Temp fluctuations whilst driving steady.

[Stumpy Nugget]

I had a great day walking the CMD Arete and Ben Nevis today ruined by my temp gauge going mad on the way home. Basically my temp reading has been a steady 88 for the last year and a half, however, today whilst driving steady its was up climbing 90,91,92 - unless I drove with revs above 2.5K??? If I dropped a gear and allowed the car to run at 3K revs the temp would go down to 88. Weird?

Its a K Series S2. No signs of HGF however I have seen in the past a small amount of water around the temp sensor. I am thinking that an air lock might be the problem based on the fact the sensor is allowing water out and air in? However, the revs thing is annoying me? Could this be linked to the water pump not circulating water fast enough. The only other difference is that whilst sitting at the lights the car certainly heated up into the high 90's a lot faster than it has ever done.

I plan to have shot of replacing the sensor and bleeding the system to see if this fixes it, but any advice would be great before I go down the wrong road.

[Rich H]

My Porsche sits at one tick mark +/- a bit....
Digital gauges cause paranoia.
You wouldn't see a 5 degree shift on a normal gauge - forget it.

Rich

[Stumpy Nugget]

My Porsche sits at one tick mark +/- a bit....
Digital gauges cause paranoia.
You wouldn't see a 5 degree shift on a normal gauge - forget it.

Rich

Rich, you are of course right.. but I dont like it when things change, it usually means something needs looking at.

[Rich H]

Leave it until it moves significantly.

Higher revs pushes a higher volume of water round so it'll run cooler.

Do you have a prrt?

[Stumpy Nugget]

No Prrt fitted.. Will have a poke around to check plugs etc but only because I like checking things..

If it is HGF and I get AA'ed from the side of the road - where should I tellthe guy to take it? MMC? I do have p&L so not too fussed if it does go. Just in case

[roadboy]

No Prrt fitted.. Will have a poke around to check plugs etc but only because I like checking things..

If it is HGF and I get AA'ed from the side of the road - where should I tellthe guy to take it? MMC? I do have p&L so not too fussed if it does go. Just in case

AA P&L wouldn't cover the cost of a head gasket job at MMC. Probably not even half of it. In my experience. They only pay a maximum if £475.

It may be worth sending it further afield.

HTH

Dan

[Rich H]

5* temp change, no water or oil lost, it's not likely to be HGF!

[roadboy]

You'd be surprised. But, I agree, I wouldn't be pulling the head off at this stage.

Dan

[Alex 111s]

Keep an eye on it. This sounds similar to the 1st signs of HGF that I had.

Car would be fine on higher revs but then temp would climb if under 2k-2.5k and would drop again quickly if you gave it a bit of revs. the revs were sufficent to clear any partial vapour locking of the radiator caused by gases getting into the coolant. This got worse over a relatively short space of time to the point that the radiator was completely vapour locking.

a couple of points;
* warm the engine up by going for a run to get up to 'normal' temp, park-up and let the temp rise above normal & check the radiator outlet pipe - (you'll need to jack the car up to get access to the pipe through the pax side wheel arch liner) if it's cold or only warm to touch then it means that the radiator has vapour locked with exhaust gases (assuming that the the thermostat is working correctly
* get a local friendly garage to do a sniffer test on the coolant to confirm the presence of exhaust gases in the cooling system.

cheers

Alex

[Rich H]

Gett he SE sniffer and sniff the coolant, there were 2 doing the rounds at some point??

[robin]

Radiator weepage?

You say no coolant loss, but if a small amount of air is being drawn in, it can, to some extent mask the change in coolant level. Air collects in the radiator and reduces the already rubbish circulation through the S2 rad at low RPM, temperature climbs to compensate.

Anyway, I agree that the block sniffer is the next step ...

Cheers,
Robin

[duggiesmith]

Completely OT and no use to your dilemma, but how did you find the CMD Arete? Been meaning to do this since going up the "tourist" route last year.
Any tips?

[Stumpy Nugget]

The CMD Arete was a cracking day out. over 8 hours of walking and some cracking views. If you are doing it I would certainly recommend a clear day as the views of the Ben are amazing. The Arete looks a lot worse than it is. In fact there is a chicken run most of the way around so you can stay well away from the edge..

On the temp problem. I had a wee shufty around the car tonight, Water - fine, Oil - Fine, Plugs Fine (although one was slightly loose.. ). However, the plot thickens.. I took the car for another spin and the temp was again all over the place. I left it idling and without the aid of the fan the temp rose up to 94 degrees and then dropped to 87 where it sat for ages????? I am now thinking its the temp sensor.

[Rich H]

Or a sticky T-stat.

[Corranga]

5* temp change, no water or oil lost, it's not likely to be HGF!

I get 3 by turning the blower on

I hate, hate, hate changes in temp when i'm in the Lotus. Sitting in traffic watching it rise, it might as well be a driver blood pressure, or heart rate monitor

Chris