996.1 Coolant Dump Issue

[Skippy]

Hi have had a recurring issue now with my 996.1 loosing coolant and in this latest occurrence, dumping all the coolant after a 20 minute drive after I switched the car off, not at traffic lights however coolant leak were noted at the lights).  The strange thing is that that the engine temperature gauge was normal at 12 o'clock on the dial when this happened. It looks like the pressure was just so great that it bypassed the coolant cap and pissed all the coolant out (second time this has done this).   Over the past three months I have had the water pump, oil separator, heat exchange, and engine fully rebuilt so I thought that I'd be driving a car near perfect but apparently not.   Does anyone have any thoughts on this matter, experience with the same issue, and possible solutions to fix this? Thanks a million!

 

[Stephen Tinker]

It sounds like you have air pockets in the system. Try this..

1) Next to the coolant tank there is the expansion bleed valve - its black with a hinged silver D shaped lever on the top - lift this lever to its vertical position.

2) Refill your coolant tank to its max level with the correct 50/50 mix.

3) Drive the car for at least 5 km to get the coolant up to temp and the thermostat open.

4) Let the system cool completely - preferably overnight. You should see the level drop in the tank. Top up and repeat until the level stabilises.

You can drive with the D shaped bleed valve open for a few heat cycles to eliminate the air pockets. The secret is to get the thermostat open and then let the system cool completely - this may take several operations depending on how much air you have in the system.

[Skippy]

Hey thanks Stephen, I'll give that a go and report back, cheers!

[firstone]

Pelican parts have a how to.

[Zelrik911]

Check this tip on water hoses rubbing & getting holes - from UK site:

http://www.911uk.com/viewtopic.php?t=42060&highlight=pipe

Cure is to install a 997 hose which has a better curve. It may not be your problem, but its worth checking for clearance anyway.

 

[Fraz]

There was a few guys on the 996 turbo page having the same issue, one replaced his radiator cap and fixed it the other replaced the whole overflow bottle and cap, apparently the overflow bottle are prone to splitting.

 

[Merv]

A not uncommon issue on the 996/986

[TwoHeadsTas]

1 hour ago, Fraz said:

There was a few guys on the 996 turbo page having the same issue, one replaced his radiator cap and fixed it the other replaced the whole overflow bottle and cap, apparently the overflow bottle are prone to splitting.

 

Am just about to replace the coolant overflow tank on my 996, as they do get brittle with age and sunlight apparently.  I haven't had any problems with leakage or overheating, but has been recommended to me as a good precautionary measure.

[GT3]

Mine was a hole in the 996.1 overflow tank. Kept loosing coolant. cost a bit to have this replaced by dealer.

[Ozvino]

I have seen coolant leak issues in my 996 and 991 - in both cases it was a pinhole crack in the plastic tank. The blue tank cap is also a known issue on the 996/7/1

[firstone]

When I did the 986 bottle the dealer wanted $750 for the bottle. I can't recall which USA supplier I bought from but it was $222 delivered. I bought extension/remote hose clamp pliers for $100 and did the job myself.

Just to add you need these pliers to do the AOS as well.

Edited to the correct name of the pliers.

[TwoHeadsTas]

 

3 hours ago, firstone said:

When I did the 986 bottle the dealer wanted $750 for the bottle. I can't recall which USA supplier I bought from but it was $222 delivered. I bought extension hose clamp pliers for $100 and did the job myself.

Just to add you need these pliers to do the AOS as well.

Bit more expensive now, particularly with the +10% GST on imports now.  AH price was not far off the EuroFCP / Pelican price, so am about to order from them.  @firstonecan you tell me more about the hose clamp pliers needed for DIY?

[firstone]

They have a cable approximately 900mm long with the jaws on the end. I think there is a picture on the pelican parts site.

Total tools had them ATT.

[TwoHeadsTas]

1 hour ago, firstone said:

They have a cable approximately 900mm long with the jaws on the end. I think there is a picture on the pelican parts site.

Total tools had them ATT.

Ok, presume this is required because a couple of the clamps are hard to get to?

[firstone]

Impossible is a better description.  ?

You'll be glad to have them. They have a ratchet on the grip to hold the clamp once you have it. 

[firstone]

If you'd like a pic PM me your number.

 

[dan_189]

Diagnostic steps are usually:

- Pressurise system + find leak

- Drain coolant + fix leak

- Vacuum re-fill (best way to go and ensures no air gets trapped in the system)  

I had my coolant bottle replaced on my 996 - had a pinhole leak from a tiny split in the seam. I'd recommend a genuine tank as well, have read a lot on rennlist about failed aftermarket ones. 

[Skippy]

Ok, so I got my car back from my mechanic and it seemed like the main problem was that the coolant wasn't flowing through the radiator - caused by some blockage.

I replaced the radiator with Porsche Centre Perth about two months ago so don't know why they were blocked.

So he took them off, ran a mixture to unclog them, put them back on, made sure to run the air pockets out, drove the car long and hard over two days, problem fixed. Got it back today and so far so good.