Temperature question

ruadh08 · Post by **ruadh08** » Wed Aug 11, 2010 5:33 pm

My 340r seems to be running at a fairly low coolant temperature, compared to what it used to be.

Currently normal running at between 75 and 85, including on track. At idle goes up to 91 after about 5 mins , which brings on the fan, which goes off again at 87.

I have recently changed the header tank cap, as the last one had broken, and was spraying out coolant on a track day. I also had an Eliseparts alloy rad fitted last year.

Car is running perfectly, so am I worrying about nothing?

Any advice appreciated!

Mikie711 · Post by **Mikie711** » Wed Aug 11, 2010 6:12 pm

The stack temp gauge works off a different sender than the ECU which controls the fan. ECU reads from the blue one and the stack from the brown one IIRC. So I wouldn't worry about it. When I had my emerald I could never get the 2 to agree on what temp the engine was at. If your fan is coming on then the temp is higher than the stack gauge is reporting, think the fan is set to come on at 102deg C on a rising temp and off at 96degC falling. You could change the Stacks temp sender and see if that makes any difference.

Gourlay83 · Post by **Gourlay83** » Wed Aug 11, 2010 6:28 pm

Your Thermostat could also be sticking open, which means your radiator is getting fed with coolant continually. Lowering your running temp

Alan

robin · Post by **robin** » Wed Aug 11, 2010 7:05 pm

Paul, I would replace the dash coolant temperature sensor and the thermostat (in fact I might fit a PRT).

I suspect replacing the stat on the VHPD in a 340R is way easier than on an elise with a boot in the way ...

The VHPD probably comes fitted with a 82 degree stat anyway, so the temperature will be a bit lower than a normal elise.

It's easy to diagnose whether or not the stat is stuck open/weak because the rad will warm up at the same time as the bypass loop, rather than the normal bypass loop getting hot straight away and the rad taking a while to warm up.

Cheers,
Robin

ruadh08 · Post by **ruadh08** » Wed Aug 11, 2010 9:26 pm

Robin, whats a PRT?

mckeann · Post by **mckeann** » Wed Aug 11, 2010 10:03 pm

Pressure relief thermostat.

http://www.eliseparts.com/products/show ... hermostat/

robin · Post by **robin** » Wed Aug 11, 2010 10:07 pm

It's like HRT for men ...

Cheers,
Robin

Gourlay83 · Post by **Gourlay83** » Wed Aug 11, 2010 10:17 pm

robin wrote:It's like HRT for men ...

Cheers,
Robin

What's HRT

Alan

RDH · Post by **RDH** » Wed Aug 11, 2010 10:37 pm

Gourlay83 wrote:
robin wrote:It's like HRT for men ...

Cheers,
Robin
What's HRT

Alan

It's like PRT for women...

duggiesmith · Post by **duggiesmith** » Thu Aug 12, 2010 8:11 pm

RDH wrote:
Gourlay83 wrote:
robin wrote:It's like HRT for men ...

Cheers,
Robin
What's HRT

Alan
It's like PRT for women...

What are women?

r10crw · Post by **r10crw** » Thu Aug 12, 2010 10:11 pm

Paul, as Robin says your car has the 82 degree thermostat as standard so if like mine it will run around 78 for steady state driving at 60. Dont think you have anything to worry about, since the sensor relies on the ground path it could be that as the car is ageing the earths are not as good as they once were giving a slightly different reading, I believe this would be a lower reading with increased resistance. You could try the old jump leeds over the car trick before replacing the sensor.
Craig.
PS be careful when checking the bypass loop since in the 340 with no cabin radiator, it tends to heat up very fast, I was shocked at how fast my temp gauge starts to display after leaving the house, it can be less than 1 mile to see 50 degrees where as the elise with the same engine took more than 4 miles.

Ferg · Post by **Ferg** » Fri Aug 13, 2010 1:27 pm

Just precautionary, but I swapped both my temp sensors out when I got my car. I had heard so much about the temperature probs in an Elise(&variants) that I thought for the sake fo £20 I may as well have piece of mind. They took 10 minutes to fit, worth every penny to know that what you see on the dash is as correct as it can be.

ian974 · Post by **ian974** » Tue Mar 15, 2011 8:49 pm

Gourlay83 wrote:Your Thermostat could also be sticking open, which means your radiator is getting fed with coolant continually. Lowering your running temp

Alan

Been searching through things!
Temperature is running low on my car, generally heating up to about 78-80 degrees, and the heater isn't as hot as usual, is this likely to be the thermostat stuck open?
radiator does get warm, head gasket done just a couple months ago, and replaced the temperature sensors start of last year I think it was.

Rich H · Post by **Rich H** » Tue Mar 15, 2011 9:22 pm

I got through about 3 temp senders in 18 months once....

robin · Post by **robin** » Tue Mar 15, 2011 9:39 pm

Stat stuck open or air lock in the

Easy to tell if the stat is just buggered.

From cold, start engine and run at fast idle - say 1,500 to 2,000 RPM (you can use the tip of a tie wrap inserted between throttle quadrant and end stop just to hold the throttle open a teeny bit).

Now watch the temperature gauge and also periodically hold your hand over both the driver's side and passenger side of the radiator.

You should see it start blank, then climb steadily to somewhere around 85C.

Before this point the rad should be stone cold on both sides.

Then the temperature should hold steady at that temperature for a few minutes. During this time the heat should spread across the radiator.

Once the radiator is nice and hot, the temperature gauge will start to climb again up to around 100C depending on the car (S1 a bit higher, S2 a bit lower).

Then the fan should cut in and the indicated temperature will drop.

Now when you get to the point where the fan is cutting in/out, turn the heater to hot and turn the blower on and see whether you're getting hot air out (leave it running for a while to make sure it stays hot).

If the stat is stuck open the radiator will start to get warm before the 85C point.

If there's an airlock the heater still won't be hot even when the temp is at 100C.

If there's an airlock in the radiator, the temp will climb faster, the fan will run more frequently and for longer and the radiator won't be hot across it's whole area.

Cheers,
Robin

Scottish Elises