Ok
So ive been working on the D90 lately trying to sort out several bugs ive been having.
I think ive got it all sorted out except for my cooling issue.
It has begun to overheat some
I replaced the thermostat and fluids - and I THINK I got out all the air.
no dice.
So upon further inspection..
Ive found that when I let it get up to operating temp, shut it off, and feel of the radiator and hoses - both top and bottom hoses are hot, the bottom of the rad is hot, but the top of the rad is cool.
So im guessing the rad is clogged in the upper part??
It seems pretty straightforward, but I know alot of people have trouble with air pockets - So
Any suggestions??
Should i try to get it rodded out, replace, :confused:

oh yeah - its a 94
Thanks

It is far more likely that the lower portion of the radiator is clogged and you have little flow of hot water to the top of the radiator. In a '94, you have the vent on the heater hoses so it is unlikely you have an air pocket. I have only once had an issue with airpockets and the old "park it on a hill" trick worked! :flipoff2:
You CAN have it rodded or recored. Some say it works, some say it doesn't.

My experience has been that it is less expensive to replace than recore, or nearly the same price (but I hear stories of folks having it done dirt cheap YMMV). Rodding is a roll of the dice, especially on a 12 year-old truck. The core is likely corroded badly enough that the process of rodding may tear the core tubes, or it may not survive the disassembly/reassembly.

Whatever you do, do it soon. I found out the hard way just how sensitive these trucks are to cooling issues, it was an expensive lesson for me.

PT

Yeah i did the park on a hill trick when i filled it just in case:cool2:
that seems to work good.

Ive messed with it a little more
I took the T-stat out, and hooked everything back up.
I filled the system back up and ran it.
I unhooked the upper hose and no water comes out of it - I get some water running out of the top of the Rad, but none from the upper hose?
Is it the Water pump? I thought the pump pulled from the bottom of the rad, through the motor, back to the top of the rad - Is this correct?
If that is so - shouldnt water be coming out of the upper hose?

I am having the exact same symptons on my D-90 after installing a new water pump. I believe it is air trapped in the water pump and therefore the water pump isn't pushing coolant.

I read this article. http://www.evanscooling.com/html/techrefc.htm And I am thinking about instead of ramping up a hill, just ramping up the drivers side of the vehicle and see if it gets the air out and fluid moving.

B

Thanks for the link - Ill give it a shot.
That would certainly be easier and cheaper than replacing the pump.:)
If you could - post up any progress you have as it would be alot of to me, and im sure there are others here who have had the same problems before.
Ill probably have to wait till this weekend to try it out, but ill let you know how this works.

Ok that worked. So if you are having similar problems ramp up just the drivers side and run it up to cruising temp. The air from the cabin heater should increase in heat as your truck warms up. If it doesn't the coolant still isn't circulating.