Boxster Coolant (pressurising?) & escaping through overflow.
Discussion
Hi everybods.
Recently bought 2000 Boxster S. Love it to bits but ive just discovered that even if the coolant is topped up to minimum i have noticed that with the engine running
the water level rises until it runs out through the overflow. just topped it up with eight pints after 20 miles. Any ideas out there ?
Recently bought 2000 Boxster S. Love it to bits but ive just discovered that even if the coolant is topped up to minimum i have noticed that with the engine running
the water level rises until it runs out through the overflow. just topped it up with eight pints after 20 miles. Any ideas out there ?
Sounds like gasses are pressurising the water system, only way this usually happens is a cracked cylinder liner or head gasket failure, you need to get it to a specialist to pressure test the system BUT DO NOT drive it until you have found out the problem or you could cause a lot more issues. Sorry for the bad news.
glenokehhewitt said:
Hi everybods.
Recently bought 2000 Boxster S. Love it to bits but ive just discovered that even if the coolant is topped up to minimum i have noticed that with the engine running
the water level rises until it runs out through the overflow. just topped it up with eight pints after 20 miles. Any ideas out there ?
I had this on my old Lotus Elan many years ago and it turned out to be the cylinder head gasket. As already said, would suggest getting it to your Porsche Indie ASAP.Recently bought 2000 Boxster S. Love it to bits but ive just discovered that even if the coolant is topped up to minimum i have noticed that with the engine running
the water level rises until it runs out through the overflow. just topped it up with eight pints after 20 miles. Any ideas out there ?
What do you mean that it runs out through the overflow? Is it escaping from the cap? If so, the first and cheapes thing to do is replace the cap. Cheap from dealers.
If the cap doesn't hold the pressure, the water level will rise as if you hadn't had the cap on. Similarly if the expansion bottle is cracked.
If you have AA membership, or a locak friendly garage, you can get a sniff test done to see if you have a gasket issue, but its very likely that the cap or bottle are faulty
If the cap doesn't hold the pressure, the water level will rise as if you hadn't had the cap on. Similarly if the expansion bottle is cracked.
If you have AA membership, or a locak friendly garage, you can get a sniff test done to see if you have a gasket issue, but its very likely that the cap or bottle are faulty
before you panic about head gaskets, remember that the expansion tank in the boot splits and leaks - its a very common fault on these cars.where are you finding the leak? is it under the boot carpet? if so, thats textbook for this fault.
Also, has been said cars had an updated coolant cap fitted in 2003 or so due to failures under pressure on the early ones.
Check a Boxster FAQ for the number that it should read on the cap to tell if it is new or old.
Also, has been said cars had an updated coolant cap fitted in 2003 or so due to failures under pressure on the early ones.
Check a Boxster FAQ for the number that it should read on the cap to tell if it is new or old.
Wadeski said:
before you panic about head gaskets, remember that the expansion tank in the boot splits and leaks - its a very common fault on these cars.where are you finding the leak? is it under the boot carpet? if so, thats textbook for this fault.
Also, has been said cars had an updated coolant cap fitted in 2003 or so due to failures under pressure on the early ones.
Check a Boxster FAQ for the number that it should read on the cap to tell if it is new or old.
Assuming the boxster cap is the same as for a 996, then a part number ending 00 is the old design. The latest cap part number ends 04 and is about 14 pounds .Also, has been said cars had an updated coolant cap fitted in 2003 or so due to failures under pressure on the early ones.
Check a Boxster FAQ for the number that it should read on the cap to tell if it is new or old.
Thanks for your replies guys. The way my luck is running i suspect a dodgy head gasket i have very steamy exhaust from start until engine warms up.the the fluid filling compartment gets quite sweaty so i,ll be changing the filler cap first.It figures that ther would not be an overflow pipe if the coolant is in a pressurised system but there is deffinately an open pipe in offside rear wheel arch
which passes water.Its just in front and below the coolant resavoire.
which passes water.Its just in front and below the coolant resavoire.
Don' replace cap and expansion tank just yet or assume that worst like head gaskets or piston liners etc etc.
Go into the rear compartment where you pop oil and fluids in. Remove the oil filler cap and oil dipstick, and coolant cap. Then remove the oval plastic part that sits within that recess[
url]
|http://thumbsnap.com/NGbkJ739[/url]
This is what you will see.
There will be an additional round receptical under that plastic oval one with bolts and what looks like a ring pull. Get your coolant ready baring in mind a Boxster will swallow up I think 18litres or there abouts. Pop the dipstick and oil cap back on, or you'll get covered in oil on next step.
Start car and switch the heaters up to HI and full on. The heater matrix is the highest point in the system.
Right the ring pull needs to put in the up position, which is the bleed/purge valve. Fill the expansion tank to the maximum, and get someone to hold the revs around 2500-3000 rpm, until the car reaches the point of expansion. Do all this with coolant cap off. The coolant system will purge itself of air. Porsche are a nightmere if there is a slight bit of air in the system, and what happens is the air will shoot the water out the right rear wheelarch just in front of the drive shaft. It is just expanding and has nowhere to go. You will probably see some steam when opening the rear boot above the coolant cap as the cap has a valve in too with o-rings. When you let car rest a idle you can fans, the fans should now come on and fluid should drop in tank, top up.
Now pop the ring pull down and make sure coolant is at maximum and take for a drive like you stole it, then let the car rest on drive and check level after it has cooled down and then top up to maximum. As a side note you shouldn't use tap water as a rule and use distilled water with a 50% mix of a coolant like Febi which is purple/pink.
What has probably caused this, especially on Boxster S and some 996s is the vents to the radiators at front are struck by debris, twigs, leaves and even birds. The Debnis causes moisture and corrosion and tiny holes along the bottom edge of side radiators, where there is a rubber seal on bumper and you'll loose tiny amounts of coolant but you'll top it up, which is where you'll introduce air into system over the period and then suddenly it won't cope and dump a large amount of coolant in a car park.
As a second side note always clear the radiator vents as often as possible.
There you go, easy fix
Go into the rear compartment where you pop oil and fluids in. Remove the oil filler cap and oil dipstick, and coolant cap. Then remove the oval plastic part that sits within that recess[
url]
|http://thumbsnap.com/NGbkJ739[/url]This is what you will see.
There will be an additional round receptical under that plastic oval one with bolts and what looks like a ring pull. Get your coolant ready baring in mind a Boxster will swallow up I think 18litres or there abouts. Pop the dipstick and oil cap back on, or you'll get covered in oil on next step.
Start car and switch the heaters up to HI and full on. The heater matrix is the highest point in the system.
Right the ring pull needs to put in the up position, which is the bleed/purge valve. Fill the expansion tank to the maximum, and get someone to hold the revs around 2500-3000 rpm, until the car reaches the point of expansion. Do all this with coolant cap off. The coolant system will purge itself of air. Porsche are a nightmere if there is a slight bit of air in the system, and what happens is the air will shoot the water out the right rear wheelarch just in front of the drive shaft. It is just expanding and has nowhere to go. You will probably see some steam when opening the rear boot above the coolant cap as the cap has a valve in too with o-rings. When you let car rest a idle you can fans, the fans should now come on and fluid should drop in tank, top up.
Now pop the ring pull down and make sure coolant is at maximum and take for a drive like you stole it, then let the car rest on drive and check level after it has cooled down and then top up to maximum. As a side note you shouldn't use tap water as a rule and use distilled water with a 50% mix of a coolant like Febi which is purple/pink.
What has probably caused this, especially on Boxster S and some 996s is the vents to the radiators at front are struck by debris, twigs, leaves and even birds. The Debnis causes moisture and corrosion and tiny holes along the bottom edge of side radiators, where there is a rubber seal on bumper and you'll loose tiny amounts of coolant but you'll top it up, which is where you'll introduce air into system over the period and then suddenly it won't cope and dump a large amount of coolant in a car park.
As a second side note always clear the radiator vents as often as possible.
There you go, easy fix
Edited by stacy.chandler77 on Tuesday 28th March 21:24
Edited by stacy.chandler77 on Tuesday 28th March 21:25
Edited by stacy.chandler77 on Tuesday 28th March 21:32
Edited by stacy.chandler77 on Tuesday 28th March 21:35
ohhhh yes after 7 years i have the same prob , when my RPM up to 3000 , all water come out from the cap tank , if i drive all day less then 3000 rpm , my car is normal what ever traffic hours driving no overheat no nothing , when i touch 3000 all water coming out , and till now no one can help me about this , its boxter 2006 , ichange radiator , water pump i change tank reservoir , water bleed ring , just the cap i dint change it yet
It's just the physics of the system; you have four high points in it: header tank, heater matrix and radiators (left and right) and it holds up to 28 litres!! The system works fine if bled properly and there are no leaks (obviously?!?), there is a vacuum bleeder that is used now to remove any air from the system and flush in coolant - before that, various ways were possible:
- Jack up the car making the header tank the highest point
- Fill and rest, fill some more, rest and fill some more
The most succesful way - if there is no access to a vac bleeder system is as described previously; I will redescribe as I haven't read it for a while! Works on all 9x6/9x7:
- Cap off; from cold, fill the header tank with premixed coolant (50:50)
- Fill until the header tank is full
- Open the bleed bow (the wire loop on top of the expansion tank) it remains vertical when 'open'
- Fill the header tank again until 'Max" is reached
Ensure you have enough coolant and water for the next bit a watering can full at least - maybe more. Also; get helper/throttle stop or in the last resort a brick for the next bit:
- You (or get helper to); start the engine, run at idle for 20-30 seconds; enough time for you/them to set heater to max, vents to centre and fan speed 1/2 way; AC OFF!
- Bring revs to 3500rpm (look sternly at helper and tell them not to lift off until you tap them on the shoulder!!!! OR; position brick.....
- Fill the header tank to max
- Watch as coolant is drawn into the system in a swirly bubbly manner; topping up as/when necessary
- Once no more coolant can be filled, flip the bow over to 'close' it - the coolant will drop again - top up to max/top of the bottle
NEXT IS THE CAREFUL PART:
- Fit the coolant cap - DO NOT CROSS THREAD IT!!
- Tighten cap fully
- Tap helper on the shoulder / remove brick
- Check bleed bow - will likely be lifted off its seat by the system pressure.
- Run engine to operating temp; let rad fans cycle (AC OFF or fans will be on already and the engine will take an age to warm up!)
- Switch engine off and recheck level when COLD - bring back to Max if required.
- Jack up the car making the header tank the highest point
- Fill and rest, fill some more, rest and fill some more
The most succesful way - if there is no access to a vac bleeder system is as described previously; I will redescribe as I haven't read it for a while! Works on all 9x6/9x7:
- Cap off; from cold, fill the header tank with premixed coolant (50:50)
- Fill until the header tank is full
- Open the bleed bow (the wire loop on top of the expansion tank) it remains vertical when 'open'
- Fill the header tank again until 'Max" is reached
Ensure you have enough coolant and water for the next bit a watering can full at least - maybe more. Also; get helper/throttle stop or in the last resort a brick for the next bit:
- You (or get helper to); start the engine, run at idle for 20-30 seconds; enough time for you/them to set heater to max, vents to centre and fan speed 1/2 way; AC OFF!
- Bring revs to 3500rpm (look sternly at helper and tell them not to lift off until you tap them on the shoulder!!!! OR; position brick.....
- Fill the header tank to max
- Watch as coolant is drawn into the system in a swirly bubbly manner; topping up as/when necessary
- Once no more coolant can be filled, flip the bow over to 'close' it - the coolant will drop again - top up to max/top of the bottle
NEXT IS THE CAREFUL PART:
- Fit the coolant cap - DO NOT CROSS THREAD IT!!
- Tighten cap fully
- Tap helper on the shoulder / remove brick
- Check bleed bow - will likely be lifted off its seat by the system pressure.
- Run engine to operating temp; let rad fans cycle (AC OFF or fans will be on already and the engine will take an age to warm up!)
- Switch engine off and recheck level when COLD - bring back to Max if required.
Hello Porsche people.
Looking for some info related to this thread. 2004 996 C4S, circa 50k
Following a cooling inlet hose failure. Replaced hose and fitted a low temp thermostat. After a few days of venting system it is now water tight, level and temperature are stable at around 75 degrees C. However the vent/purge valve on top of the expansion tank is open when the engine is up to temperature. Closes when cool.
Does anyone know if this is normal?
Any advice most appreciated.
Many Thanks.
Looking for some info related to this thread. 2004 996 C4S, circa 50k
Following a cooling inlet hose failure. Replaced hose and fitted a low temp thermostat. After a few days of venting system it is now water tight, level and temperature are stable at around 75 degrees C. However the vent/purge valve on top of the expansion tank is open when the engine is up to temperature. Closes when cool.
Does anyone know if this is normal?
Any advice most appreciated.
Many Thanks.
Caledonian said:
Hello Porsche people.
Looking for some info related to this thread. 2004 996 C4S, circa 50k
Following a cooling inlet hose failure. Replaced hose and fitted a low temp thermostat. After a few days of venting system it is now water tight, level and temperature are stable at around 75 degrees C. However the vent/purge valve on top of the expansion tank is open when the engine is up to temperature. Closes when cool.
Does anyone know if this is normal?
Any advice most appreciated.
Many Thanks.
Seems to be normal:Looking for some info related to this thread. 2004 996 C4S, circa 50k
Following a cooling inlet hose failure. Replaced hose and fitted a low temp thermostat. After a few days of venting system it is now water tight, level and temperature are stable at around 75 degrees C. However the vent/purge valve on top of the expansion tank is open when the engine is up to temperature. Closes when cool.
Does anyone know if this is normal?
Any advice most appreciated.
Many Thanks.
https://rennlist.com/forums/996-forum/931286-bleed...
I’ve never noticed it in the up position on mine though!
I had a similar problem with my MY99 996.1 C4. Everything was fine until it warmed up then I would get some very worrying steam coming from the back.
The AA couldn't work it out although they pressure tested the cap and all was ok. I took it to indy Autostrasse in Coggeshall Essex - they found a hairline crack in the reservoir. So from cold all is ok, then engine warms up and the thermostat opens and its routed through cooling the engine. This additional pressure shot water out of the crack onto the exhaust...
Was fixed 5-8 years -,no problems since.
Good luck
The AA couldn't work it out although they pressure tested the cap and all was ok. I took it to indy Autostrasse in Coggeshall Essex - they found a hairline crack in the reservoir. So from cold all is ok, then engine warms up and the thermostat opens and its routed through cooling the engine. This additional pressure shot water out of the crack onto the exhaust...
Was fixed 5-8 years -,no problems since.
Good luck
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