Water temps high when heater on!?

Water temps high when heater on!?

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shrink1061

Original Poster:

102 posts

90 months

Monday 10th October 2016
quotequote all
Hi all

I'm delighted to have joined caterham
Ownership and have a lovely little 1.6 K roadsport that is an absolute delight.

One full track day under its belt and by the end of the day we were one of the quickest things out there, confidence inspiring!

However....

I notice that if I pull the lever to open the heater matrix, my water temperature reports that it's at 100 degrees all the time. Never goes up or down.

Close the valve and temps come down
And are reported correctly.

Is this normal behaviour?

Any advice appreciated


nigelpugh7

5,996 posts

189 months

Monday 10th October 2016
quotequote all
shrink1061 said:
Hi all

I'm delighted to have joined caterham
Ownership and have a lovely little 1.6 K roadsport that is an absolute delight.

One full track day under its belt and by the end of the day we were one of the quickest things out there, confidence inspiring!

However....

I notice that if I pull the lever to open the heater matrix, my water temperature reports that it's at 100 degrees all the time. Never goes up or down.

Close the valve and temps come down
And are reported correctly.

Is this normal behaviour?

Any advice appreciated
Wow first ever post, and it's one here re your Caterham!

Welcome to Pistonheads and of course to Caterham ownership too.,

It's worth checking to see if the gauge is working properly first, followed by the sender.

You need to disconnect the sender cable and earth it, so see if it goes from zero to full deflection once earthed, IE from cold to hot on the gauge.

If that is all good it could be the sender.

It's also worth checking to see if you have an air lock, which is common on k series, but if it is running ok and not overheating, I can't see it being that.

Another thing to check is the thermostat , but check the easier bits first.

I assume the car is running ok, and no water leaks?

When the heater is turned on, does hot air come out of the vents?

Feel all the hoses from the engine up to the heater when the car is hot, and make sure all are warm ( or very hot be careful!)

I hope that helps as a starter for 10!

Good luck,






shrink1061

Original Poster:

102 posts

90 months

Monday 10th October 2016
quotequote all
Thanks for coming back to me!

Yep heater works a treat, all pipes warm.

As above if I push the lever for heater in my temps read normal (80 ish degrees) and the dial goes from cold to hot as the engine increases in temp.

But open the heater valve and all of a sudden temps rise to 100 and then stay there rock solid.

One full track day and temps didn't waver or go above that. Just very odd smile

shrink1061

Original Poster:

102 posts

90 months

Monday 10th October 2016
quotequote all
also worth noting that even when it reads 100 degrees, the front radiator only feels reasonably warm, and the fan isn't kicking in. So it's not like I think the engine is actually getting too hot.

as soon as i close the heater valve, the temps fall back down to 80 degrees within a few minutes.

odd!

shrink1061

Original Poster:

102 posts

90 months

Monday 10th October 2016
quotequote all
Bit more reading suggests i may just have an air lock in the heater itself. When it's not in circuit the system is fine. I'll see about getting that cleared out.

Graham D

14 posts

102 months

Monday 10th October 2016
quotequote all
Sounds like an air lock. The heater matrix is the high point in the system, therefore the likely place for air to collect and prevent/restrict coolant flow around the bypass.
I always fill the engine with coolant from this high point and have never experienced the problems other K-series owners constantly complain about.
I disconnect the highest bypass hose from the heater valve, then attach an old 90 degree bend to the heater valve. I now have two open ends of pipe pointing upward.
With the radiator bleed plug and expansion tank cap removed I fill with coolant from one of these open ends (I don’t think it matters which – have alternated on one occasion).
The plug is replaced when coolant appears at the bleed plug hole and the cap is put back on when the coolant reaches the required level in the expansion tank.
Unfortunately, once coolant appears in both ends of the open pipework things get complicated and occasionally messy.
I can’t explain the last step of removing the temporary bend and reconnecting the bypass to the heater valve (without letting air in) - it’s one of those things I have to reinvent every time I do the job - it's useful at this point to have 3 hands!.
I know it’s not easy, but as I said earlier it works.

shrink1061

Original Poster:

102 posts

90 months

Monday 10th October 2016
quotequote all
I think I get you!

So unplug top Hose from heater valve and attach something to it which gives it an upward facing fill point.

Then with bleed cap and expansion tank top off, fill one or both the open hoses with cool and until it comes out bleed valve.

Seal up bleed valve and make sure level is right in expansion tank.

Then try not to make a total mess plugging the hose back into the valve? smile

shrink1061

Original Poster:

102 posts

90 months

Monday 10th October 2016
quotequote all


A sneak preview of my new pride and joy. Will report back on heater front!

Graham D

14 posts

102 months

Monday 10th October 2016
quotequote all
Yep, that's it.

Good luck

anonymous-user

53 months

Tuesday 11th October 2016
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get a infra red thermometer and check every thing, you can then use it to set up your tyres, great little tool for the track

subirg

717 posts

275 months

Tuesday 11th October 2016
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I had a similar problem with mine. Turned out to be a small split in one of the heater hoses causing havoc with pressures. The split was so small it was hardly noticeable... right pain to diagnose. Good luck!

shrink1061

Original Poster:

102 posts

90 months

Tuesday 11th October 2016
quotequote all
Thanks all

its not causing any major running issues, and the fan is kicking in and engine seems happy. Just not keen on having the temps stuck at that high (assuming its not 100% normal and its the gauge thats out of calibration!


Steve Campbell

2,109 posts

167 months

Tuesday 11th October 2016
quotequote all
Been 6 years since I had a K series but I seem to remember the best way to refill the water was with the front of the car jacked as high as you can so the high point is at the radiator end. I'm sure blat chat will have something in the archives.

shrink1061

Original Poster:

102 posts

90 months

Tuesday 11th October 2016
quotequote all
I thought general advise was to jack up rear of car, and use the heater valve as high point?


shrink1061

Original Poster:

102 posts

90 months

Thursday 13th October 2016
quotequote all
So to further this!

Last night I took it out and got it up to temp.

-radiator top hose hot
-both sides of heater pipe work hot (don't think heater has air lock)
-when radiator bleed opened, coolant comes out.
-bottom hose on radiator only mildly warm.
-return path on cooling system back into block only moderately warm.

Could it still be a problem at radiator? It seems that everything is fine until this point. The return path is never hot enough for thermostat to open. Something is stopping the hot water getting from top
Of radiator back out.

However when squeezed, all hoses cause movement in expansion tank including the bottom radiator!

Stumped!

justleanitupabit

201 posts

106 months

Thursday 13th October 2016
quotequote all
Still an airlock. (Although is the thermostat definitely ok?)

Jack up the front as high as possible - massage the pipes as much as possible and open the bleed on the top of the rad.

When I was doing mine a while ago we also put (more) pressure into the expansion tank too.

Eventually there was a gulgling and it cleared.

shrink1061

Original Poster:

102 posts

90 months

Thursday 13th October 2016
quotequote all
Impossible to know if thermostat is ok as the water leading to it is too cool to open it.

I'll jack up later and see if I can fix it.

shrink1061

Original Poster:

102 posts

90 months

Thursday 13th October 2016
quotequote all
Interestingly everyone keeps talking about a bleed on top of the rad! I don't have one... what i have is:



the only thing that looks like a bleed, is the 4 inch rubber hose that comes out between the electric switch and the large rubber inlet hose.

Should I be bleeding from there?

best pipes to massage to get it all clear?

Graham D

14 posts

102 months

Thursday 13th October 2016
quotequote all
The radiator in your photograph is different to that in my 98 car. It looks plastic whereas mine is steel and has a bleed point just to the right of the inlet hose.
The old radiators don’t have the smaller diameter pipe between the inlet and the fan switch. To what is this pipe connected (I can’t tell from your photograph)?

shrink1061

Original Poster:

102 posts

90 months

Thursday 13th October 2016
quotequote all
To nothing!

It's just four inches of hose with a hole in the end (giggidy)

It's plugged up with a screw to stop fluid getting out.