’84 300SD 233000 miles – decent shape – average MPG around 26-27
Had a new thermostat and M/B coolant installed first part of the year.
Installed all new belts in March this year.
Installed a new fan clutch a month ago – felt engine was running a tad warm (hovering around 100c way to much)
Radiator new in latter part of ’99 along with head gasket – less than 15000 miles

Situation: All of a sudden, stuck in L.A. stop and go traffic – temp gauge is sitting around 120C --- pulled over to shoulder stopped engine and checked water level (boiled out about a couple of quarts or so). Waited around 5 minutes, filled expansion tank and took off. Traffic sped up and temp fell to normal very quickly (a little below 90). I just shrugged it off.

Happened again, normal running at freeway speed, and very hot in traffic. No oil residue in expansion tank, or water in crankcase oil. I’m not having any of this garbage---
A friend suggested trying a “fail-safe thermostat” – never heard of um. Could be only two things – bad thermostat and or water pump (which looked like an original one).

Instead of fooling around with local parts houses and their aftermarket stuff, I bounced on Fastlane and ordered a BEHR thermostat and a new Laso pump.
From the time I placed my order via the website until items were in my paw –
--less than 24 hours -- although I’m not that far from Orange Co. (So. Calif.)
KUDOS PHIL
Installed the Behr thermostat (took out a Wahler less than 6 mo. old) and Laso pump (old pump wasn’t leaking or making noise, and looked as good as the new one, but since I had the new one and I intend on keeping this ‘mutha’ for a while --), and changed oil and filter just in case – cheap insurance. Overheating will kill a diesel faster then most anything! I speak from being around them for many years, both heavy equipment and high-horsepower big trucks.
--Situation remedied. -- Must have been the Wahler thermostat considering the old pump looked very good. Around a two hour job (I tend to take my time) which is VERY easy.

PS cleaning threads and using new bolts are a must for me. Old ones that held pump in almost caused a problem – could’ve twisted one or two very easily.

Jim