mattatk

Yes this has been covered lots of times....I am trying to narrow down my search process....

First start of day gives lots of white, sweet smelling mist/smoke. Pretty sure its coolant. Subsequent starts don't smoke but every now & then when i check the car whilst idling, there is a small amount of misting out the exhaust (is that normal?)

Coolant reservoir looks OK, I've changed the coolant cap, but there is still a slight leak somewhere in the bleeder area, as there is usually some misting on the boot lid above the coolant reservoir.

Fluid in the reservoir looks OK, possibly a bit murky, but there are a few small black plastic (?) flakes in the fluid (2-3mm in diameter).

Pump looks good from the outside & makes no unusual noises.

Apart from the obvious head gasket, how else could the coolant be getting into the exhaust?

Cheers,
Matt

Macster

A bit of 'mist' (water vapor) out the exhaust upon startup or shortly thereafter (as the engine/exhaust warm up) is normal.

Depending upon the ambient temp and humidity where you are the engine's exhaust might show a bit of water vapor at various times after startup.

Now that many areas are experiencing cooler temps this will be more common. (I have the last week or so caught some water vapor wafting around the back of my cars shortly after starting the engine... I let the engine idle a bit until the idle rpms drop to their near normal hot idle level.)

In the case of your car, the sweet smell of this vapor is not a good sign. As you observed and I have to agree this is almost certainly a coolant leak, likely a head gasket.

However, the coolant might be getting in the engine (combustion chamber(s)) via a crack in the head or even the block a cylinder has developed a crack. Some engines can develop a crack at the top of a cylinder -- the center cylinder is often it is said the one more likely to experience this but it makes no difference the situation is dire no matter which cylinder is involved -- which can grow and result in a 'D' shaped piece of cylinder wall coming free. Fatal engine failure almost always results when this happens.

If you want further proof you can send a bit of oil out for analysis. Any anti-freeze components in the oil... Also, you can pull the plugs and note any differences in their condition. A plug in a cylinder that is getting a dose/diet of coolant will probably be cleaner than the other plugs.

The coolant tank can have a slight crack that allows a bit of vapor to escape. Or it maybe the vent valve.

The dark plastic flakes in the coolant are probably from the water pump impeller. The factory water pump has a composite plastic impeller. The pump impeller can be suffering from material fatique or from the ravages of cavitation which can happen under some conditions.

Regardless of how the coolant is getting into the engine I'd not delay in getting this looked into. The engine needs professional attention is my take and the sooner the better. And I would avoid even starting the engine let alone driving the car any distance.

Sincerely,

Macster.

mattatk

Think I might be an automotive hypochondriac!! Took your sound advice, took the car to Nine Plus (Melbourne Australia), an excellent independent Porsche mechanic. They couldn't fault the car, no oil in coolant, or coolant in oil, they think it's most likely condensation as it's very moist where I live at the moment.
I'll change the water pump next chance & flush the coolant.
Thanks for your time & expertise Macster!!

Macster

Glad it turned out to be a false alarm. Do not delay on the water pump. If the material in the coolant is water pump impeller debris that may not be the all of it. The pump's impeller might be more degraded than you think or suspect.

When you remove the old water pump carefully note how much impeller material is gone and how much of what is suspected to be impeller material you find in the coolant you *carefully* drain into a large clean drain pan.

If there's a large amount of impeller material unaccounted for, it is in the coolant system somewhere. The cooling system needs to be back flushed to hopefully dislodge the pieces of impeller and flush them out of the system.

Catch the flush water so you can determine when you have the large majority of the impeller material accounted for.

After you get everything back together and the cooling system refilled as the engine idles and warm up check the hoses to/from the radiators to confirm hot coolant is flowing to and from the radiators. Carefully check oil/water heat exchanger to ensure coolant is flowing to and from this as well.

If you find a radiator cold or a hose to or from a radiator cool compared to the other side... this may be a sign some piece of impeller is interfering with coolant flow and this possibility needs to be addressed.

Sincerely,

Macster.

mattatk

Wow, yet again a very informative post. I've ordered the pump & will follow your advice & Pelican's procedure.
Thanks again Macster for your expertise & education.
Cheers

logray

In addition to Macster's great comments.

Certainly if the impeller is found to be in pieces, then the pieces need to be found or removed as suggested. In fact, a worldwide renown reputable M96 engine builder, Flat Six Innovations recommends engine dismantling in some extreme cases. But don't let that scare you as those are worst case scenarios, my H20 pumps impeller blades were 100% perfect after 75k miles of use.

PLEASE DO. Be sure to research how to properly fill and bleed the coolant system.

Air in the coolant system is not good.

The best way to fill is using a vacuum fill tool, such as the uview 55000.

However it can be refilled and bled properly using the bleeder valve and special varied rpm sequences.