Engine/Transmission (1998.5 - 2002) Thermostat Burp???

[Mad Max]

Previously I changed my 190' thermostat for another 190' b/c of its behavior. When I went through cold start up and drove, the temp would roll just north of 190' presumably the thermostat opened and it settled down to near 185-ish.



I put a new one in, identical part number I replaced, ie the current part and it did the same thing?



When it came to for my cooling system flush I switched over to red ELC, still running two bottle of RL's watter wetter, threw in a new 180' thermostat and a new radiator cap. In the days to follow the servicing I was finding traces of red coolant about the passenger's side of the radiator.



As I surveyed the engine compartment I again wondered, why DC placed a spring clamp on the expansion tank where the hose meets, but no clamp on the hose up by the radiator cap?



In looking at the cap end of the hose, no scars from where a clamp had been, no sign of one ever being there, I felt around and found coolant right at the juncture. I got a spring clamp and put it on, no more coolant traces and coolant level is stable too.



Coincidentally, I have not observed the thermostat bounce, but given my change to a 180' I can't attribute this entirely to just adding another spring lock hose clamp to the expansion tank line.



Looking back I suspect my gradual loss of coolant may have had more to do with a pressure/temp leak due to a loose hose fit rather than evaporative losses.



I'd be curious if someone with the 190' thermostat still in who's truck does the cold start/warm up thermostat bounce, if adding a spring clamp cures this.



A WORD OF CAUTION, THE NIPPLE ON THE RADIATOR FILL NECK THAT THE HOSE ATTACHES TO IS BARBED PLASTIC, AVOID OVERTIGHTENING ANY TYPE OF CLAMP ON IT FOR FEAR OF CRACKING.



MaX

 

[zman]

mine does the same thing...

It goes past 190 to about 195 or so and then settles down to about 185 and stays there unless I'm towing heavy - then it goes just a little over 190 and stays there. I figured the thermostat was bad. I have been trying to decide if I want to go with a 180 or 190.



Steve

 

[fj40charles]

Zman,



I installed a 180 a couple of days ago. The old 190 thermostat was broken on the bottom. I guess that would explain why it took forever for the engine to heat up.



It seems like the engine has a little more power with the 180. I don't know, but could it be due to advanced timing. I saw a post by Marco and he said the timing would be advanced since the engine is not as hot.



The engine does not seem to run as smoothly as when it is fully warmed up with a 190 thermostat. This has been the consensus by many that have installed the 180 thermostat. I'm going to buy a 190 and try it out.



I wish there was a definitive answer on which thermostat to use.



Charles

 

[THancock]

I put a 180 in mine and it runs fine. I still notice a bounce, where it warms up on start up above where it normally runs, but settles into it's normal area after it's initial opening. It has great power and mileage is 19. 5 to 20. 4 empty.