K Series - Heater not blowing hot Air

[CliffC]

I have replaced the thermostat today as i thought i had a faulty one as the lower hose did not get warm. After checking the stat it appears to be working but i replaced it now so i have a spare.

 

When filling with coolant following all the little tricks about lifting the front of the car etc.. and i have the bleed T piece i began to fill the system slowly. Everything appears OK but during the test blat i noticed the heater was blowing cold air when normally when the temp is up to 80c it blows hot air. Shortly after this i noticed the engine temp going up so i did a quick turn for home before it got too hot.

 

So have i got a air lock in the heater and how do you get rid of it please?

 

i have filled the system with the car running and the heater valve open but still no hot air.

 

thanks

 

Edited by - cliffc on 23 Mar 2014 17:05:12

[Jonathan Kay]

What did the temperature go up to?

Did you do anything else at the same time as changing the thermostat?

Does the fan cut in appropriately?

Any evidence of leakage?

 

I'd start by seeing what comes out of the bleed piece when you top it up again.

 

Jonathan

[Roadsport06]

Let it cool, check if you can fill up from the bleed tee. If the bleed tee is at the highest point and you can add more coolant then that could well be your problem.

Start up car and check the fan switch is cycling with car up to temperature.

Check the heater cable is actually pulling the valve open too.

[revilla]

Was the heater turned on/hot while you filled the coolant system? It needs to be to let the water in and air out. Make sure you turn it on while trying to fill from the bleed tee as above (and lift the bleed tee as high as you can with one hand to make sure it is the highest point in the system while filling slowly with the other hand).

[Stationary M25 Traveller]

Definitely an airlock in the heater. Echo the above ref opening heater valve and raiding bleed tee higher than anything else. After releasing any pressure through expansion tank cap, remove cap of bleed valve and top up through there if it is empty.

 

Did you drill a 3mm dia hole in the top of the flange of the new thermostat ? Helps to let air bubbles through.

[CliffC]

Update and thanks for the replies above.

I have drilled the hole in the stat and I filled the system slowly and I thought all was good. The heater began to work as normal and I thought that the issue was gone. The temperature began to rise and the fan cut in as expected. But...the heater then went cold so I assume the airlock has some how got back to the heater unit. So after further massaging of the pipes etc and also filling up via the bleed t piece the heater will initially come back but will then go cold again.

I have done this thermostat change before and never had this issue with refilling the coolant in the past.

 

Out if interest how would you know if the water pump had failed on a 1.8 K Series?

 

Thanks

Cliff

 

[Stationary M25 Traveller]

They usually weep as sealed bearings fail. Easy to replace

 

I have been playing all week with a k-series cooling system. Plagued with airlocks in heater, despite hole, cooling system mod and bleed tee.

 

Chased it out eventually through bleed tee topping up.

 

Gauge now sits steady at 80C all day.

[CliffC]

Ian

Ian

I have changed the stat and filled the coolant many times without an issue. This time it's a a right bugger....hence the water pump question in case I was overlooking something. I am not losing any coolant and topping up at the bleed t piece but this generally just fills the header tank. I have even lifted the T piece to be the highest point and made sure the coolant is flowing towards the heater.

I shall keep on trying the tried and tested methods until I succeed but does anyone else have some tips?

Thanks

Cliff

 

[revilla]

Cliff,

 

If its any use, I've got a drilled 'stat and a bleed tee like you: This is how I do it:

 

- Open the heater valve.

 

- Remove the header tank cap.

 

- Remove the radiator bleed screw.

 

- Open the bleed tee. Lift it up as high as possible (I hold it up with my left hand whilst pouring using a cloth scrunched up underneath to catch any spillage, with the lid somewhere in easy reach and a plastic jug to pour the coolant in my right hand).

 

- Fill it from the bleed tee, really, really slowly, until water starts to come out of the radiator bleed screw - then replace and tighten the radiator bleed screw.

 

- Continue to fill from the bleed tee, really, really slowly, until it reaches the correct level in the header tank - then replace and tighten the header tank cap.

 

- Continue to fill from the bleed tee, really, really slowly, holding it up as high as possible, until it is brim full and you can't get any more in - then replace the bleed tee cap. The level in the expansion tank shouldn't continue to rise as you do this as, with the cap on, the tank is sealed and air cannot escape to let more coolant in. If it continues to fill up the header, your cap is leaking.

 

- Job done.

 

If it's already fairly full, you will probably need to let some out before removing the radiator bleed screw as it isn't by any means the highest point in the system and coolant will come out of there it it is too full. I may be being over-cautious but when I was pouring the coolant in I really did just trickle it in at a snail's pace to let air escape upwards ahead of the rising water level. It's worked for me several times now on two engines but it does seem that everyone has their own favourite technique that they swear by! Hope you get it sorted soon, I remember the first time I tried to do it, with no drilled thermostat and not much of a clue, after changing the head gasket - it was indeed a complete bu**er.

[oldbutnotslow]

You will be aware that the water pump is cam belt drived so whilst the actul process of replacing the pump is simple you have to go through what is in effect a cam belt replacement if the belt is other than new. The belt if it is being refitted must run in the same direction as when it was previously fitted.

[Roadsport06]

I fill mine up the same as revilla.

Once you have a expansion cap on and are filling from the bleed tee you should have got the air out if done slowly. It might take a few goes of starting the car getting the car to heat cycle and squeezing the hoses to work out any air. Then coming back to the car once cooled and checking that the bleed tee is full.

[CliffC]

Thanks fro your replies. Update:

i emptied the coolant and refilled it this time using the Bleed T piece. i have always used the header tank and lifted the car as high at the front as possible in the past so i thought try the T piece method. I made sure the T Piece was the highest part and began filling slowly...The Header tank got to its level first and then i locked it with the cap. The radiator breather followed shortly afterwards and i blocked that off. i then continued to fill via the T piece until i could get no more in. I massaged the pipes as much as possible during warm up and some bubbles appeared in the header . i had the heater on and this was blowing hot air.. ,,so off i went for a quick drive and after 1/4 mile i notice the heater went cold and the engine began to heat up. Got home OK and waited for it to cool down. T piece was not full so added some more coolant as before until i could get no more in. again some bubbles via the t piece. Went out again and thought i had cracked it (3-4 mile run with no problems then the heater went cold as before)

i'm getting there but this is tedious and i have never had this issue before.

I will just keep on little by little at a time.

 

Cliff

 

[revilla]

Unless your car is different to mine, it sounds odd that the header tank reached it's level before the radiator filled up - unless you were still trying to raise the front of the car up high? I don't do this, and filling from the bleed tee at the back it would probably be counter-productive. If you think of the whole cooling system being just like a complicated shaped hollow pot, if you fill slowly enough to allow everything to settle as you fill, the water level should just be a flat plane across the engine which rises as you fill, and should therefore reach the lower holes before it gets to the upper levels. On my car the radiator bleed screw is well below the level in the header tank, so the water level should reach this first. As an analogy, imagine filling a teapot slowly through the lid. It would be odd if it started to overflow from the lid before it started leaking from the spout, as the spout is lower, however complicated the shape was inside. This would suggest that water isn't able to flow around freely, or air isn't able to escape somewhere to let the water level settle. One thing that may be worth checking is the "jiggle valve" or "auto bleed valve" where the small pipe comes off the inlet manifold (but disconnecting this pipe would mean having to refill again). If you take the rubber pipe off the manifold, inside the metal pipe stub there is a little ball check valve that is designed to allow airlocks to bubble through and return up to the header tank while restricting coolant flow. If this is clogged up (it is very small so could clog easily) it could encourage air to get stuck, and make it difficult to fill and bleed correctly. You should be able to wiggle the little ball valve around with a little screwdriver and (I think) you should be able to blow through it (inwards from the pipe fitting). If that is flowing freely and you have drilled the thermostat correctly (the hole in the bezel should be at the top as installed), I can't see where else there may be an obstruction as even the water pump is just an open impeller. It should be just like filling up a big pot.

 

Edited by - revilla on 30 Mar 2014 20:46:14

[CliffC]

I will give that a check tomorrow and let you know if it was blocked. I am still,getting the odd bubble from the T piece if I massage the hoses and I 'm able to add more coolant every time.

The strange thing is I have never had this much problem in the past which would suggest something is up.

 

Thanks for your reply.

Cliff

 

[jamiegb]

I once managed to fit the thermostat the wrong way round so found the car overheating after a short drive but didn't notice whether the heater was working or not. Might this explain things?

[johnnyseven]

Hi Cliff- did you get this sorted?

[Jonathan Kay]

Quoting revilla: 

If you think of the whole cooling system being just like a complicated shaped hollow pot, if you fill slowly enough to allow everything to settle as you fill, the water level should just be a flat plane across the engine which rises as you fill, and should therefore reach the lower holes before it gets to the upper levels. On my car the radiator bleed screw is well below the level in the header tank, so the water level should reach this first. As an analogy, imagine filling a teapot slowly through the lid. It would be odd if it started to overflow from the lid before it started leaking from the spout, as the spout is lower, however complicated the shape was inside. This would suggest that water isn't able to flow around freely, or air isn't able to escape somewhere to let the water level settle.

I think the rising plane is a useful concept. The problem is the air pockets. It's hard to understand what's happening in some cars, and there are several descriptions of cars that have been refilled successfully in the past but then, with no apparent reason, accumulate airlocks (or something that has a similar effect).

 

Jonathan

[CliffC]

Update: thanks for all your words of wisdom first and foremost.

 

I emptied all the coolant out again, removed the stat and confirmed the 3mm hole was at the top. I then lifted the rear of the car slightly which made the T piece the highest point. I then began to fill SLOWLY...and I mean slowly. First to go was the radiator overflow ...blocked this off then the header tank came up to the level...put the lid on and carried on filling. Even when the T piece was full I massaged the heater return pipe and lifted the T piece hire with further bubbles still coming from the T piece. I also lowered the car to normal level and was able to get more water in and air out of the T piece. I was convinced I had followed the procedure and had got more coolant in this time than before.

 

Started the engine and went for a drive around the block. Heater was warm but not hot for 10 mins and the car was at 80degrees when all of a sudden the heater goes cold very quickly and the engineer temp begins to rise above 100 😔

 

So I left it to cool and the T piece was showing empty so again filled and massaged with further bubbles appearing. What I have noticed is if I squeeze the small hose that runs between the lower heater outlet and the stat housing I can hear air bubbles in this pipe. I have not had the big gulps of air appear In the header tank as before neither ☹️

 

Could the heater have a fault ( there appears to be no leaks though and it does work intermittent)

How else can air be getting into the system?

What if I shut the heater off and see if engine temp stays at 80?

 

Thanks

Cliff

 

 

[revilla]

Mmmm ... You're really really having problems aren't you?

 

When you drained the coolant out again, did it all look healthy and clean? Is there any sign of it blowing water out of the expansion bottle cap? Are you saying that it warms up gently and normally at first, then the temperature rises very suddenly after it reached normal operating temperature?

[CliffC]

No water is being lost via the expansion bottle via the cap. When the coolant is hot you can hear the pressure release when you open it. Same with the T piece .

The coolant looks the same as it did when it went in.

 

Yes the engine if just left to tick over will take an age to warm up and you can tell the stat is opening as in time the J pipe will begin to warm up as expected.

It just seems to get to operating temperature and then for no reason the heater goes cold.

 

So to me it would appear there is an airlock but I cannot believe much if any air was left in when I filled it.

 

Edited by - CliffC on 3 Apr 2014 21:45:09

[revilla]

Cliff,

 

If you leave the car just idling, what happens?

 

I'm assuming from your description of the problem that it warms up normally, that all the pipes get properly hot. Is this true? Do both of the heater pipes initially get hot, i.e. the one from the head and the return to the thermostat? I'm guessing they must if the heater initially blows hot.

 

What then happens? Does the heater go cold again even while idling, or only when you take it out for a drive? And once the heater has gone cold again, how much coolant are you able to add at the bleed tee? (Be careful opening the bleed tee while the system is hot and pressurised, I'd let the pressure off at the exapansion bottle cap first). Can you tell if there is any significant pressure building up in the cooling system (i.e. hiss of escaping gas when slackening the expansion cap) BEFORE it gets properly up to temperature (it will develop some pressure when really hot, but shouldn't be gassing when just warming up).

 

Did you measure how much coolant you had managed to get in? When I filled mine I did it using a measuring jug and managed to get a good five litres in.

 

The cooling circuit only has a finite capacity; if you are able to repeatedly run the car, get air in the heater and top up with water, and you are adding about the same amount of water each time, eventually it will be full with no air left (a good thing) or the water is going somewhere. If the water is going somewhere it must be leaking either outside the engine (which should be visible, especially if it does it when hot and idling with the bonnet off so you can have a good look around for water or steam, or the whitish staining of dried coolant) or inside the engine.

 

The only likely point of leakage I can think of inside the engine, and therefore not immediately visible, would be the head gasket, through which water could leave the cooling circuit either into the cylinders or into the oil. I presume your oil still looks basically healthy, no obvious mayonnaise or grey opaque oil?

 

The reason I asked earlier about whether it was blowing water from the pressure cap and whether the coolant still looked clean was I was just wondering if the head gasket was allowing combustion gasses out into the water, however it doesn't sound like you've noticed anything in particular that shouts out head gasket issues, so at this stage I'd just go round the loop a few more times of running it for a bit and topping up, running for a bit and topping up until hopefully things settle down. It does seem to be being unusually resistant to filling properly though, and your description of the process you used sounds pretty much the same as mine, except I didn't at any point raise the nose of my car; I think the idea is to arrange the car such that the filling point is the highest point in the system and that all other parts of the cooling system have a direct "upward" path to the filling point without local high points to trap air, so when filling from the bleed tee at the back rather than the expansion bottle, you want the front of the car down low if possible.

 

Let us know how you get on. I can imagine this is getting very frustrating!

 

Andrew.

[CliffC]

Update:

 

Andrew, thank you for your message.

I have today been tinkering with it and i was getting no where. At one point i thought i had cracked it as all seemed to be OK but again the heater went cold and the engine began to overheat.

 

So i checked the oil cap and....... some small amounts of a mayonnaise like substance 😔 ☹️ HGF i suspect. Now this would also point towards the engine running a little rough before the winter hibernation but even then it seemed to running fine most of the time and it did not overheat before the winter break.

 

So that explains why i was unable to get all the air out of the system as i knew i was filling the coolant slowly and doing it correctly. As i said earlier in this thread i thought there was something strange going on.

 

Now, where to get the HG replaced in Dorset/UK South? Any suggestions gratefully received. DVA upgrade time??

 

Cliff

 

 

[Stationary M25 Traveller]

I understand Tom New is your local guru. New Engineering ?

[revilla]

Cliff,

 

A little bit of mayonnaise under the filler cap doesn't necessarily mean HGF as it can be down to condensation, especially in a car that is used for short journeys, BUT ... given the apparent disappearance of water and the appearance of air/gas in its place, it sounds like it needs checking out. If it is failing, sounds like its only in the early stages and best to get it sorted before it does any further damage. To be honest, the same could be said about anything that is causing airlocks and/or overheating on a K-Series - even if its not HGF; if you've done your best to get the air out and it really won't play ball it would be best to get it looked as a.s.a.p. as you'll otherwise end up with a cooked head.

 

Your local guru/garage should be able to organise a "sniffer" test for combustion products in the water, which will prove it one way or another. Head gaskets can fail in different ways leading to different fluids coming into contact, however in your case if explains the filling problems it must be at least letting combustion gases into the coolant. To be honest someone who has seen it all before will probably be able to tell you one way or another after a good look at it anyway. I wouldn't presume to diagnose it over the internet but there's enough alarm bells ringing to get it checked out.

 

Good luck and keep us posted,

 

Andrew.

 

[David Mirylees]

Only just seen this. Just a thought but if you remove both heater hoses and join them (use eg. a piece of copper pipe) this will bypass the heater.

Run the car gently and see if you have the continued problem. Pretty sure that if you do then it would indeed point towards HG. If not then a prob with the heater.

Assuming of course that modern Caterham cooling systems are not dissimilar to my old truck.

Also assuming that someone else hasn't already mentioned the above...