Don.

So today was a fairly hot day and I've been driving around with the A/C on. After work, I leave my house to go on an errand and a couple blocks later, the ! warning light goes on, and the red area in the temperature gauge lights up. The needle is not in the red, its just creeping over the second white mark. As I come to a stop to make a U-turn white smoke is rising from the passenger side of the hood. There is also a fairly loud rhythmic pumping sound coming from the right side of the car. After I park in front of the house and shut off the engine, the pumping sound continues, even after I lift up the hood. There seems to be coolant gushing up somewhere over onto the the cover that goes over the airbox and the heater box. Its mostly on the passenger side.

I needed to get somewhere so I left the car there and took off in my other car. When I got back I tried to find where the coolant was coming from, but didn't find a hose near where I thought the gushing was happening. I did find a expansion tank overflow hose that looked suspiciously wet. So my questions are:

1) Is the expansion tank overflow hose normally routed through the firewall to the airbox? It looks like theres a hole for it. Did the force of the coolant push it to the other side? If it isn't the overflow hose, I'm perplexed.

2) If I can't find any busted hoses I plan to:
a) Replace radiator cap, fill, check.
b) if still overheating, replace thermostat, fill, check
c) if still overheating, deal with water pump
Could the problem just be #a above? Or is this just wishful thinking? Does this sequence seem reasonable?

3) Why did the ! warning go on when the temperature was only over the second white line?

Thanks,
Don

MikeN

Sounds more like a bad heater valve/associated hose. Carefully check these items for the leak(s)........they are all located on the passengers side below the air filter housing.

185318

Don,

I've worked on cooling problems all summer on my S4. What I would do before you replace anything is bring the fluids up to proper levels and run the car to operating temps, and then see exactly where the leaking water is coming from. Could be a simple hose replacement. On my car, the drain hose from the coolant tank is routed straight down through the engine bay and goes out to the ground. I don't know if this is the way it was originally or not.
I have 2 cooling fans and they HAVE to be working correctly. Check your fan operation. The temp gauge on my car does the same thing. The red light will come on before the needle reaches the top mark, but I don't rely on the gauge as being very accurate, but I know when the red light comes on it's time to check things out.
All I can reccomend is not to start replacing parts unless your fairly certain the parts need to be replaced, ie;water pump.
Let us know what you find....

DG84S

I suppose that you could lose enough coolant that your temp sensor is in an air bubble and understating the actual temp of what little coolant is remaining. Fill the system with water, remove the airbox and start the car. You should see the source of your leak almost immediately. It sounds like a heater supply hose to me.

BarryW

There's a pressure switch in a small hose running along the passenger side fender. On mine, it's about halfway between the radiator and the tank. It may have failed or the hose came off, turning the warning light on.

Don.

I guess I need to do a little more diagnosis before I go replacing stuff. If the overflow hose is routed straight down, I'm not sure where the coolant was coming from. Thanks for all the suggestions! Perhaps I should have done more sleuthing before I posting, but the loud and sudden nature of this problem alarmed me. For a second I thought the engine was eating itself alive!

-Don

John Struthers

Don,
Pattycakes did the same two years ago at the shARKANSAS (SITO) event.
I had a normal heat indication -at or below the 1st white line.
Brett -OHIO- driving Rosie flashed his lights several times behind me so I scanned the gauges, all normal.
He continued to flash his lights so I pulled over, while doing so my Temp warn for H2O came on and the needle pegged instantly.
I went to neutral and shut the engine down before stopping.
The coolant was indeed blowing out of the overflow -pass.side fenderwell-.
I always carry a ton of "STUFF" with me, so while Pattycakes was cooling down, Dave-Pittsburgh- rigged a jumper for the fan which checked out O.K.
I then refilled with coolant and distilled water -STUFF I carry- after a 40 minute cool down. Started back -up and within 2 minutes she overheated again at idle.
Brett went down the hill and into the woods for some 'creek water', which we filtered with a chamois cloth- STUFF- into the empty coolant/water containers. Brett went for sHARk Group assistance while we pulled the thermostat -we managed to save the gasket.
As the 928 won't function -and will leak- without the thermostat- we decided to drill few holes in the puppy to insure adequate bypass even while it was in the closed position. Dave talked a passerby -LlOYD- into carrying us around rural Arkansas to find a drill and 8 miles latter a drill bit to accomplish our mission.
As we re-assembled the coolant system the thermostat came apart in three pieces -assembly tabs broke off- . I put it loosely back together and used the thermostat housing and bolts to hold it together for assembly.
It worked fine for over a year.
As to the LATE WARN; Dennis -Oklahoma-, and or Jay- Arkansas- figured that the temp sensor is located on the "far side " of the bypass and will not register till the thermostat opens up.
Aye, there's the rub...
When the temp got out of hand due froze thermostat the closed loop block coolant started turning into steam.
When the 'gas pressure' finally forced the thermostat to a partial bypass the sensor 'FINALLY' get's the overheated water/steam and the warn comes on as the temp gauge spikes. Ain't that a giggle!
Some of the above sounds like good advice, but I'd do the thermostat first as it's cheap, and at least on the early models a 10/15 minute job. then check for pinholes in your hoses.
I hope you are as lucky as I was, with no coolant forced into the block due to weak head gaskets.
HTH

Don.

Just thought I'd post an update: Put in a 75C thermostat and the car runs cool. On a hot day in traffic with the A/C on the needle struggles to get a hair above the first white mark. If this keeps up, I may consider switching to a lower viscosity oil than the 20W50 I have in there. The oil pressure now never gets below "4" at idle. I've run the car for about a week and there are no apparent leaks. For all I know, my temp scale may be off, so from now on I'll just assume the second white mark is the "line of death" for the shark. The radiator cap did its job, so its probably OK, but I replaced it anyway. I've had cars overheat, but this is the first car I've had that overheated with no warning in such a dramatic fashion. I'm just glad there was a simple solution!

Thanks for all the help,
Don