Very slow radiator leak ... advice?

[Chris]

Vauxhall Zafira, 1.9 litre diesel ... has a very slow coolant leak, by which I mean it has just taken a month or so for the fluid level to drop a little over an inch, from the line where it should be to the bottom of the reservoir.

Dealer pressure-tested the system during its service last month and couldn't identify a leak at all. So ... I have heard of stuff you can put in the reservoir that plugs small leaks. Can anyone recommend this approach or should I be trying something else?

[Osem]

Could it be this?

http://www.vauxhallownersnetwork.co....nt-leak/page2&

Best of luck.

[Gary L]

You can cause more problems by adding 'leak' stuff to the system.
it doesn't sound that bad the amount you've lost. someone I know has a Zafira petrol and he has a slight loss. supposed to be a common thing them leaking at the bottom of the rad where it mounts.

[Chris]

Oddly enough it was in for a recall as well as the service, and they did something to the mounting that was supposed to prevent potential coolant leaks. But in my case it made no difference ...

[alferret]

Originally Posted by Chris

Can anyone recommend this approach or should I be trying something else?

Try Bar's Leak http://www.barsproducts.com/barsleaks_products.htm

Or

RadWeld http://www.halfords.com/webapp/wcs/s...egoryId_255217

Used both of these with header tanks & raw eggs with older normal radiators.

[raging bull]

The downside of using things like Radweld is it blocks the fine holes in heater matrix.
Use with caution or could end up driving with less heat from heater!
(Vauxhall driver for 30 years)

[martyh]

Originally Posted by Chris

Oddly enough it was in for a recall as well as the service, and they did something to the mounting that was supposed to prevent potential coolant leaks. But in my case it made no difference ...

are you sure it's the rad that's leaking and not the water pump .sometimes the pump will leak but only when doing speed and not on tick over because of the lack of pressure my van has such a leak and only leaks a very small amount at about 50mph

[AbyssUnderground]

Mine does this (Peugeot 306) but it has a breather/overflow pipe on it which releases high pressure. This allows steam to escape very slowly at that same rate (1 inch a month or so). To be honest I wouldn't worry about it unless it gets any worse.

As stated, radweld can make things worse in other parts of the system and should be used as a last resort only.

[heero_yuy]

Try a new pressure cap? If they let the pressure get too low then some coolant can boil off and vent out of the cap as steam leaving little trace.

[alferret]

Originally Posted by AbyssUnderground

Mine does this (Peugeot 306) but it has a breather/overflow pipe on it which releases high pressure. This allows steam to escape very slowly at that same rate (1 inch a month or so). To be honest I wouldn't worry about it unless it gets any worse.

As stated, radweld can make things worse in other parts of the system and should be used as a last resort only.

Had my 306 for 2 years now (around 20k) & aside from topping up when I replaced the thermostat I hasnt used a drop of fluid. Mind you I might have to check tomorrow as it doesnt seem to be getting up to temp (85c) as it did when I last checked. Seems to be running a little cold, around 77-78 I guess, could be a fluid issue.

[AbyssUnderground]

Diesel turbo? 78 is fine. Mine sits there when it's cold outside, maybe 80-82 on the motorway.

Either that or the thermostat is stuck.

Anyway back to the issue, mine doesn't lose much and it's just what evaporates that I lose. It's probably less than an inch a month really.

[alferret]

Originally Posted by AbyssUnderground

Diesel turbo? 78 is fine. Mine sits there when it's cold outside, maybe 80-82 on the motorway.

Either that or the thermostat is stuck.

Yea a 98 D'tub, will get round to checking water @ the weekend. Replaced thermostat just after I got it due to low temps.