Thermostat question

[Rookie2]

Just finished replacing the PHH, thermostat and doing the annual coolant flush. One thing I was kind of puzzled by... after doing the coolant flush and drain, I installed the thermostat. I then filled the radiator up, but it only took about a gallon and a half of new coolant (and knowing that it took close to three and a half gallons last time. I figured, I'll start her up and get everything circulating, then see if the rest would go. I shut her back down after a minute or two and checked again. No dice. The radiator was still full, in fact some came back out after I open the cap again. Now I was getting a little worried. Everything was pretty straight forward... what could I have F-up?? So I cleaned up the tools, then moved the rig out of the driveway and into the garage. Next move was to write this thread to figure out what was going on. Figure I'd check one more time... then she was low. Put the other two gallons in, and stopped hyper-ventilating.

So what's up. Had the thermostat just not opened up yet??

Thanks,
Rookie2

 

[turbocruiser]

Hi R2, it sounds like the thermostat has not opened up yet, are you watching the temp gauge to see that the engine is at operating temp? It will take more than two minutes, probably at least six or so. Plus, after adding my aftermarket temp gauge I'm noticing that the thermostat opens up at least another two minutes after the factory temp gauge reads at regular operating temp so it does take some time to open up. If the temp gauge is reading at regular operating temp for three or more minutes of idling without the rad accepting any more coolant then perhaps something is stuck but that is not really likely. Remember to keep the heater valve on hot for complete circulation of coolant. Also remember to keep the little jiggle valve at the top of the thermostat aligned with that notch on the casting. HTH

 

[Rookie2]

Thanks Turbo.

Sounds like me T-stat had not opened up yet. Glad I didn't go for any extended test drive. Hopefully all's good now..., except for the knuckle rash .


Rookie2

 

[Romer]

Why do you do an annual coolant flush? Seems a bit extreme to me. After you flush, the coolant should be good for a few years (3-5).

 

[IdahoDoug]

Romer,

Agree with that. I flush/fill every two years which is still a bit excessive, however fluids and an hour and a half of my time are so cheap I feel fresh fluids and oils are by far the best value for the money in terms of maintenance dollars. Since many of these rigs are getting up in miles, it's also an excellent way to stay in touch with the cooling system health.

Rgds,

DougM

 

[Romer]

Doug,

Being an engineer I believe in preventive maintenance. I also feel excessive maintenance puts additional wear and tear on the bolts and plugs and threads you have to work every time you do it. If your fluid is within specs, I see no benifit in changing it and only the downside of the wear and tear. Not a lot of wear and tear, but also the opportunity to cross thread and cause damage. Probably not a lot to that, but thats were I come from.

Ken

 

[Bear80]

just flushed mine and replaced the crappy airplane clamps with oem clamps. what a pain, here's what I did:

Pulled the thermostat and used my 5 gallon distilled water tanks, I didn't want any chance of tap water in the system. Drained the radiator and the block, pulled the thermostat out and filled it and set the heater on, let it run about 15min then drained. Ofcourse had to let it cool each time, about 45 mins. I did this 3 times, so it took all day. After I re-installed the thermostat, it only took about 2 to 3 gallons, where as without the thermostat it took about 4. I've driven it around and it has yet to pull the excess fluid out of the overflow but I'm sure after a few days it should be back to normal. Nothing else I'll just pull the cap and keep and eye on the level and if needed I'll just add some each time.

I too don't see why eveyone flushes the system so much, I did mine because the fuild looked like it was mixed with some green somewhere in the past and I wanted to change the hose clamps. I probably won't do it again for about 5 years and I saw no sign of that "slug" some of you have talked about.

 

[PHAEDRUS]

Not that I am particualrly anal about my truck but I dump mine every spring, my ritual is to replace the t-stat, change out the plugs check the wires, usually do ths when it is time for an oil change so I do that at the same time. I also like to dump the diffs and refill them while I am at it. its kind of a ritual to do it all but then I dont have to think about it all summer.
Dave

 

[Rookie2]

Why do you do an annual coolant flush? Seems a bit extreme to me. After you flush, the coolant should be good for a few years (3-5).

Romer:

I've had this rig for about 1 1/2 years and this is the second flush I've done. Basically at the recommendation of folks on this site (Beowulf, C'dan etc..). It get's back to the head gasket failure issue and the idea that a compromised coolant system is the cause for it. To me, the coolant flush isn't because the 1 year old fluid is bad, but if the tell-tell signs of radiator clogging are there (gray sludge), then hopefully this will be seen during the flush and I can take some pre-emptive action. Besides, I wanted to PM the thermostat and PHH, so I did the flush while I was in there.

I may start extending my flush intervals a little further since for the second time I've seen no signs of sludge, and I'm getting a little more comfortable about this issue.


Rookie2