With what temp stat? I have a 180 and on initial warm up the temp gauge will go up to about 200 then stat opens and it stay under it.

 

192 or whatever the stock one is. Acts like a 180 stat. Tested it about ten times and it opens at 190.Closes a few temps later.

Got all the air out. Not sure what the problem is.

 

Mine does this too with 180 stat but I don't think this is "normal". I was going to post about it. Mine actually goes to about 210 on initial warm up, then quickly down to 180 within seconds, then stays. Trapped air in system maybe?

 

Or a normal thermostat. They don't snap open, but instead take some time to get from fully closed to fully open. During that transition you've got some but not all possible flow through the thing.

 

There may be nothing wrong with the stat but maybe something with the cooling system. I've never seen on any car I've drove where it overshoots the temp by that much then drops down quickly like that. Mine gradually heats to 210, then quickly down to ~160 (like you can see the gauge move) then gradually to 180 and stays solid on 180 from then on.

 

That's kinda how mine does. Instead of staying steady. It seems to be constantly opening and closing slowly. My fan has resistance same warm and cold. Is that normal? The fan is really expensive. And don't want to replace unless absolutely sure. I was on the highway home from work and it was at about 210 and wouldn't come back down till I got off. Sitting at stop sign it stayed there until I hit the gas then it seems to come right back down. It also seems to get to operating temperature really fast within a few miles of leaving even on cold starts. Within minutes it's already at temp

 

$40-60 buys a replacement fan clutch . Not overly expensive , and rather cheap vs a new engine .

I don't like lighting the wick on the parts cannon , but if me , I'd be dropping in a dealer 195 t-stat it calls for , and ordering a new fan clutch . IMO , it's one of these two causing your problem . Maybe a touch of both .

It's not your mileage , it's the lack of use . I've had to replace a few things on my 96 which just rolled 50K , certainly not worn out . Some mechainical things just don't like staying dormant too long . Fan clutches and t-stats are on the list .

My problem was on a 1984.5 anniversary Mustang . Any time I hit 60 mph the temp would rise , any time I pinned it , the temp would rise . When I would slow and stop , temp would stay up for a minute , then I'd rev it and watch the temp go back to normal in seconds . I did the flush , new stat , water pump and nothing helped . Being young , I was just getting into mechanics (2nd car , 2nd Mustang) Finally , a mechanic told me to replace the clutch . 1.5 yrs I had this car till then and always that problem . I just didn't go on the hwy much . I put the new fan , actually , I think I went used . No more cooling issues . I beat , and beat on that poor Mustang for 2/3 years after w/o an issue . I remember once driving for 8 hours straight at a speed I'm now ashamed to say I maintained , but , without issue after the clutch .

I doubt I would ever get the HD replacements . Loud ! Go stock replacement IMO . Here's one on ebay

http://www.ebay.com/itm/New-OAW-Fan-Clutch-Wrangler-TJ-4-0-Pickup-Van-RAM-1500-3500-3-9-5-2-5-9L-92-06-/400561815982?hash=item5d435841ae&vxp=mtr
the guy even has 100% feedback

 

Keep in mind that the the water on the other side is still cool and it didn't circulate yet. Once it opens/circulates and everything gets up to temp it will stay at around the stat temp. If you hear the fan roar when you first start the truck(1500-2000 rpm) the fan clutch is ok. The fan clutch is mainly for getting air to flow threw the radiator at low /no speeds. It's doing nothing at 50 +.

 

So you don't think these trucks are not PICKY? well I have ordered my truck back in 1995 and still have it. I've been thru everything with it. electrical gremlins, motor noise's, all kinds of check engine light, ball joints, steering, New Motor, Trans, There isn't a bolt on this truck I have had my hands on. So yes they are PICKY

 

Also now I get a check engine light do to that fact of the 180 T- stat, Engine not up to operating temp