87 weird weird heat problem

[ddk114]

no heat except going down highway. heat going backwards from return heater hose up through T that goes toward throttle body at idle. Thermostat heater hose cold. Heater core open. Pulled thermostat and waterpump. Water pump has straight impellers. Never seen one like that before. Also found oil in antifreeze. Cooling system holds pressure with stant tester. Mechanically inclined, but completely baffled! Thanks in advance for any replies.

[Psychopete]

Originally Posted by ddk114

no heat except going down highway. heat going backwards from return heater hose up through T that goes toward throttle body at idle. Thermostat heater hose cold. Heater core open. Pulled thermostat and waterpump. Water pump has straight impellers. Never seen one like that before. Also found oil in antifreeze. Cooling system holds pressure with stant tester. Mechanically inclined, but completely baffled! Thanks in advance for any replies.

Do you know what kind of temperature the engine is running? The stock gauge is turd, and cannot be used to accurately gauge the engines temperature. But it should give you a general idea I suppose. If it is running hot, it would seem that the thermostat isn't opening. Oil in the water is usually a sign of a blown head gasket. Not sure which engine.. 2.9Ls are known for cracking heads if over heated, but you'll usually find water in the oil in that case. Any other symptoms?

Pete

[ddk114]

Originally Posted by Psychopete

Do you know what kind of temperature the engine is running? The stock gauge is turd, and cannot be used to accurately gauge the engines temperature. But it should give you a general idea I suppose. If it is running hot, it would seem that the thermostat isn't opening. Oil in the water is usually a sign of a blown head gasket. Not sure which engine.. 2.9Ls are known for cracking heads if over heated, but you'll usually find water in the oil in that case. Any other symptoms?

Pete

gauge is barely in the normal area. It seems about right temp. What would make the flow go in reverse? Normally the flow goes from the thermostat housing, through the heater, back to the bottom radiator hose, and along the return hose that feeds the throttle body. All I had was a warm reverse flow from the bottom radiator hose up through the T to the throttle body. The rest of the heater hoses are cold. I tried pinching off the throttle body hose and that didn't help.
The oil in the water has surfaced in the overflow tank. Sometimes when hoses are new oil is secreted. I saw this with a brand new hose. But these hoses have been on for a while. Imagine the surprise I got when I checked the level in the tank with a scredriver and out came thick oil.
What gets me is that it holds 15 psi pressure with stant without any drop.
I'm going to see what a new water pump looks like before actually purchasing one. I hope they made something better. Other than the rubber on the thermostat expanding to a bigger size after removal, the thermostat seemed normal. I tried replacing the rubber with an o-ring, but that doesn't work. WIth it being loose, the feet easily fall into the block cavity and doesn't seal straight. I'm just going to get new everything. I guess its been out of the factory too long.
Reply back if you have any suggestions.

[fordin K]

did you try spinning the water pump impellar ? try boiling some water and see what temp t-stat opens if it does open. if crud on back sticking valve closed, it may not open all the way also.

[2000mudder]

a stuck open thermostat will only give heat when sitting still and a thermostat that dosen't open will overheat when sitting still. if it gets hot going down the highway it's prob the radiator cloged up. oil in antifreeze is a bigger prob than not getting heat!!!! i would check head gaskets first then worry about your heat prob.