Vauxhall Frontera - Losing coolant - head gasket?

Whatever you do dont use any 'stop leak' type sealer!

Oil coolers tend to leak on these, check the dip stick for mayo- otherwise it could well be leaking into a cylinder.

Tim..

There's no such thing.

Find a garage who can do a pressure check on the system. If it's showing a problem and they can't find a leak get them to add a dye. If there is still no sign of where it is going only then expect the worst...

Does it have a heater bypass valve to turn off the heater matrix when no heat is required. In the Omega with this engine the HBV is behind the drivers side cylinder head, it has two pipes in one side and one the other plus a vacuum pipe to the top. These leak fairly commonly and a head gasket failure isn't that common on these engines, but it does happen. Have a feel around the coolant pipes behind the engine, they do split occasionally.

Don't put just water in it for too long. Without antifreeze the system corrodes very badly and very quickly.

Hubby's just brought the car back from work (20 miles each way). He said he had to top it up (1 litre) before coming home, but that may have been cos I didn't put the expansion cap back on properly and it blew off - duh! I've just checked the levels now, and the water is still at the max mark, so it didn't use any at all on the way home. Hubby said he had the blowers on cold on the way home, whereas they are usually on warm. (Everything else looks fine, coolant is clear, no mayo anywhere, oil is clean.)

I'm hoping it's a heater matrix/pipe problem - that's got to be better than new head gasket!

I had a look but I can't find anything like what you describe. Would setting the blowers to cold bypass the heater matrix anyway?

Hmm, I'll try, but there isn't much room there, and by the time the engine's cooled down, I bet the pipes will have dried off! I did have a careful feel and a look with a torch but couldn't see anything.

Ok, but I've always been told not to mix antifreeze, and I don't know what's in there already. It's not blue or pink, it's just like water really... which is rather concerning now you mention it cos it was only serviced a couple of months ago! I've just dunked a kitchen towel in it and it looks and feels just like water. I've got some blue anti-freeze - I'll chuck some of that in when it next falls below max. I think we've put about 2.5 litres of water in in the last week or so, but there should still be signs of old coolant, surely!

I think the plan now is to run it for a day or two with the heaters on cold (or switched off) and see if the water level stays up. Then if it does, try it with the heaters on hot. If it then dumps water I can top it up with antifreeze and I know the problem lies somewhere in the heater system.

Many thanks :)

Ok, a couple of people have concurred with you, so I'll take that advice!

No mayo whatsoever, but I've posted in my reply to rp that the symptoms may be pointing towards a heater matrix problem.

Thanks for your advice.

I've spoken to our local garage (who currently have our Prelude for a timing belt - flipping cars!!) and they said they can pressure check it if they have the right adaptor and to take it in and see.

I've posted in my reply to rp that the latest symptoms may be pointing towards a heater matrix problem.

Thanks for your advice.

If it's a heater matrix leaking you should expect water inside the cabin on the mats and it will certainly mist up the windscreen if the aircon is off.

Not usually unless it has a bypass valve. They are usually only fitted on Omegas with airconditioning. In the Omega it's right behind the drivers side head, picture just showing the top of it here

but it mightbe hard to see without knowing what it is. If you follow the right handedge of the left head you come to a blue plug at the back of theengine, just behind that you can see a sort of cap with a hose goinginto the top, that's the HBV. If it does have a HBV it will shut off the flow to the heater matrix when the heater is off and with a leaky valve it can stop leaking when it's in the bypass position. If it was head gasket I'd expect it to use coolant whether the heating was off or not but with the cap off the expansion tank it wouldn't pressurize so may not loose it.

It might be easiest starting with a cold engine, put the expansion cap on and start it up. As it warms up it will pressurize and then you may be able to see, feel water spraying out but it might just be a tiny dribble.

With the pink in the water looks clear in the header tank. You can mix the pink with the blue but then it only lasts as long as the blue. The blue last for 2 years and the pink lasts for 5 I think.

That will tell you if it's leaking while under pressure and may tell you if it's related to the heating. If it is a hose or the HBV water will come out while it's under pressure but it will suck air in while it's cooling so you are unlikely to see any drips on the drive. On the Omega the DIS pack is mounted behind the other head and the HBV seems to like spraying it's water in that direction and the DIS pack take exception to that :-)

Is the engine mounted with the front of it facing the front of the car or is it mounted sideways, I don't know in the Frontera. If it's mounted sideways the HVB could be at side or it could be at the back of the engine bay near the heater hoses. I know it's right below the wipers on the Omega and you have to remove the scuttle to get to it.

Best of luck anyway.

I'm not convinced about that. The valve only operates on the flow, and the system is pressurized so water will be forced in via the return. It may reduce the speed of the leak, though.

Running unpressurised may stop a tiny leak!

Running unpressurised will reduce losses due to head gasket failure as excess fumes can easily find their way out rather than forcing themselves out.

To eliminate the heater circuit you would need to physically bypass it.

Get a gas test done, this will instantly and conclusively show up a faulty head gasket. It is not the same as a pressure test. Most garages will have a kit to check (they are only about 30 quid to buy) Or they can use the exhaust gas analyser to sniff the fumes from the water system (this is harder to do than use a head gasket test set, also known as a block test)

Mrcheerful

I agree with everything you say but some people have reported that the leak stops when the valve switches, possibly not completely but no longer dripping. I assume the diaphram is being pressed against the lid somehow and if the split is in that section the pressure will seal it against the lid. There is also a water pump in line with the heater on some models and that, at least on mine, runs all the time the ignition is on and that applies a negative pressure to the matrix when the valve is diverting the water.

When I first got my car the air conditioning really cooled things for about ten minutes and then seemed to loose efficiency once the engine had heated up. I felt the heater matrix tubes in the footwell and they were too hot to touch so I had a nose around under the bonnet and found the pump but no electrical connection. Once the lead was located and plugged in the matrix stopped getting hot and the air con worked all the time.

Hubby's just brought it back from work (20 miles each way) - it drank a litre of water on the way there, and nothing at all on the way back - exactly the same as yesterday!! I don't understand it. Heaters were on cold both ways today, but not turned on. Oil is still oil, water is still water, car is running just fine, not overheating or anything.

Nope, neither of those.

Done that, but it never loses water when I'm watching it...

I took a couple of pics of the engine bay. I can see where the pipes go into the cabin, but still can't see a bypass valve. Some pics here if you're interested:

I'm stuck. I think I'm going to have to take MrCheerful's advice and take it to someone who knows more than me!! I'll keep this thread updated anyway for the next poor sod that searches usenet for the same problem.

Many, many thanks for all your help and advice :)

It must like coming home :-)

Looking at frontright.jpg there are two pipes at the back and I'm assuming they go to the heater. Do they turn towards the front of the engine and go under the black cover with V6 on it? There is a big lump of something under the cover at the front, where the thermostat is on mine. If you have a bypass valve it might be under there. If water is leaking at that point it will evaporate fairly quickly with the heat from the engine.

That sounds like a reasonable next step to me, best of luck.

We're finally making progress! I've sussed that it leaks when it's stopped, not when it's going! That's why the coolant remains full for the journey home - hubby fills it before he leaves work and I check it as soon as he's home. Then it loses overnight, gets driven into work and loses more through the day, then hubby finds he has to fill it again before he can come home. I had to drive it around quite a few places last night, and I was checking it at every opportunity and that's when I figured it.

I think (and hope) that rules out the head gasket! Also probably any hoses, as I'd imagine they'd soften and leak more when wet? I'm guessing therefore that it may be leaking through something metal which expands when the engine is hot and stops the leak. Maybe water pump?

I've topped it up with blue coolant, and I'm going to put some paper or tissue under various bits of the car as I still can't see any water on the floor. The paper will stain and I will hopefully find the leak. There's guards under most bits of the engine so it may well be collecting there and then falling out when moving.

They are definitely the heater pipes, but I didn't poke around too much as the car was hot. I'll have to wait for the weekend now as hubby won't be back before dark now until then. Hopefully we'll get his Prelude back from the garage by then so he can stop breaking my car!!

Thank you so much for your help rp, you've been brill :o)

After a run the system remains pressurised and pushes out water even with the engine stopped. A typical component which can show a leak when the engine stops is the water pump, these can sometimes drip a lot when stopped but be quite ok when turning.

Mrcheerful

Usually the other way around though in my experience. Don't forget that when hot the coolant etc will expand and then when it cools it may appear to have gone down overnight when in fact some has been lost whilst driving.