New Caterham Overheating

[softedave]

Hi, I have a new Caterham 1.6K Series that I built over the winter. I have done around 600 miles in the car most of it trouble free. However, occasionally when I get the car out it overheats very quickly - the bottom radiator hose is cold indicating that the thermostat has not opened. I have changed the thermostat for one that opens at 80 degrees but it has not helped. Caterham think that I have an air lock (and I agree). I blow fluid through the system and I can clear all the air out - the car then runs fine until it is left to cool down. The next time it is started (sometimes) the problem returns. It's driving me mad - I never know when the car is going to overheat.

Any thoughts?

Dave

[webmobo]

I'm having a similar problem - real pain - is the fan kicking in at all? Mine's going up to around 100 degrees (and above) and fan not being turned on - bypassing the switch activates the fan so there's two possible faults I think - fan switch broken or water not actually touching the switch - assuming an air block will cause this try squeezing all hoses with the front jacked up higher than the heater unit (if you have one). This should force air bubbles to the front, which you can release through the bleed hole in the radiator. That's the general opinion for clearing any air, although I'm not having much joy at the moment. You could also try searching blatchat - there's lots of info on this.

[DKL]

If you get an airlock at the thermostat it doesnt open so yes high temps but cold pipes. Lots of people (me included) run with small holes drilled in the thermostat which in theory allows any air to circulate but doesnt really hinder the operation of said thermostat.
I'm no mechanical expert but its worked for me.

[peter-2006]

Does the radiator bleed back to the expansion bottle? If it does try re-routing it so the small diameter hose goes from the head(next to in let manifold) straight to the expansion bottle then bleed the system through the small top cose off the radiator do this with the front of the car jacked up and engine running. when coolant is coming out of the hose then block it off with a bolt and jubilee clip.

We had this problem when we built my academy car and caterham had just started using a new design of radiator and self bleed system but it never work.

Edited by peter-2006 on Thursday 15th May 00:46

[dino ferrana]

Fan switch is a bit of a weak point in the system and they are prone to failure. Also the K is very hard to bleed, many people jack the front of their cars when filling to release air locks from the system. Also check you are using the right coolant, because of their construction they are very sensitive to the correct coolant being used.

[Jack_and_MLE]

On my car, 21 VVC, when I change the coolant, I run the engine with the cap of the expension bottle off until I can see a constant flow of coolant coming back.

Using this technic I never had an airlock issue.

Jack

[softedave]

Thanks for all the replies - there are some really good ideas here.

I am fairly sure the problem is air locks and not the fan switch as the pipes are cold. When I do manage to release all the air (by raising the front as you suggested) the fan kicks in.

My main concern is that once all the air is out the car runs normally all day; then I put it away for a day or two and the problem re-occurs. I may try re-routing the top hose from the manifold back to the expansion bottle so that I can vent the radiator via it's small top hose (as suggested by Peter-2006). If that fails then perhaps some holes in the thermostat (or remove it completely??).

The radiator has no bleed at the top and uses the new Caterham self bleeding system. I am using Comma fluid (the pink stuff recommended by Caterham).

Finally (Jack and MLE) even with the lid off the coolant bottle I never get a flow of coolant back to the expansion bottle. Some liquid comes out whilst it is heating up but there is certainly not a constant flow - is this correct?

Thanks again to you all, love the car - so frustrated by the problems. Dave

[Jack_and_MLE]

I believe you should have a constant flow going back to the header tank. The water pump should make the water circulate around the cooling system.
For that to happen on my car I have to leave it to run for quite a while.

Have you got enough coolant in the system?

Jack

[RAWENG]

I had a similar problem with my duratec when first built, the stat would sometimes not open. My fault was traced to a faulty expansion tank cap. It was not holding pressure.

[thinfourth2]

don't forget the standard caterham temp gauge is shall we say a bit piss poor in the accuracy and repeatability stakes

[sjr-997]

i'm considering changing most (if not all) of the hoses on my R300 VVC. Its been for a service today and the garage quite rightly pointed out the hoses are cracked and might break. this suprises me as the car is less than 2 years old..is this a common problem ? not sure whether to buy silicone hoses or just regular replacements. anyway, its a job i'll attempt myself even though its for sale. Any gotchas other than what has already been said ? I know VVC engines are not easy to get the air out of.

[caterhamnut]

Go for silicon hoses - makes everything a hell of a lot easier, in terms of fitting, squeezing (air out) and life, as the hoses don't perish or stiffen up like th eblack rubber ones do.

[OJ]

I had a chronic problem with this in my Mega

- Solution to air locks (I recommend you do this while cold, I also assume you have a radiator with a bleed bolt)

Remove bonnet and nosecone

Get a jack under wherever you want to jack it from

Jack it up as high as it will go.

Undo the bleed bolt on the top of the radiator, and the expansion tank cap

Start the engine, and keep filling the expansion tank until coolant starts spurting out of the bleed bolt hole

Either switch the engine off and do up the bleed bolt, or for maximum effectiveness just brave it and do up the bolt while the fluids still coming out, it wont be too hot if you've done it from cold

Top up expansion tank to suitable level (don't worry if its a bit high)

Replace cap, nosecone and bonnet

Et voila, no more overheating

[mrsxllifts]

Hi. I am posting this on behalf of a non-t'interweb friend who has trouble with his Caterham 7, so will try to give as many details as I know.

It is a 1600cc 8v with an Astra engine (c16nz type) approx 9 years old.

He has trouble that it keeps overheating (to over 100 on the cockpit dial). It happens everytime it goes out for a run. But has only started happening since it was laid up for the winter and then brought out for the summer season this year. The fans kick in when they should and we have removed the thermostat to eliminate that potential problem.

So far we have:

1) Checked for air locks, jacked up front, pushed water through etc

2) Checked radiator is clear, heat seems fairly even through out but chucked rad-clear through anyway!

3)Bypassed matrix, just in case valve was mucking around

4)Replaced water pump, looked ok but changed it as we had it out.

but so far nothing has succeeded.

Caterham have totally confused everything! Technical said it must be radiator, stores say they have never heard of one going wrong and it must be the pump, but we seemed to have covered both of these, still with no joy.

It has been suggested that it may be the head gone, but there is no loose of power, no oil in water, no water in oil and no smoke of any sort from exhust.

Please help, any ideas welcome!

Any information would be gratefully received and will try to get any further information required as soon as possible.

Thanks in advance.

[rdodger]

DKL said:

If you get an airlock at the thermostat it doesnt open so yes high temps but cold pipes. Lots of people (me included) run with small holes drilled in the thermostat which in theory allows any air to circulate but doesnt really hinder the operation of said thermostat.
I'm no mechanical expert but its worked for me.

This is a very popular mod with K series mid engined cars and works well. As an alternative try a remote thermostat with bypass or the PTP thermostat.

[thinfourth2]

mrsxllifts said:

Hi. I am posting this on behalf of a non-t'interweb friend who has trouble with his Caterham 7, so will try to give as many details as I know.

It is a 1600cc 8v with an Astra engine (c16nz type) approx 9 years old.

He has trouble that it keeps overheating (to over 100 on the cockpit dial). It happens everytime it goes out for a run. But has only started happening since it was laid up for the winter and then brought out for the summer season this year. The fans kick in when they should and we have removed the thermostat to eliminate that potential problem.

So far we have:

1) Checked for air locks, jacked up front, pushed water through etc

2) Checked radiator is clear, heat seems fairly even through out but chucked rad-clear through anyway!

3)Bypassed matrix, just in case valve was mucking around

4)Replaced water pump, looked ok but changed it as we had it out.

but so far nothing has succeeded.

Caterham have totally confused everything! Technical said it must be radiator, stores say they have never heard of one going wrong and it must be the pump, but we seemed to have covered both of these, still with no joy.

It has been suggested that it may be the head gone, but there is no loose of power, no oil in water, no water in oil and no smoke of any sort from exhust.

Please help, any ideas welcome!

Any information would be gratefully received and will try to get any further information required as soon as possible.

Thanks in advance.

Is your temp gauge 100% accurate?

[mrsxllifts]

We assume so as the fans kick in when they should. I know they are on different switches but they come in at the right temp on the cockpit guage, if that makes sense! Before the problem occured, the fans would only kick in when the car was really 'driven' but now its everytime it runs even if its a pootle down the road.

[OJ]

I'm sure you've checked it, but you haven't mentioned it... Thermostat?

Other end of the scale, is it running lean? Faulty pressure cap?

[mrsxllifts]

We have taken out the thermostat completely so we know its definately not that but will certainly look in to the pressure cap just in case. Assume you mean the one on the radiator? Thanks for the clue!