Can a leaking vapouriser seem like a Head Gasket?

kooky_guy · Mar 11, 2015

Hi All,

My P38 has been off the road for a couple of years - I suspected the head gasket was blowing between a cylinder and the water jacket as the coolant was being pressurised so the intention was that I would do the head gaskets while it was off the road. Unfortunately life got in the way and it didn't get done.

Having had to recommission the Range Rover in order to move house and after spending weeks in the garage having various bits done for the MOT, it now seems that the head gasket blow has come back with a vengeance.

Having said that, I've just been tinkering with it attempting to bleed the cooling system after it's last outing which resulted in it spewing coolish coolant out at quite high pressure.

What I discovered was the instant I turned the lpg on (for some reason it didn't auto switchover), the expansion tank started spewing out large amounts of 'air'. After a few minutes I realised that this 'air' smelled of lpg. This stopped when I switched back to petrol.

So, I'm assuming that my vapouriser has developed a leak but my question is, would such a leak be able to put so much pressure into the cooling system that it would cause it to 'boil' over?

I'm kind of hoping that this has actually been the problem all along although I have no idea where I can get the vapouriser fixed round here.

jamesmartin · Mar 11, 2015

lpg is under some pressure more than cooling system , so could link the 2 water hoses missing out the vapouriser and prove the point

Datatek · Mar 11, 2015

I know nothing about LPG, but I have read that leaking gas from the vapouriser will give similar symptoms.

3.5 efi · Mar 11, 2015

You've answered your own question really. Yes it could pressurise the water if leaking into the water. Think Saint on here had very similar issues a while back.

kooky_guy · Mar 11, 2015

Unfortunately most of my tools are currently in storage so I'm going to have to find someone to tinker with it. I'm slightly encouraged though.

Anyone know of any lpg installers in Surrey/Berkshire/Hampshire? I used to use New Farm Auto Services in Arlesford, but they're a bit of a trek for me now.

Saint.V8 · Mar 11, 2015

There used to be Autogas Surrey - Known as Bentleys Garage in Brookwood (Bisley/Knaphill area) on Connaught Road......

Castor · Mar 11, 2015

Passing thought on vapouriser failure: I bet there are some interesting electrolytic effects to be had with these & the coolant......

MrGorsky · Mar 11, 2015

kooky_guy said:
Unfortunately most of my tools are currently in storage.

You could go and buy yourself a new screwdriver for the jubilee clips, and just bypass the vaporiser entirely where it T's off the coolant pipes.

Leaking Vaps can pressurise the coolant system easily. LPG only turns to liquid at something like 300psi.

Bypassing the vap wouldn't rule out HG failure, but it would rule out leaking vaporiser.

Having said that, switching the LPG system off will have the same effect. If it runes fine on petrol with no coolant issues, then repairing the vap will be your next job. Kits are available to repair the diaphragm inside.

ovalandrover · Mar 12, 2015

MrGorsky said:
You could go and buy yourself a new screwdriver for the jubilee clips, and just bypass the vaporiser entirely where it T's off the coolant pipes.

Leaking Vaps can pressurise the coolant system easily. LPG only turns to liquid at something like 300psi.

Bypassing the vap wouldn't rule out HG failure, but it would rule out leaking vaporiser.

Having said that, switching the LPG system off will have the same effect. If it runes fine on petrol with no coolant issues, then repairing the vap will be your next job. Kits are available to repair the diaphragm inside.

I think its 180psi that Propane turns into liquid and if you bypass the water into the vapouriser you wont stop the gas leak but it will leak into the engine bay and lay under the car as its heavier than air so dont park over a drain.
if you do you will have to turn off the gas at the tank and run on petrol until the diaphragm is renewed

kooky_guy · Mar 12, 2015

I don't think there's a problem until I switch it to lpg. Certainly the gas stopped bubbling out of the expansion tank when I switched back to petrol.

Unfortunately, it's got another separate problem with the petrol supply - some sort of intermittent supply problem I think, which randomly makes it lose power and not idle so it's not much fun to use on petrol especially in traffic! Ah, the joys of Range Rover ownership.

MrGorsky · Mar 12, 2015

ovalandrover said:
If you bypass the water into the vapouriser you wont stop the gas leak but it will leak into the engine bay and lay under the car as its heavier than air so dont park over a drain.
if you do you will have to turn off the gas at the tank and run on petrol until the diaphragm is renewed

If you bypass the coolant feed to the vap, it will never heat up, therefore the system will never switch over to gas, so you shouldn't get a gas leak.

Better to turn off the gas at the tank though.

Datatek · Mar 12, 2015

kooky_guy said:
I don't think there's a problem until I switch it to lpg. Certainly the gas stopped bubbling out of the expansion tank when I switched back to petrol.

Unfortunately, it's got another separate problem with the petrol supply - some sort of intermittent supply problem I think, which randomly makes it lose power and not idle so it's not much fun to use on petrol especially in traffic! Ah, the joys of Range Rover ownership.

In tank pump on it's way out maybe.

kooky_guy · Mar 12, 2015

MrGorsky said:
You could go and buy yourself a new screwdriver for the jubilee clips, and just bypass the vaporiser entirely where it T's off the coolant pipes.

Leaking Vaps can pressurise the coolant system easily. LPG only turns to liquid at something like 300psi.

Bypassing the vap wouldn't rule out HG failure, but it would rule out leaking vaporiser.

Having said that, switching the LPG system off will have the same effect. If it runes fine on petrol with no coolant issues, then repairing the vap will be your next job. Kits are available to repair the diaphragm inside.

Going by my brief experiments, it only seems to be pressurizing the cooling system when it's actually switched to lpg. So by my thinking, I just need to leave it set to petrol until I can get it fixed.

davidsmith1307 · Mar 12, 2015

It'll be quicker too as you won't have any money that you'd otherwise need to carry about.

Rob4x40 · Mar 12, 2015

ovalandrover said:
I think its 180psi that Propane turns into liquid and if you bypass the water into the vapouriser you wont stop the gas leak but it will leak into the engine bay and lay under the car as its heavier than air so dont park over a drain.
if you do you will have to turn off the gas at the tank and run on petrol until the diaphragm is renewed

There should be a solenoid shutting off the LPG supply when the system is set to petrol. This should be before the vapouriser (probably at the tank) so there shouldn't be any gas to leak when on petrol...

Kooky_Guy, all that time, the Audi and the BM - and it wasn't the HG after all???

kooky_guy · Mar 12, 2015

Rob4x40 said:
There should be a solenoid shutting off the LPG supply when the system is set to petrol. This should be before the vapouriser (probably at the tank) so there shouldn't be any gas to leak when on petrol...

Kooky_Guy, all that time, the Audi and the BM - and it wasn't the HG after all???

Well, fingers crossed it wasn't! The Beemer is at least fun!!

Rob4x40 · Mar 12, 2015

kooky_guy said:
Well, fingers crossed it wasn't! The Beemer is at least fun!!

Indeed! Fingers are crossed...

Saint.V8 · Mar 12, 2015

kooky_guy said:
Well, fingers crossed it wasn't! The Beemer is at least fun!!

Beemers are BMW bikes, Bimmers are their cars!!

ovalandrover · Mar 12, 2015

MrGorsky said:
If you bypass the coolant feed to the vap, it will never heat up, therefore the system will never switch over to gas, so you shouldn't get a gas leak.

Better to turn off the gas at the tank though.

The systems I know the change over is by timer not heat related

kooky_guy · Mar 12, 2015

ovalandrover said:
The systems I know the change over is by timer not heat related

Mine's definitely heat switched. The gas leak explains why it's stopped switching over as there's no coolant in there when it's been running.

I've set it to petrol only now until it's fixed.

Can a leaking vapouriser seem like a Head Gasket?

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