Has my thermostat gone

Sep 25, 2009
666
1,003
south yorkshire
Funster No
8,624
MH
coachbuilt
Exp
since 2004. Tugger 10 years on and off
Driving home from Scotland temperature gauge went to hot .on stopping to check I noticed top radiator hose was Not hot.header tank still full engine did not feel red hot. No steam or anything to suggest overheating. A couple of times gauge went between full and half hot.managed to get home.Do you think it' the thermostat or radiator sensor. It needs a new timing belt this year so wondering whether to change water pump at same time.Its on a 2.8jtd 2004.
 

mfw

Banned
Sep 16, 2017
1,232
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Worthing
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50,537
I don't know about your thermostat but I would go for the new water pump at the same time as your new belt ,
If the water pump runs off timing belt it is better to change at same time if pump fails it can damage engine same as timing belt failure

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May 31, 2015
1,374
903
south oxfordshire
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36,639
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Hymer B584 classic
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2017
Yeah , i would fit a new pump with the timing belt for what they cost , but as for your other problem . Were you climbing a hill when it moved , or push the motor along in anyway . Were you giving it cause for the temperature to rise , that's what i'm asking .
 
Oct 2, 2008
3,958
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J10 M40
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Bucher Duro 6x6 motorhome
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since 1968
As prev posts if belt drives water pump change pump same time .
Check coolant level when cold , esp in header tank .
May be sensor , or check wire from sensor is not shorting to earth, as this will show top of guage reading . If all checks OK then possibility of sticky thermostat although pretty rare .

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Two on Tour

LIFE MEMBER
Sep 16, 2016
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Near the junction of the A14 and A1, Cambs
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Elddis Autoquest 175
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Since 2010
We had this last summer. Temp gauge went up to hot hot and then down to normal then up to hot and so on. Pulled over all seemed ok under the bonnet. Was a pig to start again but got it going and we drove the next 80 miles to our destination with the windows down and the heater on and the blower going full blast just in case. Turned it off when we got there and to cut a long story short we came home on the back of a flatbed as the electrics were acting very odd.
Scratched my head and checked over the van and found there was no earth strap between the engine/gearbox to the chassis. Although it should have had one it looked like one had never been fitted. Made up a strap from 10mm2 cable, bolted it on and bingo, all working as it should do again. Never played up again.

This was on a 2004 Ducato 2.8 jtd

If you wont to check for an earth strap on your then it should run from a bolt on the gearboc to the chassis leg on the passenger side (RHD)

earth-strap.jpg
 
OP
Masman
Sep 25, 2009
666
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Yeah , i would fit a new pump with the timing belt for what they cost , but as for your other problem . Were you climbing a hill when it moved , or push the motor along in anyway . Were you giving it cause for the temperature to rise , that's what i'm asking .
No.not pushing. Got up this morning gauge still showing red.Its booked in for cambelt. Looks like a wiring fault. They will sort it .

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dave newell

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Oct 31, 2008
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There is no need to replace the water pump with the cambelt as it is not driven by the cambelt on the 2.8 engine, obviously if there is a problem with the pump, it leaks or is creating a water flow issue then it needs replacing but there really is no need for a routine replacement with the cambelt. The 2.3 however is driven from the cambelt so it makes sense to replace the pump as a routine job with the cambelt.

D.
 
OP
Masman
Sep 25, 2009
666
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south yorkshire
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coachbuilt
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since 2004. Tugger 10 years on and off
Thanks for replys. Booked in for cambelt, water pump ,The guy I use thinks it' a wiring fault or sensor. Hopefully all sorted then we can look at going to spain for a month
There is no need to replace the water pump with the cambelt as it is not driven by the cambelt on the 2.8 engine, obviously if there is a problem with the pump, it leaks or is creating a water flow issue then it needs replacing but there really is no need for a routine replacement with the cambelt. The 2.3 however is driven from the cambelt so it makes sense to replace the pump as a routine job with the cambelt.

D.
Dave. The van is a 2004.Do you think it' worth changing the pump.we will probably touring spain for a month or more.The guy I use regular sèms to think so to be on the safe side.Had a new radiator fitted last year as it was leaking. So cooling system should all be covered then
 

dave newell

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Oct 31, 2008
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Thanks for replys. Booked in for cambelt, water pump ,The guy I use thinks it' a wiring fault or sensor. Hopefully all sorted then we can look at going to spain for a month

Dave. The van is a 2004.Do you think it' worth changing the pump.we will probably touring spain for a month or more.The guy I use regular sèms to think so to be on the safe side.Had a new radiator fitted last year as it was leaking. So cooling system should all be covered then

Unless there is a fault with the pump there is no need to change it, they generally go on for hundreds of thousands of miles, we only recommend replacing the pump when it is cambelt driven because if the pump fails it will almost certainly wreck the engine.

Your temperature gauge issue may be the instrument panel, it could be an earth fault although the engine earth strap usually causes other faults first or it could be a faulty sender.

D.

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Apr 14, 2008
635
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huntingdon
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a class Arto
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Also have a 2004 2.8 jtd . Had a problem with the temp guage jumping up to the red and back again , it turned out to be a faulty sensor. I have replaced 2 cambelts in 10 years and not touched the water pump.

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Jan 27, 2009
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Unless there is a fault with the pump there is no need to change it, they generally go on for hundreds of thousands of miles, we only recommend replacing the pump when it is cambelt driven because if the pump fails it will almost certainly wreck the engine.

Your temperature gauge issue may be the instrument panel, it could be an earth fault although the engine earth strap usually causes other faults first or it could be a faulty sender.

D.

I thought one of the main reasons for replacing both the cambelt and water pump at the same time was to minimize possible future garage labour cost for stripdown/rebuild to replace the waterpump only?

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Oct 2, 2008
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If the waterpump driven by cambelt , waterpump failure is same as belt failure, If not driven by cam belt then consequences not catastrophic , and also does not usually require removal of cam belt so lot less costly , they also usually last lot longer than belt change interval.
 
May 31, 2015
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Just ignition on.Hopefully .will get it sorted Monday

Hmmm right , well that would rule out the thermostat , so that leave's either the sensor or wiring . You don't mention any other electrical problem's , so the probability it's wiring is low . i've gotta go with the the temperature sensor , my friend .
 
OP
Masman
Sep 25, 2009
666
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Hmmm right , well that would rule out the thermostat , so that leave's either the sensor or wiring . You don't mention any other electrical problem's , so the probability it's wiring is low . i've gotta go with the the temperature sensor , my friend .
Van sorted. Yes it was the temperature sensor. Had thermostat changed at same time.waterpump changed while having cambelt changed as there was a bit of play in it.So, new radiator last year ,Got myself a complete new cooling system

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May 31, 2015
1,374
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south oxfordshire
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2017
Van sorted. Yes it was the temperature sensor. Had thermostat changed at same time.waterpump changed while having cambelt changed as there was a bit of play in it.So, new radiator last year ,Got myself a complete new cooling system

Lol , i hope you've changed the coolant too , huh . Well done .

No , on a serious side my friend , it's rare for a thermostat to fail . They do , but i personally have yet to have one go , I've not even heard of one failing in 40 year's of motoring . Now pound to a penny , that's gonna change in the next couple of minute's . The wiring will be in with the main loom , so again the chance's of any damage been strictly limited to just the temperature sensor wiring is almost impossible . I will concede though a bad connection is possible , especially were water is concerned , but that's more likely to be at the sensor end (i would now spray that with silicon spray) , and will probably be the earth . The gauge itself is also unlikely to fail , though again they do , the way to test them is to wire positive to the battery and earth to the chassis , were then it should run it's full sweep , that was being done for you . So that left the sensor as being the most likely culprit ! .

Now let me explain myself regarding the water pump . I have a 2.8 idtd , very similar engine to the jtd , and our van's are of a similar age , old . The water pump being down the off side of the van , mean's access is not good , and it's also partly obscured by the timing cover . You wanted a new timing belt fitted , so it made sense to me to change it while the timing cover's are removed . Yes i know they are quite robust unit's , are unlikely to need changing , and will cost extra . But for what the pump cost's , and an extra hour's work , is it really worth the extra grief , and you did say the old had a little play in it anyway . The bonus is , as you say yourself , you have a new cooling system . Nothing beat's that peace of mind .

I've also got this job on my to do list next year , and started collecting bit's already . As i cant see the coolant level , i use a digital coolant level checker , take the cap off and stick me digit in . So in addition to what you have changed , i'm including a new header tank , cap , and full set of new hoses . Oh and brand new coolant , lol .


I've got a full brake overhaul planned for this year .
 

PaulMarlin

Free Member
Oct 14, 2020
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4 years
Ooh, it looks like I'm a little late on this one.

My 2004 Ducato 2.8JTD also has the erratic temperature gauge. I've had the van for 4 years. The gauge can hit the top at 200 yards, 200 miles, anywhere in between, or never. The coolant level is ok and the engine doesn't seem hot when it's happening. I've had a few fixit episodes:

1. I found the rubber boot round the sender connection had split and was full of water, dispensed with the boot and the gauge went better for a while.
2. The crimps in the sender wiring were badly corroded, so I replaced the crimps and the gauge went better for a while.
3. I replaced the sender and the gauge went better for a while.
4. Found a suggested fix of unplugging the instruments, checking the PCB for dry joints and reseating the plugs. Unplugging the instrument cluster isn't too hard: two big TX screws at the back and two smaller ones under covers at the front of the surround. On the other hand, getting to the PCB is very fiddly, no dry joints found and the gauge went better for a while.
5. Just been through the service history (my van has been pre-owned a few times) - the sender and thermostat have both previously been replaced two or three times, so I don't like the sender or thermostat theory anymore.
6. Sometimes the gauge seems to play up more when driving in the rain - anecdotal and I haven't measured it. The terminals face the front of the vehicle and it is plausible they are getting wet, see item 1, but I can't seem to find a part number for a new boot. Anyway wet / dry behaviour may point to a bad / missing ground connection suggested by two on tour above.
7. Another suggestion is the sender wires grounding out somewhere else due to chaffing. On mine there's about 6" of free wire before it disappears into the loom, so I reckon that will be ok.

Next steps:

The van is due a cambelt and I was going to change the water pump at the same time, but if the pump isn't driven by the cambelt, as Dave Newell lvs suggests, maybe I just check / fit the engine earth strap.
 
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