I've had this problem with the thermostat housing bolts, and the thread got me thinking. Would it make sense to use nonferrous hardware for the housing, like brass? I may give that a try next time I have to service a cooling system.

No.

Noooooooo!

two words: tensile strength

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

+1 for broken bolts. Reinstall with anti sieze on these and never a problem again.

__________________
82 MB 300TD, 87 Audi 4000TQ, 05 Audi A4 avant 1.8T 6spd (Wifes), 63 356C, Samurai VW 1.6TD, 71 NSU 1200C, 71 Toyota Hilux, tractors and junk

AAA would be the choice if he had a 200 mile cap and got towed all the way home, but he had a 100 mile cap and got towed 60 miles to a friend in CT. He had to come back the next day (around 240 miles round trip with another driver) to get the car. He would have spent much less time total (and less fuel/ tolls) if he was able to drive it back at a slower pace.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Ignoring corrosion compatibility of brass to aluminum for the moment, you don't think a brass bolt will handle 5 psi tensile strength? I have copper nuts on my VW exhaust manifold and they are torqued higher than the T stat housing bolts. Brass is stronger than copper so I think a brass bolt will suffice tensile strength wise in the T stat housing.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

It would have been faster to get towed the first hundred miles, then drive the remaining distance at the slower pace.

Agreed.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Sometimes s**t happens. By the time I made it to NJ, I had a definite overheating problem, and as I said, even letting it cool again, it would overheat as soon as you drove it, coolant flow to the radiator was almost fully blocked at that point in the trip.

The only real course of action was to have it towed, and the fastest resolution would have been to replace the thermotat, and not break the bolts, but it is what it is.

__________________
This post brought to you by Carl's Jr.

so now I pretty much own this car and ive had an opportunity to really observe its heating issues.

Last year the removal of the thermostat and replacement really improved the overheating issue, but now it very consistently gets hot under heavy load, and cools down when you get off the throttle.

The coolant checks out ok with a hydrometer, and is new of last year, and the records I have with the car show a newish radiator 5 years ago. the vanes are not blocked up or anything, looks clean actually.

This is the new normal condition. Get on the highway and break or stay around 70, and the temp gauge will creep up to about 100-110c. drop down to 60, and it will maintain at about 90c. Unlike the earlier issues with the thermostat, it will now run a low temp in hot stop and go traffic, instead of a high temp.
Im thinking my new plan is replace the water pump and see what happens since I have no idea how old that is. Unless something is blocked somewhere.

__________________
This post brought to you by Carl's Jr.

so, the temp climbs above the 100C mark, but does not make it to the 120C mark... see if you can find a 83+ SD in the yard, and snag their plastic fan blade/clutch combo, and the water pump pulley. that'll pull more air, and spin the WP faster. (you will need the smaller 1000MM fan belts though...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

so the mystery is solved.

Turned out to be a strange split in the top of the behr radiator, somehow the aluminum tab was forced back here, and would intermittently leak with little evidence. I can only guess that running the car essentially WOT on the throttle past 65 was forcing the radiator open at this split, but it would never leak consistently, and it withstood a pressure test! The coolant was simply getting lower every time I went on the highway, and was fine around town, sometimes for weeks at a time with no change in coolant level and without overheating.

Finally it blew out and stayed open and I actually saw some coolant this morning. It was disappearing slowly and I thought it might be a headgasket.



I replaced the unit with another Behr, but this one was newer had a much better tab attachment between plastic and aluminum. They are both Behr replacement radiators though. comparison-

old-


new-


I also took care of a crappy waterpump that was in there, replacing it with a nice OEM unit that is way more efficient courtesy of fastlane.



Now it sits right past 80c where it belongs, no matter the load.
I seem to have gotten lucky that no additional damage was done, its been overheating for years and years it seems from the records. I have record of 4 different water pump installations done from 03-09. The bad radiator was only 5 years old as I said earlier, pretty disturbing. If you order one, check those crimps

__________________
This post brought to you by Carl's Jr.