Broken thermostat housing bolts '86 22RTE

[Black_TurboSR5]

'86 22RTE:smashputer:

Was going to inspect/replace the thermostat, tried to unscrew the bolt a little at a time going back and forth spraying liquid wrench, but broke both of them off! Screw extractors suck, so I'm thinking of tapping new treads, original threads were M8 1.25 what size should I go up to? M10 would be 14mm bolt heads and that might be too big! M9 was not available at the auto parts store.
If anyone has done this please let me know the specifics of
#1 the size of drill bit used.
#2 the depth of the new hole
#3 the size of the tap and thread details
#4 the size of the replacement bolts

 

[mike1979]

are the bolts still in the cylinder head? if so, I removed my intake manifold, which gave me better access, I center punched the two bolts and drilled them out, stepping up to the original size. when you get close to the threaded area of the "drilled out bolt" it usually turns out very easy, use a pick or a small screw driver and it will fold and crinkle out like tin foil. This way your cylinder head is not drilled larger to avoid getting real close to the inside coolant jacket... it is VERY close to the bolt, and If I remember correctly.... one of them is actually a plug for the coolant when screwed in! .... probably causing the corrosion in the first place... make sure the coolant is below the problem area, and very clean and install sealant on the new bolt so it doesn't have to be so dam tight to seal the T-stat housing and also blocking coolant from accessing the bolt itself down the road. :bigok:

 

[yotarob]

Drill the broken bolt out & drill / tap the intake for a heli-coil. You should be able to get a heli-coil kit at the auto parts store. I would not go with a larger bolt.

 

[Black_TurboSR5]

The t-housing on mine is on the intake manifold, the broken bolts are in there, tried the drilling or hollowing out of the the bolt but these Frs are seized in there. The bolts however don't go though and plug anything I can feel the inside with my finger and the threads don't go though, This is the turbo model but in my chiltons manual the pic for the regular 22re has it in the same spot. the

 

[Black_TurboSR5]

yeah sealant, there wasn't even a gasket on the housing just the rubber on the T-stat.

 

[mike1979]

yeah, I meant where the bolts thread into the cylinder head might seal off a coolant jacket, not the tstat housing. it sucks breaking them loose to get the intake off for sure!...if no luck then gotta drill through the bolt and work your way up to the original size and the intake will come off.. I never liked the design of the little bolt that is almost as long as a alternator bolt but half the size.. hang in there, the turbo engine is worth saving!

 

[mike1979]

crap.. i just realized the bolts your talking about. I am sorry about that.. gonna have to drill up in size tho if it was mine.

 

[Black_TurboSR5]

Thanks mike, I'm borrowing a tad and die set from a friend today, I'll start looking for a quality set for me to keep because I don't think this will be the last time a bolt will break off on this thing, the ones on the turbo I'm sure will not come off in one piece when and if I need to get the turbo rebuilt/replaced. but hey these Toyota vintage were so reliable that parts stay bolted on for decades :thumb3: then when they finaly need replacement bolts are seized.

 

[Black_TurboSR5]

drilled, and taped an m8 x 1.24 thread, just like the original. Threads look good I guess the steel from the bolts had fused with the aluminum, New bolt torque in fine. Thanks everyone.

 

[yotarob]

drilled, and taped an m8 x 1.24 thread, just like the original. Threads look good I guess the steel from the bolts had fused with the aluminum, New bolt torque in fine. Thanks everyone.

Glad to hear you got it fixed. Broken bolts are always a pain.