K series overcooling?

[TomB]

My temperature gauge / thermo or sender is being odd. I can get my 1.4 K supersport up to temperature on the gauge when it is at idle, but as soon as I take it out and the air flow gets going, the gauge goes down to the blue.

 

I have cleaned the sender contacts. As it is a former track car, could it have been set up to always run cool because of the higher temps of racing?

 

As far as I can gather it is either a dead or faulty thermostat, it has never had one fitted, or it is stuck open. I got it from caterham midlands a fortnight ago & if I want them to rectify it, I have to take it down to them & make a 300 mile round trip. Is there any thing obvious to try? How easy would it be to replace the thermostate with a replacement Metro unit from halfrauds?

 

Thanks in advance

 

PS the car has a heater fitted

 

Edited by - TomB on 13 May 2002 20:08:46

[Allen Payne]

It's difficult replacing the thermostat just fiddly if you have large hands as the space is very tight.

 

If you follow the water pipe from the bottom of the radiator into the engine the thermostat is in the black plastic piece that's between the end of the water pipe and the engine. To remove it remove the bolt that holds the oil dip stick to it and the the assembly will pull away from the engine. There are three screws that hold the black plastic assembly together and the thermostat is in-side.

 

Does that make sense?

 

Regards

Allen

[Bangers quotNquot Mas1697456953]

Try the sender, doubt if you'd get overcooling problems with the K (Speak to Bob Corb, he works all day at Cosworth Engineering trying to keep 'em cool!!!.)

 

I know two people who's senders have given up the ghost recently.

 

Worth a try, and you don't skin your knuckles changing it!!!

 

Good luck!

 

Andy Marks

VHPD7@aol.com

[Bob Corb]

Thanks Andy (its Cosworth Technology actually!)

 

It sounds like either the stat is jammed open or it just isn't fitted. I spoke to Jez Coates a few weeks ago about cooling and he confirmed that on SLR race cars they have to remove the stat completely. This isn't because the stat isn't doing its job but because it imposes a restriction on the flow thru the rad circuit (race rads are also more restrictive due to their 3 pass design, they can be identified by having their tanks on the sides rather than top/bottom) so removing the stat just allows the flow to move more freely. I've fitted a restrictor in my bypass hose instead to help force the coolant through the rad, your heater should have the same effect. It really does sound like a duff stat (but check the senders first).

 

Anyway back to your problem, does the radiator start to get warm straight away or does it stay cool while the engine warms up and then suddenly heat up? If it warms gradually then you have no stat or its jammed open. I presume it takes quite a while to heat up? Running a race engine with low coolant temp is good for performance (although you should get the oil quite hot anyway) but wear will be high as the clearances will all be wrong.

 

Changing the stat isn't too hard but there is a strict procedure to follow. A search through the archive should find it.

 

Let me know how you get on.

 

Cheers

 

BC

[PAUL MARRIOTT]

I've just had similar symptoms, at Cadwell, the temp on gauge was fluctuating and finally refused to go over 60degC.

 

New stat in pot of boiled water gave 80degC. changed stat guage now stabilises at 80degC.

 

When ticking over does your fan cut in, should do about 80degC. if so change stat or think about gauge (had to change that last year) you could check that against oil temp.

 

My only problem now is that ECU tells me temp is 94degC., gauge tells me 80degC. Fan cuts in and out and when I removed old stat no water fell out???

 

Paul M.

 

 

[Bob Corb]

Paul

 

Are you saying that when you removed the stat housing no coolant poured out, thats kind of worrying? When sensors aren't in the coolant they can say anything (such as 94°C). Perhaps you should have a good bleeding session Paul just to be safe!

 

See you saturday (BHP run).

 

BC

[TomB]

I had a play tonight with the car. The radiator gets warm gradually, within 1 -2 min of starting & ide running.

I have determined I do not have a race radiator, as the tanks are at the top/bottom.

 

The fan cuts in when left still for long enough & the dial has got round to 80 90 ish.

 

I earthed the temp sender wire with the ignition on & the temp dial fully deflected. Therefore i think my temp sender is OK.

 

It looks like a duff stat or absence of a stat. is it the standard Rover 1.4 part? Would someone kindly put idiot proof instructions of how to replace the stat / check its there etc here?

 

I have only had the car a fortnight - Caterham should have fixed this before I got it. They should sort ot now on warranty, but I dont really want to make a 350 mile trip to get it fixed when the part is only a few quid & it will cost £40 in fuel + hassle etc. Any ideas as to what it would cost at a Caterham agent? Could I take it to a local Rover garage?

 

 

[Delberts Wallet]

Doesn't earthing the senser wire just prove that the gauge is working?

 

Refering to what Paul said about no water coming out when he removed the stat when I removed my temp sender no water came out of the water rail. I guess I may have a problem with air in the system??

 

Gareth

 

Who Dares Twins bum.gif bum.gif

[PAUL MARRIOTT]

I've aquired a surface temp probe so will be playing with mine again tonight will let you know result, as you say Bob it is a bit strange.

 

Paul M.

 

 

[Bob Corb]

Tom

 

Where are you based? Surely there is a closer Caterham Service agent closer than 350miles who could do the work.

 

BC

[Mark Chilton]

I was at Thruxton on Bank Holiday Monday. It wasn't a warm day. Many of the superlights there had duct tape across the lower half of the nose cone grill.

 

.....seems a nice low tech solution to the problem and cheap!biggrin.gif

 

I've recently fitted an Apollo to my VVC and the car runs significantly hotter (when it finally warms up!).

 

...........A rather more expensive solution but with 7.5 to 8 litres of 'Mobil 1' thrashing around the engine it eliminates any risk of overcooling!.gif

 

Mark

 

CATCH THE WIND

[PAUL MARRIOTT]

I had a go at my system last night, checked to water and confirm that the system was full, tick over at 1100rpm with an temp in the garage of 20degC.

 

Once everything had settled noted the following

 

1. Temp at Fan sensor on rad. Fan on 93–89 degC, Fan off 88-55 degC.

2. Temp at exit from rad 90–78 degC

3. Temp at guage sensor point on water rail 96-91degC

4. Oil temp at oil cooler (Laminovo) 88-86degC, at top of Appollo c.86degC.

5. Temp gauge was indicating about 7degC low on both oil and water temps.

 

I’ve spoken to Caterham Tech line and they tell me that this is all is OK. That the fan should cut in about 95degC and the thermostat open at about 83degC.

 

Paul M.

 

 

 

[TomB]

I negiotaited a waranty from caterham midlands for an ex race car, which they dont usually give. Basically _they_ will look after my car for the warant period. I think I will invalidate my waranty with them if I take to the caterham agent in Liverpool (10 miles away). It amounts to hassle, & as theyd want the car for few days, fuel cost for 2 cars there and back, all for a £10 thermostat.

 

So I will either do it myself, or wait till the waranty period is over then pay £40 - 50 at the agent in Liverpool. Ive been told by three people at caterham that it wont do the engine any harm to run cool for a few months. They are more concerned with hot cars.

 

I am going to experiment with blocking half the rad up & see whether temp rises.

 

 

[mav]

Tom,

 

Take your car to Ryders at your own risk. Speak to myself and Buda at the next meeting for more information, or drop me a line off list if you want to know sooner.

 

Regards,

 

Martin

[Phil]

Just wondering if the antifreeze has anything to do with this as it is a summer coolant as well, would this effect the temp if over filled, it should I believe be about 33% of the total cooling system capacity.

 

 

[TomB]

My antifreeze for whatever reason is only 20% strength. I need to change it. Would this affect the temperature of the engine in normal running?

[Bob Corb]

Weaker antifreeze concentration improves the thermal conductivity and heat capacity of the coolant. If you could keep the car in a warm (i.e. above freezing) environment then it would be best to use almost pure water with a small amount of anti corrosion additive such as Havoline XLI although I've never seen it for sale anywhere (just mentioned on their website).

 

Rovers new long life coolant is Havoline XLC (but re-badged), this is a mix of propolyene glycol with the anti corrosion agent (the XLI stuff) which is an organic acid compound which is all the rage with OEM at the moment. Havoline coolant are now used by most OEMs under their own brand names. Its recognsable by its orangey pink colour.

 

Increasing your coolant strength will only increase temps further but not a lot. I dont think that your coolant is the problem at the moment.

 

Bob

[Phil]

Increasing your coolant strength will only increase temps further but not a lot.

 

I thought this was the other way around, the more coolant the lower the tempreture?

and less means higher running tempreture?

 

 

[Blatman]

Increasing coolant strength means the ratio of water to "antifreeze". It's an efficiency question, not a volume question........ More antifreeze makes the coolant (coolant being the liquid produced by mixing antifreeze and water) less efficient, so a 66/33 water/antifreeze mix will be more thermally efficient than a 50/50 mix, but not by a lot. Certainly not enough to worry about, even on a K series engine........

Re read Bob Corbs last posting carefully. He says it far better than me, the important bit being:

Weaker antifreeze concentration improves the thermal conductivity and heat capacity of the coolant. If you could keep the car in a warm (i.e. above freezing) environment then it would be best to use almost pure waterid=blue> with a small amount of anti corrosion additiveid=red> such as Havoline XLI although I've never seen it for sale anywhere (just mentioned on their website).

[Phil]

Thank you.

 

 

[TomB]

Hooray! A happy chap who has just done his first proper mechanical job on his 7.

 

Today i installed a stat - a fiddly job to say the least. I hope I dont have to that again. As suggested, there wasnt one fitted. Now the temp gauge gets up to temp quicker and runs at a proper temp. The fan kicks in at 90 ish

 

I noticed how sensitive the gauge is when i took it for a test drive. At traffic lights you can see it increase a degree or two, cooling if when you drive away.

 

Also with a sudden squirt of throttle, the temp quickly fell, then increased. Presumably the pump is engine driven, faster revs making cool water rapidly move out of the radiator down the rail towards the sender.

 

At 90 - 100 mph, the temp hovered slightly below 80 degrees.

 

Thanks for your advice. An afternoon of work that saved a lot of hassle delivering the car to Caterham Midlands for them to do under the waranty.

[mav]

Hope you were not on the 'Queens Highway' at those speeds Tom.

 

A few 7er's are going to Anglesey for a trackday at the end August. It is with bookatrack.

 

 

 

 

[TomB]

Certainly not, who'd do such a thing. My cat was driving, officer...