C9 CAT t'stat housing frozen bolt

[Don Colapietro]

Hi everyone, I'm having a real problem with a frozen bolt on the t'stat housing on my C9 Cat. 5 out of the 6 came loose, but #6, middle, left side won't budge. I've drilled a 7/64 hole into the housing at the edge of the washer to the shank of the bolt and have been spraying Free All penetrant for several days with no luck. Can't get at the block to try heating it with a torch without pulling the A/C compressor. had a severe overheating problem on the way out to Hungry Horse Mt, so I really need to change them. any suggestions? Thanks, Don Colapietro  239 940 6199 '06 Monterey

[Eric Maclean]

Don
Heat is your best bet
The next thing to try now that you have got penetrateing oil into the bolt hopefully into the threads is to beat on the head of the bolt to try and free the seized bolt by jaring and shacking the rust loose.
The shank of the bolt is likely frozen in the housing so heating the housing area around the bolt and beating on it may do the trick.
If you break the bolt you may have to weld a nut to the remainder to extract it.

Eric

[Carl Boger]

Don,

I have to agree with Eric that heat is probably your best bet.  Since that is impractical right now try a can of freeze out along with numerous shocks to the bolt head with a hammer, or rocking action with a small impact going in forward and reverse multiple times to hopefully break it loose.

You may have to do this numerous times and it may or may not work.   If you get to the point that the bolt breaks I have had decent luck drilling them out with left twist drill bits after leveling and center punching the shaft.  Hopefully you won't get to that point.

Hopefully this will help you or at least give you some ideas.

[Joel Ashley]

As Carl and Eric say, penetrant and vibration and heat are the go-to for these situations.  I had a warped, noisy 454 exhaust manifold on our old Pace Arrow, some 35 years ago, and it took me weeks of crawling in and out of the wheel well to get the one stubborn bolt out.  Ultimately it broke and I had to drill it out, an complicating circumstance I can't recommend.  The ultimate loosening wasn't with heat, but with PB Blaster and many days of soaking, high-speed tapping/hammering, and cursing.  If you can safely get at it, without igniting things or fluids nearby, heating the bolt head is worth trying, as I've used it successfully on other seized fasteners.

But the trick with penetrant and hammering is the vibration rate, in my opinion.  Soak with penetrant and tap the head in a manner to vibrate the fluid into micro crevices along the thread path.  It can take many, many sessions before the corrosion dissolves enough to succumb the bolt to removal stress.  I never had an impact driver until recently, and am thinking the vibration set up by such a tool might help drive the fluid into the threads better than hammer tapping.

But certainly, heating to change the molecular nature of the bolt relative to the block is a great option.

Joel

[Don Colapietro]

Hi everyone. thanks for all the suggestions. As luck would have it, heat was not an option since I would have had to remove the A/C compressor to get at the block where the threads are. No room to swing a hammer either, but a brand new Milwaukee 18v impact gun got it out. Turns out Cat forgot anti seize on the last bolt??? everything is now apart, but I found a small SS pin about 3/4" long by 1/8" dia when I pulled the housing off. Don't see where it could be from. T'stats don't appear to have anything missing. Also why 1 large and 1 small t'stat? Thank you, Don .

[Steve Huber Co-Admin]

Don,
Most large diesel engines have dual thermostats to control engine temp at various loads. Under light loads the lower temp one opens to ensure the engine is operating in the normal temp, ~ 185-204F for the C9. When the engine is put under heavy load, e.g pulling a grade, the larger t'stat opens to increase fluid flow and keep the temp close to normal temps.
Steve

[Don Colapietro]

OK, that makes sense. Sure would like to know where that nice shiny SS pin came from before I try to button this up??? Again, thanks for all the info and support. Don

[Steve Huber Co-Admin]

Don,
The pin is the "jiggle pin". It goes into the small thermostat. One end of it should be slightly flattened so it will drop into the top of the stat and not fall out. Without it you will have cooling problems.
Steve

[Don Colapietro]

Thanks Steve, I can see a similar "pin" in the small t'stat, but I have 2 new t'stats due here today. Can't wait to fire it up and see if the fan comes up to speed with the new wax valve. Don

[Don Colapietro]

Hi Steve, well, I got the new t'stats today and the small one does have a pin in the top just like the old one?? there is a hole in the bottom that the pin fits into, but it falls right out when you try to turn it over and there's nothing in the engine side to hold it..  hate to be a pain, but I sure would appreciate a call at your convenience. Thanks, Don.  239 940 6199

[Bill Lampkin]

Use a dab of wheel bearing grease to hold the pin in

[Don Colapietro]

Many thanks to Steve and Dave for their advice and support. Finally have the C9 back together and running with no leftover parts. First road test was a bust, with temp hitting 239!!! Changed out the hydraulic filter and got an immediate fan speed increase.  Much better, but still hit 207 with 65* air temp pulling a medium grade. Waiting on a hydraulic test gage kit to see if the pump is up to snuff. The fan just isn't moving as much air as it should. Any thoughts?  Thanks again, Don

[Steve Huber Co-Admin]

Don,
207 on  a medium grade is fine for the C9 with CAT's speced  t'stats. Normal operating temp on that engine was 204 on the flats. This is with a 43' tag coach weighing in at 36480 lbs fully loaded and fueled running 65mph.
Steve