07-15-2021, 08:49 AM
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#1
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Boxster in the snow
Join Date: Oct 2016
Location: MN
Posts: 7
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Coolant system can't hold any pressure
Hey, all --
I'm hoping you can help me figure this out:
New to me 2000 Boxster S. Previous owner reported an overheating issue, and the water pump was replaced by a Porsche-friendly indy shop. Still had temp issues -- the shop said bad head gasket and the owner then parked it for two years deciding what to do next.
Issue: I can't get it to stop ejecting coolant out of the tank's overflow.
It has a new (German) coolant expansion tank and it has a new '-04' cap on the tank, both from Pelican. I've flushed and refilled coolant and performed the usual air bleeding routine several times. If I run with the bleeder valve open, it will drizzle coolant constantly. If I rev the motor, upon deceleration it will eject a large volume of coolant. When I shut down the vehicle hot, it will dump even more coolant. If I close the bleeder valve, I will get steam coming from the overflow area when the car heats up (and it still dumps coolant).
I tried to pressure test the new tank, and I can't get it to pressurize at all. If I plug the overflow tube and just blow air into the coolant fill opening, air comes directly out of the overflow hole (what leads to the overflow tube - between the bleeder valve and the fill cap). This happens immediately -- it doesn't build any pressure first. No matter what I try, the coolant system won't hold any pressure.
Thoughts?
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07-15-2021, 08:51 AM
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#2
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Boxster in the snow
Join Date: Oct 2016
Location: MN
Posts: 7
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One other note:
The old (cracked) coolant tank seems to have the same issue. It's out of the car - if I plug all of the holes with my fingers, air just pours out the overflow hole. It doesn't build pressure at all it just comes straight out.
I'm so confused!
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07-15-2021, 09:09 AM
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#3
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Registered User
Join Date: Apr 2021
Location: Lansing, MI
Posts: 350
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sounds like head gasket to me...
it should not eject coolant at all. There might be some burp or level rise, but not spitting.
Spitting would suggest air coming through.
Not sure if that could work here, but on other cars the best test was to rev the engine (coolant would rise and spit) and let off the gas (level would drop and some coolant would be gone).
The former says gases get through the gasket, the latter suggests liquid got sucked into the engine.
If it was overheated - it is hard to judge what exactly it means.
Was it 120 C for a couple of minutes or was it 150 C and coolant was gone? Engine will work OK with coolant is even at 150 C, but the coolant must be present in liquid form.
Once it starts evaporating - well, no more cooling there.
__________________
Current rides: 2003 Porsche Boxster MT (me), 2019 Bolt LT (me), 2015 Audi Q5 (wife), 2008 VW Rabbit (2.5 inline 5, MT, well, for kid... but you now, it is the 5 straight)
Previous: 2014 Fiat 500e, 2016 KIA Forte5 SX, 2016 Fiat 500X, and some old days: Trabant, Fiat 126p...
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07-15-2021, 09:26 AM
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#4
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Registered User
Join Date: Oct 2014
Location: California Central Coast
Posts: 1,476
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The seam on the side of the coolant tank where the manifold and hose connections pass through can cause the symptoms you describe if the tank is not properly assembled from the manufacturer. It would be a major coincidence for this to be common to both tanks, but this is where I'd check first. This is where saving money and not buying a genuine part can cost more in the long run in both money and frustration.
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07-15-2021, 09:33 AM
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#5
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Boxster in the snow
Join Date: Oct 2016
Location: MN
Posts: 7
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Even if the tubes were blocked off, shouldn't the tank itself be able to hold at least a little pressure? It's boggling me that if I just put my lips on the coolant fill tube and blow, it just blows right back at me through the overflow hole. Shouldn't it hold pressure to something like 14 pounds before the overflow opens?
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07-15-2021, 09:52 AM
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#6
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Registered User
Join Date: Apr 2013
Location: Lincolnshire, IL
Posts: 446
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My coolant tank had lots of "spider cracks" that were invisible until the coolant got hot and the system's building up of pressure would cause those cracks to expand and leak all over.
Solution.....NEW TANK! (the original tank was 18 years old)
__________________
98' Boxster
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07-15-2021, 09:59 AM
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#7
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Registered User
Join Date: Jun 2021
Posts: 93
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I had major overheating issues that startedwith the thermostat.
The hot coolant cracked the heater valve and while in there we pulled the water pump which had no impeller
Blades left. Now it runs 180 to 190 on very hot 90+days
I am burping the system with the
Clip.i added some coolant but will.likely need more, that even lowered the temp a scootch. Funny too the car just runs better.
Sent from my SM-G991U1 using Tapatalk
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07-15-2021, 10:51 AM
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#8
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Registered User
Join Date: Feb 2005
Location: It's a kind of magic.....
Posts: 6,273
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Quote:
Originally Posted by MeanDrLily
Hey, all --
I'm hoping you can help me figure this out:
New to me 2000 Boxster S. Previous owner reported an overheating issue, and the water pump was replaced by a Porsche-friendly indy shop. Still had temp issues -- the shop said bad head gasket and the owner then parked it for two years deciding what to do next.
Issue: I can't get it to stop ejecting coolant out of the tank's overflow.
It has a new (German) coolant expansion tank and it has a new '-04' cap on the tank, both from Pelican. I've flushed and refilled coolant and performed the usual air bleeding routine several times. If I run with the bleeder valve open, it will drizzle coolant constantly. If I rev the motor, upon deceleration it will eject a large volume of coolant. When I shut down the vehicle hot, it will dump even more coolant. If I close the bleeder valve, I will get steam coming from the overflow area when the car heats up (and it still dumps coolant).
I tried to pressure test the new tank, and I can't get it to pressurize at all. If I plug the overflow tube and just blow air into the coolant fill opening, air comes directly out of the overflow hole (what leads to the overflow tube - between the bleeder valve and the fill cap). This happens immediately -- it doesn't build any pressure first. No matter what I try, the coolant system won't hold any pressure.
Thoughts?
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As goofy as this may sound, you need to find someone with the vacuum filling system and pull a vacuum on the system. If you have air trapped in it, it will all "burp" out under vacuum; if it does, top off the system with a 50/50 mix by using the vacuum system to pull it in.
if the system does not "burp" out any air, or refused to hold vacuum, something in the system is leaking (cracked head, etc.) and further digging is required.
__________________
“Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
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07-15-2021, 10:53 AM
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#9
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Registered User
Join Date: Jun 2021
Posts: 93
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I am a bit of the Head Gasket.
Sent from my SM-G991U1 using Tapatalk
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07-15-2021, 11:04 AM
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#10
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Registered User
Join Date: Feb 2005
Location: It's a kind of magic.....
Posts: 6,273
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Quote:
Originally Posted by alansdavid
I am a bit of the Head Gasket.
Sent from my SM-G991U1 using Tapatalk
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The head gaskets in the M96/97 are multilayer steel and actually stronger than the cylinder head or block, which is why you never see them failing.................
__________________
“Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
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07-15-2021, 11:05 AM
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#11
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Registered User
Join Date: Oct 2020
Location: KY
Posts: 1,216
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The head gasket is an easy test - buy an exhaust leak detector kit on Amazon or harbor freight. Fill the test tube up with blue dye, stick the tube on to the coolant fill port, rev the engine, and pump the ball on the test tube. This sucks gases out of the coolant tank and if there are combustion gases present it turns yellow.
FWIW I just went though a similar process. Coolant spewing EVERYWHERE from overflow tube with every drive. The burp valve was bad and needed replaced. Also, I'm convinced that I somehow overfilled the coolant system. As you pressurize the system it forces the coolant level down, and if its overfilled then there's no where for it to go but out.
You are correct though, the system should hold 1.4 bar pressure without problem. At that point the bleed valve should start to rise like a turkey timer. Around 1.8bar it will actually start to bleed of excess pressure.
Sent from my SO-02K using Tapatalk
__________________
2000 Box Base, Renegade Stage 1 performance mods complete, more to come
When the owners manual says that the laws of physics can't be broken by this car, I took it as a challenge...
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07-15-2021, 11:42 AM
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#12
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Registered User
Join Date: Jun 2021
Posts: 93
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Quote:
Originally Posted by JFP in PA
The head gaskets in the M96/97 are multilayer steel and actually stronger than the cylinder head or block, which is why you never see them failing.................
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Thank Ferry or whomever....
Sent from my SM-G991U1 using Tapatalk
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07-15-2021, 11:43 AM
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#13
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Registered User
Join Date: May 2017
Posts: 1,182
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As JFP suggested, this is going to be a good way of finding an issue. The vacuum systems to fill coolant are pretty cheap (under $100 for a decent one). Makes doing a flush & fill pretty quick too.
__________________
2000 Boxster Tiptronic
2003 Boxster
2003 996 C2 Cab
2002 996 (SOLD)
1986 944 (gone but missed)
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07-16-2021, 03:26 AM
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#14
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Registered User
Join Date: Apr 2021
Location: Lansing, MI
Posts: 350
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Quote:
Originally Posted by JFP in PA
The head gaskets in the M96/97 are multilayer steel and actually stronger than the cylinder head or block, which is why you never see them failing.................
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What if the head is warped due to overheating?
There is no good information evidence what the previous owner experienced/did.
__________________
Current rides: 2003 Porsche Boxster MT (me), 2019 Bolt LT (me), 2015 Audi Q5 (wife), 2008 VW Rabbit (2.5 inline 5, MT, well, for kid... but you now, it is the 5 straight)
Previous: 2014 Fiat 500e, 2016 KIA Forte5 SX, 2016 Fiat 500X, and some old days: Trabant, Fiat 126p...
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07-16-2021, 03:38 AM
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#15
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Registered User
Join Date: Feb 2005
Location: It's a kind of magic.....
Posts: 6,273
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Quote:
Originally Posted by PLP
What if the head is warped due to overheating?
There is no good information evidence what the previous owner experienced/did.
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These heads tend to crack before they warp.
__________________
“Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
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07-16-2021, 04:42 AM
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#16
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Registered User
Join Date: Jun 2021
Posts: 93
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Thankfully mine never leaked, but at its peak temp.it blew coolant out the cap.most drained.i have added a new cap, but the Tech told me the cap.I had was fine.
Sent from my SM-G991U1 using Tapatalk
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07-26-2021, 08:07 AM
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#17
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Boxster in the snow
Join Date: Oct 2016
Location: MN
Posts: 7
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Hey, folks -- just wanted to close the loop on this in case this turns up in someone's future search.
The problem ended up being a faulty coolant expansion tank. There was a small gap in the seal, letting pressure escape through the overflow passage. Replaced it with a new (Porsche OEM) tank and all is good.
The tank replacement job sucks bad on it's own, doing it twice is just adding insult to injury. If you have to do this job, get the OEM part!
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