# Hymer on Fiat Ducato - engine temperature



## LittleGreyCat

Our B544 (2002) with the 2.8JTD engine takes a very long time to warm up and the temperature never goes above 1/4.

Our friend with a similar Hymer (a bit older and larger - no! The Hymer, not the friend!) also sees the same thing.

The Fiat handbook shows the temperature coming up to normal (1/2 way).

So:

(1) Is this the same for all 'A' class Hymers?
(2) Is it a problem?
(3) Has anyone fitted a radiator blind or similar to bring the temperature up higher?

Cheers

LGC


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## erneboy

It is probably to do with the Fiat part, unless they make a different, exclusive Ducato just for Hymer, Alan.


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## macone48

Just a general comment.

How warm is your heater/does it feel very warm, when it "reaches" the 1/4 mark?? Does it move to 1/2 in the summer??

If it does feel v warm I would not worry, although diesels do take quite a while to warm up this time of the year.

If your heater is never v warm, you may need your thermostat checking at a Fiat garage.

Gauges are not the "most" accurate devices, especially water/fuel.

As for radiator blinds -- be VERY careful. You have a Turbo diesel which has an intercooler which looks like a normal radiator. Make sure the blind, if you use one, goes infront of the Water radiator - the two may be behind one another so you may not be able to do it (masking the cooling of the Turbo will reduce performace considerably and increase fuel!!).

HTH 

Trev


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## cumbriangeorge

i just replaced my thermostat, it had broken up completely so the engine was not reaching temperature. Now the heater is much better. you can check the temperature of the hose going to the radiator after starting up. it should not get warm for a while, until the thermostat opens at 80C or more


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## al3674

*Temp problem*

I would hazard a guess that your thermostat may be stuck in the open position, meaning that the coolant in your engine is circulating right round the system (including the radiator) when cold and this will increase the time taken to heat the water.
When it works properly, the thermostat will be closed and only allow coolant to circulate the engine until it heats up and this in turn will open the thermostat, allowing the hot mcoolant to circulate through your radiator.

Hope this helps, and as i say it may or may not be the cause of your problem.

best wishes

allan


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## LittleGreyCat

I would suspect the thermostat but when I first bought the van I posted about this and someone reported that they had had their thermostat changed but it hadn't cured the problem.

In fact, here it is 
Original thermostat post

I know my friend's Hymer shows similar behaviour.

That is why I am asking here to see if anyone else sees this.

Nobody so far has reported here that their temperature guage goes up to 'normal' (although there was one in the original post).

One thing I suspect is that because this is an 'A Class' and the body around the engine is supplied by Hymer there may be a much greater cooling effect on the engine and radiator due to the large air space around it compared to the van cab on Coachbuilt models.

This in turn could mean that a smaller radiator is all that is required to maintain normal engine temperature and that the engine is not producing enough heat to get the coolant up to the expected working temperature.

Think large radiator, very small boiler - it may never reach operating temperature.

I may contact Hymer in Germany to ask them about this - however I am asking around this forum first.

Cheers

LGC


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## davesport

My van's a 2006 JTD. 

My temp gauge sits where it should, half way up the scale.

If your gauge is displaying incorrectly then you have a problem. Either the gauge/sender is'nt providing you with the correct information, the coolant is infact at the wrong temperature, or both. Running the engine in a permanently cool condition is'nt good for it. Diesel engine thermostats begin to open at a slightly lower temperature than their petrol counterparts typically at circa 84 degrees-ish. 

Personally I'd verify the coolant temp by independant means. Do you have a temp probe on your multimeter or an infrared thermometer ? The best place to take readings from is from either end of the top hose.

It could be as simple as the gauge reading incorrectly. Remember it's not a temperature gauge, it's a voltmeter & the readings are analogous to coolant temperature.

Radiator blinds or anything else that makes the radiator behave less like a radiator are never a good idea IMO. The cooling system has a lot of inbuilt redundancy & a blind is simply reducing this. If the gauge is reading incorrectly (low) & you cover up part of the rad, what will happen when it's trying to reject a lot of heat ?

I hope you find out what the problem is.

D.


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## macone48

davesport said:


> My van's a 2006 JTD.
> 
> My temp gauge sits where it should, half way up the scale.
> 
> If your gauge is displaying incorrectly then you have a problem. Either the gauge/sender is'nt providing you with the correct information, the coolant is infact at the wrong temperature, or both. Running the engine in a permanently cool condition is'nt good for it. Diesel engine thermostats begin to open at a slightly lower temperature than their petrol counterparts typically at circa 84 degrees-ish.
> 
> Personally I'd verify the coolant temp by independant means. Do you have a temp probe on your multimeter or an infrared thermometer ? The best place to take readings from is from either end of the top hose.
> 
> It could be as simple as the gauge reading incorrectly. Remember it's not a temperature gauge, it's a voltmeter & the readings are analogous to coolant temperature.
> 
> Radiator blinds or anything else that makes the radiator behave less like a radiator are never a good idea IMO. The cooling system has a lot of inbuilt redundancy & a blind is simply reducing this. If the gauge is reading incorrectly (low) & you cover up part of the rad, what will happen when it's trying to reject a lot of heat ?
> 
> I hope you find out what the problem is.
> 
> D.


+1 and as I inferred earlier.

Get a temp check (10mins in a garage) to vefirify your gauge and that the thermostat isn't stuck open (fail-safe mode).

Conjecture about fitting into an A Class is IMHO a going down a rabbit hole. The engine wherever its fitted will reach operating temp despite any size of radiator IF the thermostat is working!!

HTH

Trev


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## SueandRoger

Hi,

My Camper is a 2003 2.8 JTD and the gauge has always reached normal in the winter after about 10km and the heater by then is nice and hot.

Regards

Roger


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## DocHoliday

SueandRoger said:


> My Camper is a 2003 2.8 JTD and the gauge has always reached normal in the winter after about 10km and the heater by then is nice and hot.
> 
> Regards
> 
> Roger


Same for my 2003 A class, although on very cold mornings it can take quite a while. It always sits around halfway on the gauge eventually.


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## LittleGreyCat

davesport said:


> My van's a 2006 JTD.
> 
> My temp gauge sits where it should, half way up the scale.
> 
> If your gauge is displaying incorrectly then you have a problem. Either the gauge/sender is'nt providing you with the correct information, the coolant is infact at the wrong temperature, or both. Running the engine in a permanently cool condition is'nt good for it. Diesel engine thermostats begin to open at a slightly lower temperature than their petrol counterparts typically at circa 84 degrees-ish.
> 
> Personally I'd verify the coolant temp by independant means. Do you have a temp probe on your multimeter or an infrared thermometer ? The best place to take readings from is from either end of the top hose.
> 
> <snip>
> D.


I haven't had time yet for a prolonged test but took the camper out for a 15 minute run and the temperature gauge was up to the usual quarter and the heater was pushing out warm air.

Used an IR thermometer to measure the temperature where the top hose went into the radiator and it was around 60C.

I assume that the water flows as per a gravity circulation system - cold return at the bottom and hot feed at the top?

[ As opposed to a pumped CH radiator with hot feed at the bottom and cold return at the bottom  ]

Should the top hose be around 80C after a reasonable run - say half an hour?

I will check it again after a longer run, and if it is staying at around 60C I will take it in for a checkup.

I am still a bit puzzled - I would expect that the thermostat would stay closed until the engine was up to temperature and then progressively open allowing cold/cool water to circulate from the radiator and hot water to go into the radiator to cool.

Once the thermostat was open then the radiator as a whole would come up to operating temperature and if the temperature rose above a certain level then the fan would cut in to provide additional cooling.

If the radiator is not coming up to temperature ( I haven't confirmed this yet) then should engine temperature be maintained by the thermostat remaining partly closed?

Does the temperature gauge measure the temperature before or after the thermostat?

i.e. does it show the internal engine temperature or does it only register when the thermostat starts to open?

Cheers

LGC


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## davesport

60's too cool. Your stat should begin to open roughly at mid to low 80's.



> I assume that the water flows as per a gravity circulation system - cold return at the bottom and hot feed at the top?


Hot water out at the top of the engine cooling on its way down the rad.



> I would expect that the thermostat would stay closed until the engine was up to temperature and then progressively open allowing cold/cool water to circulate from the radiator and hot water to go into the radiator to cool.


That's the idea. It sounds from what you describe like your is stuck in the open position. IE flowing all the time.



> should engine temperature be maintained by the thermostat remaining partly closed?


Yes the stat will remain partly closed during normal use. As I said, there's a lot of redundancy built into the cooling system as it may have to operate in much hotter climates than the UK.



> Does the temperature gauge measure the temperature before or after the thermostat


That depends where the temperature probe is in the coolant circuit. Typically though at the hottest part. IE near to where the hot coolant exits the head. Sometimes in the coolant by-pass loop.



> i.e. does it show the internal engine temperature or does it only register when the thermostat starts to open?


It shows the coolant temp. The stat has a small hole drilled in it to assist in getting air out of the coolant. There is enough flow either over the sender if it's in the water jacket or in by-pass loop to reflect the current engine temp.

D.


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