Thermostat mod

Hi guys just fitted the lower temp thermostat mod at the weekend, I did this with the kit of 3 plates and the m60 80degree stat, so today I plugged in Hawkeye to monitor coolant temp. Radiator averaged around 65-75 degrees driving, engine upto around 97degrees, under load, I then got stuck in traffic for around 20 mins and temp peaked at 106-107degrees, is this roughly correct with an 80 degree stat? I've seen posts where people have said the car stays constant at around 90degrees. Is it possible I have a blockage somewhere?
My rangie is a 2003 4.4 vogue

I am (naughtily) running without a stat fitted and sitting in M3 traffic this evening with Air Con on full tilt, she never rose beyond 87degC.....

I'd have thought with a lower stat, you'd reach around the 100mark at the most....might need to do some investigative work and check the rad for flow and make sure you don't have an airlock!

That's roughly where I thought it would sit, and I never had air con on either, after moving it would drop to 104 but was only moving short distances, I have noticed flow to the heater decreases at tick over (which I know it would) but temp seems to drop too so possible air lock there. Another job on my to do list lol

Saint.V8 said:

I am (naughtily) running without a stat fitted and sitting in M3 traffic this evening with Air Con on full tilt, she never rose beyond 87degC.....

I'd have thought with a lower stat, you'd reach around the 100mark at the most....might need to do some investigative work and check the rad for flow and make sure you don't have an airlock!

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I would guess at airlock, i was travelling the other way up the M3 mate past the recovery of the burnt out lorry and that didn't look fun

RRkev said:

Hi guys just fitted the lower temp thermostat mod at the weekend, I did this with the kit of 3 plates and the m60 80degree stat, so today I plugged in Hawkeye to monitor coolant temp. Radiator averaged around 65-75 degrees driving, engine upto around 97degrees, under load, I then got stuck in traffic for around 20 mins and temp peaked at 106-107degrees, is this roughly correct with an 80 degree stat? I've seen posts where people have said the car stays constant at around 90degrees. Is it possible I have a blockage somewhere?
My rangie is a 2003 4.4 vogue

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That would suggest to me that the viscous fan is not doing it's job, you may find it better with the aircon on as the electric fan will operate if things get too hot.

i did wonder about the fan, on the drive home last night, which is about 20 miles i had the heating and the aircon on, plus it was considerably cooler outside around 10degrees, (it was 21 degrees in the afternoon) the car stayed at 94 degrees all the way back with a rad temp of around 50-60, this was averaging around 60mph for the first 5 or 6 miles then 50 rest of the way. i do have a long, fairly steep hill about half a mile from home temp rose to 99 degrees with 77 in the rad but didn't really get chance to see it drop as the last 1/2 mile is just coasting downhill. this of course is all depending on if the hawkeye is reading the temps correctly. i did notice last night i seemend to have a lot of system pressure, i would have thought system pressure would drop with the lower temp.

you maybe onto something with the viscous fan but there seems to be conflicting methods of how it works on the net, some are saying it's speed controlled (fully engages at low engine speed and releases at higher revs) others say heat controlled.

anyway mine isn't engaging as they say at low revs, and after taking the car for a run this morning, not a long run but was upto temp and rad was hot, after switching off the fan was still unlocked (same resistance whilst trying to turn it when cold) so i think i will monitor it for a few days/runs and see what happens, the cars temp gauge stays in the mid position all the time so i don't think it's over heating as such

RRkev said:

you maybe onto something with the viscous fan but there seems to be conflicting methods of how it works on the net, some are saying it's speed controlled (fully engages at low engine speed and releases at higher revs) others say heat controlled.

anyway mine isn't engaging as they say at low revs, and after taking the car for a run this morning, not a long run but was upto temp and rad was hot, after switching off the fan was still unlocked (same resistance whilst trying to turn it when cold) so i think i will monitor it for a few days/runs and see what happens, the cars temp gauge stays in the mid position all the time so i don't think it's over heating as such

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As far as I'm aware the viscous fan is one place the electronics nerds have not got to. It should lock up with heat, as long as the RAD is getting hot all over it should lock at tickover, there will still be some slip at high revs.

thanks datatek that's how i thought it should work, a couple of other sites also said it 'should' still be locked when the car has cooled after it has been engaged, or should still be engaged when warm and turning engine off, mine definately was not locked this morning (although never tried it last night when hot) and wasn't this morning after a run, i'm not sure how long they should last but at 135,000 miles on the original i'm guessing it is probably gone. i 'may' look into fitting an electronic fan but thats another job totally

RRkev said:

thanks datatek that's how i thought it should work, a couple of other sites also said it 'should' still be locked when the car has cooled after it has been engaged, or should still be engaged when warm and turning engine off, mine definately was not locked this morning (although never tried it last night when hot) and wasn't this morning after a run, i'm not sure how long they should last but at 135,000 miles on the original i'm guessing it is probably gone. i 'may' look into fitting an electronic fan but thats another job totally

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On the P38, it's possible to do a mod to use the aircon fans for cooling, should be easy enough to do the same on the L322, don't know if the fan would be man enough though. Certainly a good back up for the viscous.
The viscous on the P38 doesn't last 135K miles

cool cheers datatek, i've since been out and tried to replicate the issue from last night, but at tickover max i can get it upto is 102, with rad temp at 60, but i can feel the fan working, as soon as i raise the revs to 1000rpm, it very soon brings the engine temp back down to 96/97 and rad temp raises to 70. when i started driving temp came back down to 91, with around 50 in the rad, but pipes are still virtually rock hard with pressure (as they were before on original stat) but everything seems to be working as it should, heaters are ok, no gurgling or bubbling sounds when i switch off. so perhaps it is how it should be or i have a slight blockage somewhere.

RRkev said:

cool cheers datatek, i've since been out and tried to replicate the issue from last night, but at tickover max i can get it upto is 102, with rad temp at 60, but i can feel the fan working, as soon as i raise the revs to 1000rpm, it very soon brings the engine temp back down to 96/97 and rad temp raises to 70. when i started driving temp came back down to 91, with around 50 in the rad, but pipes are still virtually rock hard with pressure (as they were before on original stat) but everything seems to be working as it should, heaters are ok, no gurgling or bubbling sounds when i switch off. so perhaps it is how it should be or i have a slight blockage somewhere.

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I'm a bit surprised at the big temperature difference between RAD and engine, where are you measuring the RAD temperature?
The fan will not lock with a RAD temperature of 50.
14psi does tend to make the pipes feel hard and I guess that is the sort of pressure at which the system runs when hot.

i'm not sure i read somewhere online that with the standard 108 degree stat there is 22psi pressure in the system, i would have thought it would be less with a cooler stat, i'm reading rad temp with hawkeye throught the diagnostics port, i'm guessing it's rad exit temp rather than actual rad temp, but i can certainly feel warm air being dragged out behind the fan at tickover

RRkev said:

i'm not sure i read somewhere online that with the standard 108 degree stat there is 22psi pressure in the system, i would have thought it would be less with a cooler stat, i'm reading rad temp with hawkeye throught the diagnostics port, i'm guessing it's rad exit temp rather than actual rad temp, but i can certainly feel warm air being dragged out behind the fan at tickover

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22psi would tend to make the hose's pretty damn hard

Does the pressure desipate when the engine cools?

Yes sometimes very slight pressure when opening the cap after 7 or 8 hours but usually totally depressurised

That's way to hot with that stat. mine never goes over 90 now. These babies don't like cheap water pumps either.

I'm wondering if it could be water pump related, funds were a little tight after having gearbox done etc and I fitted a britpart pump, it was supposed to be genuine oem it did have metal propellor, but looking at temps flow at tick over seems low

Best water pump make is Hella. Costs c. £80 + Vat) - Avoid First line (had 2 go in under 2 years). Not sure on Britpart but most people tend to rubbish Britpart stuff??

that's what i seem to be reading, but so far the britpart pump has been on just under 2 years and around 20,000 miles