Calling HGF experts

I have been having this problem with my Exige where the temperature shoots up very quickly when the engine is under load.

I found that air was getting into the water system and under further inspection found a cracked water rail (the return one that fits to the thermostat) which I attributed the problem to. I have now fitted a new water rail but the problem still uccurs. I have done all the usual HGF checks and there is no oil/water mixed, the engine has excellent and even compression and there is no steam being blown out of the exhaust even when the car has been restarted after being run. Is there any other way air could be getting into the system or is HGF the only possible cause???


It is normal for the temp to drop suddenly once the thermostat is open - then steadies to around 82 gegrees quickly thereafter. You may, or may not have a HGF problem!

The following will assist:

Copied from Eliseparts site

[color:“blue”]Remote Thermostat
The design of the Elise cooling system is not ideal as the �K� series engine was designed for a FWD car and the Elise is a RWD car… Specifically designed for the Elise, this remote thermostat can be fitted almost anywhere in the cooling system although we advise the best location in our instructions.
The cylinder head takes the brunt of many oscillations in temperature ranges caused by the thermostat constantly opening and closing and very cold water coming back through several metres of pipe work from the front of the car. These temperature variations can cause the head to expand and contract many times ultimately causing head gasket failure.
Our remote thermostat alleviates the thermal shock caused by the cold water hitting a hot cylinder head. It can be fitted in under an hour and comes complete with new hose clamps and full fitting instructions.
Fit it sooner than later as the cost of a head gasket failure will be 10 times the cost of this easy to fit simple unit.
The unit is supplied with a 82� thermostat. �99.00
Complete Kit with New Hoses and Hose Clips [/color]

Hope this helps.

I wish it did drop!! I have the opposite… it rises and rises and rises . Strange thing is that the engine does not feel hot when you stop so it must the the air in the system confusing the sensor. If there is air churning around in the head though it could be very bad indeed.

Whoops - sorry, obviously can’t read properly this morning

It could be an air lock in the system - that produces the same results.

If the cooling system is standard it can be a bugger to bleed !

Doesn’t the ECU get a different temp to the stack… So it could be the stack temp sensor is foobar’d.

There’s a thread on SELOC about something similar, the temp reading is more random but it could be a similar solution.

Could be worth a go


I just had this happen to me yesterday.
On a road run with Tut nearing the end of thr un Tut took me to his local playground and we started hammering it, very very nice :gring:

But at some stage the temp went up fairly quick to 105 DegC, coasted but it made no difference and it continued rising up to 117. Then it started to go down.

We were arriving to Tuts house, so let the engine running and I checked for leaves. No leaves, nothing blocking the radiator.
Air coming from the fan was hot.

Scratching my head, put my hand again in the air stream coming from the fan, and it was cold
Scratched my head again and it was hot. It stablized then at 82. Water level was slightly lower but still there.

Let it cool and go home taking it easily. No problem.
On arrival check the water level and it’s empty
Topped up with water, let it cycle until the fan came on and it stayed ok.

Next morning use the car to go to the gym, supermarket, rover dealer (to get more coolant) and no problem.
Purged the cooling system and there was a little bit of air in the rear bleed port, the one beside the engine. The one on front had no air.

Topped up with 100% coolant (to compensate for the added water) and used the car a couple more times.

My doubt is this: should I use it to go to Knockhill tomorrow? (not trackday, just meeting others).
It could have been just that I had been fooling around just the previous day with the water tank cap, maybe I left it badly screwed and some water escaped.
Or it could be a HGF starting, and it just happens at full wellie, combustion gases leaking to the water circuit

No oil in the water and no water in the oil so far, and no steam.



The only way to be sure is to get a dealer to “sniff” the header tank - that way you know if you have a problem or not - hope it sorts out OK

Some more input on my problem…

Took the car to Henley Heritage this morning and they tested for combustion gases in the header tank and also exhaust emmissions. Good news is that it was given the all clear on both counts, in fact the emissions were excellent and they recon it would pass it’s MOT even without the CAT installed!

Now that HGF is most likely ruled out I’m still scratching my head. Next thing I’m going to look at is the water pump in case this is cavitating or sucking in air.

Thanks for all you help guys, I will lt you know how I get on.

Went to the dealer in the morning but they didn’t have the sniffetr tool, but they reckon that if it passed the 7000 rpm test, it would be safe to drive.

I set on my way to Knockhill, but didn’t make it, as on a particular part of the mountains where it’s fairly steep and twisty and I like to let it go, the temp went high again, about 30 miles from here.
Water spilled from the tank and everything.

Turned around and limped home. Temp ok if I drive it “decently”
Would you say it’s confirmed? 100% HGF?


Sounds like it

Have you got a compression tester or a bleed down kit ?

Nope, but just called Dave Andrews who said that it’s a HGF.
This happens when due to maufacturing defects (wrong liner heights the most common) when under load the head and block expand, they do so unevenly and at one tiny place it’s letting combustion chamber pressure pass on to the water circuit.

Bugger, I didn’t need this now, I intended to use the car for a job interview on Thursday down in England. Will have to go by train or rent a car.

Maybe replace it with a scholar evo 2 block ?

Sorry to hear your probs.
Isn’t this the excuse you need to get the engine tuned now?


Yes, it is, but without having planned it I’m afraid it would take too long, as DVA is fully booked until July

Will have to be either standard fix or do it myself.

Water spilled from the tank and everything.

Turned around and limped home. Temp ok if I drive it “decently”
Would you say it’s confirmed? 100% HGF?

Uldis, I’m no expert in this type of thing, but are you sure its not just the header tank cap that’s gone u/s, I’d still say its worth getting the “sniffer test done”. KH today was quite good fun, It was left to Rox and myself to entertane the crowed, I’ve also been told to quiz you about Russian woman that hang around trackdays



Just to repeat my offer today - I am happy to sell you my fully sorted 213.5 BHP DVA prepared VHPD, (very low mileage since work done), plus the close ratio gearbox if you need that…

I’ll be listing the engine on a few bulletin boards shortly, hoping not to dampen the demand for Rob’s engine…

Well, if it was the tank cap, it would go any time the temp rose around 80Deg, right?
I mean, it would just leak any time there was pressure.
But in my case I could drive the car for hours “decently”, like below 5000 rpm and everything would be OK. It’s just when I’m on full throttle for some time, like climbing up the mountains that the temp suddenly (in 3 secs shoots from 82 to 110 Deg) and at this time I coast and slow down and there is coolant spillage from the bottle.
If the cap was not holding surely the temp would stay pretty constant.

Talked with Dave Andrews and gave him the symptoms. He almost told me the exact place where I would find the gasket leak.

It’s good to hear you had a good time, as I was sad as a sad dog on a rainy day at home.

Anyway, not a big deal, it’ll be fixed in a week.
\The thing is that I wanted to go to the job interview down south in the Exige.
Now I will have to go by train.

And cheers Mike, I will think about it (and fantasize about having the Audi installed instead

Hi guys,

Only just caught up with the thread but as a few of you might know a month or so back I had my head gasket fail.

Luckily it was done mostly under warranty but yes all the symptoms everyone has mentioned were the same.

Temp started shooting up as soon as I pressed the fun pedal,
It was blowing water out of the header tank,
No real visible signs of any problems,
Generally running rough and spluttering! No change there then

Id heard of the tank cap probs and replaced it but no change!

I also thought it was the thermostat but unfortunately was HGF!

Now Ive had it done its running much better and never rises above 85degrees when you boot it

Just got to get my sticking trottle bodies replaced now