Running Temperatuire -- what's the verdict?

[Ross]

Hi,

I'm really confused as to what normal coolant temperature readings should be. I posted a while ago and found that my cool 'on the go' temps are common, but now I'm not so convinced that it's "normal" after some searches... so what is the definite answer of how it should behave??

Basically, one of the freezing nights I went on a run to work and it barely rose above the 50 mark... regardless of temp, once she's running warm, if I stop you can watch the guage slowly rise to 92 when the fan kicks in and brings it back down again.

What I'm concerned about, is the temp sensor - I've been reading that when it registers a low running temp then the engine runs in it's 'cold' mode and overfuels. Is this is the case? If the temp climbs to 90+, then as soon as I'm on the move it drops again - the faster i go, the lower it gets... sometimes back down below 60deg. Do i need to replace a sensor, thermostat etc, or am I just being paranoid? Should the temp stay up in the 80-90 region even on the move?

I want to ensure she's running right before I start bolting extra goodies onto the engine...

Cheers
Ross

[stevieyid]

Mine stays just above 50 in this weather. When you are stuck in traffic for about 5 mins it rises to 90 and the fan kicks in. As soon as u get going again it drops to just above 50. From here i have learned the thermostat is stuck open and the next thing on my list to get done. Hope this helps

[4WheelDrifter]

I think it could be just wind chill on the MFTS. Mine behaves similar. I think there is supposed to be some sort on cowl around it.

[AAH!]

Mine sits just around 50-60 at speed and around 90 in traffic.

I always thought it was meant to sit at a constant 90-ish.

I am changing the thermostat at the garage meet so will see if it makes any difference

Angus

[Ross]

Hmm.. how much is this temp. sensor? Could be a good idea to join the club here; or jsut wait and see what the effects are now there's a few guinea-pigs

Cheers
Ross

[AAH!]

I think it could be just wind chill on the MFTS. Mine behaves similar. I think there is supposed to be some sort on cowl around it.

I will try making a make shift cowl to cover the MFTS and see how it behaves on the drive up to the garage meet.

how much is this temp. sensor?

The thermostat and seal is about £18 inc VAT, but is apparently a bit of a bitch to get at as there is so much in the way. I will be replacing it when I do my coolant hoses.

Angus

[ross25480]

Here you go guys solution to your probs.

Guys it sounds to me as though you are all suffering from a broken thermostat. What it does is stop the coolent flowing round the rad when she is still cold. It only opens up once the water reaches running temp. Which then lets the coolent run through the rad. If the coolent temp then drops the thermostat then shuts again. The temp should stay at around 90 degrees even when on the open road doing speed If its broken it stays open all the time and stops the temp rising on cold days. This will also have an affect on the efficency of the heater in the car. Had exactly the same prob myself. GSF part number is 17636 £8.25 plus vat for thermost and the seal 17692 £1.00 plus vat.

[T2Andy]

mines the same and it uses a **** load of fuel guess its the thermostat as ive changed the lambda.

[Ross]

Guys it sounds to me as though you are all suffering from a broken thermostat. What it does is stop the coolent flowing round the rad when she is still cold. It only opens up once the water reaches running temp. Which then lets the coolent run through the rad. If the coolent temp then drops the thermostat then shuts again. The temp should stay at around 90 degrees even when on the open road doing speed If its broken it stays open all the time and stops the temp rising on cold days. This will also have an affect on the efficency of the heater in the car. Had exactly the same prob myself. GSF part number is 17636 £8.25 plus vat for thermost and the seal 17692 £1.00 plus vat.

Cheers - at that price, it might be worth picking one up and giving it a try. Any adverse effects of the coolant temp falling on a run though?

How's it going anyway Ross? Long time no post.. how's those rear brakes working with the EBC's? (Shocking as always I bet ).

[Jas11n]

Guys it sounds to me as though you are all suffering from a broken thermostat. What it does is stop the coolent flowing round the rad when she is still cold. It only opens up once the water reaches running temp. Which then lets the coolent run through the rad. If the coolent temp then drops the thermostat then shuts again. The temp should stay at around 90 degrees even when on the open road doing speed If its broken it stays open all the time and stops the temp rising on cold days. This will also have an affect on the efficency of the heater in the car. Had exactly the same prob myself. GSF part number is 17636 £8.25 plus vat for thermost and the seal 17692 £1.00 plus vat.

Both my brother and myself have changed the thermostat and it has not made a jot of difference. Sit in traffic and the temp climbs to 91/92 then the fan cuts in and drops it back to 87/88.
Zip down the motorway and it falls to around 60 normally, but I've seen it even lower when the outside temp has been well below zero.
I'm going with the MFTS like the other guys above, may follow Angus and Stu and make a shield of some description.

[andre]

Not sure if this applies to you folks, but since we here in SA have a number of vehicles that were fitted with variations of the I5 (notably the VW bus), there are actually two thermostats available. The one is an 83deg and the other is a 87deg (or something along those lines).

I had a similar problem as listed above with my S2. It would take ages to warm up and then it would dip right down on the open road or down a long hill. Fuel consumption was really bad and you could feel the car was sluggish at the cold temp. I had the main dealers change the thermostat twice to no avail. Then I finally took it to a specialist firm. The guy there took one look at the thermostat that was fitted and declared it the wrong temp (to cold). He fitted the higher temp one and all has been well since.

[iain1067]

Well based on my experience in the winter mine has a new stat and temp sender, but still runs colder on the motorway than around town, this is the 2nd car i have had (7a engine) that does this, each time i have tried 2 different stats but to no avail, i think it's just the way it is, as for wind chill on the sender hmmm doubt it it's well buried and protected imo

Iain

[s2driveruk]

any chance its just a highly efficient radiator, so as soon as there is positive airflow the temperature just drops off.....?

[s2avant95M]

Where exactly is the sensor?

[Greg_S]

There are two, the MFTS which drives the dash gauge and one next to it on water manifold. Im not sure which that is for though.

The thermostat is mounted near to the water manifold mounted into the block which controls the flow to the rad.

the thermostat may be working fine and the MFTS misreading on the dash