I don't understand the coolant bleeder/tank system
 

On my American vehicles there is a pressurized expansion tank at the high point of the cooling system. There is no bleeder valve, just a medium size hose entering at the base of the tank and there is no bleeding during refilling. Just keep adding coolant until you get to the right level recognizing some air will migrate to the tank at first and you might have to add a little more coolant.

Therefore I don't understand the reason and function of the Boxster system. Why are there two "caps"? If you never touched the bleeder would any entrapped air move into the pressuized tank? What does the diaphram inside the bleeder do?

I'm considering a coolant flush and replacement on the 2000 S I bought a couple of months ago. I just want to understand the system before I start working on it and have never encountered a separate bleeder except I have seen distinct bleeders on the motor plumbing when the up and down routing of hoses and components left an isolated high spot in the system. My 1990 Thunderbird had a bleeder vent on the motor.

If you don't have a Bentley book but plan on working on the 986, I'd get one. The procedures, photos and tips are really very good in preparing for any work. I'm confident it's covered step by step, I've looked at it but it was a while ago.

The reason for the bleeder assembly is quite simple: Large sections of the cooling system lie below the coolant levels inside the engine. As such, air can become trapped, particularly in the radiators way up in the front of the car, causing poor cooling, “hot spots”, and associated steam pockets, which lead to further air entrainment and potential engine damage. There are two possible ways to get the air out; the easiest, fastest, and most effective is to pull a vacuum on the system which will immediately purge all traces of the air; but what happens if you do not have a vacuum filling tool, or are stuck out on the side of the road with air in the system? You add a mechanical bleeder as high up in the cooling system as possible, which is where the tank is located. Manually open the bleeder and the system is running at atmospheric pressure and trapped air can vent as the coolant circulates.

Believe it or not, most hot water home heating systems have a similarly functioning device for the exact same reason………..

A long time ago I was a licensed plumber and worked on many hydronic heating systems, including their expansion tanks and air separator valves. I guess that experience adds to my confusion of the Boxster system. The large hydronic heating plants have a specialized fitting that swirls the fluid inside like a little cyclone. The air is lighter and stays in the center and at the top of the center of the fitting is a discharge line that leads to the expansion tank(s). That line is left open all the time and you get air out of the system by venting the expansion tank. But I digress.

Say there was no separate bleed valve on the Boxster. A tee fitting on the highest coolant hose directs a new hose into the bottom of the expansion tank. It seems to me such a system would work (as it does on my Corvette). Think of the Boxster bleed being open all the time with the discharge line plumbed into the pressurized plastic tank.

I'm not trying to argumentative. I enjoy thinking through why engineers choose one solution over another and I want to understand why Porsche used the design found on our cars. Especially since I've never seen it on any other car I've owned.

One function for the bleeder that you are overlooking is that it also is part of the coolant overflow vent, the one that pukes coolant onto the ground under the car when there is an issue. Yes, it is overly complicated, but that is just some of the “charm” or owning a Porsche. As for the “where’s and why for’s” of the chosen design, just remember that these are the same guys that created the AOS system as a substitute for the $3 PCV valve most OEM’s use………… :rolleyes:

I've seen this Uview vacuum refiller tool on ebay:

uview tool

Do you need to buy a vacuum pump separately? Hopefully a vacuum won't implode the coolant resevoir, or cause other problems. That would suck (so to speak).

you don't need a vacuum pump for that tool, but you do need an air compressor.

Here's something similar, but cheaper:

http://www.tooltopia.com/uview-550500.aspx?utm_source=shoppingdotcom&utm_medium=c se&utm_term=UVU550500&utm_campaign=shopping_r1

Anyone have experience with these or want to make any recommendations? I was hoping Pelican might have something, but if they do I couldn't find it.

The 550000 is a much better unit, comes with adaptors to fit anything and is made out of solid brass rather than molded plastics. For the extra $20 or so (Amazon.com) than the $79 plastic unit, you have a much more flexible and long lived tool.................. It is also the same tool Porsche sells for over $500.....

http://ecx.images-amazon.com/images/...500_AA300_.jpg

We use these just about everyday in the shop, and on everything from 986/987's to motorcycles. And, no, the vacuum will not collapse the tank........

What kind of psi and cfm do you need from your compressor?

As it creates vacuum by air flow over an eductor nozzle assembly, it depends more upon volume rather than pressure. As such, any level of flow will do, the higher the flow rate, the faster it develops vacuum; but it always gets to the same level (24-27 inches). The manufacturer recommends at least 90 psig air delivery for optimum performance with larger volume cooling systems, such as Porsche’s. It is a neat tool, and it will pull a totally empty Boxster cooling system down to around 25 inches of vacuum in about 90 seconds, and then refill the system in about 3-5 min., leaving absolutely no air behind. And, as mentioned earlier, it will work on any cooling system. Real time saver around the shop and no “come backs” due to trapped air or coolant levels dropping later.

Yes the cooling system is a little odd. Crazy Germans. Remember that Porsche has been building air cooled motors for over 60 years and the 986/996 is essentially a first generation water cooled flat six production motor so we are guinea pigs to some extent. Chevy has been doing water cooled motors since 1914?? so by now they have the bugs worked out.

Do pay attention to purging all the air out as air entrapment and hot spots in this motor mean cracked heads or worse.

I guess what I'm really asking is how big of a compressor and tank do I need to run this. Mine's kinda small - great for filling tires and blowing off dust but not adequate for most air tools.

I've seen people run them off rather small portable compressors, so it can't require all that much. Other than the recommendation for 90 psig, I'm not aware of any other requirements. You may want to drop them an email as I'm sure this question comes up all the time........

http://www.uview.com/index.php

Draw vacuum after coolant flush.
 

I have just replaced the coolant in the 2000 Boxster and thought I would bleed the system manually via the comments here. I'm not absolutely sure the system is free of air pockets and have ordered the suggested 5500 unit. If I draw a 25# vacuum on my already filled system will it still draw out any entrapped air or do I have to refill the system using this tool? Thanks

It works best while filling the system because it totally prevents any air entrapment, but you can use it on a full system to pull out any major air pockets.

I know this is an old thread but.......

I don't have a workshop air compressor and I want to flush and refill my coolant and would happily spend on getting a vacuum refilling system but not both pieces of equipment.

Is there a vacuum system that does not need an external air compressor or alternatively has anyone devised a way of using a vacuum system without a compressor maybe with a 12v tyre inflator or some other devious way to provide the air power?

Borrow an air compressor ? Or go to an Indie to get this job done.

I borrowed a small 8 gallon unit, and it pulled the required vacuum no problem. A smaller one would likely work too, just would take longer to evacuate.

RR, I live in a city with a pop of about 700K. Just Googled tool rental and found 18 places I could rent a compressor at a fair price. I looks like your in the UK and would think there it would be about the same. You might find someone who has a compressor but no bleeder and do a loan.

I use a 6 gal pancake compressor and a UView. I think that is probably the smallest you could go. I did 2 Distilled water flushes and then filled with 50/50 pink stuff
I felt like I had to run the purge valve a couple cooling cycles anyways as I was not familiar with the temp behavior after this and new WP and low temp thermo replace.

The hardest part here in NJ is getting rid of the stuff, 12 gallons. Auto parts stores don't take it. Finally had a House hold recycling day where the county takes things like paint and antifreeze

I would like to know better how one uses the Uview with a full system to help remove any potential trapped air.
Anyone done Vacuum on a full system???
I have just started seeing condensation under trunk lid and I had a drop or 2 come out the overflow after driving an hour and half. It's been 4-5k miles since all the coolant work with no issues. Temps run cool
I have a new tank as of last Dec (2015),WP, thermo Flush. I had put an '04' cap on 3 years ago.
I just order a new cap to see if that is it

I have changed coolant when I added the S center radiator to my 99. I also replaced the thermostat, engine mount, and water pump. Didn't find it that difficult. I removed the lower coolant hose that connects to the water pump and drained into a 5 gal storage bin I bought at Walmart then brought the coolant to the recycling station. When I put everything back together I added new fluid and filled as best I could. there is 1 bolt that holds a cover over the oil, coolant in the trunk. remove the bolt and take that cover off. there is a burping valve a little clip on top flip it up start up the car let it run the air will come out and the system has been burped. I had one of those uview devices and sold it. I thought it was a PITA! Review DIY on pelican and pedros board not overly difficult.

So a difference of opinion. Some saying it is a pain in the arse to bleed it manually and others saying it's not a major problem.

Decisions decisions......

Sent from my ONE A2003 using Tapatalk

What works for me is to drive to the steepest parking ramp i can find. Open the purge valve. Then with the car pointing down the ramp, rev the car a bunch of times like the pelican write up says. Works every time. Take a couple of gallons of coolant since the level can drop dramatically.

So...... Do vacuum tools help in the draining / flushing of the system in any way or do you still need to go through the routine of removing hoses, tilting the car etc or is there a method of forcing the coolant out through a single drain point on the car?
Seems to me that the draining is the time consuming part.

Sent from my ONE A2003 using Tapatalk

The draining does not change; however, the refill is a 5 min. and you are done proposition with the Uview vacuum system.

Thanks for that. You are always willing to help and are a great asset to the forum and boxster owners in general. I for one very much appreciate it.

Sent from my ONE A2003 using Tapatalk

+ 1 on JFP

Regarding JFP, totally agree. We'd be lost without his experience. Most of us only have experience of one car and do the job 1 time. He has thousands ! Yet noobs still dicker with his advice - hilarious !
JFP has a business to run yet still finds time to help us. Amazing dedication . See him over on RennTech also. No bad behavior tolerated on Renntech so it is a refreshing change sometimes.
I used the U View over the weekend. I am puzzled about how it works when the thermosat is closed. But it does. I guess it may work better with a warm engine ?

Thread resurrect...Any instructions on how this system works?

best way to go, is get one of this:

https://www.amazon.com/UView-550000-Airlift-Cooling-Checker/dp/B0002SRH5G/ref=sr_1_1?s=automotive&ie=UTF8&qid=1518322496&sr= 1-1&keywords=airlift+cooling+tester


if not, i found the procedure on pedro's garage website to be most practical:

1. Check whether the coolant shutoff valve is open.

2. Fill with coolant up to the bottom edge of the filler neck.

3. Run the engine at idle speed and top up with coolant until no more coolant flows into the cooling system when the engine is revved moderately. (Coolant level now at lies lower edge of filler neck.) The coolant temperature must not exceed 80°C; proceed directly to the next work step if necessary.

4. Close reservoir and warm engine up to operating temperature at a speed of -2500 rpm until the thermostat opens after approx. 10 minutes (coolant temperature -90°C).
Check: The radiator supply lines and return lines in the front wheel housings must be hot.

5. Allow engine to run an additional 5 minutes at ~ 2500 rpm. Every 30 seconds, briefly rev up the engine to -5000 rpm. RPM surges are important for proper bleeding.

6. Allow engine to run at idle speed until any activated radiator fans switch off again. Then switch off the engine. Open reservoir cap with extreme caution until the reservoir is de-pressurized (danger of scalding!).

7. Top up coolant expansion tank until level reaches lower edge of filler neck.

8. Reposition bow on bleeder shutoff valve, Unscrew oil cap.

9. Put on cover and body seal. Screw on both caps.

Thanks Meir!! I've been so busy at work lately.. Weather bad here so was tinkering around with my coolant leak problem.. Should start another post but but... coolant tank replaced 2 years ago 10k miles.. Was going to drain and replace the water pump till I saw this..http://986forum.com/forums/uploads02...1518333227.jpg

Could a bad coolant cap cause this?http://986forum.com/forums/uploads02...1518333700.jpghttp://986forum.com/forums/uploads02...1518333730.jpg

Drove the car and for got something at home. Returned to the garage, coolant everywhere in front the passenger side rear wheels.. checked the coolant resvoir for leaks... nothing but saw the bleeder valve showing signs of leakage.. Was going to replace the water pump but kinda lost now.. Been leaking for a while. Replaced shifter cables and saw red coolant from a drain hose that I know now is coolant...Could this still be a water pump issue or bad cap? I'm spent right now can't think...

I have a 99. I replaced coolant when I replaced the first water pump, thermostat, front engine mount. I purchased a UVIEW device and gave up trying to use it and sold it. I thought it was a PITA. I did what others have done on this forum. I jacked up the rear of the car, filled up the system, open the bleeder valve and drove around my neighborhood. Worked fine for me! I did it again when I added an "S" center radiator and again never had any problems. Just speaking from my experience.

In other words, what Meir said!

I have less expensive Air Lift system $88 from Amazon. It works fine, and for the home mechanic will probably outlive the owner.

If your cooling system will hold a vacuum, you can use pretty much any small compressor. The sub $100 ones from Harbor Freight will work, it will just take longer. I run my old Craftsman/Devilbis at wide open pressure and about 8 cfm.

You can't use these things to "burp" the cooling system. It pulls the coolant back into the reservoir and then spews it out into the trunk or the side of the car. Need to almost completely empty the system before you start. And if you're draining the system, you need to drain the parts behind the engine, then pull the big hoses off, jack up the front of the car, and let the coolant in the radiators run downhill to drain out. There are no short cuts. Jack stands are your friend.

I'm doing heavy work on my engine, when it's done, I'm gonna pull the front radiators out and either replace them or have them boiled out at a radiator shop. Previous owner used tap water, and my old engine was full of calcium.

The drain hose is an overflow hose. Fill the reservoir too much and it will spew out onto the pavement. It's generally in front of the right rear tire. If you have coolant dripping behind the right rear tire, you have a coolant reservoir leak and coolant is draining out of the trunk.

If you have a wet floor in your trunk, you need a new reservoir. If you do, get a new cap and a coolant level sensor, too. The clip clamps make it a pretty miserable job, they all seemed to be facing the wrong way. While you're in there, replace the little sections of hose between the reservoir where it goes thru the firewall and the metal system tubes.

I did all this stuff last fall, my hands are finally healing up!

I'm a fan of the "AirLift" system. Replaced the WP, T-stat, and engine mount on my '02 base a couple of years ago. After watching a few YouTube tutorials on use of the "AirLift" system it was easy peasy. Used a 6 gal. pancake compressor to draw vacuum.

I like the fact that you can verify the integrity of the cooling system based on whether or not it holds vacuum. If there is a problem you can recheck your work prior to re-filling the system. Saves a lot of time in potential rework and you can refill the system in no time with no worries of air in the system.

It really doesn't do any good if you can't hold a vacuum. Need to get it to 20 to 25 inches of vacuum, and have it hold. Problem with trying to use it as a diagnostic aid is that the compressor and the venturi vacuum make so much noise that you can't hear the leak.

The sealing and bleeding the system is just one of the things I'm currently working on. The little manifold that's part of the coolant tank is a little cute for my tastes. It will be simplified by drilling out the plastic sections and run longer lengths of rubber hose, I think. Fewer connections mean less chance of leaks.

I've got leaks.:ah:

Testing. No new posts for days?