tsmysak1

Some time ago, I started loosing coolant. Every four or five days I had to add some, not a whole lot, but after several months I went through a gallon.

I have read all the knee jerk reactions on the site and figured the best advice I would get is "time for rebuild". Not giving up that easily.

I took the cap off and sometimes I would see bubbles and sometimes not. I never could tell if this wasn't from boiling or circulation or a blown seal. I knew that the water wasn't going into the combustion chamber for sure, but I was not sure that combustion gas was not escaping.

I bought a new cap from Ray and installed it. Problem went away for about a month. It was a 13 psi cap. The problem then came back and it started to push coolant out without sucking it back in from the overflow. The old cap looked fine, the new cap looked fine. Heck, I don't know what going on.

So, I was at Advance the other day and bought a 16 psi cap. If the engine is blown, what the heck? I thought I would try it. Slapped that bad boy on there and no more coolant problem. This was a cheapo Stant cap. They have both 13 psi and 16 psi caps. I bought one of each but have not tried the 13 psi cap yet. Why mess with a good thing?

I pulled the cap off yesterday thinking that after a month of driving at 16 psi it would be down a little. I was SHOCKED. The coolant was full to the brim. No space in there at all. How could this be? I did not check the overflow to see if it was getting used up.

I don't know if it was the cap brand or the pressure level. Like I said, I have not tried the Stant 13 psi cap. I am afriad to. LOL

So, if the system is in good repair (good hoses etc..) what is the risk of running hte 16 psi cap? Is the engine coolant fire risk real? or what is the real consideration...I don't want to blow up a good engine... *laugh*

RotaryResurrection

iTrader: (8)

Coolant...fire? Nah.

The system is designed to run at a max of 13psi, though it can probably hold twice that in reality (when healthy). More than anything, old hoses are the weakest point, and might not be up to the task of higher than stock pressure. Other than that, I wouldnt worry about it at all.

RX7 allnight

how can you tell if coolant is going into the cumbustion chambers? how can you tell if gases are pushing coolant out of the overfill? i am having the same problem... 93 r-1 bone stock. my AST stays full. my T-stat doesnt.. i have to fill every other drive. i dont drive it much. i see no visable coolant leaks. i have checked all lines to and from AST. i used to see the (over flow tank) over flow and have the AST not suck it back in. changed the caps.. now the over fill doesnt over flow... my AST always stayed full in both cases but the damn T-stat doesnt stay topped??? i do not see any white smoke on start up. my car does not bog. even after sitting for weeks/months on cold/hot start ups. my heater does not work that great. i have been searching for months on this problem. error codes read egr and air intake sensor. but i still have to add coolant to the t-stat hosuing (cap) everty other drive.. even if i just start it let her warm up shut her off the coolant is a little low... i always start/run the car when toppin off any help would be more than appreciated

tsmysak1

Kevin, is the Mazda cap suspect?

And ya, I have read that one of the recalls had to do with coolant leaking and then causing a fire...Supposedly the residue burns after the coolant evaporates. Just wondered if there was any truth in all that. Mazda changed the caps for some reason...but that one seems a bit far fetched...

tsmysak1

Smoke if it is going in, overflow if the gases are coming out. Usually only smokes if the leak is small and the coolant seeps in while sitting parked.

So is the overflow staying constant, or does it creep up higher and higher?

Mine always did the exact same thing until I put the 16 psi cap on.... Quite the mystery... But most cars I think use a 1 bar cap so I figured it couldn't hurt. Mine always flowed out and not back in. Changed the hose and made sure there was no leaks. No change until I got the 16 psi cap.

RX7 allnight

i have 16 psi on the AST with the red safty lever.. i tried a 13 psi non safty lever cap no differnce. same problem.. ya know, my over fill is always full but not over flowing onto the ground.. so i think its not.. but i will drian the over flow half way.. go on a drive and check what happens. so gases coming out? not coolant coming in. bad o-ring ? bad seal?

takerwolf

I'm haveing the same problem with a 88 vert I just picked up except the 16psi cap didn't fix it. Anyway, just thought I'd chime in, the 87 turbo had a rebuild/bridgeport/3rd gen oiling system/aviation grade seals done last year. I've had a 16psi cap on it with a fluidyne radiator for a couple years and the only problem I've had is cracking one of the heater core hoses so it's probably okay to run that. The fluidyne came with the 16 cap though it could be a universal thing. The reason for the rebuild was an overheat caused by the electric fan eating into the rad by sucking itself in as I guess it was weak. So even though the Fiero fan is supposed to be good b/c of having a shroud I ditched that, patched the radiator, rebuilt, and went perm-a-cool. No problems since. It actually overheated when the hose blew but it holds 13psi of boost anyway, I think it's b/c of the aviation seals.

RotaryEvolution

iTrader: (30)

the problem is worn coolant seals, luckily it sounds like your irons are still ok but the coolant seal is acting like a one way valve, since the combustion gases are much higher than the coolant pressure the engine can pressurize the cooling system but the cooling system does not have enough force to push coolant into the engine. this really is only a bandaid so keep saving your money for that inevitable rebuild because time will come when the 16psi cap will not hold up to the job any longer either.

i know this because i also have done this for several months when i first got my car and it had overheating issues, eventually it just quit one day alltogether.

CantGoStraight

The original cap was a 1.1 bar pressure cap due to the fact the 13 psi could be at the marginally high threashold of the thermosensor. Then there was that other problem of the 16 psi cap putting an extra strain on the turbo hoses and after a while they would spring a leak and put coolant ll over the turbo manifold and exhaust and sometimes cause a fire. They added the fan control modifacation that keep the fans on if it got over a certian temperature and while running would kick the fans up one more speed if it was over a certian temperature, now since the fans are comming on sooner and running longer they dropped the cap to a .9 bar (13 psi) to help with the longgevity of the coolant hoses. Allot of people have gone back to the 1.1 bar (16 psi) cap increase there boiling point threshold and have had pretty good luck with it. Just have to keep the coolant hoses in good condition.

tsmysak1

That was pretty much the answer I was looking for. It also explains why my engine harness looks like someone repaired it, perhaps. I bought another harness from a forum member and I was surprised to see it repaired the same way with the same color wires. So maybe both had been through the recall??

Is there coolant hose kits available at a fair price? I think mine are fine, but when I do the eventual overhaul, I will want to replace all the hoses..

CantGoStraight

There is the coolant hose recall kit that is considerably cheaper than buying them individually. You can call Ray at Malloy Mazda and see what the has and what it includes. Mazda trix sells them at a better price than most dealers but is still pricey for one hose purchases.