Hi - 2016 Dodge Grand Caravan - I was replacing the thermostat. Top bolt came off vey easily. But 2nd bolt underneath ... not so much. Head broke off. With the thermostat removed, I have about 3/8 inch of a stub left sticking out. (see picture)
I've coated the remaining part of the bolt with deep creep and will be leaving it for a few hours. Tomorrow I'll try vise grips.
- i can try welding a nut on but space is tight
- can I remove the 5 bolts you see in the pic and remove that 'face plate' that the thermostat attaches too?

any other suggestions/ideas?

 

Any update on this? Did the vice grips work?

 

Nope - been spraying deep creep everyday since the post but no luck yet. I’m reluctant but but may have to try welding a nut to the piece remaining

 

Let us know how it goes (and please share a photo).

What about those 4 lower bolts around the circumference? If you remove those will the whole thing just come off so you can replace it with another one? That would help bypass having to weld or deal with a stuck and broken bolt.

 

Hi, there’s actually five bolts – one’s not obvious in the picture. I took those five bolts out, but the ‘piece’
(whatever it’s called) didn’t pull away easily and I was afraid to put too much pressure on it. If somebody has taken those bolts out, and removed that piece before… can you let me know what to expect? Will I have to use a gasket or RV sealant maybe to put it back? Can I just use a screwdriver to pry it from whatever it was bolted to? Knowing what that part is called (I.e. what the thermostat mates to) would be helpful also.

 

A service manual I have calls the part the thermostat housing bolts into a "water crossover", which is integrated into what it calls the "coolant outlet housing". This is bolted to the timing cover and can be purchased. It is not just that part immediately below the thermostat, but it's part of the whole coolant outlet housing which extends to the opposite side of the "V" shaped timing cover. See below; I put yellow arrows all around this singular piece (the coolant outlet housing) which includes the water crossover (the part of it which is directly behind where the thermosat goes). As you can see from the diagrams/photo, if you only remove those 5 bolts directly around where the thermostat goes, you won't be able to pry it off because there are several other bolts to the left of it securing the entire coolant outlet housing to the timing cover:



Here is what the coolant outlet housing looks like removed from the engine (a new part in the photo):



Here's the gasket for the water outlet housing:



The two bolts securing the thermostat housing to the water crossover/water outlet housing only thread into the water outlet housing itself, not into the timing cover, which means you can simply replace the water outlet housing if you can't extract the broken bolt. No need to mess with the timing cover in that case.

 

thanks John - you've been awesome! I'm going to try welding a nut to the broken bolt - if that doesn't work then I'll try replacing the water outlet housing as you describe previously. I'm researching how to do the welding without frying any electronic components. I've welded stuff before (trailers, metal implements, etc.) but never a vehicle. Its further complicated because the surface is actually vertical - not horizontal as it appears in the picture - and very tight on space.
Thanks again John. I'll get back here after i get a chance to try the welded nut.

 

Hi --

So ... i welded a small nut on the exposed broken bolt. Welding wasn't easy - for one thing I could not find a place to attach the ground clamp. So what I did was attach small needle nose vise grips on the base of protruding bolt and then attached the ground to the vice grips. I still had enough room to weld on the nut. I was feeling euphoric until ... the bolt broke again! Now instead of 1/4 inch of protrusion, I have about 1/8. I'd like to try to weld another nut onto the remaining protrusion but I'm at a loss as to where to attach the ground clamp now. Any ideas for attaching the ground clamp? I'm starting to question whether that bolt actually touches metal. Is it fully contained inside the coolant outlet housing? if so then there is nowhere to place the ground.:-(

I'm debating drilling out the broken bolt and tapping the hole. I have a tap and die set but have never used it ... maybe this is the right time?

thanks for any suggestions.

 

I'm not surprised because the bolt is seized. Welding another cap on the seized bolt puts you back in the same position you were in at the beginnig, which is that the seized bolt was stronger than the cap of the bolt. Same thing with the welded cap. The thermostat housing bolts into the coolant outlet housing with two......I don't know what they're called, but they are integrated metal threads inside the plastic coolant outlet housing. They don't touch anything else. Your coolant outlet housing does look like plastic to me (it is plastic, right?). If you do drill it out, you can see if you can drill it out small enough to rethread the same size threads into that integrated metal nut/thread. I can't tell if it has enough material for you to drill it out slightly larger to then use the next size larger thread tap, but I'd try to drill it out with the goal of rethreading with the same size threads if possible. Other option is to replace the whole piece.

If the bolt broke with the original head, and it broke with a welded replacement head, I see no reason why you would get a different result welding on another head. Besides, you said there's now no room to attach the ground clamp anyway. Try drilling it out (it's not very deep, so don't over-do it). I'm not sure how hard of a grade that broken bolt is. You might frustrate yourself going through a bunch of drill bits to go drill through it. If you can do it and rethread it, then good. If it doesn't work, you'd have to replace that whole outlet housing.

Another option is to get a drill attachment which drills an outer circle. I mean it would bypass the bolt, and you'd be drilling out that integrated nut leaving just a plastic hole. You wouldn't have to drill through the bolt that way. Then find a nut of the same thread size and thickness and insert it where the drilled out integrated nut was and secure it with epoxy. The integrated nut has burrs on the outside circumference which digs into the plastic to hold it in there. I have no idea if you can find those anywhere. Besides, you'd likely drill a bit of the plastic away and then if you did have an integrated nut, the outside burrs wouldn't engage with the plastic hole because the hole was enlarged. Unless you found a ever so slightly bigger integrated nut. That's why I thought just a regular nut of the same thread size would do and epoxy glue it in there.

 

Hi John - thanks for sticking with me - you've offered great insights. As you noted it does look like the bolt is entirely within that hard plastic-like housing.

A friend of mind suggested another option that worked for him. He cut the exposed bolt off flush and then used a self tapping screw of the correct thickness and length. He used the old thermostat housing to guide the screw to the center. Worked for him going on 6 months now without issue. I realize this is just a variation on the tap & die method but one less step.

However, I REALLY liked your idea to drill 'an outer circle' around the broken bolt - and then epoxy a threaded 'post' into that hole. that's brilliant. Now to find a hole saw bit small enough

the good news - now I have two more options to try before replacing the outlet housing

thanks John you've been very helpful.