3200's with Kaiser valves

[mchristyuk]

Gents,

Just a "heads up" really.. whilst messing about under the bonnet of my 3200 checking everything is good after it's recent work I thought I would check the one way valve that sits between the Kaiser valve and the air box.

I took my one way valve out and it's about as one way as a.. well, can't think of a suitable example, but it's blowing both ways!

From my understanding the Kaiser valve is there to bring the air intake into play as an extra vacuum supply to boost the braking power. Obviously there needs to be some form of valve in that line because you don't want pressure going up wrong way as it would defeat the point of it.

If I remember correctly the Kaiser valve plumbing connects the airbox side straight through to the engine side, therefore if the one way valve is faulty in the airbox line then that must be the same as an air leak under boost?

So.. in a round about way a failed one way valve would potentially result in poorer braking response and loss of performance under boost?

I've ordered some generic one way valves to replace the dead one, however in the mean time I've bunged the line to the airbox.. and noticed no reduction in braking performance... which leads me on to two questions..

1) How much braking performance does the Kaiser valve really add?
2) 3200's which don't have the Kaiser valve.. is there some form of one way valve between the engine and the brake servo? (The EuroSpares diagram shows none.. and there must be one?!).

Cheers

Mark

 

[alfatwo]

Very interesting theory Mark,I can see where your coming from...

There must be a loss of boost pressure if the valve is open both ways

I'm going to check out the circiut in the manual

Dave

 

[mchristyuk]

Hi Dave,

Actually thinking about it some more.. what I said isn't strictly true about the boost, well it is and it isn't.. The one way valve is there to only let the air intake to "suck" and create a vacuum. Therefore even with a correctly working one way valve you must be losing boost pressure from the engine to the air intake?! If the one way valve fails then you have the potential of losing braking assistance when the dump valves are operating and the throttle body has snap shut causing positive pressure in the air intake area.

What I don't really understand is I'm not aware of a different servo booster between cars with and without the Kaiser valve.. When the Kaiser one way fails we know that can fill the booster with pressure, so why do the cars without a Kaiser not fill the booster with pressure?!

Either way.. seeing as the brakes don't feel noticeably "worse" without the airbox in play I am sorely tempted to remove the Kaiser valve completely as it's a known weak spot and just install an extra one way valve in its place..

Just for completeness here's the diagram:

Mark

 

[rs48635]

Is the Kasier vlave number 6 in the diagram?
Will have a look under the bonnet of the 3200 when I get home. Hoping mine does not have this fitted, being a later 2001 registered car (chassis 4807)

 

[mchristyuk]

Rob,

Yep, the Kaiser is number 6 and that is what most people have fail at one point or another. It has a one way valve in it to stop boost pressure getting to the brakes, they should only see vacuum. In my case number 2 had failed which meant that boost pressure could nullify the vacuum effect of the engine at high RPM/Boost when you jump off the throttle on to the brakes.

The whole things seems a bit of a bodge/heath robinson affair.. But this shouldn't be a surprise considering the engineering prowess that went into the handbrake design!

Mark

 

[rs48635]

Not sure this bit of vacuum has much effect.
On my old 911 there was zero vacuum for the first ten years. Then I fixed the mangled gasket on inlet manifold and voila! The brake pedal no longer felt like treading on a block of wood.

 

[allandwf]

Did you test it by blowing, or sucking? May make a difference.

 

[mchristyuk]

Rob,

I don't know how much effect the normal vacuum connection has, but I don't think the airbox attachment makes a lot of difference. However a broken valve has shown that pressure in any of those lines does make a nasty difference!

Cheers

Mark

 

[mchristyuk]

allandwf,

I tried both blowing and sucking, and it shouldn't make any difference anyway.. it's just a simple one way valve. I think the plastic interior has just degraded over time and given up the ghost.

Cheers

Mark