10 replies to this topic

[lewBlew]

Hi everyone. My Mayfair's had this issue for a while but it's getting worse (maybe the weather?!).

 

Basically for the last year I've had to keep topping up the water every few weeks, but recently it's been every week. Anywhere between a cupful and a pint seems to disappear out of the overflow hose. I don't know why.

 

I don't think it's head gasket or another leak because the car runs fine, no loss in performance, economy, no leaky hoses, no overheating (although the temp gauge does rise to halfway when it's a pint down on water! top it up and it goes down again), no dodgy smoke out of the exhaust and no mayo on the oil cap.

 

Not sure whether it spits out the coolant when stood still after a run or when moving or both. I know it's the overflow pipe because the end of it's wet and the bracket under the radiator is usually damp.

 

Rad cap is new and the fit seems to be ok. Any ideas? Totally standard 998 setup.

[rally1380]

Have to noticed any wet patches under the car after a run??  Get the car hot and look for a leak (if there is one).  Could be a very slight leak from a hose clip, or gasket, or even the water pump might be leaking.

 

Is the carpet wet at all??  could be the heater matrix leaking?

 

Also the heater tap (should be on the cylinder head) can fail and leak.

 

Usually, a leak is easy to find as it will leave a tell tail sign of rusty looking water or coolant colour.

[lewBlew]

No leak inside the car (from what I can see) and no leak from the hoses. Both top and bottom rad hoses were replaced last year. I swear it's coming out of the overflow but why.....? I don't know.

[Teapot]

Huey had a similar problem recently which turned out to be a punctured bypass hose.

 

I thought at first it was bubbling out of the overflow but that was because when I first stopped to check, what was left of the water was boiling out. When I topped it up it would run all day, but it always took about a pint before the next trip.

 

If you've been topping up with just water there won't be any antifreeze in there by now, so refill with blue antifreeze mixture before winter sets in!

Edited by Teapot, 28 November 2013 - 10:57 PM.

[lewBlew]

Thanks for your reply but no, it's not the bypass hose. Used to go all the time when I put the fluted ones in there but now I have a Mini Spares armoured special!

 

I think it's the cap/overflow pipe. Hopefully not the radiator itself but can't rule it out yet. What a pain! Why does it boil over?

[Craig89]

I had what must have been a small pin hole in my rad that would only leak when it was hot (only notice it because I could hear the hiss). New rad sorted it, no more loss of coolant

[Stevie W]

Yes as Craig rightly says above...

 

Had a very annoying slow leak and couldn't trace it. I was losing water but from nowehere definite and couldn't really see any particular area where the water maybe coming from.

 

A friend of my Dads pressure tested the system with the engine off so all was quiet and there, at the bottom corner of the radiator, inside the cowling, was a very fine pinhole leak in the brazing where the bottom tank of the radiator was attached the to gills/fins.

 

A new rad later, water loss problem was gone, so definately worth a look in this area!!!

 

Cheers, Steve.

[Gremlin]

You may have a cracked head or broken head gasket, this would pressurise the system and cause the cap to blow.

[lewBlew]

Thanks, will check the rad first. I can imagine this could be the case.

[Joe555]

I used an old drink bottle to see if water was coming from the over flow.

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[lewBlew]

I used an old drink bottle to see if water was coming from the over flow.

 

Excellent idea, and a makeshift expansion tank