Coolant System Flush

[kdanh]

Hello Everyone...

I have 99 boxster and it has almost 60K miles. About a month ago, I check the coolant level and incorrectly tighten the cap. The coolant evaporated as I drove and the temp. gauge light blinked. I temporarily top-off with the Firestone coolant. The Porsche dealer, Reeves Import of Tampa, FLorida, asked for $200+ tax for the system flush. They recommended to let them do it because it would required to bleed which meaning release the air pockets in the radiator. Has anyone flush the system before? Does anyone have the DIY instruction? If I'm getting the pink coolant from VW/Audi, how many gallon will I need?

Thanks in advance.

[djantlive]

Not sure how much coolant you need but your manual would have that info. It's got to be several gallons. You might have to fill up the coolant several times after the flush to completely get it filled. Air trapped in the lines will be removed after a few minutes of idle. You will then fill and repeat this several times. I think P car coolant is pretty expensive so $200 is probly not much more than parts cost.

[Loren]

Coolant capacity is listed in the back of your owners manual by model and transmission type. For instance a manual transmission is 18 liters and a Tiptronic is 19 liters. Porsche and good independent shops need to remove several plugs and a couple hoses to completely drain the old coolant. When adding the new coolant the only way to do it without introducing air into the lines is to draw the coolant in by vacuum. Good shops have this setup. If it is not done that way you will likely have air problems for several weeks and perhaps even overheat the engine. You may want to just take it to a shop that has the proper vacuum setup.

[fil756]

loren is right. the best way to flush the system is with the right equipment but there is a way to do it without.

There is actually a bleeder valve under the black cover that surrounds the oil fill neck and the top of the coolant reservoir. i flushed my 98 boxster a while ago for 30k service and ill try to remember as accurately as i can what i did... so here goes

take off the oil fil cap and coolant cap and pry up the black plastic piece that sits at the bottom it should come out with a little work. under the plastic is a round black plastic thing with a metal clip on top. pull up on the metal clip and it will release the trapped air in the coolant system. you will have to fill and pull it repeating this several times to alow the air to escape for enough room to add coolant. when the coolant level doesnt go down anymore cap off the oil and coolant reservoir and go for a test drive. as you drive it will cause more air bubbles to surface and thus turns on your coolant light on the dash. stop fill and bleed the system a couple times. BE CAREFUL the coolant will be hot and under pressure. bleed it slowly before removing the cap. fill it up and keep driving. this will probably happen several times before the light will not come on anymore. when you think you got all the air out make sure to top off the coolant reservoir.

i would recommend using porsche coolant. it is formulated for porsche engines and the metals and alloys in them. i think the coolant is about $40 a gallon. but you will mix it half and half with water. i would also recommend using distilled water to reduce deposits from forming in the system due to calcium and other sediments. after all it is a porsche and it should be treated like one.

let me know if you need any more help

phil

[Tool Pants]

Have you had any problem with your cooling system after the top-off? And about how much did you put in?

[WeekendWonder]

Isn't the air bleed valve designed to allow air to escape automatically? As in leaving the metal clip in the horizontal position?

[CJ_Boxster]

Isn't the air bleed valve designed to allow air to escape automatically? As in leaving the metal clip in the horizontal position?

I dont think its a one-way valve, when its open and the coolant cools, it will suck air back in the if the metal clip is in the up position.

Ohhh sorry, i see what your saying, and i dont think its made that way cause if that were true, what would stop the coolant from flowing out with the air... plus if it did automatically expell air, it would cause lots of condensation in and around that area under the trunk lid.

[Loren]

I dont think its a one-way valve, when its open and the coolant cools, it will suck air back in the if the metal clip is in the up position.

It has a membrane so it is in fact a 1 way valve. Pressure normally pushes the valve open and air escapes through the membrane but not liquid. Cup cars run with the valve open all the time.

[WeekendWonder]

Be gentle I'm a newb :rolleyes: - just debating what the purpose of the metal clip is. When the clip is vertical I understand it's forcing the valve in to the open position. I'm 'assuming' (dangerous!) that allows air out with the need for excessive pressure build up? If that's right, why would you want to let air escape if the pressure isn't high enough to push the valve open?

Edited August 1, 2007 by WeekendWonder

[Loren]

You open the bleed valve when there has been air introduced into the system - like after a hose change or a radiator replacement.

It is not intended for a coolant flush procedure. For a coolant flush the new coolant needs to be drawn into the engine/system using a vacuum device. This is only way to assure that you don't get air trapped in the system somewhere when refilling or flushing the complete system.

[WeekendWonder]

You open the bleed valve when there has been air introduced into the system - like after a hose change or a radiator replacement.

It is not intended for a coolant flush procedure. For a coolant flush the new coolant needs to be drawn into the engine/system using a vacuum device. This is only way to assure that you don't get air trapped in the system somewhere when refilling or flushing the complete system.

Thanks Loren that's clear now. :)

[klueless7571]

I'm about to replace the coolant in my 2002 Boxster (I mixed green coolant into the system when the light started blinking). I've already replaced the 2 O-rings in the coolant bleeder valve, and the coolant cap to the .01 version because I was loosing coolant (tank is still intact). However, I noticed that the coolant bleeder valve is held open all the time due just from pressure within the system. The only way to shut the valve is by opening the coolant cap to release the pressure. The little metal wire is always in the closed (horizontal) position. However, after I run the car, pressure within the system pushes the valve opened again and it stays that way even after the car cools overnight. Is this normal? or do I need to replace the coolant bleeder valve?

Derek

Edited July 5, 2008 by klueless7571

[klueless7571]

anybody knows how the coolant bleeder valve is supposed to work?

Derek