Jump to content

1995 Lexus Ls 400


Recommended Posts

Hello All,

My Lexus has heat when the engine is at 1,500 RPM and higher, but no heat when below about 1,200 RPM's. Heater control valve is working, and it apperars the sensors work since even at full "HOT" the system blows cold at low RPM. The coolant resovoir is at full. Any thoughts on the problem. My guess is I may be loosing pressure thru the radiator cap, or have air in the system. Any other thoughts or experiences? Thank you.


Link to comment
Share on other sites

Maybe an air lock in the heater core? Did you recently drain and refill coolant? There is a proicedure to bleed the air out.

Also maybe check engine thermostat. If its stuck open engine will be held cooler than it should be. Does engine temp guage look lower than normal?

Link to comment
Share on other sites

Yes I have done a drain and refill about a month ago. Temperature gauge looks to be in normal position. Any idea of the proceedure to bleed air out of the system? Thanks.


(a) Slowly fill the cooling system with coolant.

Capacity: 9.5 liters (10.0 US qts, 8.4 lmp. qts)


• Use of improper coolants may damage the engine cooling system.

• Use “TOYOTA Super Long Life Coolant” or similar high quality ethylene glycol based non−silicate, non−amine, non−nitrite, and non−borate coolant with long−life hybrid organic acid technology.

• New Toyota vehicles are filled with TOYOTA Super Long Life Coolant (color is pink, premixed ethylene−glycol concentration is approximately 50 % and freezing temperature is −35_C (−31_F)). When replacing coolant, TOYOTA Super Long Life Coolant is recommended.

• Observe the coolant level inside the radiator by pressing

• the inlet and outlet radiator hoses several times by hand.

• If the coolant level drops, add coolant.


Do not substitute plain water for engine coolant.

(b ) Slowly pour coolant into the radiator reservoir until it

reaches the FULL line.

(c ) Install the radiator caps to the radiator and radiator reservoir.

(d) Bleed the cooling system.

• Start the engine, and open the heater water valve.

• Maintain the engine speed at 2,000 to 2,500 rpm and warm up the engine.

(e) Stop the engine, and wait until the engine coolant cools


(f) Add coolant to the FULL line for the radiator and reservoir.

Link to comment
Share on other sites

when was your timing belt/water pump changed?

In my time I have seen water pumps with the impellars damaged/ rusty, eaten up, (never in a lexus, we didnt work on them, since I retired and closed my shop in 1996), to where they would not move water except at high rpm's.

see if you can remove a water hose and see what kind of water movement you have.. should be easy to do, and you can elimanate the pump.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...