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Coolant leak - Flashing light, overheating, smoke..


atta

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Hi,

drow my 99 2.5 Manual on the freeway the other day. Temperature light started to flash, but temperature was normal. After a few km I pulled off the freeway and drove to a gas station. Temperature started climbing, and when I stopped the car smoke was flowing out from the engine compartment. Let it sit a little while with the heat on full to try to cool it down, then limped the short trip home. Starting to drive the temperature went down to 180 again. When home it was dripping coolant all over.

Inspected it today. Coolant expansion tank is empty. I suspected it had failed, so I pulled the carpet. No sign of any coolant in the rear trunk. In the engine compartment there is was puddles on the engine, eg. below the AOS. Inspected the hoses and can't really see where it is leaking.

Could it be that one of the cooling expansion tank nipples on the back of the manifold has failed? I dropped the engine about 3 inches when changing the front engine mount a few weeks back. That might have caused some extra stress on the nippes.

If this is the cause, is the fix to drill out the failed nipple and just use a hose, like Wayne did on picture 6 in this article? http://www.pelicanparts.com/techarticles/Boxster_Tech/33-WATER-Coolant_Tank/33-WATER-Coolant_Tank.htm Or should I just swap out the tank while I'm at it? Mine is a .04 revision.

Atle

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Hi,

drow my 99 2.5 Manual on the freeway the other day. Temperature light started to flash, but temperature was normal. After a few km I pulled off the freeway and drove to a gas station. Temperature started climbing, and when I stopped the car smoke was flowing out from the engine compartment. Let it sit a little while with the heat on full to try to cool it down, then limped the short trip home. Starting to drive the temperature went down to 180 again. When home it was dripping coolant all over.

Inspected it today. Coolant expansion tank is empty. I suspected it had failed, so I pulled the carpet. No sign of any coolant in the rear trunk. In the engine compartment there is was puddles on the engine, eg. below the AOS. Inspected the hoses and can't really see where it is leaking.

Could it be that one of the cooling expansion tank nipples on the back of the manifold has failed? I dropped the engine about 3 inches when changing the front engine mount a few weeks back. That might have caused some extra stress on the nippes.

If this is the cause, is the fix to drill out the failed nipple and just use a hose, like Wayne did on picture 6 in this article? http://www.pelicanpa...oolant_Tank.htm Or should I just swap out the tank while I'm at it? Mine is a .04 revision.

Atle

Anderson:

If it is one of the nipples on the manifold, bypassing the nipple design by installing a hose all the way through the manifold plastic base could certainly work as it did in Wayne's excellent article. As he says, it started out as a temporary fix but has held up at least as well as the original design would have.

You may have to source a hose of a different diameter than the hose coming from the engine and use a plastic adapter/connector, depending on the size of the nipple on each side of the manifold (if they are not the same size). I know that one of the nipples on the underside of the coolant tank on the 1997 Boxsters is different than the size of the nipple in the same location of the replacement coolant tanks with the revised part number, although I can't remember which particular hose/nipple it was.

If your coolant tank is original, this might be a good time to use this repair as an excuse for replacing the tank. If the tank is fairly new, bypassing the nipple would be my approach as a new tank is around $200.

Regards, Maurice.

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Anderson:

If it is one of the nipples on the manifold, bypassing the nipple design by installing a hose all the way through the manifold plastic base could certainly work as it did in Wayne's excellent article. As he says, it started out as a temporary fix but has held up at least as well as the original design would have.

You may have to source a hose of a different diameter than the hose coming from the engine and use a plastic adapter/connector, depending on the size of the nipple on each side of the manifold (if they are not the same size). I know that one of the nipples on the underside of the coolant tank on the 1997 Boxsters is different than the size of the nipple in the same location of the replacement coolant tanks with the revised part number, although I can't remember which particular hose/nipple it was.

If your coolant tank is original, this might be a good time to use this repair as an excuse for replacing the tank. If the tank is fairly new, bypassing the nipple would be my approach as a new tank is around $200.

Regards, Maurice.

Thanks for your advice. I'm guessing the tank is the original one. It is an .04 revision stamped 99. Sounds like a good idea to replace it. I was contemplating the nipple bypass just because I would love to get it fixed this weekend. :)

But I'm not even sure that's the problem - it there a way to tell other than pressure testing it? Or any experiences that helps to point in this direction?

Atle

99 Boxster w/996 Turbo front end conversion, 03+ rear w/PDC, 03 roof w/glass window, ++++++++++(!)

Edited by atta
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Anderson:

If it is one of the nipples on the manifold, bypassing the nipple design by installing a hose all the way through the manifold plastic base could certainly work as it did in Wayne's excellent article. As he says, it started out as a temporary fix but has held up at least as well as the original design would have.

You may have to source a hose of a different diameter than the hose coming from the engine and use a plastic adapter/connector, depending on the size of the nipple on each side of the manifold (if they are not the same size). I know that one of the nipples on the underside of the coolant tank on the 1997 Boxsters is different than the size of the nipple in the same location of the replacement coolant tanks with the revised part number, although I can't remember which particular hose/nipple it was.

If your coolant tank is original, this might be a good time to use this repair as an excuse for replacing the tank. If the tank is fairly new, bypassing the nipple would be my approach as a new tank is around $200.

Regards, Maurice.

Thanks for your advice. I'm guessing the tank is the original one. It is an .04 revision stamped 99. Sounds like a good idea to replace it. I was contemplating the nipple bypass just because I would love to get it fixed this weekend. :)

But I'm not even sure that's the problem - it there a way to tell other than pressure testing it? Or any experiences that helps to point in this direction?

Atle

99 Boxster w/996 Turbo front end conversion, 03+ rear w/PDC, 03 roof w/glass window, ++++++++++(!)

Pressure testing the entire system is the correct way to go...............

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Thanks for your advice. I'm guessing the tank is the original one. It is an .04 revision stamped 99. Sounds like a good idea to replace it. I was contemplating the nipple bypass just because I would love to get it fixed this weekend. :)

But I'm not even sure that's the problem - it there a way to tell other than pressure testing it? Or any experiences that helps to point in this direction?

Atle

99 Boxster w/996 Turbo front end conversion, 03+ rear w/PDC, 03 roof w/glass window, ++++++++++(!)

Anderson:

It's a relatively easy matter to determine whether the leak is coming from anywhere in front of the plastic manifold of the coolant tank support.

That same photo #6 on Wayne's DIY shows you the bolts to remove to free the coolant tank. Once you remove those bolts, you can pull the coolant tank rearwards into the trunk by a little more than one inch. That should be sufficient to determine whether there is a broken nipple and/or whether any of the hoses or connections are leaking behind the manifold.

If the escaping coolant is landing in the area in the vicinity of the inside of the right rear tire, or further towards the center in that area, then your likely suspects are the coolant tank itself (which you have already determined is not cracked or leaking), the connection at the coolant sensor under the tank, the hoses or connections where they meet the front of that manifold, or the water pump.

Get the right rear of the car up and also take a look underneath at the "Y" hose at the thermostat. Here is a photo of that Y-hose area (usually partially hidden by the rearmost underbody panel):

post-6627-042756400 1283382162_thumb.jpg

Regards, Maurice.

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Ok, confident the leak was near the connections to the tank I filled up the expansion tank and started the engine. Coolant started squirting out from the tube that goes to the oil cooler. It has a dent in it, and it actually looks like it melted. Can't believe I missed that last night. Any ideas as to what could have caused this?

post-32293-025129400 1283448320_thumb.jp

A.

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Ordered the part, but conserned that this was just a symptom - can't really see what would cause the tube to melt. Perhaps it's the hot water rushing out from the tube that made it look like it had been melted?

I also noticed that the oil filler tube is very drity. Lite it has been sweating oil. Is this normal, or should I suspect a failed AOS causing a vacuum in the tube?

Thanks.

Atle

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Ordered the part, but conserned that this was just a symptom - can't really see what would cause the tube to melt. Perhaps it's the hot water rushing out from the tube that made it look like it had been melted?

I also noticed that the oil filler tube is very drity. Lite it has been sweating oil. Is this normal, or should I suspect a failed AOS causing a vacuum in the tube?

Thanks.

Atle

coolant mixed with oil does hint at an AOS issue. Quick check: with your engine on, remove the oil filler cap and feel for suction with your palm. Or for a more convincing check, see the throttle-body for any oil deposit.

I faced a similar situation of collant overflowing a while back. It was quite likely an issue with just the reservoir cap. The old version apparently has a known issue and if you are still running with that, might be a good idea to switch, My AoS also needed a replacement about then but I dont think that had anything to do with the coolant overflow.

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Ordered the part, but conserned that this was just a symptom - can't really see what would cause the tube to melt. Perhaps it's the hot water rushing out from the tube that made it look like it had been melted?

I also noticed that the oil filler tube is very drity. Lite it has been sweating oil. Is this normal, or should I suspect a failed AOS causing a vacuum in the tube?

Thanks.

Atle

coolant mixed with oil does hint at an AOS issue. Quick check: with your engine on, remove the oil filler cap and feel for suction with your palm. Or for a more convincing check, see the throttle-body for any oil deposit.

I faced a similar situation of collant overflowing a while back. It was quite likely an issue with just the reservoir cap. The old version apparently has a known issue and if you are still running with that, might be a good idea to switch, My AoS also needed a replacement about then but I dont think that had anything to do with the coolant overflow.

Hi, thanks for your advice. Just to clarify there is no mix of coolant and oil as far as I can tell. The oil filler tube is the only thing that I know for sure is touching the tube that got the leak, so it got some attention and I noticed it is more dirty than the rest of the engine bay. I changed out the cap last year. I did check the end of the AOS' j-tube where it goes into the throttle body, and it did have some oil in it. But I'm thinking a little oil is normal?

Atle

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I am not sure how little is okay but mine had also started blowing out excess smoke on startup (another tell-tale of AOS issue). So if yours ain't doing that, it should be fine.

Good luck

Hi, thanks for your advice. Just to clarify there is no mix of coolant and oil as far as I can tell. The oil filler tube is the only thing that I know for sure is touching the tube that got the leak, so it got some attention and I noticed it is more dirty than the rest of the engine bay. I changed out the cap last year. I did check the end of the AOS' j-tube where it goes into the throttle body, and it did have some oil in it. But I'm thinking a little oil is normal?

Atle

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UPDATE: Got the new tube the other day. Asked the mechanic what could have caused it to fail, and he told me oil could cause a tube to swell and give up. So I cleaned the oil filler tube and now I find traces of fresh oil on it. So that seems to be the culprit. I also noticed the new tube is curved (L-shaped) in a way so that it does not go directly below the oil filler tube anymore. Changing out the AOS, oil filler tube, all the coolant tubes (they are short) and the coolant tank while I'm in there. Should sort this out.

Atle

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