Urgent advice required - temp gauge very high in France

[The Wanderer]

Hi all

We're on holiday (honeymoon actually!) in the Dordogne and the temp gauge has gone very high a couple of times.

The day we drove down was very hot but the van behaved perfectly normally. The next day we started out on a local trip and I spotted the temp gauge creeping up towards the top of the scale - it's never gone above 11 o clock before, so I was immediately worried and pulled over. After letting the engine cool down, I checked the coolant level and it had lost very little. I topped it up a bit with a coolant mix I keep on board and we set off again to a nearby village, but the temperature soon started heading up the scale again so we parked up, and walked to the village for lunch.

When we got back, we set off rather gingerly for the campsite and found the temp gauge stayed normal and the van drove fine, so we arrived back without a problem. At that point I had a look around this forum for clues, but couldn't find many posts that described a similar problem.

Anyhow, we took the van out again the day before yesterday to see what would happen and covered maybe 60km with no problem. Then yesterday we set off for a new campsite and before long the temp gauge was once again heading up towards the top. We pulled over, the van had dumped a little coolant through the header tank overflow, and after letting her cool down, we headed for the nearest village.

I'd already swapped the fuse for the scavenger fan just in case, but I don't know if that would normally be operating that quickly anyhow. I could hear a fan on in the engine bay, but I think that may have been the usual rad fan. I suspected the thermostat may be intermittently sticking, and having failed in my attempts to remove it with some basic but inadequate tools, we decided to try and limp back to the previous campsite. We set off, and once again the van behaved fine with the temp gauge showing normal all the way.

I'm going to take it to local recommended Peugeot garage tomorrow and ask them to remove the thermostat so we can hopefully continue our holiday. Is that a good idea? There are a couple of Mazda dealers in the area so I'm considering trying to get hold of a new thermostat so it can be replaced by the garage - is this part shared with other Mazda/Ford vehicles? I am aware Bongos are not at all common over here. I will tell them it's possible to work from above with the right tools by moving the dipstick tube slightly, I changed the thermostat that way several years ago, but any other advice would be welcome.

If the thermostat is removed/changed, does the coolant system absolutely need bleeding afterwards? Or if the front is put on ramps, would this help so bleeding may not be necessary? The campsite owner will print the French translated article on changing the rad and coolant for me, so I can show the garage the correct method for checking the coolant.

Any thoughts or advice please? Or does anyone happen to know a Bongo friendly garage near Nontron

[g8dhe]

If you remove the thermostat then you will loose all the coolant and it will need to be re-filled and bleed of air - this is the danger point!!! If they don't do it properly - then you assuming its a diesel - you might end up with a cracked head!
I would suggest you read up the bleeding process video's on you tube and perhaps give that ago first https://www.youtube.com/watch?v=jRAKOSxgbKo
if you have for some reason got air into the cooling system then that will get it out, this will also check out the thermostat without removing it and maybe either point to it being a problem or not. If it isn't the thermostat then other reasons need to be found for the overheat....

[The Wanderer]

Oh, OK, I didn't think all the coolant would be lost, at least a UK Bongo garage I rang said I might get away with just topping up. It's tricky for me to do the bleeding because I'm in the middle of nowhere on a French campsite with hardly any tools. I've done it a few times before with a funnel and some work gloves (using the same vid you posted as a guide in fact but not sure I can do it here without them. I am aware of the dangers, and yes it's a diesel.

Reading between the lines, you seem to be suggesting I may just have air in the system, and that it may not be a thermostat fault. I'm not sure how air would get in the system. We have been running perfectly since I changed the radiator in July 2014. Can you explain a bit more please?

What other issues could cause these symptoms?

Thanks,

Geoff

[scanner]

First question...

Is your temp gauge modified or standard?

Sorry to say but for some reason known only to Mazda the gauge as standard is useless as it is over damped and just does not show anything over 11 o'clock until over heating has happened. There is an easy modification that makes it's readings far more relevant.

If it does overheat again just let the engine tickover and put the heaters on full blast* when you stop don't turn it off or the heatsoak from the block could make things worse. Leaving it ticking over keeps the coolant circulating through the system so one section (the block and head) doesn't continue to heat up whilst the rest cools down.

*Not pleasant if you stay inside, but it helps dump heat very quickly.

It sounds to me as if your system now needs bleeding to ensure there is no air in the system. There are videos on you tube that show what needs to be done.

Edit
Just read that you've seen them.

PS "boiling" the system can put "air" into the system.

[The Wanderer]

Hi Scanner

Original gauge. I've seen that mentioned before. I can only say our gauge sits steadfastly at 11 o clock so anything more worries me! I'll check out the mod when I get back to the UK, thanks.

I did put the heating on the last time this happened actually and it did help lower the temp a bit. I also tried this with the air con. Does that have the same effect? It's certainly more pleasant!

I'm familiar with the bleeding process (although rather under-equipped at present), but unsure what would cause air to get in the system in the first place?

Ah, just saw your PS. Why would it boil over in the first place if there was sufficient coolant etc?

Also, I should mention when I put the heater on the air wasn't very warm, and when I felt the bottom hose it was more or less cold.

Geoff

[scanner]

Original gauge. I've seen that mentioned before. I can only say our gauge sits steadfastly at 11 o clock so anything more worries me! I'll check out the mod when I get back to the UK, thanks.

If it hasn't been modified 11 o'clock is all you'll see until it is too late.
Unmodified = Meaningless.

I did put the heating on the last time this happened actually and it did help lower the temp a bit. I also tried this with the air con. Does that have the same effect? It's certainly more pleasant!

Depends upon the temp the system is set to - you have to set the temp as high as possible to dump as much heat as possible. The advantage to using the air con is that it forces the cooling fan to come on.

I'm familiar with the bleeding process (although rather under-equipped at present), but unsure what would cause air to get in the system in the first place?

Ever watched water boiling in a pan or kettle? Where do you think the bubbles come from?

Ah, just saw your PS. Why would it boil over in the first place if there was sufficient coolant etc?

Too much heat.

If the coolant exceeds it's boiling point - it boils, the quantity is neither here nor there.

Also, I should mention when I put the heater on the air wasn't very warm, and when I felt the bottom hose it was more or less cold.

Geoff

What temp was the system set to? If you aren't getting much heat when the system is set to high temp you have air in the system or a blockage. Make sure you open up both circuits to get the coolant circulating through the whole cooling system.

I think you are going to have to bleed the system somehow, but don't leave the air con on for that, as you want the cooling fans off.

[helen&tony]

Hi
First things first. You need to get a pressure test done to determine whether you have a leak, then you can start narrowing things down. There are a number of ways air can get into a system, from a pinhole leak that may have been letting air in over a period when the engine cools, to an unseen leak in a radiator or heater matrix. A pressure test should eliminate a small leak. If there is one, it could take a European garage ages to find it on the Bongo....IF it's a worst case scenario, then a cracked head will only show on a hot pressure test , but let's not get ahead , and think "doom"
Start with the pressure test and go from there! A competent garage will manage that.
Cheers
Helen

[The Wanderer]

Thanks for the info Scanner.

I get what you're saying. But I still don't get why on a really long run in hot weather all was OK, but from virtually cold the next day, it overheated almost straight way?

Helen, good idea. I'll ask garage to pressure test.

And in case I need to change it, does anyone know if there's a thermostat from another vehicle that fits please?

Cheers,

Geoff

ps off on a walk for supplies now, back in a couple of hours hopefully!

[Bob]

Ian has Mazda ones for thirty quid and he can ship very quickly, otherwise the Ford Ranger one MIGHT fit.

Good luck.

[helen&tony]

Hi
Give us the results of a good test (I.E. how long it holds pressure) and you'll get some answers...anyway..don't panic yet...the test shouldn't cost a lot ...a mobile mechanic can do the business.
Cheers
Helen

[scanner]

I get what you're saying. But I still don't get why on a really long run in hot weather all was OK, but from virtually cold the next day, it overheated almost straight way?

After the "really long run in hot weather" did you just stop and turn the engine off?

If so that is when "heat soak" can cause BIG problems.

Read the end of page 2 - start of page 3.

http://cjbfire.com/Heatsoak.pdf

If you turn the engine off when it is very hot the temperature of the water in the block and head can continue to increase and that can lead to the water boiling which can release dissolved air into the system (the bubbles you see when water is boiled).

If you boiled the water after the "really long run in hot weather" the problem could occur "from virtually cold the next day" when the engine next started.

I always let an engine idle for a while after a long hot run.

PS I would still try and bleed the cooling system first.

[The Wanderer]

I let it run on for a short while but to be fair, not as long as I might normally. How long do you leave it Scanner? We positioned the van on its pitch and our exhaust was straight in our neighbours face so Mrs Wanderer suggested we should switch it off. I'm not passing the buck here, I felt guilty for filling their tent with fumes and I feel guilty for turning the engine off too quickly . So I take your point (thanks for the article), that it's likely to have introduced air into the cooling system.

And I suppose it's then luck of the draw maybe, in terms of where the air pocket is? As we have overheated twice but also had a couple of drives, one quite long, without any temperature problems. Is that just down to where the air happens to be? Why is it happy to run sometimes with trapped air but not others?

Just trying to formulate a plan of action now. I could take the van to a garage or get a mobile mechanic to pressure test the cooling system, although I'm not sure I will be able to get anything done here if any problems show up. Assuming it's a minor issue, should I carefully carry on my holiday and attempt to make it back to the UK and sort it with a trusted Bongo garage then?

If I can go and get the required bleeding bits (work gloves, funnel) tomorrow and assuming I can manage to bleed the system, how do I know if everything is OK or not to carry on driving? Is it a case of carry on driving and see what happens?

At least the sun has been shining and we are surrounded by beautiful scenery ...

[scanner]

I let it run on for a short while but to be fair, not as long as I might normally. How long do you leave it Scanner? We positioned the van on its pitch and our exhaust was straight in our neighbours face so Mrs Wanderer suggested we should switch it off. I'm not passing the buck here, I felt guilty for filling their tent with fumes and I feel guilty for turning the engine off too quickly . So I take your point (thanks for the article), that it's likely to have introduced air into the cooling system.

If you had to check in at a campsite I would have thought that was long enough or was it when you stopped there that you turned it off?

And I suppose it's then luck of the draw maybe, in terms of where the air pocket is? As we have overheated twice but also had a couple of drives, one quite long, without any temperature problems. Is that just down to where the air happens to be? Why is it happy to run sometimes with trapped air but not others?

Pass

Just trying to formulate a plan of action now. I could take the van to a garage or get a mobile mechanic to pressure test the cooling system, although I'm not sure I will be able to get anything done here if any problems show up. Assuming it's a minor issue, should I carefully carry on my holiday and attempt to make it back to the UK and sort it with a trusted Bongo garage then?

If I can go and get the required bleeding bits (work gloves, funnel) tomorrow and assuming I can manage to bleed the system, how do I know if everything is OK or not to carry on driving? Is it a case of carry on driving and see what happens?

I have managed with just a funnel by being very careful, but if you can get a pair of "Marigolds" they should help protect your hands.

From what I know if you can get the bottom hose to go hot and any gurgling to stop you should be OK.

However in 8 years and 100,000miles of ownership I have never done a full bleed of the system, despite having done 2 changes of coolant, so can't really say for sure.

However 2, given that I now have what seems to be a slow leak, that day may not be far off

[Northern Bongolow]

Thanks for the info Scanner.

I get what you're saying. But I still don't get why on a really long run in hot weather all was OK, but from virtually cold the next day, it overheated almost straight way?

Helen, good idea. I'll ask garage to pressure test.

And in case I need to change it, does anyone know if there's a thermostat from another vehicle that fits please?

Cheers,

Geoff

ps off on a walk for supplies now, back in a couple of hours hopefully!

when on a run and the engine is hot there is positive pressure inside the coolant system, so any leaks cause coolant to escape, even if just a tiny bit. when the engine is stopped the system is relaxing so as the heat drops so does the internal pressure. the cap will hold about 1 pound neg pressure when the system is fully relaxed and cooled, this last pound negative will allow any leak to pull in a small amount of air until the system is at zero. it may repeat this over several days or weeks until the air that is being sucked in accumulates in volume and stops flow, then a local hotspot makes the coolant boil and blow the cap.

it sounds like you have a small leak somewhere, as said a pressure test is the way forward, then a fix, then a bleed. if you need you can remove the stat in full, (but leave the outer seal in place to seal the 2 halves of the stat housing) or remove the stat and remove the inner seal to effectively make it stuck open, the engine will run cooler but will not harm much till you get home.

you can pressure test the system yourself by fitting a bicycle pump to the little pipe on the expansion tank, give it 4 or 5 good pumps then look round for drips.

[The Wanderer]

f you had to check in at a campsite I would have thought that was long enough or was it when you stopped there that you turned it off?

We met the owner as we arrived and were directed straight on to our pitch.

if you need you can remove the stat in full, (but leave the outer seal in place to seal the 2 halves of the stat housing) or remove the stat and remove the inner seal to effectively make it stuck open, the engine will run cooler but will not harm much till you get home.

How do I decide if I need to remove the stat? If system is bled and problem persists?

Any more info on if I can use another stat - Ford Ranger maybe - if required?

Thanks to all for your input.