Not the same thing Lynn.
Ian is doing away with the low pressure catch can. Some late model
cars and trucks are doing this. The pressure tank is
only about 2/3 rd of the way full. There is no back flow valve
in the pressure relief cap. If the coolant expands beyond the
volume limits of the pressure tank it is lost over board for good.
The tank I saw on Bruce Turrentine's new Ford SUV was about a
gallon.
The car racing orgs (SCCA) would never allow that system.
BTW Ian get a coolant pressure gage that shows both positive and
negative
pressures like this one that Ken Welter uses. It is shown in the
lower right of this picture. Very instructive to watch that gage
as the engine goes through the temp cycle. In a conventional system,
with a two valve pressure cap, the pressure goes negative in the
engine when it cools off drawing the fluid back into the engine
from the low pressure catch can. Bruce and I think the reason
cars are going to the single high pressure tank is the hot coolant
is
not exposed to the air as much so it last longer. Apparently
exposure to air degrades the hot coolant. Either that or it is
just a cost issue.
Paul Lamar
Hey Paul,
Know of any good off the shelf pressure tanks of approiate capasity?
Dave Leonard
Check out some of the new Ford SUV plastic tanks.
Those are the only new cars I have looked at so far.
Paul Lamar
The GM tank used on Saturn vehicles has a 18 psi cap on a tank of about
1 gal. If I rememeber I'll take a picture of mine and send it.
Tom Webber
I noticed the same setup on my 2000 Chevrolet 5.3L pickup. There is a
large (approx. 1 gal) plastic tank, with multiple baffles/chambers and a
number of hoses attached. It has a screw-on pressure cap , but I don't
recall the actual psi rating of the cap. The plastic tank usually stays
around 1/3 to 1/2 full. The radiator has no cap.
Mark Steitle
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