Re: 25 psi too much pressure to use to pressure test system. IIRC the test pressure is 1.3 bar. |  |  |
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| The cooling woes continue Yippee38 - Friday, 6 May, 2011, at 3:06:40 pm |
Original thread here: Original thread
Basically, I replaced my engine. Bled coolant 4 times, but it kept blowing coolant. Replaced the coolant cap and all seemed well for a while. Then the coolant light came on. At that point I decided I'd replace some parts to ensure it wasn't the coolant reservoir or bleed valve. So I replaced the reservoir, but another new cap on, an LN Engineering 160 thernostat (and housing), and replaced one hose that had a nick in it.
Before removing anything, I drained the system from the plug. Then I disconnected the two main coolant hoses at the front of the engine and raised the front of the car up to drain the radiators. Then I replaced the plug and the hoses and used the UView Airlift to vacuum the system. When I did that, I kept getting coolant foam in very small amounts. I assume that's the remnants of fluid in the system with a vacuum on it. I kept doing it until it seemed like no more was being removed. I held 25 psi vacuum on the system and it kept the vacuum.
At that point, I replaced the hose, the thermostat and the coolant tank. I again used the UView Airlift to vacuum the system down and held it at 25 psi vacuum. No sign of drop in vacuum. I then filled the system using the Airlift from 25 psi vacuum.
When done with that, I figured that for good measure I'd bleed it just to be safe. When doing the bleed procedure (the one found on Pedro's Garage which is pretty much the same as the one in the Bentley book), the first step is to run the engine with the cap off and rev it a bit. When I did that, I did have to add a bit of coolant. Not a lot. It was maybe 3/4" down from the full mark. I then proceeded to the next step. Did the 10 minutes at 2500rpm, then the 5 at 2500 revving to 5000. It kept the level. I then did it a second time. This time the level was a bit low. Not much, but a bit. So I carefully opened the reservoir, but as I did, the coolant expanded until it was full. Ok. Fine. I let it idle until fans turned on and off again. Let it cool, and it was that little bit low again. I topped it off cold.
So at this point, being completely paranoid about having an air bubble in the system, I decided to drive it a day or two with the bleeder open in the hopes that it would remove any remaining bubbles (which shouldn't be there because I filled it by vaccum). The valve should be a one-way valve that only blows off excess pressure, so it's not going to introduce any air into the system that's not already there. I drove it for a day. After driving the car, I checked the level it is was full. When the car cooled off, I checked again and it was low; at the min mark. So I opened the cap and it released quite a bit of pressure, the coolant expanded and was showing full again. So at that point I closed the bleed valve and drove it normally. I experienced the same thing a few times. The tank would look fine hot, but when the engine cooled, it would be low. I'd open the cap and it would let out a lot of pressure and the level would rise to full. At this point, I figured that this was probably normal, so I just started driving the car.
The other day, when I got off of work, I walked to my car and noticed a puddle around the front of my right-rear tire. I looked underneath and sure enough, the suspension had coolant on it. I checked the level and it was about 1/2" below the min mark. I had stopped carrying coolant with me so I drove it home. I made it no problem. When I got home and got out of the car, I checked for the smell of coolant. There was none. I went inside and said, "Hi" to my dogs and wife for about 5 minutes. I then went back to the garage to get my bag out of the frunk and the smell of coolant was very strong. There was none dripping on the ground though.
Does anybody have any idea what the hell is going on? I'm about ready to take a sledge hammer to this car.
Basically, I replaced my engine. Bled coolant 4 times, but it kept blowing coolant. Replaced the coolant cap and all seemed well for a while. Then the coolant light came on. At that point I decided I'd replace some parts to ensure it wasn't the coolant reservoir or bleed valve. So I replaced the reservoir, but another new cap on, an LN Engineering 160 thernostat (and housing), and replaced one hose that had a nick in it.
Before removing anything, I drained the system from the plug. Then I disconnected the two main coolant hoses at the front of the engine and raised the front of the car up to drain the radiators. Then I replaced the plug and the hoses and used the UView Airlift to vacuum the system. When I did that, I kept getting coolant foam in very small amounts. I assume that's the remnants of fluid in the system with a vacuum on it. I kept doing it until it seemed like no more was being removed. I held 25 psi vacuum on the system and it kept the vacuum.
At that point, I replaced the hose, the thermostat and the coolant tank. I again used the UView Airlift to vacuum the system down and held it at 25 psi vacuum. No sign of drop in vacuum. I then filled the system using the Airlift from 25 psi vacuum.
When done with that, I figured that for good measure I'd bleed it just to be safe. When doing the bleed procedure (the one found on Pedro's Garage which is pretty much the same as the one in the Bentley book), the first step is to run the engine with the cap off and rev it a bit. When I did that, I did have to add a bit of coolant. Not a lot. It was maybe 3/4" down from the full mark. I then proceeded to the next step. Did the 10 minutes at 2500rpm, then the 5 at 2500 revving to 5000. It kept the level. I then did it a second time. This time the level was a bit low. Not much, but a bit. So I carefully opened the reservoir, but as I did, the coolant expanded until it was full. Ok. Fine. I let it idle until fans turned on and off again. Let it cool, and it was that little bit low again. I topped it off cold.
So at this point, being completely paranoid about having an air bubble in the system, I decided to drive it a day or two with the bleeder open in the hopes that it would remove any remaining bubbles (which shouldn't be there because I filled it by vaccum). The valve should be a one-way valve that only blows off excess pressure, so it's not going to introduce any air into the system that's not already there. I drove it for a day. After driving the car, I checked the level it is was full. When the car cooled off, I checked again and it was low; at the min mark. So I opened the cap and it released quite a bit of pressure, the coolant expanded and was showing full again. So at that point I closed the bleed valve and drove it normally. I experienced the same thing a few times. The tank would look fine hot, but when the engine cooled, it would be low. I'd open the cap and it would let out a lot of pressure and the level would rise to full. At this point, I figured that this was probably normal, so I just started driving the car.
The other day, when I got off of work, I walked to my car and noticed a puddle around the front of my right-rear tire. I looked underneath and sure enough, the suspension had coolant on it. I checked the level and it was about 1/2" below the min mark. I had stopped carrying coolant with me so I drove it home. I made it no problem. When I got home and got out of the car, I checked for the smell of coolant. There was none. I went inside and said, "Hi" to my dogs and wife for about 5 minutes. I then went back to the garage to get my bag out of the frunk and the smell of coolant was very strong. There was none dripping on the ground though.
Does anybody have any idea what the hell is going on? I'm about ready to take a sledge hammer to this car.
| 25 psi too much pressure to use to pressure test system. IIRC the test pressure is 1.3 bar. MarcW - Friday, 6 May, 2011, at 11:33:09 pm |
You may have cracked the coolant tank with that 25psi.
I do not like driving around with the vent valve open. If you have the right vacuum tool and setup to pull a vacuum on the system and then switch over to a vented to atmosphere refill tank the engine's cooling system should refill just fine with no air pockets.
If you drive around with the vent open the system does not hold pressure when it gets hot. This allows the coolant to flash to steam at the hotter points in the engine. This can introduce air pockets and at the same time blow coolant out the vent.
My advice would be to drain the system and put a 1.3 bar pressure to the empty system and see how long it holds pressure. I'm away from my references -- I'm on Vacation! and wriiting this from a motel in Elko NV -- so I can't look up how long the pressure should hold.
If the system holds pressure then pull a vacuum on the cooling system. I've been told the coolant hoses should collapse. Then refill the system with fresh anti-freeze mixed with distilled water in the proper ratio.
Leave the vent closed. (It occurs to me that in driving around with this open it might no longer effect a pressure tight seal.) Start the engine and let it idle until warm. Keep an eye on the coollant level. If it drops, shut the engine off and let it cool until it is safe to open the cap and add more coolant. My info is though if you do the vacuum/refill right you won't have to add any coolant. There will be no air pockets.
Sincerely,
MarcW.
I do not like driving around with the vent valve open. If you have the right vacuum tool and setup to pull a vacuum on the system and then switch over to a vented to atmosphere refill tank the engine's cooling system should refill just fine with no air pockets.
If you drive around with the vent open the system does not hold pressure when it gets hot. This allows the coolant to flash to steam at the hotter points in the engine. This can introduce air pockets and at the same time blow coolant out the vent.
My advice would be to drain the system and put a 1.3 bar pressure to the empty system and see how long it holds pressure. I'm away from my references -- I'm on Vacation! and wriiting this from a motel in Elko NV -- so I can't look up how long the pressure should hold.
If the system holds pressure then pull a vacuum on the cooling system. I've been told the coolant hoses should collapse. Then refill the system with fresh anti-freeze mixed with distilled water in the proper ratio.
Leave the vent closed. (It occurs to me that in driving around with this open it might no longer effect a pressure tight seal.) Start the engine and let it idle until warm. Keep an eye on the coollant level. If it drops, shut the engine off and let it cool until it is safe to open the cap and add more coolant. My info is though if you do the vacuum/refill right you won't have to add any coolant. There will be no air pockets.
Sincerely,
MarcW.
| Re: 25 psi too much pressure to use to pressure test system. IIRC the test pressure is 1.3 bar. Yippee38 - Friday, 6 May, 2011, at 11:50:52 pm |
| Re: 25 psi too much pressure to use to pressure test system. IIRC the test pressure is 1.3 bar. joris - Saturday, 7 May, 2011, at 3:40:07 am |
| Uh, yes and no. Joris covers this in his post. I will add that cooling systems are funny... MarcW - Saturday, 7 May, 2011, at 10:02:21 am |
in that they can appear pressure tight under some conditions -- mainly cold -- yet have a leak under operating (hot) conditions.
Twice now with my Boxster and Turbo in both cars the cap proved to be the culprit. And in one other case the Boxster's coolant tank was good cold but hot not so much. And when I got the system good and hot in attempting to verify a radiator fan problem (and confirmed a fan was not running) that is when the coolant tank let me know in no uncertain terms it was not able to hold pressure (or coolant) hot.
All I can recommend is to drain the system completely. Refill with a vacuum system completely. Start the engine and let it idle and warm up. If you want you can drive the car around but don't get too far from home. Driving around is to warm up the engine more thoroughly than can be accomplished by letting the engine idle away.
Have the AC off. I do not know if the heat setting on the car's heater controls makes any difference but the idea is you want hot coolant circulating throughout the car's cooling system.
Bring the car back to the garage. With out opening the cap! check the coolant level. If low let the engine cool and bring the level up to where it should be. Get the engine hot again.
If the level ok then you can raise the engine rpms to something above idle and hold the rpms high for a bit. The goal is to get the coolant nice and hot, so hot the radiator fans come on. They do this at 212F.
Let the fans run until they shut off. They do this at 205F. Raise the rpms again and hold until the fans come on. Continue to hold the higher rpms for a bit, 10 or 15 seconds, then shut off the engine. The cooling system will develop as much pressure now as I think it will ever develop.
If there's a leak your eyes, ears, or nose will tell you. It can be anywhere. Radiators. Cap. Coolant tank (I know it is a new one, but...). A hose. A loose hose clamp. Now a particularly nasty place for a leak is in the heater core. (Just last week a tech told me about the trouble he had id'ing an A/C leak that proved to be in the evaporator which is located in the heater/AC area under/near the dash. These items are out of sight but are still subject to the pressures all the other components of their respective systems are subject to.)
Ideally you would want to have the engine compartment exposed and the car on a lift to be able to check the car for leaks from the top or bottom. In a worse case scenario, and in this case your car may qualify, the front bumper cover should be removed for better access to the radiators.
Mind you are looking for a leak from a cooling system that is very hot and under high pressure. Be careful and use all appropriate precautions.
Sincerely,
MarcW.
Twice now with my Boxster and Turbo in both cars the cap proved to be the culprit. And in one other case the Boxster's coolant tank was good cold but hot not so much. And when I got the system good and hot in attempting to verify a radiator fan problem (and confirmed a fan was not running) that is when the coolant tank let me know in no uncertain terms it was not able to hold pressure (or coolant) hot.
All I can recommend is to drain the system completely. Refill with a vacuum system completely. Start the engine and let it idle and warm up. If you want you can drive the car around but don't get too far from home. Driving around is to warm up the engine more thoroughly than can be accomplished by letting the engine idle away.
Have the AC off. I do not know if the heat setting on the car's heater controls makes any difference but the idea is you want hot coolant circulating throughout the car's cooling system.
Bring the car back to the garage. With out opening the cap! check the coolant level. If low let the engine cool and bring the level up to where it should be. Get the engine hot again.
If the level ok then you can raise the engine rpms to something above idle and hold the rpms high for a bit. The goal is to get the coolant nice and hot, so hot the radiator fans come on. They do this at 212F.
Let the fans run until they shut off. They do this at 205F. Raise the rpms again and hold until the fans come on. Continue to hold the higher rpms for a bit, 10 or 15 seconds, then shut off the engine. The cooling system will develop as much pressure now as I think it will ever develop.
If there's a leak your eyes, ears, or nose will tell you. It can be anywhere. Radiators. Cap. Coolant tank (I know it is a new one, but...). A hose. A loose hose clamp. Now a particularly nasty place for a leak is in the heater core. (Just last week a tech told me about the trouble he had id'ing an A/C leak that proved to be in the evaporator which is located in the heater/AC area under/near the dash. These items are out of sight but are still subject to the pressures all the other components of their respective systems are subject to.)
Ideally you would want to have the engine compartment exposed and the car on a lift to be able to check the car for leaks from the top or bottom. In a worse case scenario, and in this case your car may qualify, the front bumper cover should be removed for better access to the radiators.
Mind you are looking for a leak from a cooling system that is very hot and under high pressure. Be careful and use all appropriate precautions.
Sincerely,
MarcW.
| I'm sure he meant 25 inches Hg, not 25 PSI. The gauge shows vacuum from 0-30 inches Hg *NM* Pedro (Odessa, FL) - Saturday, 7 May, 2011, at 9:33:39 am |
Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)
Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)
Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
| Ah, yes in reading through the post again I agree. That amount of vacuum should not cause any.... MarcW - Saturday, 7 May, 2011, at 9:44:01 am |
| Re: I did mean 25 inches Hg, NM *NM* Yippee38 - Saturday, 7 May, 2011, at 11:48:54 am |
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