Technical Broken thermostat - Is it difficult to change?

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Technical Broken thermostat - Is it difficult to change?

BrianMcL

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The engine temperature on my 8v MJet rarely gets above the first mark on the gauge so I assume that the thermostat is broken.

Is it an easy an thing to change?
 
Brian, I changed mine on my 8v a couple of years ago, it comes with the housing and cost me £63 then from the Fiat dealer. As for changing it it is tricky rather than difficult with a few parts in the way, it took me about an hour, I had to remove the battery and tray to get access.
Ironically it was not faulty, my engine was overheating but my problem turned out to be the water pump which was caused by the plastic impeller coming off the shaft.

PS, have you considered it may be the sender unit? that comes with the new thermostat as well.
 
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Hi BobbyBlue,
I hadn't thought about the sender unit being at fault.

Do you know if there is any way to tell whether it's the thermostat or the sender unit?
 
Brian, I'm not much of an electrician, in the old days you could earth out the sender wire and it would shoot the guage into the red, I don't know if that works with modern body computer systems, the thermostat itself can only be tested by putting it into hot water and observing it but I think it is a lot of work if the car is running ok. My car takes ages to warm up in the cold weather with the heater not blowing hot air for about the first 5 miles.
Sorry I can't be of more help, maybe one of the more electrically minded people on the forum can suggest something, I am sure the sender must have a resistance value to check when the engine coolant is up to temperature.
 
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I had the same problem, engine took very long to warm up, then if I went downhill the temp dropped significantly in just in one mile and there was a little drop in mpg. Replaced the thermostat and now its all good, at 5 degrees it takes 2 miles to warm up. To be sure that, thermostat is the problem, after you start the car and run it a little (2-3 miles) to let the temp go up a bit, raise the bonnet and put your hand on the radiator. If the radiator is warm, then replace the thermostat. If the radiator is cold, then you have a sensor problem, but my guess is on the thermostat which is blocked on open. They usually break way more often than the sensors. Good Luck!
 
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Hi Roberto,
That seems like a really straightforward test, thank you :)

I'll give it a bash and see what happens.

When the weather is in any way cold, as it is at the moment, it takes ages for the car to heat up, if it even heats up at all so it would be good to get it fixed.
 
If it's as horrible as on a 16v then it's a surprisingly big job.

You'll need a box of 10 jubilee clips, as the ones fitted are use-once ones. I think there's a special tool for them, but I don't think you can re-use them anyway. I just levered/broke them off and replaced with bog-standard jubilee clips.

I got the right size for the numerous smaller tubes. I think I had to use two end-to-end to go round a bigger tube. It all worked.

I think it's called a thermostat assembly - the thermostat itself is buried in what is basically a junction between a load of different tubes.
 
Yeah, I did it about three weeks ago. A huge amount of ripping to get at the thermostat. Most of the EGR plumbing, which is all stainless steel, has to be moved. One particular 10mm stud on a 13mm bolt nearly made me cry! It's the bottom of two on the stat. Patience and bandaids but a definite sense of achievment and a much warmer and economical car. Thermostat cost me €80 inc VAT (Ricambi Originale)
As Bobbyblue says, battery and tray must come out and as Doofer says loads of jubilee clips

I'm glad it's done!!
Hope this helps
CJLAR
 
Wow, sounds like I'm letting myself in for a bit of a nightmare!

I remember when the thermostat went on my Mk1 Fiesta, not quite such an ordeal to change that one :)

Thanks once again to everyone. I'll have a serious look at what's involved before I buy anything.
 
Yes I know, thermostats in the past were like changing a light bulb.

God knows why it's like it is, but it's integrated into a huge lump of plumbing. It's within the scope of DIY (well I managed it anyway), but it's a lengthy and time consuming little project.

I followed the eLearn instructions, which includes details of how to flush the air out - it is automatic, but you have to ensure you get it hot for long enough, which might be difficult at this time of year outside - I did mine in the summer. You could probably just go for a shortish drive to flush it though, just keep an eye on it for a week or so.

Mine ran like crap when I first had it. It rattled like it was cold constantly (not surprising really, as it WAS cold). I fixed mine a couple of years ago and it's been great ever since. The big bonus is that the heater and/or climate control will start working properly as soon as it's fixed.
 
The 'problem' with modern common rail diesel engines is that they are so efficient. A higher proportion of the heat generated by combustion actually goes towards moving the pistons up and down, less waste heat means a longer warm up time, many diesels now offer a supplementary PTC heating system to back up during cold starts, a price we have to pay for good fuel efficiency I think.
 
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Yeah, I did it about three weeks ago. A huge amount of ripping to get at the thermostat. Most of the EGR plumbing, which is all stainless steel, has to be moved. One particular 10mm stud on a 13mm bolt nearly made me cry! It's the bottom of two on the stat. Patience and bandaids but a definite sense of achievment and a much warmer and economical car. Thermostat cost me €80 inc VAT (Ricambi Originale)
As Bobbyblue says, battery and tray must come out and as Doofer says loads of jubilee clips

I'm glad it's done!!
Hope this helps
CJLAR

Well I've got as far as the metal tube thing attached to the thermostat thread. I've got the pipes off at either end as well as the hose. Is there anything else holding it in place or do I just need to keep working away at it?

Got the bandaids to show for it as well :)
 
I've undone everything I can find and still can't get that metal tube off the thermostat stud.

Besides the egr pipework, the 10mm nut and the hook is there anything else that holds the metal tube thing in place at the back?
 
Hi Cjlar,
I got as far as the bottom 13mm nut between the steel whatever it is and the thermostat. Getting the 10mm nut that holds the steel tube in place off was easy enough but I couldn't work out how to get the steel thing off the bolt so I could get the 13mm nut undone because the steel tube thing felt like it was still fixed to something.

I'd taken off all of the hoses around the thermostat and the steel pipes either side of the steel tube (and temporarily lost one of the shims) but it still wouldn't come free.

Is it fixed to the thermostat itself?

I can understand why you would cut down a spanner to get into the nut on the bottom thermostat bolt. Whoever desgined it cleary had a warped sense of humour. I gave up trying to free the 13mm nut because I couldn't get the steel tube off the bolt. It moved by 5mm but not enough to slip off the bolt so I could get a socket in.

I gave up trying to get it off though because I couldn't get the steel tube out of the way. Was this a mistake and do the 2 come off together?
 
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I don't remember any major issues with mine (other than the normal elastoplasts).

Things must be different in 8v-land. It might be worth a search over on www.vectra-c.com to see what they know - loads of these engines went into Vectras.
 
Hi Doofer,
Can you remember whether the metal tube fixed to the bottom thermostat stud was fixed to anything at the back?
 
Brian. I've just looked at ePER (you can do the same on this site) and it looks like the steel tube has a fixing plate on the opposite end of the tube where a large rubber hose is connected and goes to radiator offsite connection. Also there would appear to be two additional mounting tabs along the top of the pipe.

Hope this helps
 
I've had a look at eper (thanks Nick I always forget about it) and it looks as though the metal pipe (the heat exchanger part 55186465?) that bolts onto the same stud that holds the bottom thermostat bolt in place at the front also bolts directly onto the thermostat itself at the back.

Am I correct or is there another bolt holding the heat exchanger onto another part of the engine block somewhere?
 
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