Reman engine...now on it's 4th set of thermostats???

[lmorris]

Anyone run into multiple thermostat failures? Customer has never complained about it running hot. It comes in with failed thermostats, they get replaced, engine cooling system is verified good, and given back to the customer. He says it's good for a month or so, then goes bad again. This time same thing, also had a very erratic Fan speed senor signal, new fan clutch fixed the signal, but it still only reaches 136 F and EOT is 145 F, and the hoses are hot. Verified both the temperatures with a laser temperature gun. The truck is coming back later for the thermostats, I would like to have some kind of game plan when it comes back. Any thoughts?

[Matt Saunoras]

I had one truck with sand (literally) in the cooling system that would eat thermostats about once every 2 months.  I tried multiple times to flush it with no luck.  This was a few years ago, I believe the customer finally got rid of the truck. 

[RyanG]

Had one we put 3 sets. They would go bad once a year.  Maybe try flushing the system this go around and see if it helps.

[jimmy57]

What is the deal with the tstats?  Visibly broken? Grit on the wax bulb shaft making them stick open (closed)?

 

Not something I have dealt with yet.

[RyanG]

They usually stick open and over extend. Engine wont reach operating temperature, sets a p0128 wont regen etc.

[RyanG]

I've seen a lot of deteriorated seals as well and they will start to dig into the housing or the front cover.

[lmorris]

When I took them out the rubber seal on the low temp(192F) one wasn't contacting the seat, so it was stuck open. No obvious signs of damage or contamination. Coolant is clean. There was anaerobic sealer on the rubber gasket though, last place that did them seems to go over board with putting that stuff on everything they put back together for some reason. Doubt that is the cause of failure though. He has been having blend door issues with this thing for awhile too, I now wonder if he inadvertently overheated it trying to keep some heat in the cab. And it's tuned, so no codes.

[jimmy57]

Thanks.

Overextended I've seen but I wasn't sure if you guys were seeing something else odd on these multiple failure engines.

 

6.0's still are finding new ways to kill themselves. I keep waiting on one to start up by itself and go park on a train track so a train wipes it out.

[forddieseldoctor]

6.0's still are finding new ways to kill themselves. I keep waiting on one to start up by itself and go park on a train track so a train wipes it out.

That's hillarious.