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thermostat housing help!!

CBB311

NAXJA Forum User
Location
Lawrence, Kansas
i have an 89 4.0 and i went to change my thermostat today and got the bottom bolt off fine and snapped the top bolt on the thermostat housing. theres still about a half inch worth of bolt sticking out but its not moving. i doused it in PBlaster and went at it with some vice grips, nothing. i have a screw extractor set but i dont have room for a drill without dropping the radiator and fans, condenser, etc. any ideas? i have to work early in the morning and i need to get this done today. thanks
 
I think what you might need is a stud remover rather than an easy out. If you can't get your hands on a stud remover then heat is your next best bet. Either way you may loose the threads and have to use an insert.

If you have access to a propane torch you could warm the engine, then spray more penetrating oil, wait a bit, and repeat. I believe the term is convection, but the idea is as the parts cool the penetrating oil will be drawn into the threads. Please be careful of fire. Warming the engine and not the bolt slightly then spray.
 
You broke the head off of the screw? Then slip the housing off.

Once you've done that, get a block of paraffin wax and a small torch. Heat the shank of the screw only until it's a dull red, then remove the torch and touch the paraffin wax to the junction between the screw and the head. Let it melt into the threads.

Let the screw cool (5-10 minutes) and you should be able to back it out. The screw expands to force the threads in the head open, then the paraffin "wicks" into the space that is made.

Replace both screws - preferred materials are brass/bronze, stainless, or SAE grade 5 coated with PTFE or RTV/silicone (in that order.) If all you can get are SAE carbon steel screws, replace them every time you take them out (it's cheap insurance.)
 
i dropped my radiator to have room for the drill, stripped an ez out in the process of trying to get the bolt out. tried heating it up, nothing. now i still have a round nub of whats left of a bolt stuck in my motor. im running out of daylight and ideas
 
If you have access to a welder... you might consider placing a nut over what is left of the bolt; weld the nut to the stub and then attempt to twist out the remainder of the bolt.
 
soo...i drilled the hole out to 5/16, started tapping the hole, got about a half inch deep and SNAPPED THE TAP! i swear this thing is either my best friend or my sworn enemy. any ideas?
 
forget cutting the tap. Those things are hard as hell. Try a left handed drill bit? once a tap starts to back out it will usually come easy.

Good luck
 
soo...i drilled the hole out to 5/16, started tapping the hole, got about a half inch deep and SNAPPED THE TAP! i swear this thing is either my best friend or my sworn enemy. any ideas?

Wilton makes tap extractors - they have fingers that slip into the flutes on the tap and grip it, and you back it out that way. No telling how many times they've saved my arse...
 
does napa carry them? or any vendors you know of? im trying to get this thing back on the road tommorow im tired of the 12 hour thermostat change haha

Probably too late in the day - usually an MRO house will have them on hand. They're kind of a specialty item.

Failing that, the heat/wax and a left-handed drill bit will probably help. Just try to not heat the cylinder head around the broken tap overmuch - the idea is to expand the tap and wreck the temper of the thing, not melt a hole in the head.

Worst comes to worst, you can overdrill to 5/16" and use a 3/8"-16 tap (ream out the hole in the housing to 3/8" or so as well) and use a 3/8" screw - probably the easiest option you'd have. Just don't break another damned tap! You already know how much of a headache they are to get out once they're broken, don't you?:shiver:
 
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