overheating TF

Cobber wrote: I wasn't referring to the radiator, I was referring to the heater matrix (cabin heater)
If they're connected the wrong way around, it could cause an air pocket that can't be bled off properly.
Looking at a diagram in the manual, the heater hoses cross over one another on their way to and from the engine, so it would be easy for someone to get them arse about.

Aaah never thought of that, is there anyway of checking?

You could try switching them about, it would need to be at the heater end, I duuno how easy it will be to get access to, as I've not had any need to work in that area.
Maybe someone here will be able to enlighten you on how to go about it.
The water should flow from the engine to the "T" that that on one leg heads to the radiator and the leg that we're interested heads to the heater flow control valve the into the heater. It should then flow back towards the engine.

I know the Triumph TR7 (with air con) suffers from air getting trapped in the heater matrix when the hoses are arse about..

Daz, did you check the jiggle valve in the inlet manifold?
After checking the cooling system on my TF again and again (and replacing part after part) I found this valve being blocked
and causing the overheating.

Hi Rob,

The jiggle valve from the inlet manifold has been removed at some point in the past, from what I've read this is ok due to the positive pressure & shouldn't cause any problems. I'm happy to be corrected though


Cobber,


I've checked the heatet hoses & to be honest with the shape of the hoses it'd be a bit difficult to get them the wrong way round at the engine side, the heater end looks ok too as they're shaped to fit.

Todays update

I borrowed a good expansion cap from a friend & fitted that in case the new one I'd bought was faulty, that made know difference to my car or the car I fitted my cap to, they both behaved as they had before, so that's ruled out. I've fitted a lower temp stat, 82 degree, bled the system, run it up to temp & let it cool down, then bled it again, a small amount of air came out the rad. Took if for a spirited drive & bled it again, no air this time. The rad is getting warm all over & the fan kicks in, but as soon as the heater is set to anything other than hot the temps rise within minutes, putting the heater to hot again brings it straight back down.

What's confusing me is the car never overheats when the stat isn't fitted, as I said in an earlier post I was sat in stop start traffic for an hour without a stat & with the heater set to cold & the gauge sat still without moving at all.

With a stat fitted the temps rise whether pootling along, motorway speeds or sat in traffic.


I think it's time to cut my losses now

Another quick update, after going through everything again for the 100th time, I had the car running & heater set to cold, there is a definite drip from the heater control valve behind the controls, this speeds up as the revs rise, but the drip stops when I set the heater to hot. Time to find another valve.

Just a thought; you say the TF is a 2003 pre PRT? If a PRT and standard engine block return thermostat were fitted you would get the same symptoms as the heater circuit by-passes the standard thermostat back to the block allowing coolant flow; albeit a tad restricted, when the heater valve is turned off flow will stop; no matter what temperature the engine gets to.

Have a good look at the coolant circuit and check for a retro fitted PRT (an alternative position for a retro fit PRT is at the front subframe)

Brian.

Badger wrote: Just a thought; you say the TF is a 2003 pre PRT? If a PRT and standard engine block return thermostat were fitted you would get the same symptoms as the heater circuit by-passes the standard thermostat back to the block allowing coolant flow; albeit a tad restricted, when the heater valve is turned off flow will stop; no matter what temperature the engine gets to.

Have a good look at the coolant circuit and check for a retro fitted PRT (an alternative position for a retro fit PRT is at the front subframe)

Brian.

Hi Brian,

Definitely no PRT fitted, I've been all over every joint & inch of the coolant system several times now

I've been over the heater pipes & they are the correct way round.

I'm presuming that the only signs of of overheating is a rise on the temp gauge. If so my thoughts would be an air bubble around the coolant sensor area. Opening the heater circuit may be enough to move the bubble away from the sensor returning the reading to normal.

I have had this happen to me, and carefully loosening the engine bay bleed valve allowed the trapped bubble to be expelled. Beware hot coolant.

Do you have an OBD reader and torque app? This will show the temperature that the ecu is reading.

David Aiketgate wrote: I'm presuming that the only signs of of overheating is a rise on the temp gauge. If so my thoughts would be an air bubble around the coolant sensor area. Opening the heater circuit may be enough to move the bubble away from the sensor returning the reading to normal.

I have had this happen to me, and carefully loosening the engine bay bleed valve allowed the trapped bubble to be expelled. Beware hot coolant.

Do you have an OBD reader and torque app? This will show the temperature that the ecu is reading.

How convenient, I was just about to post about the temps on torque I'm away till tomorrow but before I left my obd reader finally arrived so I plugged it in, The fan seems to kick in around 103 degrees & go off at 94, but if the heaters set to cold it just doesn't go off as it doesn't seem to cool the car down (this testing was all done while the car was stationary in the garage) the highest temp I got was 117 degrees (3/4 mark on the gauge) & it seemed to sit at around that.

While I was running the car I noticed the expansion tank seems to be bubbling (Boiling?) quite a bit with the heater set to cold but it doesn't seem to do it while the heaters on hot.

During the testing while the car was cooling down I bled all 3 points with no air visible, that water's hot I also loosened the fan temp sensor & let that bleed some water, there didn't seem to be any air there either.

While I'm trying to get to the bottom of this the car is being run on water rather than coolant, does this make any difference? I can't imagine it would

The car idles at around 935 rpm even after resetting the iacv, I believe it should be around 850, could this be linked? I'm thinking an iffy sensor.

Sorry for the long post again.

Thanks,