads with some MMO then flush out with WD40 (wear goggles)

South Bay in LA is the name for the beach cities from El Segundo down to Hermosa Beach: https://en.wikipedia.org/wiki/South_Bay,_Los_Angeles as the LA basin is a large inlet/bay on the coast and those cities are at the southern most end

 

[4Runner4Leon]

I'm a native Californian and have been to the LA area a fair amount over the years and I did not know of a Bay Area down there! I will modify my Location....

Bummer, and here I thought we were neighbors and was going to offer you a hand if you needed it. FWIW, I drive past Morgan Hill on the 101 every month or so when visiting family in Palo Alto. I'll wave next time I go by.

 

[TonyB66]

Run a bottoming tap through the threads with some MMO then flush out with WD40 (wear goggles)

South Bay in LA is the name for the beach cities from El Segundo down to Hermosa Beach: https://en.wikipedia.org/wiki/South_Bay,_Los_Angeles as the LA basin is a large inlet/bay on the coast and those cities are at the southern most end

I guess since I'll be doing a flush with no t-stat, it's ok it a little WD40 gets into the system. Thanks for the scoop on SoCal's South Bay! I've learned a variety of things in this thread. :thumb3:

Oh, the comment earlier, thanks for the reminder to use use less torque when using anti-seize. I've done 1/3 less before, so will likely do something comparable here. Maybe just make it 10 ft-lbs or 120 in-lbs...

 

[TonyB66]

Well, neither local local dealerships (two) have the nuts or the studs in stock.

Looks like I will need to clean and re-use these two studs and use one of these 13 mm nuts. I should be able to replace that one nut later with an OEM one without the loss of any fluid. I'll put that 13 mm nut as that one is the easiest to swap-out and it would be less apt to lose fluid or have air enter the system...

Time to wire brush these and get them clean.

 

[4Runner4Leon]

I should be able to replace that one nut later with an OEM one without the loss of any fluid. .

I may be wrong (still new to 5VZ motor), but I don't think the studs are exposed to coolant. So you can put it together temporarily with parts on hand, and then replace later with new hardware without risk of losing any coolant!

 

[thegipper]

I replaced my thermostat somewhat recently and did not have this problem. I have seen others on here with the same problem as the OP though so it's not unheard of.

 

[TonyB66]

I may be wrong (still new to 5VZ motor), but I don't think the studs are exposed to coolant. So you can put it together temporarily with parts on hand, and then replace later with new hardware without risk of losing any coolant!

Thank you, and that is what I had hoped. Can anyone confirm or deny?

When I removed the studs, I'm quite sure I saw some coolant come out of those holes. It was dark though, but I do remember that...