Coolant level switch

[cuban-night]

Hi folks, on a resent Weekend away in our T25 our bus decided to not spit out her dummy but choose to spit out her coolant level sensor thus pumping water all over the engine causing a plume of smoke to scare the hell out of us. We have now replaced the the switch as it was broke around the screwing in thread which could have been damaged before as head looked like it had been forced in. We are concerned about what may have caused the fault in the first place as the guy sent by the RAC was looking to tow it to his garage as he was thinking that the head gasket had gone even though he hadnt really had a proper look, although we're not convinced as there was no tell tale signs before and no massive amount of smoke coming out of her now or creaminess in the oil though we have only drove her round the block. Also the second water tank still had water in it so the engin had not ran dry or over heated. What should we be looking out for to check the head gasket? How far would we have to drive her to test wether she is ok or head gasket is damaged? Would this damage her any further? Any help or advise would be greatly appreciated as we would love to get her back on the road to enjoy her we do know it would be easier to take her to a garage but after paying £355 on a tow home from Wales we're really looking for a cheaper option. Thanks in advance.

[Rich Tea]

Hi there,

You're not going to get a detailed answer unless you state your engine type.

If it's a 1.9 or 2.1 wbx then not many garages have a good understanding of these, there is no head gasket as such (perhaps avoid a garage that suggests that there is one). If you have blown a seal, then it's bad news I'm afraid.

Before spending big money, you may have a problem with your darlek cap on the tank. The system pressurises as it heats up. When the tank reaches a certain pressure the cap vents excess coolant from the coolant tank to the expansion tank (behind the flap). If this doesn't function then the tank could over pressurise and you could blow something, perhaps this might have been the coolant level sensor in your case.

By the way, the other function of the cap is to allow the coolant to return from the top-up tank to the coolant tank. This happens as the coolant cools and a vacuum is formed. This means that once you blew the sensor out of the coolant tank the tank would not have refilled from the top-up tank, so coolant in the top-up tank would not in itself mean that you didn't run dry.

I'd advise changing the darlek cap for a new good quality one (try VW or Brickwerks) obviously replace the sensor and its O-ring seal. If theres any micro-cracking on the tank (look around the filler neck), replace this as well (use good quality one again as some are poor). Bleed the system per the wiki, just use water for now as the right coolant is expensive (use coolant once you know things are ok). Remember the coolant tank needs to brimmed always.

If this is the issue, things might not be as bad as you think.

Others (with more knowledge than me) will no doubt be along to offer advice, but they will need to know the engine type.

Cheers
Rich

[cuban-night]

Thanks Rich, our camper has a original reconditioned 1915cc petrol engine we're not mechanics and very new owners of our T25 so not that experienced and only going off the paperwork we have.

[Ian Hulley]

As the engine heats up the coolant pressure builds up in the header tank (the one with the sensor NOT the one behind the cat flap) and as it exceeds a set level the pressure is relieved by coolant passing through the dalek cap into the top-up tank (behind the catflap) ... this can be seen by the level in that tank being above 'Max' when the engine is hot. If the dalek cap has failed the excess pressure has to go somewhere ... often cracking the tank if old and dried out, sometimes by pushing past the O-rings that seal the sensors into the thermostat housing OR by popping the top off the level sensor.

As the system cools the dalek cap allows the coolant to be drawn back into the header tank from the top up tank ... which is how it tops-up the coolant ... until the tank pressure falls below a set level. My money is on the dalek cap failing, buy a replacement from Brickwerks NOT GSF or Carpants and buy the original equipment one. http://www.brickwerks.co.uk/shop?page=s ... ory_id=118 . The system may also need bleeding as per the guide in the Wiki.

Hope this helps explain things.

Ian

[cuban-night]

Thanks for that Ian, I hope it's as simple as that as our main concern was that it may have been something more serious.

[kevtherev]

Thanks for that Ian, I hope it's as simple as that as our main concern was that it may have been something more serious.

...and probably the unqualified thoughts of a recovery man compounded that.
Flat four engines do not have head gaskets like normal cars, it is very rare for the exhaust gas to pressurise the cooling system from the "gasket" failure.

[cuban-night]

Thanks for that Kev, we've complained to the RAC as they were keener to recover than repair and charge more for it, they are also arguing that thier mechanic would of been qualified and thier technical team confirm all engines will have a head gasket. Are there any links or sites that I can view that will prove contrary. Thanks again.

[Ian Hulley]

Each cylinder has it's own 'head gasket' this is an anealed metal ring sandwiched between the top of each barrel and a recess in the head for each of the cylinders.

As for roadside repairs the breakdown organisations have to recover you to a place of safety as part of their duty of care .... to their staff as well as to you. Having had a Belgian mechanic drop the spare wheel carrier down onto his head trying to find the gearbox I can tell you sometimes you just DON'T want them even touching it. It was VERY funny hearing it from inside the van though

Ian

[LeeME3]

...My money is on the dalek cap failing, buy a replacement from Brickwerks NOT GSF or Carpants and buy the original equipment one. http://www.brickwerks.co.uk/shop?page=s ... ory_id=118 . ...

Hmmm...at that price I think I may change mine for a new one on principle...

(apologies for slight thread hijack)

[Ian Hulley]

...My money is on the dalek cap failing, buy a replacement from Brickwerks NOT GSF or Carpants and buy the original equipment one. http://www.brickwerks.co.uk/shop?page=s ... ory_id=118 . ...

Hmmm...at that price I think I may change mine for a new one on principle...

(apologies for slight thread hijack)

If you do that keep the old one as a known-good spare.