Ah #*&$,

I broke the bolt head off of the thermostat housing. I did a complete search and got some good advice. I lubed it overnight and am going to propane heat it and try to get it off with a vice grips. If that fails it is time to drill it out.

This thread has two purposes

If any has some more advice I am all ears.

And IF anyone is going to change out their thermostat.
Buy new replacement bolts, use liquid wrench first, and use antisieze because this really sucks


thanks

bob c

Buy a container of Mapp gas and use it in place of the propane with your torch. It is MUCH hotter than propane so should be more effective.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

-Usually the hex head breaks off and when the housing is finally removed you have a "grippable" shaft of the bolt sticking out (not that I've ever broken one ). I've had good luck using a plumber's "monkey" wrench on them (yes, plural ).

__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Get stainless steel replacement hardware.

I've spent a lot of time working on engines in sailboats. The most experienced boat mechanics would disagree with the advice to replace with stainless. They would say replace with brass or bronze if necessary. The big problem with stainless is that if you break off a stainless bolt, they are a bi**h to drill out. This is a big issue in boats since the fasteners are sometimes exposed to salt water.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Hey thanks for the info


This does stink and I knew better. I should always have penetrating oil in the garage but I was out of it. It might not of mattered.

Mapp gas sounds like a good Idea. I will try that out.

thanks again for your help..

bob c

Of course the ultimate method of broken bolt removal is to grind the busted end down a bit. Sort of shape it like a dull point. Then use your wire-feed welder and weld an old bolt onto the end of it, with the same dull point ground off the threaded end.
The heat from the welding will loosen it, and then you have a bolt head to turn. Now I ask, what could be simpler.
Oh yes, getting the wire-feed is sometimes an obstacle.

Bob,

Just a word of encouragement, I also have a VW diesel pickup and recently it needed a new water pump. Well, we broke off eight bolts removing the pump. We then took off the housing with all the bolt stubs sticking out and clamped it in a vise, heated the housing near each bolt and they came out easy as butter. New bolts and anti-seize and everything is fine.

Good luck!!

Ben
www.reproduce100s.com

Well I got the thermostat housing off the car and drill like you would never want to have your teeth drilled.

I tapped in another one no big deal...

also the part is available from MB for 80 bucks at cost (Brother works at a dealership)

So if you goof it up it is not going to kill you.

Any way I survived it. Live to fight another day.

one word of advice for future victims...... replace the water pump to thermostat housing hose. mine leaked when I reinstalled it. After 17 years things dont like to be disturbed.

The thermostat housing was easy to remove just two bolts on the side of it into the block.

ALWAYS HAVE PENETRATING OIL IN THE GARAGE.
I am going to buy a gallon of that stuff....

thanks four your help and most of all your sympathy..

bob c

Just a couple more lessons learned


The hose that goes from the thermostat housing to the water pump leaks like crazy unless you tie it down really tight.

I mean really tight.

ALso be carefull when and if you drill a vent hole in your thermostat it does effect the operating temp of the car. Less is best as you can always drill more if you want it to run cooler. Use the smallest bit you have if you dont want alot of temp drop.

Also it is common sense but if you are like me you may not have enough

Be careful not to brake the sensors on the thermostat housing during this job I broke both of them.

I grounded the wire that goes to the cold temp heating switch and mock repaired the ERG valve temp switch.

I call it collateral damage.

bye

bob c