water temperature sensor

[dreamwarrioruk]

hi all,
after some overheating issues i replaced the stat and the radiator which has helped no end, now the engine bay sits cold all the time unlike before when you could warm your hands on the handbrake.
however after the first days running the mason alarm jumped up from the 60% mark and now sits around 80%.
the lower hose on the rad doesnt get warm at all unlike before when it was red hot. is this normal.
i was wondering if changing the temp sensor would help to show a lower guage reading and if this it what governs the fans coming on.they work manually when you disconnect the plug but i cant seem to get them to operate under normal conditions.

[apole]

Hi there,

Are you sure all is working properly on the coolant side, could it need re-bleeding? I believe the bottom hose only gets hot (and should do when bleeding is done properly) when the engine is hot and that stat is open. So if this no longer gets hot then it's either the engine isn't working hard enough to get hot, or you need to rebleed. For the sake of some of your time I'd try the rebleed to be sure.

If all of that is yes, and I'm sure people that know more than me will be along soon to advise I'd think about the following:

Firstly test the coolant sensor, could you remove and test say in a kettle to see what the gauges read as you know water boils at 100?

I believe the ECU controls the fans from the coolant sensor for rad fan, and engine bay scavenger fan from the sensor next to the handbrake.

Do you have anyone locally with a proper computer that can read the data from teh diagnostics plug. I have a place near me that does the LPG and he has a handheld computer that does this and coolant temp is one of the readings available.

It would be good to be sure everything is working, and that your readings are correct but don't rule out the simple things like bleeding first just in case !!

Hope this helps.

Regards


Andy

[dreamwarrioruk]

its been running for 2 weeks now with no probs, no overheating, no coolant loss. i got the lower hose hot when i bled it first, i have since done another check but no bubbles or anything present. im quite used to bleeding these now. if the stat didnt open wouldnt i have a bit of a major overheat. i know the coolants going round as when you get someone to turn on the fans i can feel the warm water moving from the top of the rad to the bottom so its got to be flowing.
im not sure but do these have a bypass loop in the cooling system. if the engine didnt get hot enough to open the stat then the coolant has to go somewhere.

[haydn callow]

It all sound good to me.....bottom hose cool is good under normal driving conditions....there is a topic ongoing at the moment you could read...cooling system diagram

[apole]

Hi there,

Yes, the coolant goes around the engine and the 2 heater maxtixs when the car is below say 85 or whatever teh normal running temp is, then as the temp increases the stat opens and the coolant goes around the radiator as well.

So if there are no bubbles etc or leaks, and your heaters work then all would appear okay.

My mason alarm means the temp gauge reads around 12 with normal driving, then say 1 o clock on the motorway, and up to 2 if it's a hot day and I've been up a long hill or stuck in traffic for ages, it goes up and down slightly as the stat and fan etc cut in and out.

Remember others have different readings to mine, some higher, some lower. That could be down to different cooling system efficiencies, or maybe differences in the mason alarm effects. Without a digital gauge it's hard to know exactly.

Hope this helps but also hang on to see what others have to say as well, plenty of people around that have more experience than me.

Important thing is confidence you are not overheating and all is working as it should.

Andy

[dreamwarrioruk]

just had an indepth read of the cooling thread and it looks like my system is working as it should. the old rad was well blocked up and was hot most of the time, as was the lower pipe so it looks like i wasnt getting enough flow round the system. it was strange to have a cold engine bay, that was my usual test for the temperature. couldnt usually keep my hand on the handbrake area for long. when the engine is put under strain now it takes a longer time to drop back to its normal point on the mason guage so its only using the sb system and not opening the stat up much which looks like everything is working. im gonna sit it at 2500rpm for a while just to see if i can get the stat to open fully.
might also consider removing the mason and fitting the tm2 system as i can get quite paranoid watching the temp guage go up and up.

[mikexgough]

Sounds like you system is normal now, Mike.....

[Simon Jones]

Worth bearing in mind there are 2 temp senders on the drivers side of the head: one for the gauge & the other for the ECU that controls the radiator fans. I'm not 100% sure, but I think gauge sender is at the front of the head by a big hose & the one for the ECU is towards the middle / rear of the head.