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Technical Croma overheating

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Technical Croma overheating

bobbyblue

bobbyblue

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Does any Croma owner know if the coolant thermostat is prone to failure on the 8v JTD? My temperature gauge shot up into the red last night, there was plenty of coolant in the system, it was not pressurising so I suspect either the thermostat or a faulty sensor. I need to get this sorted in the next couple of weeks as I am doing the long journey from Birmingham to Cornwall and don't want to end up a steaming wreck on the hard shoulder.

Thanks, Bob :cry:
 
Bob, not much help, but I have had 4 Fiat diesels in 13 years, 170,000 miles, and have never even added coolant. This is, of course, due to extreme driving skill.
If the themostat is stuck closed the radiator would probably remain cool, but diesels tend to heat up when worked hard. Does it cool down if you turn the heater full on?
 
keithglos said:
Bob, not much help, but I have had 4 Fiat diesels in 13 years, 170,000 miles, and have never even added coolant. This is, of course, due to extreme driving skill.
If the themostat is stuck closed the radiator would probably remain cool, but diesels tend to heat up when worked hard. Does it cool down if you turn the heater full on?
Click to expand...

To be honest Keith, it has behaved itself since and has performed faultlessly. I am beginning to think it was a dodgy sensor signal, I would expect the thermostat if it failed would have stayed so, I have driven it hard and also through heavy Birmingham traffic today with no problem, maybe the sensor is on the way out, I will monitor and see. Thanks for the advice anyway. PS all Fiat drivers are in possession of superior driving skills.
 
A new thermostat sorted mine out - the temp was always too low, but raised when under load. I guess it was stuck part-open, in a fixed position. It runs brilliantly now - it was permanently cold so rattly sounding before. I did 160 miles yesterday at 52mpg, so very happy with it now.

It's a sod of a job though (well for me anyway) - you have to buy a thermostat "assembly", which is a lump of metal with lots of hose connectors. Lots of disassembly needed just to get access to it (engine under-tray off, battery tray out, etc). The factory fit hose connectors are single-use, so you need a box of long jubilee clips to hand (I used 9, as I needed two daisy-chained for the bigger ones).

It's probably not a job to do just as a diagnostic step if it's unlikely to be the problem. I'm not sure how you'd diagnose it though.

Picture of 16v version (courtesy of Vectra C forum)...

2007_1129Image0011.JPG
 
There is something "iffy" in the Croma ECU/Sensor scanning. I have had a few times the car signal "excessive coolant temperature" with read light and warning sound mostly when starting the car from COLD and possibly a couple of time when hot. Engine fails to start. Ignition off/on and starts perfectly ok. NEVER had when running OK.

Hope you find the cause.
 
s130 said:
There is something "iffy" in the Croma ECU/Sensor scanning. I have had a few times the car signal "excessive coolant temperature" with read light and warning sound mostly when starting the car from COLD and possibly a couple of time when hot. Engine fails to start. Ignition off/on and starts perfectly ok. NEVER had when running OK.

Hope you find the cause.
Click to expand...

I've had exactly the same a few times. For me, it's always been when I've run it (briefly, not until hot), then parked, then restarted it within half an hour or so.

Likewise, I've just ignored it and it goes away as soon as the engine is running.
 
TBH honest if its more than a few years old I would swap the thermostat. I have 2001 Punto HGT with 70k and that thermostat was dodgy. Dodgy engine cooling is never good so I just swapped it.

Its also an excuse to swill it out and put in some nice new longlife red coolant.
 
Hear, hear. I also used some Radflush on mine. As expected, it was completely pointless as there was no muck to flush out. It just needs emptying and refilling really.
 
I have bought a new thermostat unit and will change it tomorrow, can't risk Birmingham to Cornwall with a potential overheat situation. £63.09 from Colliers Fiat in Birmingham, I found a non OEM part on the internet, but it was actually £1.50 + £3.00 delivery dearer. I will post the outcome of the new thermostat and if it cured the problem when I get back. By the way, I'll have to change my image as Shadrach Dingle is no more I believe.:rolleyes:
 
s130 said:
Nope....you make the assumption that there is water in the system :)

No steam = big bang / siezure / lots of little pieces and big bill :cry:
Click to expand...

I had an RS2600 Capri that did that. it blew the bottom rad hose and dumped all the water, so the temp gauge, instead of going up, went down. I just thought the thing had broken until the oil pressure gauge did the same. I was about to stop when all hell broke loose under the bonnet. Needles to say it was very warm and very smelly, instantly signalling that things wre not good.

It needed, rebore, new pistons, new big ends, crank regrind, new camshaft, new cam bearings, new main bearings, new oil pump etc.etc.

It cost £150 to do (in 1980 that was big bucks, the car only cost £1200) and that was stripping and rebuilding it myself.

Heavens knows what a JTD (with turbo) would cost.
 
Last edited:
Doofer said:
It's a sod of a job though (well for me anyway) - you have to buy a thermostat "assembly", which is a lump of metal with lots of hose connectors. Lots of disassembly needed just to get access to it (engine under-tray off, battery tray out, etc).

I have fitted my new thermostat, but you have been too kind in your assessment Doofer, I would say it is a !$?@ard of a job! I would like to meet the designer so I could shake his....neck. I still have not been able to bleed the air out of the heater, I will have to use a hose and funnel on one of the heater hoses to force the air lock out I think, but it can wait.
Click to expand...
 
Well, the thermostat made no difference whatsoever. I went to Cornwall in my daughter's Focus, it never missed a beat. What is baffling me about the Croma overheating problem is that the engine does not seem particularly hot, there is no steam and it is not pressurising or losing coolant. I suspect it may even be a faulty ECU map as suggested by S130, I don't however want to pay out for an unecessary reflash, I expect that would be a couple of hundred quid at least. The car does not show as overheating all the time, sometimes it does it a lot, others not for a long time and then only once, this is why I suspect the ECU program. :bang:
 
bobbyblue

I think there is something odd about your problems.

First of all, FiatECUScan can read the "flash" date of your ECU. If you have had your car from new or for some years and this problem is only really recently appearing then I doubt it is an ECU programming fault. It is more likely some dodgy connection, high impedance earth circuit or faulty sensor. A little bit of noise in the system could be misread by and oversensitivly programmed ECU but I'm not sure an ECU reprogram is the solition.

Also, most ECU re-programs, unless done by a Fiat dealer under a specific fix campaign, can only change the basic ECU fueling/injection/timing/turbo maps. Prime function is normally off limits to most after market ECU re-programmers.
 
s130 said:
bobbyblue

I think there is something odd about your problems.

Thanks S130, I seem to specialise in odd problems, I find electrics a bit of a black art myself. I have exhausted all mechanical options with the exception of perhaps a blown head gasket, but the symptoms do not point to that (it would overheat all the time had it blown). I am thinking I may be forced to seek the services of the local dealership. Thanks for the advice.
Click to expand...
 
What I hate about great online communities / help is that I want to personally get my hands on the problem/vehicle and take things from there. Online communities gives us contact points in the UK, Europe and even world wide but sadly in most cases no ability to get ones hands physically on the problem and the ability to sort out in person.
 
Did you follow the eLearn guide to bleed it?

Probably irrelevant though, if you've been running it.

I couldn't get the thing to drain well at all. In the end I just kept draining, filling with just water and running then draining and so on until it went colourless. Then I put the correct quantity of antifreeze in, which filled it to the top.

I've no idea whether I was doing something wrong, car tinkering is all new to me (I've never had a FIAT before, so didn't need spanners in the past).

I'm reassured to hear you didn't enjoy it though - I thought I was just being a wimp.
 
Last edited:
Doofer said:
Did you follow the eLearn guide to bleed it?

Probably irrelevant though, if you've been running it.

I couldn't get the thing to drain well at all. In the end I just kept draining, filling with just water and running then draining and so on until it went colourless. Then I put the correct quantity of antifreeze in, which filled it to the top.

I've no idea whether I was doing something wrong, car tinkering is all new to me (I've never had a FIAT before, so didn't need spanners in the past).

I'm reassured to hear you didn't enjoy it though - I thought I was just being a wimp.
Click to expand...

I don't enjoy messing with cars these days, but it seems more and more that because to everything is shoe-horned in, there is less package space available (I do this for a living for Jaguar Land Rover) and it is naturally harder to get at the part you need to. I personally hate even lifting the hood these days but dislike paying garage labour rates so I'll have to put up with it I suppose. I bled the system but had a massive air lock in the heater which was a sod to shift though. Incidentally I drove all over Warwickshire today and the overheating problem never reappeared.....here's hoping.
 
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