hearting and coolant

[Cotswold Pete]

A bit of an odd one with my heating, so here is the story.

Driving home on Tuesday, lost all hot air about 15 mins into journey, stopped at the shops, checked the coolant and it was low, by about .75 litre (I have been loosing coolant - about a cupful a year for a while - so assumed there was a pinhole leak somewhere).

Anwyay, di a quick top up of drove home from shops and was fine for 4 miles, then last half mile no heat.

So next morning coolant topped up, and drove to work, okay for 12 miles, next mile sat in crawling traffic, no heat, but the last mile a sprint down the dual carriageway, and heat back.

Drvoe car to mechanic last night, he has checked it out, and said cannot see any major leaks, that would cuase me to loose lots of fluid rapidly, though there is a leak somewhere with the radiator, so it will need replacing, but not urgently, but sometime soon.

The only thing I do not get is why the heat came and went and yet thay have run the engine for 45 minutes, all is okay.

Did I have some weird airlock, or any other ideas.

The engine temp never varied during any of this.

Also if I am going to have the radiator sorted, would it be a good idea to get water pump done (as it is original, and does make a bit of noise, but does not appear to be leaking).  Next cambelt change not due for another 10-15K, so will get water pump done then (so that would be early 2019).

Picking the car up tomorrow morning, with re-topped coolant/anti-freeze and keeping fingers crossed.

Any ideas or comments appreciated.

Edited December 14, 2017 by Cotswold Pete
miss spelt radiotor

[39buss]

These Lexus are clever...hot water and music !!!!!  

[dendonc]

It sounds like ice might have blocked it, are you mixing coolant with water? check & see what temprature the coolant your using will go down to against whatever the tempratures were in your area, reminds me of when I lost me heating sometime in mid 80's & that was the cause.

[ambermarine]

Pete

It sounds like you have a airlock within the heating matrix and this is causing restricted flow that is fluctuating with increased pressure from the engine when the temp goes up.

You will be best served getting the system totally flushed and refilled properly exhausting any airlocks.

The leak in the radiator can cause the problem you have in that it will draw air into the system as it cools down after use this air lock will travel round the system and get lodged because the pressure on both sides of the airlock equalises.

[Tinonline]

If you do the work yourself I’d try removing the airlock by running up to temperature without the reservoir cap on with heater full on highest setting. 

Shame to do a total refill if you need a new rad...that’s the solution. 

I’d link the water pump change to cambelt but not the rad...if that makes sense. Do the rad. Irrespective of water pump😀.

That little hole in the rad could be repaired but it depends where and what it is and the general condition of the rad.

As ambermarine says as it cools the rad sucks in air. 

[mrdoofa]

Sounds like the cooling system needs “burping”, I had a similar problem with my old GS430 and that worked. If you decide to replace the waterpump you might as well do the cambelt whilst you are in there and vice versa.

[messi]

I'm having similar issue. Well, I replaced a leaking hose, and I'm sure I've taken air out the system but for some reason, the drivers side vent and the 2 middle vents blow out hot air, but the far passenger vent is lukewarm. 

[ambermarine]

As I said in my initial post the only way to be sure of complete evacuation of air in  the heating matrix is to drain all the coolant from the engine and associated ancilliaries, unless this is done air will remain as it will be trapped by any retained fluid.

The important procedure is refilling the system and gradually purging the air at the various vents as the fluid is poured into the engine above the water pump and not in the expansion tank,filling at the expansion tank will cause air locks .

Topping up the system at the expansion tank is fine if there is no airlock.

[Tinonline]

Yep, ambermine, I’m with you on this.

Might as well fix that rad at the same time.

I did not have to remove the rad for my cambelt/pulleys/water pump work...