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Hi, yes there's pressure in the expansion tank when you release the cap.

I have been doing some research and I'm going to take the plastic cam belt cover off, take a look around the water pump area, if there's any signs of coolant there I will quicky hand it over to VX to sort out, that would be covered under the lifetime warranty, unless they also consider a water pump gasket a hose as well ! lol
 

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How long, how many miles before it was nearly empty again? bear in mind after refilling there could have been an airlock that cleared after its first run and allowed the level to fall.
 

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Thanks Ernie for the reply, Is your Mokka the 1.6 petrol engine ?

I took another look at it earlier on after a short trip, the coolant was about 1 inch from the bottom of the expansion tank, I undid the filler cap and the level of the coolant rushed up to the top of the tank. I screwed it back down and the level went down to the fill line. I did another short trip and looked again, the coolant was now low again ?

Im really not sure what to think now, could this be a cylinder head failure or similar ?

One other thing I noticed was that I can smell coolant around the engine bay, this was before I undid the filler cap.

Will have to book it in I think and get it looked at.
 

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If you have chance before taking it in, run the engine with the coolant cap off and the climate control on its hottest setting with the fan on the lowest setting, have some coolant ready to top up and hold the engine at 2000 to 3000 rpm, until the engine is hot enough for the fan to cut in and out a couple of times, keep your eye on the expansion tank and if the level starts to get near the top let it the engine tick over until it goes back down again and be ready to top up if the tank gets low, that should clear any air locks in the engine or heater.
 

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Thanks for the advice, I will give that a try, i'm going to take the cam belt cover housing off anyway to check the water pump and timing belt at the weekend, the car has done 58k now so worth checking the belt etc.
 

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2016 Mokka 1.4T SE 4X4
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Thanks Ernie for the reply, Is your Mokka the 1.6 petrol engine ?

I took another look at it earlier on after a short trip, the coolant was about 1 inch from the bottom of the expansion tank, I undid the filler cap and the level of the coolant rushed up to the top of the tank. I screwed it back down and the level went down to the fill line. I did another short trip and looked again, the coolant was now low again ?
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The manual only refers to the fluid level when cold. When the engine is hot the cooling system pressurises and the level in the expansion tank will change.


On my 1.4 turbo the level goes down as you describe, then comes up again when the engine cools.


Also, on my car the marked level is not that clear, the normal level is about 1 cm below the marked line. and if filled to the marked line cold the extra fluid is expelled via the pressure cap and the level returns to where it was (possibly leaving a residual odour).


Your may not be the same of course.
 

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Normally the coolant level will increase slightly when hot, the coolant level dropping when hot indicates air in the system, water can't be compressed but air can, its also normal for the level to rise when the cap is released when hot as the pressure drops and the hoses relax but rising excessively or overflowing indicates air locks, an air lock can be caused by removing a hose for repair and not purging the system as in my last post or a failed head gasket allowing combustion gases into the coolant, with the cap removed and the engine hot a continual stream of bubbles in the expansion tank after purging can indicate a failed head gasket.
 

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Thanks for all your replies, I have now found the leak in the coolant circuit. Its another quick connector on top of the thermostat housing. I suspect its another 'O' Ring failure. If you look at the attached pics you'll see a pool of red coolant on the left hand side and below the riser which the quick connector is locked on to.

I cleaned all of the coolant up and gave the 'O' ring a quick clean and re-assembled, started the engine and watched coolant slowly trickling out of the top of the quick connector.

This is the second quick connector that has failed over the last couple of weeks on a six year old car !!

Its got me worried as to which 'o' ring is going to fail next !

I am going to have to try and order the complete pipe I think, I guess the VX dealer wont just sell the new 'O' ring.

I have the lifetime warranty, but again this wont be covered as its a seal !!

I guess a trip to EuroCarParts for a multi pack of 'O' rings, might be worth it !
just £4.21 with the Black Friday discount code currently running. I am pretty sure one of the smaller sized ones will fit the corroded one currently on the quick connector.

Any thoughts ?
 

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I would get new o rings from a proper bearing and transmission place your bound to have in an industrial estate somewhere. I use Derby Bearings, oh and if you want to be really posh get the new o rings in viton as it’s more resistant to heat than the normal material who’s name I forget.
Once you’ve identified the size get 4 and replace the lot
 

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ok, thanks for the advice Dog_book, I have now made a very temp repair on the o ring using some PTFE tape, I wrapped some around the damaged O ring to make it seal again, all watertight and no leaking whatsoever, I will measure up the o ring at the weekend and order a few Viton replacements.
 

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Similar problem with a 1.6 petrol mokka

Thanks for all your replies, I have now found the leak in the coolant circuit. Its another quick connector on top of the thermostat housing. I suspect its another 'O' Ring failure. If you look at the attached pics you'll see a pool of red coolant on the left hand side and below the riser which the quick connector is locked on to.

I cleaned all of the coolant up and gave the 'O' ring a quick clean and re-assembled, started the engine and watched coolant slowly trickling out of the top of the quick connector.

This is the second quick connector that has failed over the last couple of weeks on a six year old car !!

Its got me worried as to which 'o' ring is going to fail next !

I am going to have to try and order the complete pipe I think, I guess the VX dealer wont just sell the new 'O' ring.

I have the lifetime warranty, but again this wont be covered as its a seal !!

I guess a trip to EuroCarParts for a multi pack of 'O' rings, might be worth it !
just £4.21 with the Black Friday discount code currently running. I am pretty sure one of the smaller sized ones will fit the corroded one currently on the quick connector.

Any thoughts ?
Thanks for posting your findings on this thread. I am having a very similar problem with my 2014 vauxhall mokka 1.6 l petrol. i noticed a pool of coolant on the driveway under the car on friday. i looked at the expansion tank and the coolant level was low. before this weekend i had last checked the coolant level a month ago and observed at the time that the coolant was not low but on the low side. Anyway i topped up the expansion tank and looked around the engine bay to see where the leak was coming from. i was able to identify coolant was all over the underside of the thermostat housing on the passenger side of the engine bay. the thermostat housing bolts onto the bulkhead and i could feel coolant residue on here. I was initially of the impression that there must be a seal between the bulkhead and the thermostat which had gone. then i read your findings above. i double checked and i could not really feel any moisture on the o ring/quick connector at the top of the thermostat housing.

Anyway yesterday i cleaned the bay wiped up the residue on the housing, dried everything, went for a drive, let the car warm up, and (carefully) felt around the housing. nothing. No dripping or anything. i decided to clean the driveway- scrubbing it with detergent, and committed to see how things were this morning.

I went to work, but the wife informed me, that the car was leaking again. Lo and behold, this evening, there was anice big patch under the car again. im not sure if its leaking when the engine is hot, or when its cold. I couldnt check the o ring tonight as my phone died and had no lighting but ill have another look tomorrow and see if i can see any signs of leakage from the o ring.

the coolant levels are still acceptable. its probably leaked about 100ml maybe 150ml. bit of a pain really. if its a seal between thermostat housing and bulk head thats really annoying. if its an o ring connector, then thats easily fixed.


interested to hear anything further from you on your findings.

thanks
 

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Quick update

Hi all, quick update!

I took the car into Vauxhall garage to get them to look at the thermostat. They couldnt find any leakages from the thermostat or the surrounding housing. They did a pressure test, and called me to tell me that they think there are no leaks, and everything seems fine, but that the presence of some coolant residue on are area of the engine near the water pump (ON THE OTHER SIDE OF THE ENGINE FROM THERMOSTAT) sugegsts that there may be a small leak form the water pump. The told me they suggested replacing a seal. £53 they quoted me. I told them that the water pump was on the opposite side of the engine to where coolant was pooling on the driveway so i didnt see why i should replace a seal for a leak which hasnt ever presented itself to me. the only evidence they were going by was the residue on the waterpump area. I obviously refused the sugestion to replace the seal. Vauxhall were useless. so i picked up the car and have taken matters into my own hands.

I looked again at the thermostat housing. i ahve identified that: the leak only happens overnight or when the engine is completely cold. the leak is coming from either, the sealbetween the thermostat and the thermostat housing, OR from the seal between the pipe exiting the engine block coolant jacket which also joins onto the thermostat hosuing. one is above the other and so it was difficult to identify specifically which one was leaking.

Regarding the point about the leak only happening when engine is cold: This suggests that when the engine is hot, the expansion of metal and plastic parts is enough to plug any gaps. its only when the engine is completely cold, and when these parts are compeltely contracted that the leak is occurring. To me, then lead me to suspect that the first line of enquiry should eb to check that all the BOLTS surrounding the thermostat/housing seal AND the coolant jacket/thermostat housing seal are propoerly tightened. so out came the torque wrench today whilst it was still daylight.

I started by checking the bolts around the thermostat housing/thermostat. lo and behold, the lower right bolt holding the thermostat into the hosuing was very loose. i was able to loosen it with my fingers! I didnt have the factory torque settings to hand by i tightened the bottom two bolts on the thermostat housing to a tourque of 10nm which to me is a default torque setting which is much more than finger tight, but not tight enough to cause any problems (i hope). the top right bolt was not reachable so i didnt tighten this one but it seemed to be tight enough already.

I also tightened the two boths on the seal between the pipe of the coolant jacket where it joins the thermostat housing. these were also a bit loose if you ask me- certianly less than 10nm torque so tightened these too.


lastly, i topped up the coolant, and checked that everything was dry. I will see tomorrow morning if there are any signs of leakage. I hope the above tightening will have solved the problem, becaus ei cannot see any signs of cracking, or other damage on the thermostat housing, and these loose screws seem to make sense as being the cause of the slow leak i ahve been experiencing.

ill keep you updated.

PS you can see a photo of the thermostat housing and the location fot he screws i tightened below. i found this picture online. it is the mokka thermostat hosuing and shows the location of the screws i tightened. (gold/brass coloured sockets) the two at the bottom of thelarger opening were the loosest screws on my mokka!...

fingers crossed its all sorted now.
 

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Lets hope it's sorted, there is another reason small leaks don't show when the engine is hot/warm, evaporation, the water simply disappears before there's enough to see, leaving just the tell tale marks of the antifreeze residue.
 

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Coolant leak help needed
Hi,
I have a coolant leak from the heater inlet hose on my Mokka 1.6 petrol 2014 model
The leak appears to be coming from the quick fit type connector, there is no leak with the heater switched offf
I have seen on internet that the cause might be an o ring inside the connector has failed and is reasonably easy to repair / replace ,
I have looked at the connector which appears to have a metal clip fitted but am unsure how to remove it , I don’t want to force it in case I damage the heater matrix
Any advice help would be much appreciated
&
 

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Coolant leak help needed
Hi,
I have a coolant leak from the heater inlet hose on my Mokka 1.6 petrol 2014 model
The leak appears to be coming from the quick fit type connector, there is no leak with the heater switched offf
I have seen on internet that the cause might be an o ring inside the connector has failed and is reasonably easy to repair / replace ,
I have looked at the connector which appears to have a metal clip fitted but am unsure how to remove it , I don’t want to force it in case I damage the heater matrix
Any advice help would be much appreciated
&

To be honest its easier to show someone in person than explain well it is to me, id be able to show you but unfortunately you haven't put your location in or posted any pictures and not being rude im not pulling mine to bits to work it out.

I cant see any metal clip in the picture but if it the same as a Vectra one it just pulls out one click then unlocks. From general experience on these there's a lock then a tab, and sometimes you push it not the way it looks they can be really annoying i had to take 2 off on the fuel filter which did my head in. The lock tab should unclip allowing the latch to be unlocked, i would guess something like that might need a tug for it to come off.


Looking again it also looks like the air pipe fitting that mine uses for the SAI pump, you push the sides in and unlatches making it quick to remove ofc.
 

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