TECHNIQUES FOR PREVENTING FASTENER BREAKAGE? (WATER PUMP, THERMOSTAT HOUSING)
 

Hello, could some of you experienced folks out there offer some guidance for PREVENTING breakage of fasteners as one changes out the water pump and thermostat? I've read some interesting things on the forum regarding handling the aftermath in the event of breakage, but would like a better strategy for prevention, as I'm really not well equipped to handle advanced damage control.

Two things in particular that I'm considering: the use of heat (simple torch) on machine screw heads; and prior to that, spraying with penetrating oil.

Thank you!!

Try Kroil or Silikroil first. Spray and let sit overnight and maybe spray some more. I order it off net.

If corrosion in the threads is suspected, it doesn't hurt to tap on the fastener head with a brass drift and small hammer prior to trying to remove the bolt. Tap from a few directions at a slight angle if clearance allows. Might not help any, but the shock from impact will travel through the fastener and terminate at the threads, possibly helping to loosen the thin corrosion layer at the boundary.

a small nudge in the tightening direction can break away the rust bond too.

I agree more with UPS. First, several taps with a soft drift-- taps, not full force pounding!- THEN either Kroll, Mobil 254 (if you have some) or a hydrocarbon-based liquid, applied slowly and generously. Then more taps and leave it for a while.


I know some people who wait and use a pin-point welder just to heat the head a little bit.


The toughest nuts and bolts/studs to save seem to be on the M180 inline six intake and exhaust manifolds. I have seen a lot of those destroyed, sheared when that could have been avoided.


At one point in the 1950s Citroen used brass nuts to avoid this problem. It does work but requires periodic re-tightening.

When replacing fasteners it is recommended to use anti-seize on the threads of the fastener.

while removing VW 1.6 diesel waterpump bolts - it was a futile effort if I didnt apply a gentle nudge clockwise (after dousing in penetrating oil). After that, they bolts would not fight as bad.

Wouldn't the corrosion breakaway force be the same in either direction, so might as well turn to loosen?

Agree with being open-minded about tightening though, if the fastener starts to jam up while loosening. Reversing direction a bunch of times can help grind chunks of corrosion into dust if you feel the threads start to gall while loosening. Don't keep going if it starts to lock up, get some penetrating oil in there and work it back and forth until it hopefully comes out without a fight.

Edit: Ha, we posted virtually the same thing Zulfiqar, lol.

Seems like it has all been covered. The heat provides contraction and expansion (provides movement of a sort) even if you heat everything because the Aluminum expands more. In fact heating a steel bolt in a steel part has the hole expanding more then the bolt does (or anyway heat helps).

Of course if you can heat only the outer part that is better.

Heat alternated with the some sort of Penetrating Oil followed by the tapping and the turning methods all increase the chance of you getting rusted in out. However, the smaller the diameter of the threaded bolt if it is well rusted the more likely it is to break off.

I have never tried this but there is at least one thread on using an old time method of using paraphine/wax. There is likely some internet articles on that. Anyway it could be something worth knowing if no penetrating oil can be had but you have a few birthday Candles or other Candles that dripped on hot wax on a hot part gets the paraphine into the threads.

Personally as part of it I heat the part and spray the Penetrating Oil on it while it is hot then let it cool off and spray on more P Oil, let it soak in and when you re-heat it you can often see the P Oil bubble a bit out between the threads and the Part.

It could not hurt just before you get ready to turn you heat the outer part and then turn while the outer part is hot.

The thread is not about this but on Nuts it is sometimes easier just to spit the Nut if you can get at it with a chisel or Nut Splitter.

One of the issues when removing water pump / thermostat bolts on an older car is corrosion between the non threaded hole and bolt locking everything together. Couple this with the bolts shank being reduced in diameter due to corrosion and threads that have high friction leads to bolts breaking off.

What happens is coolant seeps through the gasket and is stagnant in the bolt area. Many times the only way to take this apart is to remove the bolt head, pull the part off then heat what the bolt threads into and gently work back and forth. One key is if the bolt turns slightly then stops, don't continue to force it as it may break off, continue to work back and forth.

Sometimes a steel bolt in aluminum will weld themselves together and no amount of heat will help. In this case expect the aluminum threads to stick to the steel bolt on the way out leaving you with a hole with no threads.

All of the above. After using penetrating oil and such I have found it helps to move it back and forth from clockwise to anti clockwise. Patience will almost always get them out unbroken. I have gotten them out before with half the shank of the bolt eaten away by electrolysis.

Of course replace with a new bolt and some antisieze applied.

The problem here is the long thin bolt inside the aluminum tube... water, etc collecting and compromising the bolt strength... no way to get penetrating oil to the threads, no way to get heat to the threads, etc...

Sure try all the suggestions, you might get lucky and not break it... but don’t attempt this without a plan to repair the carnage when it does break.

Kroil

PB Blaster can't touch this stuff.

never work on hot aluminum is my rule. Also not metals under 32 degrees.

You can use vibration. He who shall remain unnamed in Bellingham sells a vibration kit with a video, or you can just get the edge sander from Harbor Freight and make one yourself but you won't save much money. This works great on nuts. It works good on bolts if you can just get the bolt to turn a fraction. I had never heard of using vibration before seeing the video. Apparently the Navy submarine guys have been using this trick for some time.