I have noticed when driving anywhere, driving up to 10 mile sometimes even more. The van temp does not get very warm. I have even turned on the heater and that not very warn either.
I have also noticed when when it does get warn, then it goes cold again.

Van has 120k on the od. Just bought it used. Dont know maintenance history.

Im thinking maybe thermostat may be sticking. Any other ideals?

 

first thing i see is the thermostat then go from there
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Replace the t-stat, it maybe stucked open, causing you to have no heat or taking a very long time to warm up.

 

First make sure you temp gauge is working correctly. Let it run for about 10 minutes or so then pop the hood and place your hand firmly on the exhaust manifold.

Nothing beats the old hands on approach.

 

Then drive to the hospital to have your burns treated.

I think he means hand on the radiator hose!

Be sure when you get a new thermostat, it's a fail-safe. If it fails, it fails OPEN.
A thermostat that fails closed can overheat and kill your engine.

My 96 GC did the same thing on a roadtrip.
As a quick fix, I placed cardboard in front of the radiator to block airflow.
Now be warned, this is a risky thing. You MUST closely watch your temp gauge! If it gets too hot, remove some cardboard and expose more radiator. Still cold, cover up a little more.
Drive-thru and being stuck in traffic are a danger. WATCH THAT GAUGE!
Be prepared to jump out and pull some cardboard to cool it down.

This method got me through the night, and all day Sunday till I could find a place to replace the thermostat.

Good Luck,
EZ1

 

I actually meant the manifold. 3rd degree burns means it's nice and hot, 2nd degree burns means it may not be getting to operating temp. Tried and true method.

All kidding aside it is undoubtably the thermostat. Up here in Alaska I've seen a ton of people use cardboard trick as a permanent fix. It's always some moron taking bad advice from an even bigger moron. More than once when I explain to the person what happened and how much it's going to cost to replace the head gasket the don't understand. "My dad told me it was ok". Then after a call to the same moron they insist on fixing the headgasket with Bar's Leak.

 

Good point 2002C,

The cardboard method IS NOT a perminant fix!
Only a temporary one.

I tried not to understate the risk involved.
In my case, 2000 miles from home and away from the bulk of my tools, this was IMHO an acceptable way of making my trip more comfortable.
There's nothing like changing a thermostat in the parking lot of a hotel on a cold but sunny Dec morning.

Although, on my return trip, at a McD's in Rock Creek, WY I saw a guy pulling the gas tank out from under his Suburban, in 30mph winds and snow.
Thinking he had a fuel pump issue, I offerd my help. He was nice enough to say "Naw, you go inside an stay warm, I got it. You can be in charge of Ooos and Ahhhs."

EZ1

 

I didn't mean you. Your post was fully of warnings. If it were cold enough or I needed my defroster to get home I'd do the same thing.

 

Chances are as has been stated your thermostat is stuck in the open position.

I just did a coolant flush on mine and replaced the thermostat

WARNING though on the fail safe thermostat, i bought one, installed it and right away it was bad, it stayed in the open position and it was a new thermostat,

This is bad because the ecm will read that the engine is not reaching operating temperature and run rich.

This will foul your plugs ( and that's not cheap or easy to change )

And give you horrible gas mileage.

I bought the standard thermostat not the fail safe again, because if you do proper maintainence your engine should never overheat even with the thermostat in the closed position. The fans will just come on sooner and stay on longer.

I also changed the hoses while i was at it and everything is running fine.

You have to remember to burp the radiator to get out any air bubbles, though when you replace your thermostat or it will still not get hot air and the engine can indeed overheat on you and cause major damage such as a blown head gasket.

One last thing to check when you are done is if your TOP hose is collapsed when the engine is cold replace the radiator cap with a new one, chances are if it's been awhile since your coolant was changed there may be debris clogging the valve that uses vacuum as the engine cools to draw in coolant from the recovery tank. It's cheap insurance against future failure.

Hope this helps

 

Update. Sorry its taken a while. Change the thermostat, and no more issues. When removing the thermostat, it was slightly broken.