What do you think about using 16lb pressure cap??
 

Recently my 7's running hotter than normal.. and saw that my 13lb AST cap was leaking a bit.. Should i go with standard 13lb cap or should i upgrade to higher psi, 16lb cap?

Do you have an aluminum AST ? If so, I had to junk mine because over time the lip on the ast tank got bent and never sealed properly. Apparently, it had been leaking a little coolant and I never looked to that as being the problem.

I had the AST eliminated and car has run perfectly for 8 months now. Coolant level and temps have been perfect.

Our car originally came with 19 lb pressure cap. I ran 16 lbs cap for close to 5 years. It reduced the boiling sound and hissing in the summer but didn't eliminate it.

Now, I'm running 7 psi cap and never hissing, boiling, farting and embarassing noises. Oh, it's Evans NPG+ I'm running.

Do you have new water lines/hoses? It will be easier for them to burst with higher pressure.

I didn't know they came with 19lb cap?? I read somewhere that it was 13lbs.. But the manual says to check the cap for pressure of 16.4- 20.6.. so, i guess i could see that.. thanks for that info.

i have new hoses to and from radiator, but not to the ast.. i did check the lines couple of days ago..

I'm also seriously considering this option.. if this new cap doesn't help.. I'm going to take my cap off and put t2 cap on it. oh, i do have the aluminum ast and the lip does look little beat.

I just installed the 16lb cap and it solved my overheating issue..

Higher pressure cap wont make your car run cooler. Probably what happened is the old cap leaked, wouldnt hold pressure, so after shut down you had localized boiling.
That said, are you sure the old cap was 13PSI and not 1.3bar (which is 19 psi)? If I remember correctly my car had 1.3bar when I got it. Now I have 5psi cap and run Evans.

herblenny: also since you are in AL.. you might wanna make a 100% water mix with some water wetter... works great here in FL.

My turbo water hose burst a few days after I installed the 1.3bar Blitz cap and now it's on my CRX. You should replace both of those. They did lower the cap pressure from 1.3 to .9 I beleive. It's been discussed before.

a 13lb cap makes sense since it is after all a 13b engine sheece.

I run Evans too, where did you get your 5psi cap? Do most places carry those?

Sorry if this is stupid, why would you lower the pressure cap? Most people say to raise it if you talk the idiots at shops around here.

I only know the very basics about cars. I guess you need the pressure caps to raise the boiling point of water? That's how it was explained to me. I don't know...I gave the guy a Scoobydoo "Arrrgh" when he told me. Can anyone explain/verify this? But I run evans coolant, it has absolutely no water, so you can run very low pressure to no pressure.

Ok, this is starting to make more sense.

More water= higher pressure cap to avoid boling of the water.
Less water= lower pressure cap to so you don't need all the added pressure to avoid boling.

Thats why most people raise their pressure rating on there caps. Becasue they never change the water to coolant ratio. If anything they just add water.

Cool thanks. I have heard that somewhere too. Please chime in and correct me if I am wrong.
Thanks

If I'm not mistaken, Evans has such a high boiling point that you don't even need a pressure cap. Someone correct me if I'm wrong.

I have mine aftermarket AST leaks too. They started to leak when I first install it. The collar to cap surface isn't machined perfectly. To bad, I might find a way to fix this problem sometimes.

BC

I have an aftermarket AST with the standerd large sized cap. That was easy to find a 5psi cap for. If you have the stock rx7 size cap that will probably be nearly impossible to find a 5 psi.

You are right PandazRx-7. When I first switched to Evans I just pulled the lower seal off the cap running 0 psi. I think my lower radiator hose would collapse somewhat as the rpm's went up. The faster I went down the highway the higher my temps would go. Since switching to 5psi the temps are alot more consistent. You can run 0psi but after my experience I would keep a couple psi in there.

You are correct.. My old cap definitely had a leak..

also, Pettit AST came with 13lb cap.. I confirmed this with other guy with the same ast.. Also, now I think about it, I think my stock ast also came with 1.3bar, which is around 19lbs.. I have to go look for my old ast..

One thing i definitely notice was, on friday i drove my car to work.. got there around 8AM.. left around 4pm.. and when I opened my filler cap to see the level before leaving work, the coolant pushed out. kind of worried me a little.. and all the hoses felt really tight.. that was after 8 hours of cool down..

On my drive to work (10miles), temp never passed 88C.. on my way home after some coolant lost by opening it, peak was 94C.

Should I go back to 13lbs?? or stick with 16lb.. I'm little worried about hoses popping.. I have 220mile trip this weekend and don't want to be stranded.

I been hearing a lot about Evan's.. I might try this.. Sounds awesome.. Far as cooling ability is it about the same as regular coolant?? or is pure water still have better cooling ability (except boiling point)?