91 LS400 Heater/coolant issue!

[spazzy67]

Hi All!

My heater takes forever to heat up. I changed the thermostat and made sure my coolant is not leaking or blowing any white smoke out the exhaust, but I keep having to top off the overflow bottle. The weird thing is , it seems to heat up faster at higher speeds , then gets cooler as I aproach a signal of get off the expressway!

What could be causing this & what else should I checke or test for furthur analysis. Where is the anti-freeze going???

The top and bottom hoses both get hot.

Thanks in advance for your response!
Paul

 

[Amskeptic]

Hi All!

My heater takes forever to heat up. I changed the thermostat and made sure my coolant is not leaking or blowing any white smoke out the exhaust, but I keep having to top off the overflow bottle. The weird thing is , it seems to heat up faster at higher speeds , then gets cooler as I aproach a signal of get off the expressway!

What could be causing this & what else should I checke or test for furthur analysis. Where is the anti-freeze going???

The top and bottom hoses both get hot.

Thanks in advance for your response!
Paul

This sounds like a classic case of restricted water flow through the heater core. It could be as simple as a cable clamp at the heater valve having slipped and not allowing the heater valve lever to fully open, or it could be an internal clog, or most ominously . . . you might have a coolant leak that is preventing water flow due to "air-locking" in the heater circuit.

Start with a pressure test of the coolant cap then system itself. If you are losing pressure in the system, you best track it down.
Colin

 

[spazzy67]

This sounds like a classic case of restricted water flow through the heater core. It could be as simple as a cable clamp at the heater valve having slipped and not allowing the heater valve lever to fully open, or it could be an internal clog, or most ominously . . . you might have a coolant leak that is preventing water flow due to "air-locking" in the heater circuit.

Start with a pressure test of the coolant cap then system itself. If you are losing pressure in the system, you best track it down.
Colin

Where can I find the heater valve & do you suggest I replace the reservoir cap?

How else can I test the pressure?