I have a 93' 4x4 V6 , I've never had any significant engine trouble in 225,000 miles.

I went to flush the radiator today . I drained the old coolant , ran the garden hose through the cap , put in new coolant. When I started her back up to take a quick spin , the truck started to overheat.

A few symptoms:

1) There is no hot air when heater is on
2) Upper radiator hose is hot , but lower hose feels cool
3) The truck will not over heat with radiator cap off, but will over heat as soon
as I put the cap back on .
4) Cooling fan is running strong.
5) AC works

Is it a stuck thermostat? Bad water pump? Air needs to bleed out?

Any help / opinions is appreciated . Thanks .

 

i havent done a flush on this particular vehicle but sounds like air to me,i have one of those laser temp guns from harbor freight its real handy for times like these

 

just the fact that it started doing it right after a coolant flush makes me think it's air in the system, and bleeding is definitely the cheapest fix so definitely try that first.

 

I've looked in my Chilton , and online , how do I go about bleeding the air from the cooling system ? Just idle the truck with the cap off ?

 

park so that the radiator cap is the highest point of the cooling system (slightly uphill) idle with cap off and heater on hot and squeeze top hose repeatedly to coax as much air out as possible.

 

I get the nose pointed a bit uphill, take off the radiator cap, turn heater fan on high and all the way to hot, then start it up and let it idle.

It will slowly come up to temp and the themostat will open. Hopefully, the air will burp out. Add coolant as needed.

 

Go to your local auto parts store and buy a kit to bleed the air out of your radiator. It saves coolant and makes a LOT less mess. Comes with funnel and adapters to fit numerous radiators. Good investment.

Easy to do.

:wabbit2:

 

So I jacked up the front end a good ways , idled the truck , ran the heater , and just waited. I am happy to say that the heater came back on and as soon as that happened the temp gauge went right to normal.

I was surprised at how long it took to bleed all the air out , probably about 25 minutes of idling until the radiator would not accept any more coolant . Thanks so much for the help .

 

Im expericencing the same problem at the moment.. and the mechanics are stumped, and I don't know if they've checked thourogly for air in the system, im going to go after work, and try burping the system myself. And they are thinking its the waterpump.. but I don't understand how it could be the waterpump, when it was fine before it went in to get a tstat, and now its somehow overheating at idle, and tell tale sign they didn't burp it with the heater on, I went in and they heater controls were on cold, and a/c and the cupholder was pulled out the same way I had dropped it off, for this exact reason.. If you don't burp the system with the heater on, is there any other way to gaurentee no air in the system? Am I missing something? or thisj is the only way correct?

 

This system is prone to having a very difficult air bleed. Most systems will work themselves free of the air bubbles in a couple minutes where this one needs 10-30 minutes. Just do the hill treatment and it should solve your issue fairly quickly.

Now if someone else has done a double core rad upgrade recently I would be very interested.

 

I had a head gasket job done a week ago, picked it up Saturday, got hot within 10 minutes after I drove away. Looked under hood, radiator and top hose were hot! Bottom hose was cool to touch. Took it back, mechanic said it needed to be burped. Also had a new thermostat installed. Took it for a drive and was still hot at top and cool hose below. Can squeeze the bottom hose together, there's no coolant flow. Why not?

 

I experienced hot upper hose, cool lower hose, after flushing my '95 3vze.
Discovered that my radiator was constructed with a sort of dam inside at the upper hose outlet that permitted the radiator to show full to the top, but did not allow substantial gravity flow into the engine block.
Solved this by leaving the upper hose disconnected from the radiator and then loosening the clamp at the engine side and rotating the top rad hose until it stood vertical.
Was then able to fill the block with coolant thru the hose, reconnected and... problem solved.

 

You have a clogged radiator core. Typically it happens after 220k miles on the same radiator. Solution-----NEW radiator. Ken

 

I installed a new radiator on Sunday (been in use 2days) and it still runs hot. Ugh. So frustrating. Needle is almost pegged just driving around town.

 

Did you try and fill the block from the upper hose turned vertical, as I suggested??

 

This. Had the same problem after doing the timing belt/water pump on my '95, this little trick worked like a charm.