Date: Fri, 10 Feb 2006 16:07:42 -0800
Reply-To: Doug F <vanagon@ASTOUND.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Doug F <vanagon@ASTOUND.NET>
Subject: Re: How to - or not - bleed the cooling system
Content-Type: text/plain; charset="iso-8859-1"
Al,
Well stated, I have to agree with your logic and years of experience proving things true. Engineering and research aside what actually "works" and proves over time to simply not cause problems is difficult to dispute.
With respect to the vw cooling system, most agree the 1.9s did not self bleed as well as the 2.1s with the new routing so the 86 on may indeed be easier and less likely to cause trapped air.
On my last engine rebuild and coolant flush I rigged up a 5 gallon bucket with a sump pump and tapped into the cooling system and "pumped" the system on level ground to get as much coolant into the system as possible before finishing connecting up the cooling to the engine.
I did this as an experiment because previously on my 85 (with fresh rebuild) I had a bitch of a time getting coolant into the system because it kept boiling back into the filler tank and making a huge mess. Only after I cycled it a few times letting it cool inbetween did it finally take all the coolant and fully purge. This was a bitch on a brand new engine.
Pre-pumping into the system and cycling the heaters etc and getting as much into the engine before ever firing it up made it super easy to purge the 89 completely with a new motor. No where the mess either.
On future rebuilds I will likely do similar, one thing I feel would help is use an old coolant tank cap and mod it to put in a large hose fitting in the top and run it to a 5 gallon pail sitting on the rear deck. This would allow the tank to burp back and not let coolant run all over the hot exhaust. It would also allow you to keep a higher level of coolant going into the system.
These rigs are certainly a challenge to bleed compared to some other types of vehicles. My main consern is that air will get trapped in the long lines running under the van and end up in the radiator or cylinder heads and create known "hot spots" in the heads.
After a rebuild I really dont want to risk any air whatsoever.
If there were an even more difficult way to purge the system that was proven to be even more effective I would likely do it on a new engine rebuild. That piece of mind when hundreds of miles from home is worth it to me. Even if it does give up at least I KNOW it was not the bleeding that did it.
Happy to hear other methods "work"
----- Original Message -----
From: Al and Sue Brase
To: Doug F
Cc: vanagon@GERRY.VANAGON.COM
Sent: Friday, February 10, 2006 10:54 AM
Subject: Re: How to - or not - bleed the cooling system
Doug:
Well, maybe I'm just lazy. Maybe, after having had this car for 16 years plus 5 other vanagons and working on a few more, I'm beginning to get a feel for which bolts I should leave out. Maybe, I kinda resent the idea that I have to spend a half hour getting every bubble of air out of this thing if I so much as change a hose or thermostat.
Sure, sometime I'll pop off the grille and crack the bleed valve while the engine is revved up and warm. and I'll probably get a little bit of air out. But, not with the front OR rear end in the air. I'd rather be a quart low on coolant than a quart low on oil.
AND not before I do the important stuff I have to do today. The system will mostly self bleed. It's just not that touchy.
The idea of taking Bentley's word like Moses brought it down on 2 stone tablets is ...well.. not my choice. Bentley manuals are NOT what they use at the dealer. I've found several mistakes in the Bentley. The biggest was when I took my first late Vanagon 4 speed apart. The procedure they had in there was absolutely wrong and there is no way it could be assembled using their directions. Since repairing manual transmissions was something I had considerable experience at, I figured it out, then wrote the correct procedure in the margin. (This was back in the late 90's and I assume they have it fixed by now.)
That's one good thing I have to say about Bentley. they do respond to input and make revisions to subsequent editions. Plus, one of the main Bentley guys is on this list.
BTW, I suspect that Bentley doesn't do too much engineering on its own. (Now donning flame suit.)
Al Brase
Doug F wrote:
Why not just bleed the vanagon according to the Bentley manual suggests?
I for one do not understand why everybody feels they need a "better" way to
bleed the system. I do it EXACTLY the way the Bentley manual outlines and it
works. Why challenge the engineering. How can you know that you "know"
better. How can you "know" you have established your method based upon
"better" research? You cant! Thats why I do it EXACTLY the way the book
outlines and sure its not easy but it does work.
----- Original Message -----
From: "Al and Sue Brase" <albeeee@MCHSI.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, February 09, 2006 9:02 AM
Subject: Re: How to - or not - bleed the cooling system
I'm following this link and have to say- I don't understand what is all
the fuss about. One cannot fill the rear reservoir completely full.
About half full is right, there needs to be room for expansion. The
front (inside) bottle needs to be full all the time. but a properly
function pressure cap and air tight hose to the expansion tank will keep
it topped up.
I NEVER take out the grille and bleed the radiator. Even last month when
I put in a different engine and quite a bit of coolant was lost, I just
filled it up at the pressure cap a couple of times, started it up and
refilled it with the engine at operating temp and revved up to about
2000 (had someone else hold it there), and put on the pressure cap and
hose before releasing Then tighten down the valve on the thermostat
housing.
Sure, there is a little .air in the system, but it will self bleed out
in a few cycles. Maybe this might be a big problem with the a/c on in
the summer if it was 100 degrees outside. But I doubt it.
I've never owned a 1.9 gas car and they might quite possibly need more
care than this. The same procedure works for my 82 diesel, however.
I'll check the radiator bleed valve sometime. I realize that large
amounts of air might not be able to get out of the radiator without
bleeding. Maybe in our climate 1/2 a radiator is enogh to give me good
cooling.
Al Brase
BJ Feddish wrote:
I'd like to share something that someone on this list shared with me
years
ago. This is done after you've done all the "jack-up-the-front" stuff
from
Bentley, etc. After driving the van to full temperature let it cool down
overnight. There will be some air in the rear reservoir. Open it up and
fill it with coolant again. Drive it again until it's hot then let it
cool
overnight again. There will be more air there. Fill it back up. Keep
doing
this for about a week or until air stops appearing in the tank. After I
did
this the temp gauge is always below the led when I'm driving and when it
idles it only goes a hair passed the led even on hot days. The light has
never blinked. I'm convinced that most head problems people have are
from
too much air in their systems.
Bryan
