996 Sudden Coolant Loss - Help!ip

[Billy_Whizzzz]

So.... exactly a week into my 996 ownership and on pretty much first drive I came back up our lane - inevitably watching temp gauge which started creeping up slowly - and as I reversed it into garage it dumped 4 litres coolant out out of the expansion tank cap onto the floor. The gauge hadn't reached 100 but presumably had overheated.

It's booked into a porsche specialist but not for another 10 days so I now have a miserable 10 days with a broken new toy. For what it's worth, I've filled it up with (genuine) coolant and am now expecting a £9k bill for a rebuild... Although I may break it if it is that as I'm not attached enough to 996s to want a £20k plus 996 in lieu of a 997.

Looking for any pointers as to how to tell if it something moderately un serious... how to tell if water pump or thermostat isn't working etc.. or who to tell if it is something much more serious.

And no, as it was a private sale I have absolutely no comeback, and I took the risk of buying privately with no warranty willingly!

Any help much appreciated... Many thanks

[edc]

Have you got the 04 part number cap? You're a bit doom and gloom it's probably just the expansion cap or the expansion tank has split. Neither are huge money.

[edc]

Fill it up, open the bleeder valve, run it up to temp and raise the revs a bit, let the fans come on and replace cap. Test it with a local spin round the block.

[Billy_Whizzzz]

That sounds better! Not sure what part number - will check. Expansion tank doesn't seem split though

[Trev450]

the updated cap has an 04 part number.

[GreigM]

edc said:

Have you got the 04 part number cap? You're a bit doom and gloom it's probably just the expansion cap or the expansion tank has split. Neither are huge money.

This. I've had a couple of M96 engines boil over with no long term damage. Its not unknown. Could be a number of issues from simple and cheap to expensive, but I'd be really surprised if the bill was anywhere near £9K.

When the temp was creeping up was the fan coming on? Could just be the cap, or a fan issue, or the front rads being blocked, or the thermostat jammed shut, or the the water pump giving up.

Take out the dipstick - if the oil looks nice and oily then there's probably no engine damage.

[Billy_Whizzzz]

It has FPSH so I'd have thought the cap was the 04 one - but going out now to check. New rads relatively recently. And the oil is fine. After filling it up again, ran the engine up to about 80 degrees, and then turned it off, and checked coolant - which was cool. So I guess could be thermostat, could be water pump - or, thinking about it, haven't heard fans so I guess could well be those...

[Billy_Whizzzz]

Should the fans behind the radiators be turning all the time? Because they don't seem to be turning. Just been out and started it and the fans were definitely not turning. Any thoughts what to check...?

And assume this IS the correct cap...?

Thanks again

[EGTE]

It only takes a hairline crack for the expansion tank to leak.....ask me how I know :-)

[Billy_Whizzzz]

EGTE - How do you know? (I'd actually like to know!)

For what is worth coolant was full before I set off and surely dumping 4 litres of coolant in 20 seconds couldn't happen through a hairline crack?

[Polome]

Billy_Whizzzz said:

Should the fans behind the radiators be turning all the time? Because they don't seem to be turning. Just been out and started it and the fans were definitely not turning. Any thoughts what to check...?

And assume this IS the correct cap...?

Thanks again

Easy check on fan function...start AC ...both fans should be heard and air flow felt at bumper inlets. If not could be ...low pressure switch in AC system ( to protect compressor ) but should not effect engine cooling....highly unlikely both fans to fail but this checks that fan motors work ...the switching is a separate matter. Good luck.

[318touring]

Billy_Whizzzz said:

And assume this IS the correct cap...?

Thanks again

Correct OLD cap. Replace it with the newer version with P/N ending in 04.

[rubystone]

Do check also that you don't have a leak from the rads in the front spoiler. They do corrode and the unions can leak. Sudden coolant loss is unlikely unless you've damagec them though.

[GreigM]

Billy_Whizzzz said:

Should the fans behind the radiators be turning all the time? Because they don't seem to be turning. Just been out and started it and the fans were definitely not turning. Any thoughts what to check...?

And assume this IS the correct cap...?

Thanks again

See the picture on the cap - thats just telling you what happens when you use that one.

Check the fuse for the fan also, but once you have the new cap and the coolant has been replenished it might all be fine.

[Billy_Whizzzz]

Ok - so I've found the off side radiator fan isn't working - or at least when I start the car, only the passenger side comes on when I turn the a/c on. I've booked it in for 10 days time to a specialist but I'd like to be able to use the car this week - is there a simple mod to test/bypass the resistor/relay on the fan and get it to run all the time (assuming it works!)

[thegoose]

The temperature gauge isn't all that accurate and it's actually damped down at the upper end (i.e. at a real 100 degrees it will read 90, or whatever). For a more accurate reading use the climate control display for the "secret" readings it can give.

Print out the relevant post from this thread:
http://www.pistonheads.com/gassing/topic.asp?t=647...

I had an issue with my 996 3.4 where from the gauge it looked like it was running rather hot when driven hard, despite recent water pump, low temp thermostat, healthy radiators, mesh grille on bumper etc (all routine stuff done previously, not fault-chasing). Mike at Sports and Classic spent a bit of time working out what was going on and concluded that my gauge was reading higher than they normally do (he tried another cluster and it read lower), although in reality it means it gives a more accurate reading once passed the middle than these cars normally do (verified by comparing the climate display 6c data). When I sat on tick over after a spirited drive one night I noted that it gets to I think 108 before the fans cut in, they cut out again at 106 and it continues down to 105, then goes back up again.

I'd agree with the other advice too, new cap (£10-15) immediately, refill coolant and ensure it's properly bled, then run and drive it, making use of the more accurate data from the climate display. With any luck you may find yourself cancelling the appointment you have with the specialist.

[Billy_Whizzzz]

Thanks for all help and being able to see actual temperature is very useful on the heater unit display.

Just been out for about 10 miles - it settled around 88-90 at 60mph or so and then when I came back up the lane - 1/2 mile crawl in first - the temp gradually climbed to 95 before I got back and switched it off. Only one of the fans is working - so I know that needs looking at, and hoping to find a fix where I can run the fan constantly. But so far, the oil and coolant looks ok so fingers crossed.

How hot should the coolant get and how hot is dangerous? I'd always assumed 100 degrees C it would boil over so 95 makes me a little anxious but reading the posits above it seems that >100 is normal.

[Billy_Whizzzz]

anonymous said:

[redacted]

Mine was registered 03/2001 and works

[Polome]

Billy_Whizzzz said:

Ok - so I've found the off side radiator fan isn't working - or at least when I start the car, only the passenger side comes on when I turn the a/c on. I've booked it in for 10 days time to a specialist but I'd like to be able to use the car this week - is there a simple mod to test/bypass the resistor/relay on the fan and get it to run all the time (assuming it works!)

Just leave AC running ,your single fan should be able to control normal engine temps ok. If stuck in traffic turn engine off to help control temp..ps ballast resistor is very common fault with fans not running , easy to jumper around to test it's function...located behind rad at bottom so accessible from underneath. Regards.

[BertBert]

Billy_Whizzzz said:

Thanks for all help and being able to see actual temperature is very useful on the heater unit display.

Just been out for about 10 miles - it settled around 88-90 at 60mph or so and then when I came back up the lane - 1/2 mile crawl in first - the temp gradually climbed to 95 before I got back and switched it off. Only one of the fans is working - so I know that needs looking at, and hoping to find a fix where I can run the fan constantly. But so far, the oil and coolant looks ok so fingers crossed.

How hot should the coolant get and how hot is dangerous? I'd always assumed 100 degrees C it would boil over so 95 makes me a little anxious but reading the posits above it seems that >100 is normal.

If the system is pressurising properly then it can go quite a long way above 100 before boiling (maybe 125), However if it is not pressurised (because of the cap) then it will boil lower and piss coolant out!

If it were me, I'd do the test you did, but leave it idling longer when you come back. Does the temp still go up? Or does it settle? If it keeps going up then you def have a problem. Might be the fan (although I'd possibly expect one fan to cope with the drive you just described) or might be something else. What happens at higher temps? Does coolant come out again?

I'd let the indicated temp get over 100, but if it's still going up, not much more.

Bert