Perplexed

[Okiedokie]

After almost 60 years of driving I had a first experience. On the way back from Louisville I experienced a stuck thermostat after driving three hours at 70 mph. A cool morning, I just noticed that my gauge showed 215 degrees, it normally runs about 185/190. It was about time for a gas stop so I pulled into a station and it was spewing out the overflow. After some time at their water hose cooling the out side of the radiator it cooled down and was idling at 180, so I filled the radiator and took off for home. It ran normally at 185/190 all the way home, another 120 miles. When I pulled the thermostat it was stuck open, as it should have been since it was a Motorad Fail Safe stat. So why? First, it seems the Fail Safe stat stuck shut then opened after cooling down, does that make sense? My 40 has a TPI 350, Walker radiator, CCI electric fan and has performed well for almost 30,000 miles. How does the thermostat close while driving at highway speeds? One thing I changed prior to the trip was the PCV valve. I have had a problem with oil seeping out around the breather, oil fill, and the PCV on ot the VC's for a long time. I saw the add for M/E Wagner adjustable PCV valve so I bought one, installed to their specs and it completely stopped the seepage. I drove the 40 around maybe 100 miles or so around town and about 30 miles at highway speeds and it performed well. One thing that I did notice on the trip was some slight pinging while under load going up hills. I suspected that the knock sensor was going south and made a mental note to check it when home. I am wondering if there might be a connection although what little knowledge I have would tell me not. What do you think?

[idrivejunk]

You are not alone in experiencing this with those thermostats. That is exactly what they do. Unfortunately the fail safe wording is kind of a trick... it is safe to say they will fail, thats my experience and others. Random isolated overheating incidents with no other apparent cause is the symptom. I'm on my third fail safe whereas the others almost never failed for me. I fear that the trouble is quality has been discontinued in the manufacture of all thermostats due to some unheard regulation change. I don't have a solution to offer but an OEM thermostat might be my next move. Fair warning... radiator caps are also crap now.

[Okiedokie]

Thanks Matt, good to know.

[enjenjo]

Look into getting a Robertshaw thermostat. It's about the only one you can depend on any more. That low price ones the auto parts stores are selling are not good at all.

[Okiedokie]

Thanks ejenjo, I have used those in the past.

[chimp koose]

if anything , the better pvc would REDUCE the chance of the engine pinging . I would blame the t/stat  as well

[chimp koose]

PCV  

[Okiedokie]

I doubt that the thermostat could cause the pinging? I will put the original PCV back in and see if it stills ping. If so then I think that the knock sensor would be at fault.?

[chimp koose]

raised engine temp will cause a pinging as would excessive oil intake through the pcv but I would think higher operating temp would cause it more likely

[idrivejunk]

Look into getting a Robertshaw thermostat. It's about the only one you can depend on any more. That low price ones the auto parts stores are selling are not good at all.

Is this them?

http://www.robertshawclimate.com/

I could not find any indication that they make automotive thermostats.

[Okiedokie]

Same company only their auto line of products. Got one on it's way.

[enjenjo]

Look into getting a Robertshaw thermostat. It's about the only one you can depend on any more. That low price ones the auto parts stores are selling are not good at all.

Is this them?

http://www.robertshawclimate.com/

I could not find any indication that they make automotive thermostats.

Speedway , Summit racing, and others carry them.

[idrivejunk]

Aha. :oops: