enuttage

I've read a few posts here and there that indicate that folks might be having pressure issues with NPG+

I've been smelling coolant lately in very small amounts at WOT, but can't find a leak. After cooldown, coolant is still all the way full, so I'm thinking if there is a leak it's incredibly small, or I'm running too much NPG+ in the system.

Anyone running Evans have any input on what my coolant level should be, if less than full?

Don't like to have to worry all the time about a coolant leak, if there isn't one...

Sorry for the vague language, but I'm having a lot of trouble trying to pinpoint what's wrong.

-E

Trexthe3rd

First off, are you running 7psi or 0psi? Also, when you converted to NPG+, did you purge the whole system of conventional coolant and water?
If you can smell the coolant at wot, it has to be big enough of a leak and comming from a hot source. Otherwise the coolant would remain in liquid form and be difficult to detect due to the airflow at high speeds.

enuttage

0psi and yes. The system was purged. It went in after the engine rebuild in a engine and peripherals install by RP.

The system was then re-purged here in Austin by MZM, when they installed a fluidyne rad for me.

What do you mean by "big enough"? I'm just confused as to how my coolant levels seem to be showing no signs of change.

Still a little bit in the dark here. I guess my real question, is whether my problem is due to a leak, or due to overflow, in the experience of other NPG+ users.

-E

BLUE TII

iTrader: (9)

My experience w/ NPG+ in a zero psi system is that it expands A LOT from cold to hot and it is very aromatic so you will smell a very small leak.

I can only check my reservoir hot when it is expanded, so I should probably get a larger one. I have a 11.34 liter system VS stock 8.7 liter system, so there will be more expansion from this as well.

Have you considered a very slight leak from the heater core? Slosh out of a poorly designed reservoir when accelerating?

Ian

CantGoStraight

I'm also running this coolant with a Koyo radiator. I'd like to go to a zero psi systwm but was afraid of how much expanshion there would be and if the stock overflow tank would handle it. What I'd like to know is if anyone knows where I can get a low pressure cap (7 psi) and the same size as the stock radiator cap (not the larger after market one) as found on the pettit AST.

jimlab

Just FYI, the experts I've talked to recommend using a 5-8 psi cap, not the 0 psi cap.

7_HEAVEN

iTrader: (6)

i think jimlab's right,

i'm running NPG+ with an aluminum radiator and the M2 High Pressure Radiator cap without any problems at all.

(Aluminum AST as well) not that that makes a ****.

enuttage

Well...perhaps I AM running with pressure then. RP (who I definitely would qualify as an "expert") installed the whole system, and gave me all the info., but somewhere between selling other cars, refiling my auto info., and moving stuff in and out of our house for a remodel, I've lost their spec. sheets/info. I'm honestly not sure what the cap is.

Just assumed it was a 0psi cap. How can I tell?

-E

CantGoStraight

Jim, Where do I find a 5 to 8 psi stock style AST cap ????

rx7speed811

usually you can find the pressure of the cap...

ON THE CAP

twokrx7

iTrader: (1)

If you pull the cap and there is no spring loaded plunger you have a 0 psi cap. Mine is zero psi cap with only a seal on the bottom. Occasionally I can smell something sweet, probably from the overflow tank venting a bit of vapor.

I have had zero issues running zero psi ... 5-8 psi should only make it cool better minus the additional load on all the hoses and seals. I really like the thought of zero psi and reduced load on all the hoses and seals.

About the comment that the coolant expands more at 0 psi vs 5-8 psi ... fluids are close to incompressible, there should be no measurable difference in volume as function of pressure. May be a bit more vaporization at hot spots and maybe this is where the rec to use 5-8 psi is coming from? Anyone know?

BLUE TII

iTrader: (9)

Did you plug your waterpump weep hole? Is your zero pressure cap ON THE SUCTION side of the system?

Just throwing ideas out there...

-edit- oops, didn't need sig in there

enuttage

Hey guys,

Thanks for the help (from those of you who were helpful).

I do, in fact, have a 0psi cap. It *is*, despite (I'm sure I'll get flamed here) jimlab's experiences in his part of the country, recommended by the experts that I've dealt with working on my car (as in RP, Pineapple Racing and MZM - I finally found my notes and paperwork as well), and also by numerous folks at the event I ran yesterday.

Over and over yesterday after autoX runs I checked the pressure release valve on the AST and got nothing. I'm running 0psi, and I'm pretty convinced at this point that twokrx7 explained what happened to me, and then I got over paranoid about it (understandable based on my investment in the vehicle relative to my income ).

There were no problems yesterday after 8 consecutive hardcore runs with pressure or leakage, and my water temps never passed 91C (which is as high as I've ever seen them even in summer temps). And coolant levels remained steady.

Again, thanks for the help on the apparent false alarm, and thanks for the input, so when I DO get a leak, I'll know where to look first.

-E