808rx7VERT

aite this might seem like a stupid question.. but im just wondering if the coolant filler cap is supposed to be a presure cap or a regular flat cap?? if a presure cap how much lbs? for an 88 vert

RETed

Does it have a bypass fitting?
If it doesn't, then you don't need a sprung cap.

Standard rated pressure on rad caps is 0.9bar or just about 13psi.


-Ted

RoughRex

If your engine bay is the same as my '88 GXL... You should have a flat cap on the top of the radiator and a 0.9 bar pressure cap on the filler neck. Check to verify where your bypass fitting is for the overflow like Ted stated. That's where the pressure cap goes.

Icemark

actually on my 88 vert it was the reverse of that.

The easy way to figure out which is the pressure cap, and which is a fill cap is the small hose.

There will be a 13mm small hose coming off the one that is the pressure cap. On my 88 vert this was the top of the radiator. On my old 87 sport, this was the one above the thermostat at the motor.

So look for the small hose coming off one or the other. That is where the .9 bar pressure cap belongs.

Now if you have a leaking flat cap, it can be replaced with a pressure cap with no ill effects.

Red'vert

What's the point of the pricey aftermarket higher pressure caps? Running hot when racing?

Icemark

in theory it runs cooler, but the draw back is that the seals are not designed for higher pressure, so you may blow out a water seal when running a higher than normal pressure cap (like one of those ebay 1.3 bar caps).

For example using a 1.3 bar cap is just under a 50% increase in pressure over the stock system. I don't know if I would trust a housing seal with more than 75K miles on it too last with a 50% increase in pressure... would you?