Coolant combustion
 

Does coolant combustion always mean you'll need a "new engine?" I have had a gradually increasing coolant loss for a while now. I had it looked at twice with no diagnosis. Then 2 months ago, at a dealer clinic, we spotted a small external leak. The dealer replaced the coolant reservoir & a hose. That did not stop the loss. They found oil in the coolant but no coolant in the oil and flushed the whole system. They also pulled the plugs and found no problems with the head or combustions chambers. Yet, coolant needs to be topped off once per week. I occasionally (once every 2-3 weeks) get a puff of white smoke on start up or under WOT near redline.

There is never coolant on the ground or garage. I have never had the temp creep above the mid-range. I try to use the official pink coolant to top it off rather than water. The dealer said that if it's not leaking outside, and they checked the oil (and changed it) a couple of times then it is somehow getting into a combustion chamber and being burned off. There's really nothing they can do except wait for the problem to become more noticeable (I am not losing power) or wait for something to break. To do a teardown to look for the cause would be cost prohibitive (their words.) Is this some type of porous block? Is it possible that the engine has worn a hole in itself and is allowing oil & coolant to mix? Any thoughts or suggestions would be appreciated. I prefer not to be stranded or left with a dead car. I do have an aftermarket warranty but I would rather catch this than be forced to rely on their mercy.

2001 Boxster S
No mods
58,000 miles
Always serviced by dealer or P specialist.

My guess is the head gasket is going. Simple yet expensive to fix it. You will spend lots in labor costs, and a lot of "while we are in there".
IIRC there is a test that can be done for a head gasket failure. If it is the heads, I would sell the car while it is still running.

Oddly enough, they said they're getting no leaks at the gasket...

Small cracks in the heads are not that uncommon, unfortunately. They can be fixed by a head specialist, though the longevity of that repair may be somewhat questionable (depending upon who you ask).

Unfortunately, short of tearing the motor down, this is likely to be difficult to find.

I had a diesel smart car that was losing coolant in similar fashion. No coolant in the oil, no puddles underneath.

What was happening in that car was that the thermostat was sticking. The coolant pressure built before it opened and would force steam out through the head gasket.

It was a bugger to diagnose. Never seemed to happen when mechanics had it. Eventually resulted in needing a new cylinder head (under warranty, thank god).

Did you figure this out? I'm seeing more and more oil heat exchangers cracking and failing. Easy fix and relatively cheap part (under $200 and under 2 hours to change it out)


B

If you're constantly refilling, you should once in a while throw in some distilled water instead of solely just the pink coolant. The mixture should be maintained near 50/50 of coolant and water.

We are as well, and mostly on older cars that still have the original "green" Porsche coolant in them. Not positive there is a valid statistical relationship, but we have seen too many for it to be a total coincidence.............

Cool. Thanks for the data point!!

People who live up north.. I do NOT recommend the 50/50 mix. Live in the south? Never see temps below 50deg? run 50/50 :)



B

Why? We only run 50/50 Porsche coolant/distilled water (customer cars and our own), get freeze point test in the -40 to -45 F range; and we see ambient temps well below zero here, and have never had a problem...................

Porsche has been giving me the coolant from their stash & it's a 50/50 mix of pink & distilled water. They told me not to dilute it. We tested the oil cooler & it was fine. The service manager thinks it could be a cracked head, but will require a teardown to be sure. I'm going to have another indy shop run a leak down test & see what they can find. Since this is a problem that should be getting worse, not better, my thought is that it will eventually be diagnosed.

Soooooo... I received the milkshake of death in my coolant reservoir... looks like a new flavor from Ben & Jerry's...


Last Tuesday, driving along & the coolant light starts blinking, but when I pull over, the level seems fine. Of course it was too hot to really check it out, so I waited about 2 hours and saw the milkshake in a near empty reservoir. I topped it off with the 50/50 mixture and drove home.

Wednesday, after only driving about 2 miles, the temp gauge started to rise - not past 200 but close to it. The fans were all blowing but oddly enough the coolant light was not flashing. I tried to turn on the heater but it didn't really help. About 1 block before my destination, I hear a hissing, then as soon as I turn the corner "BOOM". The idle was still fine and the engine was still running, but when I backed into the spot I could see that the car dumped all of it's coolant in the street. So the BOOM was a coolant breach, not a blown motor as I initially thought. It started fine the next day. I had it towed to the dealership & will post when I hear what they have to say. I'm hoping that this breach will be noticeable. When I had them perform a leak down test in April for the the disappearing coolant, they couldn't come up with anything.


Wish me luck :(

Sounds like a classic cracked head/ cracked cylinder to me.. I'd bet its the head based on the symptoms.
I just finished repairing one of these, its hot on the dyno right now... Made 247@the wheels! (3.2)

How did you get 247 at the wheels of a 3.2? What did you do to the motor? I am HOPING it's the actual head or a sleeve, because it should be covered by my warranty. They don't cover gaskets (which is nuts) so I would be stuck with a head gasket repair.

Make that 248 now and its running rich (it has a flash from a 3.6 big bore in it now).. I think I can pick up 10 more tomorrow.

The engine has nothing more than a good 3 angle valve job and a freshened up set of heads along with a little bit of black magic that went on during reassembly...

And it has 88,000 miles on it, too...

This is my "loaner engine"

The dealer said they believe it is the oil cooler. Would a failing oil cooler allow oil to mix in with coolant, while not permitting coolant to get into the oil?? Engine is still coolant free. Weird. And where is the coolant disappearing to? Just evaporating? This is a dealership and they seem to be clueless in regards to diagnosing these engines. The "BOOM" was a hose giving way - only $30.

I would imagine that the oil pressure would be higher than the coolant pressure.
There is probably an internal leak in the heat exchanger which, when hot, allows the oil to impregnate the coolant. But as the engine stops & cools, there is still pressure in the cooling system (but not in the lubrication system) which forces a small amount of coolant into the oil. This coolant would then evaporate when the oil is again up to temperature.
At least that's my theory.....
I would be interesting to know if Porsches "never needs replacement" coolant has anything to do with these failures.
Looks like Brad & JFP's diagnosis were correct - again!!

They replaced the oil cooler & flushed the system with detergent. We will continue to monitor it for the next few months. They said if that isn't it, then the last option they can think of is a tear down. I will probably have to get a second opinion before I go that route. The BOOM that I heard was a hose - $30. Surprisingly, with all the problems I've had with Warranty America, they almost matched the dealership on the labor rate (paid $149 of $158/hr) and matched the number of hours. That's something they never used to do - capped out at $100/hr in the past. All I had to pay for was the tow, deductible, and a couple of gallons of coolant during the flush. I'll post feedback whether the problems persists or goes away.
:cheers:

Oil in coolant
 

hi everyone!
haveing just got a boxster s 2000 2 weeks ago i have noticed oil in water too!!!
please let me know if its the heat exchanger and i hope its not the heads! and i dont have a waranty so i might have to get my hands dirty...is it hard PLEASE HELP

Get yourself the Bentleys repair manual - it gives the explanation on how to replace the heat exchanger. Make sure you get the S exchanger as it is larger than the standard Boxster unit.
You will definately have to replace the coolant and preferably flush the system of old oil too. If this is beyond your mechanical skills, there are a few indipendants in the North of England that can help, Hartechs / Autofarm have a good reputation - or log onto BoXa.net for closer help.