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Reza

Smoke coming from under the throttle body

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Hello All,

I was about to do some general engine inspections today that surprisingly notices a light smoke (not sure blue or white, but I think more of a blue color) was coming out from beneath the plastic cover that has the "4.5 V8" logo on it... from under the throttle body. it was like you leave a cigarette under this plastic cover and it finds its way out...

I removed the plastic cover and didn't see any leak at all, every where seemed to be dry. the crankcase vent lines are all in good shape too, no crack or leak...

after a minute the smoke was gone. I turned the car on again for 10 minutes and whatever I did no more smoke appeared.

Is there any other pipe than the Crankcase Vents that passes in that area, specially under the throttle body and could leak over a hot part of the engine? Might that be a coolant leak? any coolant pipe there? (in the attached photo, smoke was coming out of the circle named point A)

Thanks for your help.

post-63813-0-74834300-1297145117_thumb.j

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The thermostat housing (with the plastic cooling pipes) is situated on this spot, maybe a small water leak ? I would take a closer look.

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Inspect the water pump also as they do fail. I remove the serpentine belt and check the pump brng for movement and roughness/noise while turning it and appling load to the pulley.

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Thank you both for guiding.

RFM: by the Plastic Cooling Pipes, do you mean the famous cooling pipes that break and could be upgraded to aluminum one?

I noticed that in about 1,700 miles of driving I have lost approximately 1 liter of coolant fluid ( the reservoir was below minimum and I added coolant to it). I know that because I topped coolant up to MAX in a about 2 months ago and now it was below MIN.

If there is any leak from water pump or thermostat housing, shouldn't that fall on the ground or on the tray and I see that, I do not see any hot spot under the serpentine or pulleys in that area that water drops could fall over it and burn! What am I missing?

Again thanks for your time and guidelines.

Reza

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The famous plastic cooling pipes are indeed connected (push in) in to the thermostat housing, a small coolant leak at that spot drips into the V between both cylinder banks and evaporated before the coolant hit the floor, that could be the smoke you have seen. A leak on the water pump typically falls on the floor or the under tray.

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RFM: Thank you very much. You are always helpful and explanations are always to the point.

To have helped others like me to understand what and where exactly are these bypass cooling pipes, I have attached few photos.

This operation nearly opens every part and gives access to many things to be replaced at this point and saves Labor cost... I heard that there are 2 hoses at the back of the engine that needs to be replaced too, because they fail and leak too... Could that be the time to have Water Pump replaced/repaired or Serpentine Belt perhaps be replaced to save labor cost in future?

If this happens due to the burst of pipes, coolant fluid pour down over the Torque Converter Seal and brings about another 2K cost in short run. Could replacing these Pipes before burst be done so careful that no coolant pour down over the Torque Converter Seal? What about replacing the hoses at the back of the engine?

Thank you for your time.

post-63813-0-08117400-1297304860_thumb.j

post-63813-0-53618000-1297304870_thumb.j

post-63813-0-14591500-1297304877_thumb.j

post-63813-0-61475800-1297304887_thumb.j

post-63813-0-71152500-1297304898_thumb.j

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The 2 hoses and plastic connectors on the back of the engine should have been replaced together with the the 3plastic pipes in the middle of the V for better access. The allu. pipes, and of course, the older plastic pipes can also leak where they are connected to the thermostat housing. The small and brittle black plastic pipes connected to the left and right cylinder head (visible above the allu.pipes in the pic., are also a source of problems.) With the allu. pipes installed, there are no longer major leaks in that area which can cause damage. Cayenne V8 and Turbo till MY06. MY08 DFI engines have an other design but are still made of plastic.

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Hello RFM:

Considering the leak (in my car) is from the connection point of pipes and thermostat housing (shouldn't be a crack in pipes), and it is minor (if I drive aggressively for 1 hour and then visit the engine, I see a very light white smoke comes out next to Throttle Body for maybe 60 seconds) If you were me, would you spend the $1900 today and fix this or you would wait until it gets worse?

If I do it today could that be done so careful to avoid spill over Transmission and damage to Converter Seal? What about back engine hoses?

Thanks,

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It is primarily important to determine the cause and spot of the smoke (steam-vapour), if it comes from the previously mentioned coolant circuit i would still consider to replace the pipes and those on the rear of the engine, before a further problem occurs with sudden large coolant loss. The coolant is first drained before they replace the pipes. Hope it helps.

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Is there any tool or device that can be pushed into there and we see the situation or the amount of leak there?

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You can give it a try with an endoscope, if you have one available..

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Just to update you, I had the car being inspected and a cold pressure test carried on it but shows nothing wrong, it keeps the pressure constant. Tomorrow a hot pressure test will be carried, maybe that could reveal something. I know that there is a leak some where because in the past months (4,000 miles of driving) I have topped the coolant reservoir 2 times each time with approximately 1 to 1.5 liter of coolant to bring it to max level. There is no sign of leak on any of the hoses or water pump, etc. and pressure test showed everything OK. Any idea / hint would be appreciated.

During this inspection, when we removed the lower tray (beneath the engine) there was 2 crystal/icicles in orange color hanging from the transmission bell housing. it is weird !! I know that I use OEM coolant which is Purple or say Pink color not orange. We know that ATF is red and does not freeze too... Could anyone have any idea what the Orange color icicles / crystals could be?

My mechanic thought I might have used ginger tabs to repair some coolant leaks somewhere but I know that I never used such stuff. Does anyone have any idea or experiences of such Orange color crystal under the Bell Housing?

Many thanks...

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Just to update you, I had the car being inspected and a cold pressure test carried on it but shows nothing wrong, it keeps the pressure constant. Tomorrow a hot pressure test will be carried, maybe that could reveal something. I know that there is a leak some where because in the past months (4,000 miles of driving) I have topped the coolant reservoir 2 times each time with approximately 1 to 1.5 liter of coolant to bring it to max level. There is no sign of leak on any of the hoses or water pump, etc. and pressure test showed everything OK. Any idea / hint would be appreciated.

During this inspection, when we removed the lower tray (beneath the engine) there was 2 crystal/icicles in orange color hanging from the transmission bell housing. it is weird !! I know that I use OEM coolant which is Purple or say Pink color not orange. We know that ATF is red and does not freeze too... Could anyone have any idea what the Orange color icicles / crystals could be?

My mechanic thought I might have used ginger tabs to repair some coolant leaks somewhere but I know that I never used such stuff. Does anyone have any idea or experiences of such Orange color crystal under the Bell Housing?

Many thanks...

Reza, my 2008 CTT was dripping coolant of the exact same color as you describe (looks very much like hydraulic fluid found in the PS system). It's oily too which throws a lot of people off, but I went over this to the point of exhaustion with my local Porsche Service Advisor who assured me that it is in fact coolant. There is some lubricating properties in the coolant Porsche uses. As far as the color, I have seen both pink and orange, maybe the color differences is a result of the coolant becoming dilutted as more distilled water is added at service intervals or when more coolant was required in the past?

BTW, they tell me that the center connector pipes (in the center of the "V") are not the source of my leak, rather it is the thermostat housing seal. Improper silicon lub was used during assembly causing the O-rings to become damaged (or at least that is the service bulletin). That connection was repaired last week and I still noticed dripping on my garage floor. I'm told it's "residual" coolant which sounds suspiciously like an excuse, but I haven't noticed anything in a couple of days.

Edited by acat2002
  • Upvote 1

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Thanks. Probably mine is the same thing. Mine has a gradual leak and it was strange to me that it could go all the way down from valley to the back of engine, over bell housing and shape icicles. Of course we have a very cold weather here in MN. I had the discussion with my advisor on how likely would be that this drops on bell housing could have damaged Torque Converter Seal !! He was totally negative on this.

I have read people talking about the time pipes blast and the whole coolant pour over bell housing and that cause damage to the Torque Converter Seal, but my advisor said: How that could happen because everything is sealed !!!!

so now I am a bit confused what really happens there. Did you have any issue after the coolant leak?

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Thanks. Probably mine is the same thing. Mine has a gradual leak and it was strange to me that it could go all the way down from valley to the back of engine, over bell housing and shape icicles. Of course we have a very cold weather here in MN. I had the discussion with my advisor on how likely would be that this drops on bell housing could have damaged Torque Converter Seal !! He was totally negative on this.

I have read people talking about the time pipes blast and the whole coolant pour over bell housing and that cause damage to the Torque Converter Seal, but my advisor said: How that could happen because everything is sealed !!!!

so now I am a bit confused what really happens there. Did you have any issue after the coolant leak?

I read the same thing as you (torque converted seal), and asked my advisor who basically said the same thing as yours did.

I try not to sound like a geek when I meet with the SA, but I also want to have a full understanding of how these problems can impact other systems in the vehicle. My extended warranty will not expire until 10/2014, but still, I want to make sure that some silly problem today isn't going to be responsible for a $4,000 failure in 11/2014!. Years of negative experience with service techs and service advisors has conditioned me to reduntantly research these things. I may not ever fully trust PCNA warranty reps or service advisors, but when we fellow owners get together and share our stories and knowlege it definitely helps.

To answer your question, it has only been a few weeks since the coolant leak was fixed, so the jury is still out (though I have not seen any more drips on the garage floor).

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Dear friends, should I replace the starter or not?

Also, do you think the leak which has found its way down into the starter hole and over flywheel, etc. could have already damaged the Torque Converter Seal?

My service advise is totally negative on this and he believes any fluid getting in there would never damage torque converter because it is sealed. He say they do not have any of previous customers who did this job returning in few months for Torque converter seal issue. Your opinion/experiences would be appreciated.

Now: more update on this leak issue:

So the coolant was really Orange in color and the 2 icicles formed under bell housing was from the coolant drips. It is interesting to see what I thought to be a gradual leak (I mean 1 liter coolant loss in reservoir every 2,000 miles and not a sudden loss / pipe burst) could have gone this far... See photos of the starter and how the coolant has formed around the area...

post-63813-0-50573800-1298602296_thumb.j

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post-63813-0-93095100-1298602423_thumb.j

post-63813-0-83786500-1298602511_thumb.j

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How much is the starter to replace? Looking at the photo it is clear that coolant was able to get into the starter, how long it will last is another question. Typically the bushings etc are a non factor as far as wear items in a starter, the solenoid was high enough to be out of the problem. If it was me and I intended on keeping the vehicle for an extended period and the price was reasonable I would change out the starter now while it's easy to get at. My service records from previous owners showed my input seal had to be done just after this leak occured ($9000.00 + warranty repair bill!) So the advisors saying this can't happen is false, there are a lot of owners out there that have had input seal failure resultant from coolant pipes bursting/leaking.

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As to the torque convertor seal being damaged, I have not seen it happen yet and have only replaced 4 or 5 coolant pipes in these vehicles. I would also replace the starter or have it rebuilt while it is out.

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Thanks for the replies, I am very much happy to hear there are people out there who have been through pipe upgrade process BUT not seen the Torque Converter Seal failure just after pipes break... that gives some hope...

Back to starter, Yes I made the decision to pay for a new one, it was expensive ($709). I could not wait and see one of these days my starter fails and have to dismantle all the parts again to reach the starter... so although money was an issue but between "bad" and "worse" i chose "bad".

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The 2 hoses and plastic connectors on the back of the engine should have been replaced together with the the 3plastic pipes in the middle of the V for better access. The allu. pipes, and of course, the older plastic pipes can also leak where they are connected to the thermostat housing. The small and brittle black plastic pipes connected to the left and right cylinder head (visible above the allu.pipes in the pic., are also a source of problems.) With the allu. pipes installed, there are no longer major leaks in that area which can cause damage. Cayenne V8 and Turbo till MY06. MY08 DFI engines have an other design but are still made of plastic.

Hi.....thanks again for these very helpful tips. I am in the midst of changingputting on the replacement aluminium kit but my mechanic had also suggested that I change the "smaller, 3 piece hose set with a T connector". Perhaps this is the one referred to above as "The small and brittle black plastic pipes connected to the left and right cylinder head (visible above the allu.pipes in the pic., are also a source of problems.)".

Do you know the part number for this, and the price?

Grateful your advise. Thank you..

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The 2 hoses and plastic connectors on the back of the engine should have been replaced together with the the 3plastic pipes in the middle of the V for better access. The allu. pipes, and of course, the older plastic pipes can also leak where they are connected to the thermostat housing. The small and brittle black plastic pipes connected to the left and right cylinder head (visible above the allu.pipes in the pic., are also a source of problems.) With the allu. pipes installed, there are no longer major leaks in that area which can cause damage. Cayenne V8 and Turbo till MY06. MY08 DFI engines have an other design but are still made of plastic.

Hi.....thanks again for these very helpful tips. I am in the midst of changingputting on the replacement aluminium kit but my mechanic had also suggested that I change the "smaller, 3 piece hose set with a T connector". Perhaps this is the one referred to above as "The small and brittle black plastic pipes connected to the left and right cylinder head (visible above the allu.pipes in the pic., are also a source of problems.)".

Do you know the part number for this, and the price?

Grateful your advise. Thank you..

Upon closer scrutiny of the aluminium kit picture, I can see that these smaller hoses are also included. Perhaps this is the "vent line"? I am getting the kit from Suncoastparts.

Thanks again...

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Happy to share I've received confirmation that the "vent line" is indeed part of the kit. Thanks anyway guys. Excellent help here..

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