Technical How do I find a coolant leak?

[Doofer]

This month's Croma challenge (the wiper mechanism was last month)...

My car's losing coolant. The header tank has dropped from the fill line to almost nothing in a week since I noticed the tank was empty last week and refilled it (then ran until hot, let air out etc).

What first alerted me was that the heater wasn't working.

One thought - I had the cam belt and water pump replaced recently (at a garage). Presumably it must have a gasket or something, must be worth a look.

There was no point in looking today, as I'd just washed the car so it was wet in the grille already. I need a couple of days of dry weather to be in with a chance of finding a trickle.

I guess a slow leak is like a slow puncture - a bugger to find.

Anyone have any tips on how to find the leak? I guess the radiator is the place to start - I had the aircon condenser replaced a bit ago, and it had turned to dust, so the radiator can't be much better.

 

[Eklipze3k]

If you can get a spare pressure cap and a bike pump with the valve off of an old inner tube you're golden.
Drill a hole in the pressure cap the right size for the valve, pop the valve through (making sure you've left enough inner tube attached to make seal on the inside of the pressure cap). Fill your reservoir to max, pop the cap on and pump away, water should start peeing out of whereever the hole is

 

[Davren]

Pump up the resevoir to about 1 bar, should show up any external leaks.

I use an old brake fluid resevoir cap with a metal tyre valve fitted through it, and a tyre pump. The brake fluid and coolant resevoir caps are the same size and thread on the Stilo, probably on your Croma too.
.

 

[s130]

Agree with above posts.

A problem you are going to have is that with the engine undertray fitted your not going to see fluid dropping to the ground and if you do then it will possibly be falling down from a place totally unreleated to where the actual leak it.

Now we have the darker and colder evenings here then you could try this.

Wait till it is dark outside
Run the car until the engine is fully warm. I mean the whole engine, gearbox etc.
Park up leaving the engine running, fan cutting in and pop the bonnet.
Slowly with a torch explore the whole engine comparment area.
What you are looking for fine whisps of steam/water vapour. Very often these are easily visible from even the smallest of leaks.

My one fear is that you could have a gasket leak around the replaced water pump. Any mist/vapour from here is going to possibly dissipate behind the cam belt cover before you can get to see it.

Last resort is to remove the front offside wheel and then remove the inspection/access plate on the inside of the wheelarch. Now you will be looking for signs of fluid around the back of the crank pulley, sump etc.

Best of luck.

 

[Doofer]

Thanks all.

I've had a look at the header tank cap. Unfortunately it's a Vectra one, which is quite complex as it incorporates a pressure relief vent. Pics attached. There are two seals, with a vent pipe in the tank between the two. A spring-loaded valve allows excess pressure to vent into the space between the two seals, so out of the vent.

I reckon I could drill straight through the centre of the whole thing and fit a valve in its place though, but I'll have to get a scrap one as I'd destroy the safety valve in the process.

I will try the "torch and steam" process this evening though, sounds like it's worth a go.

I'll be blooming annoyed if the garage have failed to seal the water pump. It's possibly just coincidental though, and the leak is elsewhere. There is a thick hose around the front that looks quite sticky.

 

[Doofer]

Well I hope it's not the radiator, having looked at eLearn. The air con system needs to be de-gassed and re-gassed to get to it. So that's a whole pile of cash for the mobile air con bloke then.

There seem to be a good few Vectra owners who've replaced radiators from a quick googling, so it is something very possible.

Has anyone changed a radiator? Is it not possible to somehow post it down the back of the air con condenser without disturbing it? This thing was designed by idiots! (GM).

If it's a huge job then I might be tempted to try bunging it up with Radweld (any thoughts?)

 

[Davren]

I've had a look at the header tank cap. Unfortunately it's a Vectra one, which is quite complex as it incorporates a pressure relief vent. Pics attached. There are two seals, with a vent pipe in the tank between the two. A spring-loaded valve allows excess pressure to vent into the space between the two seals, so out of the vent.

That's why I used an old brake fluid resevoir cap.

 

[DoIDon'tI]

Well I hope it's not the radiator, having looked at eLearn. The air con system needs to be de-gassed and re-gassed to get to it. So that's a whole pile of cash for the mobile air con bloke then.

There seem to be a good few Vectra owners who've replaced radiators from a quick googling, so it is something very possible.

Has anyone changed a radiator? Is it not possible to somehow post it down the back of the air con condenser without disturbing it? This thing was designed by idiots! (GM).

If it's a huge job then I might be tempted to try bunging it up with Radweld (any thoughts?)

Don't do the radweld thing if you plan on keeping the car.

The radiator comes out downwards, so the car has to be up in the air on ramps if possible. From what the vectra people say it's not that bad a job on manual gearbox cars, just a pain getting the aircon drained and refilled. On auto cars there is a cooler to deal with as well (well there is on mine, anyway). The radiator is a known weak spot but Vectra ones may fit, depending on model? Worth a google if you can find the part number etc.

Good luck, hope you get it sorted.

 

[bobbyblue]

I agree with everyone so far, pressure testing is the way to go. I had a difficult to find leak in my previous car and used a pressure test to find it. No one has yet mentioned to check there is no water in the sump, and although you said you recently had a new water pump, on my Croma my heater stopped working in the summer of last year, after several red herrings I finally tracked it down that the impeller had come adrift from the water pump spindle, it was one of those crappy plastic ones, there was also a lot of play in the spindle bearing and some small evidence of water leaking from there. The car had only done 46k miles. Best of luck.

 

[Radlet6]

I think I mentioned in another post that when searching for parts in Germany among the most common listed parts such as EGR valves, springs, alternators and water pumps are replacement radiators. I think I also questioned at the time if this meant this was another Croma part expected to fail.

However, the fitment of a new water pump and the loss of fluid is too much of a co-incidence. I would be looking there first and maybe the rad next.

 

[Doofer]

A huge thank you to all for the pointers.

I've spent most of today buggering about with the thing. I found that it doesn't leak a drop when parked, but drips (perhaps a drop every 5 secs) when running. I don't know whether it drips when cold and running, but it definitely does when hot and running.

I took the undertray off and found that it's dripping from right under where the timing belt is. I couldn't see into the timing belt / water pump itself though - I couldn't find a way of looking at it.

I took off the hatch inside the wheel arch, but could only see the accessory belt. I couldn't see anything after taking off the top timing belt cover.

So I reckon I'm pretty sure it's the water pump - either defective or not fitted properly. I will speak to the garage that changed the timing belt tomorrow.

Am I right in thinking that there is nothing else containing coolant around the same area?

 

[DoIDon'tI]

Am I right in thinking that there is nothing else containing coolant around the same area?

Yes, you are.

A dynamic leak would point to a failure of the water pump gland seal, or could be a static leak which only occurs when the system's pressurised.

Either way, the timing belt cover will have to come off for a look.

 

[s130]

I think the water pump is now the most probable cause.

For your info when I did the my cam belt and found I also need to replace a worn/sloppy/noisy waterpump the NEW pump came with a thin crushable metal gasket, similar in design to the crushable metal plate gasket on on the EGR valve.

I used the gasket provided but also, (with the help of the wife at the dining room table rotating the pump housing) placed a thin bead of silicon gasket sealant around the pump house flange. Then placed the gasket plate on top, and then placed another thin bead of sealant on the gasket. This was then all bolted back into place onto a cleaned engine face.

It could be that the garage just used the thin crushable on its own with any sealant. I was tempted to do this but decided that the sealant (if used sparingly) could not do any harm.

Anyway, good luck with the garage tomorrow.

 

[bobbyblue]

I think the water pump is now the most probable cause.

For your info when I did the my cam belt and found I also need to replace a worn/sloppy/noisy waterpump the NEW pump came with a thin crushable metal gasket, similar in design to the crushable metal plate gasket on on the EGR valve.

*Sorry Doofer, I didn't know if yours is a 16v or 8v, mine is the latter, whose pumps are sealed by an 'O' ring, I guess the 16v is a steel gasket?

 

[Doofer]

It's the 16v.

It's going in the garage tomorrow, so will hopefully all be well again. I'll update with what was wrong.

So hopefully my radiator's OK. I do dread it needing replacing though. I've already done the air con condenser, and that was a big deal. The fact that you have to pay someone to de-gas and recharge the air con probably means it's not worth DIYing. I'm pretty sure you're not allowed to release the gas into the air, so you have to pay someone to come out twice.

The biggest hassle was removing the front bumper. It shouldn't be a big deal, but the crappy philips head self-tappers were rusted seized (rusted solid, with no means of rotating them). I had to use a variety of heavy handed means to get them out. Now I've replaced them with stainless M6 hex head bolts and washers, into proper tapped spire clips (in place of the bits of bent metal that were there). After priming and body-coloured paint they look better than original. So at least I'll only need to touch up the paint on the bolt heads next time.

 

[Doofer]

All sorted now.

The new water pump itself was leaking, not the seal around it.

I always think the true test of customer service from a business is what happens when things do go wrong. Full marks to the garage in this case (Halfords Autocentre). They fitted a new water pump and replaced the timing belt again too, in case it had been contaminated by antifreeze. They also did another little job for nothing too, by way of apology.

 

[s130]

Great news doofer. Glad you got it sorted Ok.

One advantage of taking your pride and joy to a garage and getting them to:

1) source the parts themselves
2) do the work

Is that as you have found they fix stuff at their expense when things go wrong cover both parts and labour.

Supplying a garage with parts and asking them to do the work means that if your supplied parts fail withing the part warranty period then yes you can get replacement parts but you have to pay the garage for removal and fitting all over again.