Coolant overflow from expansion reservoir

[hucqym]

Hello all,

I took my 2001 boxster on a drive down from San Francisco to Santa Barbara this weekend and had problems.

First, as I pulled into the driveway in SB, I saw coolant spilling off the side, opened the trunk and found it oozing out from around the cap perhaps and out through overflow tube. Put the key back in ignition to check temp and it showed around 200. No CEL or any other signs. It didnt look like it had been draining all the way along. probably happened just when i stopped.

I let it cool and next day was a sunday and couldnt take it to the shop for a checkup. Got some coolant and topped it up. Seemed like a about a gallon of coolant had drained off. Started up, no bad signs ran well (temp still about 200) and so I decided to carry on and bother about the issue once I got back home to SF.

Then again when I took an exit for gas after about 200 miles, I noticed the check engine light come up and soon stopped and noticed the coolant spilling off again. Let it cool for a good couple hours. Checked around with little hope but obviously no shop open on a sunday evening. Topped up the coolant again and then was able to drive again and reached home (another 250 miles) without further events. The car ran smooth as ever and temp still sticking around 200 (apart from check engine light that stayed on - but wasnt blinking)

Car hadnt been showing any other trouble signs before this as well. It does give out some good smoke (which appears white) at startup from the exhaust and kinda smells like gas (I had looked that up and it seemed like that was a regular thing with boxster's flat engine so didnt bother).

It is currently doing 94K miles. Around 90K the coolant pump broke which I had replaced on my own (with help from the board of course). Also had it undergo a 90K major service soon after and that changed the drivebelt among other things

Any ideas on what could be the problem? I will take it to the shop for the check engine light anyway but thought a self-assessment was in order before that, as usual.

Thanks in anticipation

Hakim

Edited November 30, 2009 by hucqym

[larez2]

Sounds to me like you need a new coolant cap and/or thermostat. A gallon is quite a bit to have drained or evaporated off. The check engine light may or may not be related.

[mikes_box]

sounds like all you need is a new coolant cap... the old ones didn't have a good seal so if you have an older one then buy a new one and see if that fixes the problem. I had that happen to me after changing out the waterpump too and a new cap fixed the boiling over issue...

[1schoir]

Hakim:

As the other posters have suggested, first check to make sure you have an updated coolant reservoir cap. It should be at least an 001, but I think they are up to 003 or 004 at this time (last three numbers on the cap).

Since you did your water pump recently, are you sure that you bled the system properly to get all of the air out? If you didn't, that could be a cause as well. If you don't have a vacuum tool, such as the Airlift by UView, you can leave the pressure relief valve on top of the coolant tank (underneath the thin black plastic trim cover that surrounds the oil and coolant cap bases) open for a few days and drive around that way, topping up with coolant or distilled water if it's a minor amount.

If you were able to replace the water pump by yourself, you sound like a good candidate for a Durametric, or at least a code reader such as Actron so that you can read the codes yourself in the future.

Regards, Maurice.

[hucqym]

Thanks folks for the info.

I am sure the system was bled though. If you missed it, I have run a good 4000+ miles since the waterpump change. Or are you saying there could still be air bubbles after this long?

Also I did bleed the system then with the pressure relief valve open.

I'll change the cap and give it a try and post updates here.

Yes I guess I'll get myself a Durametric kit soon.

[hucqym]

so the engine fault codes turned out to be P1128/P1130 and MAF.

compression test on the cooling system showed no leaks but they are suspecting a bad AOS (I have been getting smoke at startup, and as far as I can tell its only at startup and I havent noticed anything while running but I might have just missed noticing)

does this tell a tale or more like a bunch of unrelated issues?

[mikes_box]

so the engine fault codes turned out to be P1128/P1130 and MAF.

compression test on the cooling system showed no leaks but they are suspecting a bad AOS (I have been getting smoke at startup, and as far as I can tell its only at startup and I havent noticed anything while running but I might have just missed noticing)

does this tell a tale or more like a bunch of unrelated issues?

the P1128 and P1130 were the exact same codes I got when my AOS went boom in addition to tons of smoke.. not too hard to DIY so i would suggest doing it yourself and save some money.... i think sunset sells the parts for like $90 plus shipping... when mine went out i couldn't wait so picked one up from steade porsche in walnut creek for $103+ tax so not too bad would have come close to sunset after shipping and i didn't have to wait... once you've done the aos clean out the maf with cleaner and you should be good to go.....