patou55

if the temperature is normal, can we have compression gas in cooling system. What else could it be. What tests should be done before removing motors and checking for cracks in cylinder head or worth.

Bought a 996 recently on Ebay that has been a real nightmare. Drove it 1 day from Las Vegas to Monterrey. Smell of coolant. Temperature high around 200+, but no lights warning. Oil pressure OK, but less than 1 at iddle in traffic. Next day a lot of steam coming out of the motor bay. Stopped the car on the highway. Had it towed.

After close to $4000 bills (spark plugs, water pump...), the car was shipped to Canada. The car was supposed to be OK. Upon reception, car smoked like crazy (same as pictures on you tube of intermix). Oil separator changed (around $1500). Left the Porsche repair shops, but coolant hose broke within 10 mn. ($500 to repair). All that to be told that compression gas inside the cooling system, coolant hose expansion and that I will need a new motor or at best cylinder heads.

Yesterday, I decided to drive the car 3 hours (first time since California). Temperature between the 8 and the 0 of the 180, but 1 inch of coolant disappear from coolant expansion tank. All coolant went back in the reservoir overnight.

Is it possible that more coolant is in the cooling system, especially in the block when hot and return to the expansion tank when the car is not running? I would have thought the opposite.

Thanks for your help before I spend another $15000.

318touring

Would be useful to know the year of the car, model, mileage, trans. type.

patou55

Porsche 996 cabriolet 2001 with 106,000 miles.

patou55

tiptronic transmission

Macster

These engines have been known to crack a head. Depending upon where the crack is this can result in "compression gas inside cooling system".

But I take it no CEL thus no misfire (or any other) error codes?

That doesn't really read like a cracked head or a severely compromised engine cooling system.

If the coolant level drops then returns to normal this is kind of weird but if the cooling system is not properly filled with coolant, if there are air pockets, strange things can happen.

One has to I guess prepare for the worst and hope for the best. I guess what I'd do would be to collect a good oil sample and have the oil analyzed for presence of (among other things) anti-freeze compounds. If these turn up in the oil then this is a pretty good sign there's a real problem.

At the same time I'd look for signs of oil in the coolant. Dark globules of oil in the coolant in the tank is one place to look.

You are going to probably have to enlist the help/expertise of a reputable and experienced Porsche tech.

When the water pump was replaced, was the old water pump intact? Did it have all its impellers?

Are you smelling antifreeze odor from the car when hot? Sniff the engine bay with the engine compartment lid open but give a sniff around the front of the car, around the radiators.

While I am reluctant to advise you to drive the car it is up to you (and you probably should consult with a tech in your area first). If you can drive the car then drive the car and with the A/C off get the engine and everything up to temperature. Then back at your house raise RPMs to say 1200 and hold until you or a helper hears the radiator fans come on. Be sure both are running and blowing the same amount of hot air, too.

Then shut off the engine. The heat load will raise the coolant temperature and pressure and if there is a weak hose, coolant tank, cap, radiator, whatever, the odds are it will make itself known with a leak. Careful. The leak can be a gusher and it will spew hot coolant.

patou55

There are no coolant in the oil. No oil in the coolant.

Thanks for your response. If the temperature is OK, can I still have an engine failure?

I used to smell coolant. I think i still do a little bit just behind the driver's seat. However with all the coolant that may have dropped on the motor, i am not sure of it or if it could be a small leak.

Re the air pocket, i think it could be possible as on a 996 it is difficult to remove them. Because of the hose leak, i had to pour 4 gallons. Although the Porsche mechanic most likely had to remove it to change the hose, may be they did not bleed the system properly.

What test can we do to check if the head gaskets are blown?

fpb111

If the air pocket is not too large you can "burp" the system yourself. With the engine cold. Remove the blue coolant cap (part number should end in 04, if not get a new one) and fill the reservoir to about 1/2 way between the min-max lines.
Snap the metal bale up (on the black cap) drive with varying RPM until the car is fully warm ~180. Park the car and let it cool, overnight is best. Make sure that it is still at least 1/2 full or more refill to 1/2 if needed. Snap the cap down and drive it until it is warm again. Let it cool and check the coolant level, refill to 1/2 way again if needed. If you fill the coolant to MAX when it is cold it will push coolant out as it expands when it gets hot. If the coolant does not settle at just above the min line when cold or right at the MAX when hot you can "burp" it again.

patou55

Water pump was touching the case but no broken part. No metal in the oil.

Re the metal pin on the expansion tank. Something looks strange. I can put it up, however, it does not seem to do anything as the metal seems loose, there is no resistance nor pressure to bring it up.

I should think it should lift something (the black square that is attached to it) . When I put the pin down, it just flop down. There is no feeling of either closing or opening something. It just look like a pin attached on the expansion tank.

is this normal? That garage in Canada did install that new expansion tank ( I do not know why) and the oil separator.

I put the car on a hill ( motor down) fill up the extension tank. Let the motor run for 15mn. Top the expansion tank up on a flat surface, then drove the car for 20 mn with pin up. Parked it top it up again.

That pin seems loose. How it should feel?

mattie_k

After a drive and the car stabilizing at operating temp, the burp valve is forced up and open. The hoop will seem loose and floppy, this is normal.
When it's warm can you push the black square post the loop is attached to down a few mm and feel resistance?

patou55

Thanks
I will try tomorrow.

Does that mean that all the time, the burp valve was up and opened and that if there was combustion gas in the coolant, the temperature will not go past 180. In that case, could I have still a cracked head?

johnireland

What about just bleeding the cooling system completely and then refilling it from scratch. With all the stuff going on, I would want to make sure the system has been properly filled with the right amount of fluids.

patou55

I think it is a good idea.

Barn996

Constant coolant smell might also be a crack in the coolant tank. Look for dry residue under the area of the tank.

Imo000

It's not a good idea. Park the car nose down and jack it up until the bottom of the front bumper almost touches the ground. Then open the talk and start the engine. Turn the heat up and let it run for a while. Once the coolant start to drop, slowly top it up. At some point the coolant will stabilize. Close the tank and open the pop off valve. Lower the car and go for a drive. After the drive have a look at the tank. If it needs coolant, add some, otherwise close the pop off valve. I call it a pop off valve but I'm sure the Porsche name is something else.

fpb111

The bail opens a vacuum break it does not open the tank/system to atmosphere while it is hot.
The bail opens a vacuum break it does not open the tank/system to atmosphere while it is hot.
The bail opens a vacuum break it does not open the tank/system to atmosphere while it is hot.
It breaks the vacuum to allow air to escape to the tank as the system cools.

The blue cap pressure valve allows air and coolant to escape as the system warms up creating pressure.

Before you pull the engine apart for air in the system why not bleed it correctly as Imo00 and others have suggested? EDIT: Post 8 reads like you did. How is the level now? It reads like you had the engine down hill? Turn the car around so the engine is uphill. You want the engine and tank higher then the rest of the car.
Use one of these:
http://www.tooltopia.com/uview-55000...Fajm7AodokcAXQ