Coolant Flush

Time to flush the coolant - is this a DIY, dealer or independent project? Suggestions?

According to Porsche coolant flushes are unnecessary. The fluid is "lifetime", but in this case the lifetime in question is that of the water pump, radiator, or hoses. If any of these fail you must replace he coolant as part of the procedure. I've never seen the drain & fill procedure documented.

Coolant will need to be flushed and fille with a vacuum system, that will draw out the old fluid and fill with new without any air bubbles. I believe Snap On tools carry the vacuum system you will need.

Best done at least every 4 years. Lifetime coolant is BS. Well, not exactly.... BS. It is lifetime coolant. Lifetime of the coolant. You won't know what this is until the water pump bearing fails, or a radiator develops a leak, or the oil cooler develops a leak. That's an expensive way to know you should have changed the coolant a year or two earlier. BTW, when's the last time you have the brake fluid flushed and the system pressure bled? And had the tranny/diff fluid changed? Coolant change is a bit of job cause it is hard to refill sysem with no air pockets. Both times I've had my '02 Boxster's coolant changed I had it done at dealership. 1st time was after I hit some road debris and busted a radiator and lost coolant. 2nd time was when water pump failed (at nearly 200,000 miles). Sincerely, Rockster.

Re: Best done at least every 4 years. Lifetime coolant is BS. Well, not exactly.... Why is it "time for a coolant flush"? Where did that come from?

I've been hoping someone would post an article detailing the procedure before I have to approach it.

It is a number I pulled out of my hat. Still a good number much better than... leaving the stuff in the engine for a lifetime, or at least what people interpret this to mean. Lifetime of the car when in fact it is the lifetime of the coolant, whatever that is. That 4 years number based on when it was easier to check/view the coolant noting when the coolant's color starting changing. Might be a way to analyze the stuff but who wants to bother? How frequently does one have to analyze the coolant? Every year then every 6 months then every 3 months then every month until one has wrung the last bit of life out of the stuff? No thanks. Frankly my goal is not to wring the maximum service life out of a few bucks worth of coolant but to maximize the life of a very critical cooling system that plays a vital role in keeping a very expensive collection of parts cool and operating efficiently. Dealing with the problems that will arise from a leaking cooling system arising from running coolant past its replace by date will make the savings one has "gained" by not spending a few bucks for a cooling system drain and refill seem silly. Sincerely, Rockster.

My advice would be to have a dealer or trusted indy shop do the ... coolant drain/refill. Be sure the indy shop (or dealer) uses the neat tank for this. The tank that holds the proper amount of pre-mixed coolant. The tech turns on a vacuum pump and pulls a vacuum in the drained cooling system. Enough so I've been told the rubber cooling hoses collapse. He then turns off the vacuum and opens the valve that allows this vacuum (pressure diff) to force that coolant into the cooling system. No air pockets. And no having to start and run the engine at fast idle until coolant hot enough to flow past thermostat and make enough room to add more coolant. This technique documented in the Bentley manual but frankly I think it Boxster or Cayman engine torture. Both times I had my '02 Boxster's cooling system done by the tank method and afterwards I've not had to top up or add any coolant. System comes back to me fully air pocket free. Beautiful. And place that does the drain/refill has to dispose of the old coolant. Another technique I've read about but haven't tried -- circumstances required a coolant change before I could try this technique -- is to use hose clamps to pinch closed the radiator hoses to keep coolant in the radiator hoses and radiators then open the engine coolant drain valve and drain 1 or more gallons of old coolant from engine. Close drain valve and then add new coolant mixed properly with distilled water until system full. Remove hose clamps. Start and run engine until hot and top up coolant if level low. This replaces approx. half the old coolant with new and thus the corrosion resistance is improved. Do this every year, 18 months, 2 years -- you pick an interval you like -- and the cooling system essentially maintains a pretty high level of corrosion resistance without the expense/trouble of changing the entire cooling system contents. But if you want to do a full drain/refill yourself...IIRC check out www.mikefocke.com site and follow the links to a cooling system drain/refill DIY link. Sincerely, Rockster.

Any connection between your user name and your interest in changing the coolant?

GB - You are Wicked............... (But Correct...) Wish I Had Thought of That Answer.... But................ Perhaps - Changing Underwear........... Strikes a Chord....

My apologies if I offended anyone. I didn't mean to. I was seriously trying to ascertain if maybe he was goofing around. Urban Legend, welcome to the club. Seriously. Today's coolants are very good and when used in an all aluminum engine they last very long, as suggested by the term 'lifetime' used by the factory. That being said, I don't think I'll be leaving mine in for the life of my car. But I doubt I'd consider changing it out any time before say 60,000 miles. Is there a reason you feel yours needs replacement? I am not a fan of replacing fluids unnecessarily because disposal of those fluid often has environmental impact. I like to be careful about the waste that I generate.

Hmmm..... I can't see any reason why a Porsche , or any car for that matter, should use any coolant. It's a closed system. The only way for coolant to vanish is through some sort of leak, or through the pressure relief valve if overheated (still a leak, just a planned controlled leak). In the case of the BMW on the track, I could assume that maybe the track use created temps that you never see on the street, causing the coolant to expand more than usual, and causing the relief valve to vent some off. Then it cools, contracts, and you're low. But that scenario would leave visible coolant somewhere (unless it's happening while the car is in motion, more like to happen after it's turned off). If you're not seeing any coolant, and the car is truly consuming coolant, than the only place I can imagine being consumed is around the head gasket into the combustion chamber. That's not good and if left unchecked it will destroy the engine. To me, loss of coolant = cause of concern.

The reason to flush a cooling system, periodically, comes from having cast iron engine blocks. Cast iron exposed to water leads to rust. Rust ocludes water passages. Then the engine overheats. In addition, sometimes the electrical circuit can be poorly grounded, causing electrolysis to take place, gradually dissolving the radiator core, water pump impeller, etc. So, annual flushing gets all that crud out of the system. If the coolant in a system doesn't have an effect on the materials of the system, then there isn't any need to replace the coolant. If the coolant breaks down, then maybe it doesn't work any more??? Water pumps fail because either a seal wears and lets coolant get to a bearing, thereby causing failure. Or weight/tension on the shaft can cause bearing failure. Unless the system is leaking or performing incorrectly, there isn't any reason to mess with it IMO.

I'm on that page too, which is why I'm doing a Blackstone analysis on my next oil change. I'm also anxious to see if the CS uses more coolant or stops. One theory a friend has is that the CS was delivered with small air pockets in the cooling system, and over time they work their way out, so the coolant level falls. This might explain why so many members have had to add coolant when their cars are new, or not. If his theory holds water (ha!) then coolant usage should trail off and stop. We'll see! On the other hand, if some coolant usage is somehow unavoidable a flush isn't a bad idea, because that means the system isn't perfectly sealed.

Gator: In my case, I went to one "Driving Event", came home with a stuck thermostat. Got that fixed then went to another "Driving Event" at the same track 250 miles from my house, and the water pump failed after a day of tire and brake shredding. I had been seeing coolant loss for a while. I read that the expansion tanks on these cars have been known to crack, so I bought one and had been thinking the little bit of coolant I was losing (and seeing traces of on the engine for the last 10 or so DE's) was caused by the tank. What I now think is that the seal on the water pump had been marginal and the coolant was coming out of there. Tank didn't leak. My point is same as yours, if it's leaking, something is wrong. At DE's, my car never gets hot. Always in the middle of the temp gage. Really hot with A/C on stuck in traffic it might get up to almost 3/4 but never higher...until this failure. By the way, retrieved the car this weekend and all is well again. No leaks. Coolant is topped up and stays topped up. Don't assume that it's "Normal" for a liquid cooled engine to use coolant. It's not. -TB

Blueone: 3 pints of coolant is a LOT. That's more than "working bubbles out of the system". I'm pretty sure you have an issue of some sort here. Oh, and my head gasket is OK. The coolant was definitely coming out into the engine bay, not out the tail pipe. I don't know who this BMW expert is, but if you tell him you lost 3 pints of coolant in 7K, I think he'll agree that something has got to give on this. Good luck and watch that temp gage. Hope you find the answer before it gets to the point mine did. I'm happy my engine is still solid. I think I was pretty lucky on that score. FYI: BMWs of my vintage have iron blocks and aluminum heads. The new blocks are aluminum/magnesium alloy. I believe Porsche has used all aluminum alloy blocks with Nikasil (or whatever they call that coating in the cylinder walls nowadays) for quite a long time, correct? I owned an '83 911SC for a while.

The only time I had a coolant flush done was on my gf's subaru, we thought it was time at 10 years and 80k miles. One week later the head gasket blew and the engine was toast. Shop was a subaru specialist so it was hard to blame them, anyway we had no proof that they caused. I'd be very leery of an unnecessary flush since that bad experience. My guess is, if we hadn't messed with it, that car would still be fine.

The first pint was clearly factory underfill, as the car had 40 miles on it. Out of curiosity, mostly due to this thread, I checked the coolant level last night, and the level was perfect, after ~2000 miles since the last check. I have no idea if my friend's air pocket theory is true, but it's looking better. I'm also anxious to do the Blackstone oil analysis coming up. Considering the numerous folks that have posted in the past about having to add coolant when the car was nearly new, I'm not too concerned yet. Realtime data from OBD2 also shows no cooling issues. (Ignore the coolant temp gauge, it lies.)

Very cool. Glad you got your baby fixed up... :cheers: I agree. A modern liquid cooled engine should not consume coolant.

With sealed, pressurized coolant using ethylene glycol even iron doesn't rust. Where is the oxygen going to come from? Before the advent of sealed systems what you said is true, but aluminum oxidizes too. The last iron block I had, a BMW M Coupe, did not have any rust in the cooling system.

hey guys no offense taken - and yes urban_legend does indeed have something to do with the car (but not me). As it turns out before I could do the flush my coolant pump failed badly. The entire shaft came loose and the s-belt just flew off. The only warning I had was a little ping or knock on start-up and then the altenator light coming on. Lost a lot of coolant and steam came out of the right vent. So not good. I am going to replace the pump, coolant and s-belt and hope for the best. I could use a little luck with the 'legend".

Any idea why that happened. It is an unusual occurrence as described. Any details or speculation? Flushing the coolant would not have prevented what you suffered. Here is some wishing for better luck.

Wow.... First time I've ever heard of that happening. Sounds like a catastrophic failure of the water pump. In fact, I've never heard of this happening to any car with any mileage. What year is your car, and how many miles are on it?

What I found very unusual - was the car was running very quiet. In fact do to a repair of the top (torn rear window) - I replaced the s-belt and was running the engine without the engine cover or carpet. Just to listen for any odd sounds or squeaks from the new belt. Then about 200 miles later a small ping or knock on start-up. Then 15 miles later the battery warning light. Then a thump - but no other warning lights. Was not pushing the engine just a sunday drive at 65-75mph. No more sound so made it home (another few miles) and then when pulling into the drive way - steam from the right vent. Upon inspection - pulley and shaft are competely loose from the pump. S-belt is off. Some coolant in the plastic under carriage - I assume it cam out the pump. Looks like impeller is shreaded. Car has 92K miles w/ limited service history - last dealer records are 2-3 years old - original pump - green colored coolant - new s-belt - and it looked a hose is new with a new clamp (maybe a prior draining.) So I will change the pump and gasket and go from there. Any advice - words of experience is appreciated.

Did you check the new belt against the old belt to make sure they were the same size? I have often seen water pump and/or alternator damage following a belt replacement. That can happen if the belt is too small, which creates extreme pressure on the water pump bushing and/or alternator bearing. Sometimes a new belt can worsen an already worn out water pump because the new belt isn't stretched out like the old one, so there is a bit more pressure on the bushing after replacement, a bushing that is already worn but not really leaking because the old belt is not applying a lot of pressure. In the old V belt days, many people would destroy their water pumps by tightening a worn V belt that was sqweeling (the proper thing to do would be to replace the worn belt).

New belt was a gator belt - correct size and not too much trouble putting it on. (Other than it helps to have three hands to do it.) Then just release the tensioner so for a boxster not sure how it could have been a belt issue. Pump was original at 92K miles so I am not suprised it failed. What shocked me was how it went from good (no noise, no leaking - unless it fell in the plastic and never hit the garage floor) to a pile of rubble in 15 miles. And only warning light was the battery. So i was thinking altenator problem while driving.

I used the Uview airlift tool to refill my Cayman after changing the thermostat. It was a semi-religious experience as it completely filled the system with no topping up required. The unit was ~$100 on Amazon and is driven by your air compressor.