58 replies to this topic

[Chinna]

Hi all
My 998 city is losing water.
I noticed that the radiator cap was leaking. So I got a new one and topped up with water. The radiator holds water overnight. but still loses water when driving. What else should I look for ?

Thanks

[Jordie]

Could be anything.

Physical leak from hose etc
Engine too hot (timing fueling etc)
Headgasket

Pressure tester will show up any external leaks which is where id check first.

[sledgehammer]

you may have a leak , but also -

 

The rad water level is normally a bit lower than the cap neck (so it may look like some has leaked)

 

so if the rad is brimmed, it will stay that way when engine is not in use

 

when the engine is run the water expands , & usually pushes out the overflow , it eventually stays at that level when hot

 

when cool the level drops & air is let into the system , this is the normal cold level - a long as the level is approx 1/2 to 3/4 inch above the cores it shouldn't be a problem

 

cars with an expansion tank will have a rad brimmed all the time - & the expansion is in the expansion tank

 

(hope the above makes sense) (also I have not measured the water level above the cores - 1/2 to 3/4 inch is a guess)

Edited by sledgehammer, 30 September 2015 - 10:34 PM.

[Chinna]

Jordie, sledgehammer thank you for your response.
When I say leak,The radiator is actually nearly empty.also there is bit of water under the radiator.
Pressure testing is a good idea. Would any normal garage do it ?

If it is the radiator Would a used radiator do the job or would you recommend a new aluminium one ?

[Aaran13]

Hi Chinna,

I can't comment on the pressure testing but to your question re. new radiator:

Yes, a used one would work fine after a decent flush through BUT you obviously take the risk it has a hole in it...

As for a new aluminium one, assuming you are talking about a two core unit, this is probably more cooling than you need in a 998. Even with a reasonable level of tuning the standard rad should be fine. This one from minispares will do the job:

http://www.minispare...px|Back to shop

It's also a fair amount cheaper than a 2 core aluminium one so perhaps consider changing the water pump, bypass hose and thermostat. You'll still be spending less but then have nicely refreshed cooling system!

Hope that helps

[Chinna]

Aaran13: Thank you for your advice. £57 is not a lot for a new rad ! Should I go for silicone hoses ?

 

When you say "More cooling than needed" is that going to keep my engine too cool that it is going to be detrimental to the engine ? Apologies if my question is a bit daft ! it is sheer lack of knowledge ;)

Edited by Chinna, 01 October 2015 - 07:46 AM.

[Aaran13]

Personal preference on the hoses. I think the main advantage is they last longer (plus the opportunity to make the engine bay more appealing to the eye).

Good question re engine temp. I wouldn't be confident commenting so hopefully someone else will come along for that. All I meant was that the standard radiator has plenty of cooling capability for your engine if it is a near standard 998 and you maintain the cooling system well (hence thermostat and water pump suggestions). If you have a bypass hose, make sure you get a Kevlar or Silicone replacement, not one of the ones with ridges in. They don't last. Minispares sell kits with those in

[Mini Manannán]

A pressure test on the rad is simple enought o set up, all you need is an airline and find some kind of bung to block the rad cap and pump air in.  Spray some kind of soapy water about until you find bubbles.

[Blatherskite]

Are you sure its the radiator that leaks? What about:
Cap doesn't seal properly any more
Leak in one of many hoses
Leak from water pump seals
Leak from cabin heater valve

Any one of these means a radiator change is a waste of time & money.

I suggest you look carefully around the engine bay for areas that look steam-cleaned, and with the engine running & at temperature for steam / water leak. Mind you don't get caught in the fan, though.

[Chinna]

Are you sure its the radiator that leaks? What about:
Cap doesn't seal properly any more
Leak in one of many hoses
Leak from water pump seals
Leak from cabin heater valve

Any one of these means a radiator change is a waste of time & money.

I suggest you look carefully around the engine bay for areas that look steam-cleaned, and with the engine running & at temperature for steam / water leak. Mind you don't get caught in the fan, though.

 

Blatherskite: That's fantastic advise. Trouble is, I can't seem to track it down visually. I've tried taking the front grille off and checking, but in vain.

 

Can doesn't seal properly anymore - True, even though it is a new cap, it might still be faulty. But, how do i check this ?

Leak in one of many hoses  - Again, any tips on figuring out how to check ?
Leak from water pump seals  - Good point. Again, i assume this is under the radiator. So, any ideas how to check ?
Leak from cabin heater valve -  I wouldn't know where to check for this. I will google this.

 

Thank you for your advice once again.

[Mini Manannán]

 

 

Leak from water pump seals  - Good point. Again, i assume this is under the radiator. So, any ideas how to check ?
Leak from cabin heater valve -  I wouldn't know where to check for this. I will google this.

 

 

 

 

Yellow is the water pump pulley, it is directly connected to the fan.

Green is the heater valve.  It is a known problem, lots of dodgy versions about, many people (myself inc.) have replaced it with this: http://www.dsnclassi...ngled-1-2-hose/  Pros: it will never fail. Cons: you can't turn off the water movement through the heater.

 

I'm not sure how you check a rad cap, but, like you can do for oil leaks, with the water leak, you could put some UV dye in the water and check it out in the dark with a UV light

[Blatherskite]

If you have antifreeze in the water, it will often dry as a bluey-white deposit where it got wet. You might see some of that from the overflow pipe at the cap. Also, look for where its unusually clean (at least, on our car) where its been steam cleaned by the leak...

Not sure where you live, but leaks here in Norway can usually be tracked by the vapour trail in the cool air. This spring, solved the Landy leak that way (rad & pump at the same time - nuts!)

[Blatherskite]

 
 [/quote]
 

 
So clean... So jealous!

Edited by Blatherskite, 01 October 2015 - 05:23 PM.

[Mini Manannán]

 
 [/quote]
 

 
So clean... So jealous!

 

It's seen a lot of everyday miles since then, it's not quite so nice now

[maximas]

Get it nice and hot...leave it running for a while then check underneath for water...if it's loosing that amount of water maybe you can easily see it...