Jump to content
Sign in to follow this  
zob

Cooland boiling over when stopping after motoway driving (Summer in France)

Recommended Posts

zob

Just did 8 hours of driving from Oxford to Dijon - the first leg on a 3 week tour around France in our Mk2f. I'd planned ahead meticulously and the car has probably been over-maintained before the trip as a precaution.

 

Drove like a greased rocket out of Coquelles - car behaving perfectly and doing 130km/h for hours like a champ. However when we stopped for fuel I totally forgot about how hot the head may have gotten on l'autoroute so as soon as the pump stopped the coolant boiled over. No biggie I thought - only lost a few hundred ml and I brought a gallon of deionised water just in case. Topped it up and didn't thinka ny more of it.

 

4 hours later the same thing happened again, even after letting it idle for a while and let the fan kick in a couple of times before turning off. Am I just being an idiot and this is what driving in a French summer was like 26 years ago? Does anyone have any tips? Should I run the heater on full whack when we stop suddenly like that (i.e. in an aire off the autoroute) and try and bring the head temp down for a while?

 

Was fine just stopping in Dijon now as we had to do some slow city driving before stopping. However when idling just before we turned off for the day the pump was squealing away - sounded like the old one before I replaced it in Jan and that was knackered. Could it just be dead hot?

 

Probably should lay off sitting at 4k revs for 4 hours at a time from now on eh...!

Share this post


Link to post
Share on other sites
steveo3002

soemthing doesnt sound right , the fan should be already on if its super hot , could try another coolant cap

 

yes pop the heater on if you feel its getting overheated  

Share this post


Link to post
Share on other sites
zob
3 hours ago, steveo3002 said:

soemthing doesnt sound right , the fan should be already on if its super hot , could try another coolant cap

 

yes pop the heater on if you feel its getting overheated  

 

Its at 90 degrees the whole time we were driving and under 100 when we stop. The fan kicks in around 110 (on the temp gauge) and turns off around 90. I think whats happening is the head is so hot that when we stop quickly like that it doesn't have anywhere to go and the latent heat of the head boils the coolant locally. The fan only knows how hot it is in the thermostat elbow but it could be much hotter elsewhere if the pump isn't running right? And if the fan isn't running there won't be much of a convection current through the system, or at least not as pronounced?

 

Do you feel another cap would be an idea if the system isn't getting to pressure? I'll check the hoses are all taught when its warm tomorrow.

Share this post


Link to post
Share on other sites
steveo3002

i just know caps can cause trouble...cheap thing to try thats all 

 

you can look see if theres flow from the small tube on the coolant tank, proves the pump is working

 

another guess ...could the thermostat be slow to respond ? i dunno cant be too much wrong if it copes with hours of high speed use , and you say once its settled it will sit there and idle with the fan coming on/off ? 

Share this post


Link to post
Share on other sites
zob
8 hours ago, steveo3002 said:

i just know caps can cause trouble...cheap thing to try thats all 

 

you can look see if theres flow from the small tube on the coolant tank, proves the pump is working

 

another guess ...could the thermostat be slow to respond ? i dunno cant be too much wrong if it copes with hours of high speed use , and you say once its settled it will sit there and idle with the fan coming on/off ? 

 

I'll see if I can't find a cap - may be tricky where we're headed but you never know!

 

Yeah - definitely flowing back through the return pipe in the header tank, had my partner rev it and it gushed out so pump is fine.

 

Honestly the whole cooling system appears to be working as it should and nothing is out of place, i get the feeling the driving and the conditions might just be on the limit of what its capable of! When we stop at an aire later on this morning I'll idle it for a good while and use the heater as a secondary heat sink to see if it helps.

Share this post


Link to post
Share on other sites
zob

Well well well.

9 hours ago, steveo3002 said:

i just know caps can cause trouble...cheap thing to try thats all

 

I think you might be on to something mate - just had a check and the o-ring inside the cap has snapped and was bunched up to one side - probably been like this ever since I've owned it which likely means I've had an un-pressurised cooling system! This must be the source of the boiling as pressurised fluid wouldn't boil in the same way.

 

Pretty impressed that it survived the punishment of yesterday with floppy hoses... Now the question is where am I going to find a replacement cap? Is there anything I can do as a bogan fix in the meantime? I brought a bunch of O-rings with me and one potentially would fit but its thinner than the one that was originally in the cap - might fit and make some sort of seal

Share this post


Link to post
Share on other sites
steveo3002

if its the round tank then theyre common to most 90s onwards vag cars , black was the original blue was a slightly better one

 

any car parts store or breakers should be able to help you, or main dealer  might stock one

Share this post


Link to post
Share on other sites
dvderlm

Try 2 o-rings until you find a spare cap (bouchon de radiator)?

  • Like 1

Share this post


Link to post
Share on other sites
zob
13 minutes ago, dvderlm said:

Try 2 o-rings until you find a spare cap (bouchon de radiator)?

 

Managed to squeeze a fat green O-ring (came with my elring head gasket set - maybe a camshaft seal?) into the cap - it'll be sealing along its inner edge. Tightened le bouchon down with a pair of stilsons and a rag (new oring needs some squishing) and idled the engine up to temp until the fan kicked in - the tubes are nice and tight and there's no boiling. Should be a sound fix until we get a replacement.

 

Thanks for the pointers guys

Share this post


Link to post
Share on other sites
steveo3002

was it a black cap?

 

im sure they have dealers or equivalent of gsf there

Share this post


Link to post
Share on other sites
zob

 

Sorry - few things got in the way since friday!

On 19/07/2019 at 09:15, steveo3002 said:

was it a black cap?

 

It was a black cap yeah. I have french friend who offered to phone a few places to see if they can get a part in and no luck (few of the garages seemed open, although Fin might have just picked some duff places to call accidentally). I managed to navigate French Oscaro and order a blue one (Metzger) to be sent by 24-hour post to a carrefour on our route back, not certain it'll be delivered in time but we'll see... Tomorrow we have to Drive to Italy to continue our trip and will be on Corsica next, might be harder to find one down there, hard to tell. Half the problem has been where we are - currently up near Val Thorens which is pretty remote. Thankfully we only have to do down the mountain to get off, not much chance of overheating there.

On 19/07/2019 at 09:15, steveo3002 said:

im sure they have dealers or equivalent of gsf there

 

I'm struggling to locate one - does anyone know the name of any French auto part stores? I feel like there should be something we can walk in to rather than having to order.

 

On 19/07/2019 at 08:25, dvderlm said:

Try 2 o-rings until you find a spare cap (bouchon de radiator)?

The two O-rings didn't hold air in the end - you can hear air wheezing out of the expansion tank overflow when you squeeze a hose with the cap on. Could be that the seal is fine and the check valve is shot, but either way its duff.

 

Bought a ton of coolant and had to use some when we got up here and stopped - it spat out a few hundred mil again even after some idling with the fan cycling and the heater on full blast. I guess the thermal intertia of the head takes a while to clear. Had a real scare then as the idling was crazily lumpy and it appeared like two cylinders weren't firing... some very quick checks later (haven't had a whole heap of time to work on this on holiday!) and it seems like it was just running very rough with some fouled plugs. My theory is I tried running too high a gear going up the mountain and just coked up the plugs something rotten. Hopefully.

 

Thanks for the help guys - really can't stress enough how good having this forum is when you're up the creek sans paddle!

Share this post


Link to post
Share on other sites
steveo3002

why dont you google main dealers ?  audi /vw/skoda can most likley help...take yours in and point at it 

 

or id rock up to any garage you pass and see if you can communicate ...they might tell you where the nearest seller is 

 

worst case i dont supose it would cripple you to have one sent out from uk on 24/48hr

Share this post


Link to post
Share on other sites
zob
31 minutes ago, steveo3002 said:

why dont you google main dealers ?  audi /vw/skoda can most likley help...take yours in and point at it 

 

or id rock up to any garage you pass and see if you can communicate ...they might tell you where the nearest seller is 

 

worst case i dont supose it would cripple you to have one sent out from uk on 24/48hr

 

Managed to find a garage just now and he speaks english, he's going to try and get one in for tomorrow.

 

Aye true - worst case we're on Corsica for a while in the same place so I'm sure we can get something sent there.

Share this post


Link to post
Share on other sites
zob

Well that turned out to be a right faff! Ordered 3 different caps and they never arrived on time in the places we were staying before we had to leave - I guess Corsica is a little more out-of-the-way than I gave it credit for! Couldn't get hold of the right size O-ring either so ended up fitting a couple of flat rubber washers (for pvc plumbing fittings) which restored the system to holding pressure and got us another thousand miles without any issues. Back home now and able to replace the seal properly.

 

Thanks for the help!

 

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. Terms of Use Privacy Policy Guidelines