Hey guys, I'm beginning to fear a serious problem... First, here is what is NOT happening... I am NOT getting a lot of smoke (none visable from the rear view mirror, except for a poof on startup, and sometimes just a tiny bit under hard acceleration) and I am NOT overheating (the gauge does read a bit higher than I would like, the needle touches the left side of the little wave picture when driving, and will go straight through the picture when idleing for a while in traffic.

here is what IS happening... I constantly need to refill my coolant. I cannot see any leaks anywhere, hopefully I can find one sooner rather than later. I will be going home in about two weeks and will be able to do a better inspection. However, after driving for about 3 minutes, the "add coolant" light goes off. I try to stay on top of things though, so I like to add coolant after seeing the light, even if it's just for a second or two. Latley, when I go to re-fill it, there is a LOT of pressure build-up, like, I unscrew the radiator cap, and if I even release my grip a little bit, coolant comes bursting out, allong with a lot of "gurgleing" noises from what sounds to be the overflow tank.

I have alywas had some sort of cooling issue, including very rusty water getting spit out of the overflow tank after driving on the highway (and creating quite a mess in the front passenger side of my engine bay). There is a tiny hole in the top of the overflow tank, and that's where it gets squirted out.

My question to you guys is this: what in the world is going on?! I am most likley going to get a new radiator in the next few days/weeks along with a black magic fan, but is there any other possible problems I should look out for? Do I possibly have a seal going bad or something? Why would there be so much pressure in the system?

thanks
~Andrew

 

if the car is warmed up there is going to be a lot of pressure in the system... its normal... water expands when heated... the only way u wouldn't have pressure in the system when warmed up is if ur running Evans NPG, because it doesn't need water in it, and it doesn't pressurize when heated up.... if its pressure in the system after everythings cooled down thats another story, and quite honestly i don't know how you would achieve that...

 

With it warm but not so hot as to burn you. Remove the cap and then start the car. have someone rev it a bit, Look in the rad for bubbles.

Report Back.

 

Well, nobody wants to tell you this, but the symptoms you're describing are classic of an internal water seal going out.

The radiator and coolant system is only pressurized to 12-14psi as controlled by your radiator cap (listed on the cap, usually). This is so that there's positive pressure to alleviate any air bubbles in the system. Unfortunately, this also means that the coolant will have sufficient pressure to be pushed past any O-ring seals that may be marginal; the end result is that the coolant is being pushed past the sealing 'rubbers' around the inside edge of the housings and entering your combustion chambers - probably on the intake side where there's additional vacuum from the manifold and intake cycle. This coolant is going straight from the water jacket into the combustion chambers, then out the exhaust as steam, so you're unlikely to see any obvious coolant leaks at the front of the engine. Further, if your regional humidity is very low, you may not even be seeing the steam coming out the tailpipe due to rapid evaporation.

The pressure that you're feeling in the radiator cap when you release it (and causing the overflow tank to spew) is due to combustion pressure being fed back into the coolant system when you run the engine; likely due to a bad sealing rubber on the inside edge of the housings on the combustion side of the engine. This excess combustion pressure is likely allowing fuel and exhaust gas to enter your coolant system, which will result in the coolant smelling like gas/oil, and/or the coolant having a lot of bubbles in it (hence the above poster's request to run it and then open the radiator to look for bubbles). In extreme cases, you'll also see an oil 'slick' in the coolant and it will smell like raw gasoline.

Engine temperature is up because the coolant isn't being pressurized correctly and isn't functioning efficiently with all the air bubbles in it from the combustion pressurization. Coolant in the radiator is 'rusty' because it's picking up the carbon from the exhaust gases and trying to dissolve this, but keeps circulating it with the coolant.

You're going to need a rebuild in the near future. I give it about another 1500-2000 miles before you're adding so much coolant that you have to refill it at every stop - at that point, it will become a serious inconvenience and you'll have to do something about it.

FYI - my 80LS died this way. I wish I had better news for you,

 

I had a feeling that was my problem (coolant seal going). the "refil ratio" is getting pretty bad, as I have to refill just about every 3 - 4 days. Another problem I have recently been having is the first 3-4 seconds upon startup, it feels as if one rotor isn't firing at all, then it kicks in. I guess this would be further proof that my engine is on its way to being fubar, is this a correct assumption? The rust colored coolant has been an issue ever since I got the car, but then again I've only put on about 2k miles (it's now at 98k). Looks like I might be selling her soon, or saving up for a TII swap... ::sigh:: it's a sad sad day in my world.

 

On startup, it's likely that one of the rotors seals is worse than the other, allowing the coolant to leak in - this will cause that plug not to fire until it is sufficiently dry to allow it to fire the A/F mixture.

If you're curious which rotor is bad, you could always pull the Leading plug from each combustion chamber - the one with the bad seal will be black/wet, and/or rusted up.

Sorry to break the news to you. Throw a gallon container of 50/50 water/coolant mix in the back or bins - you'll be needing it if you keep driving the car around. Also, run a quick search on 'block seal' and you might get some unconventional suggestions from others who have had this problem and limped along for a bit longer.

I would drain, flush, and refill that coolant, however - that rust is not good for the pump, radiator, or anything else in your coolant path.

 

hey guys...

looks like she's shot.

after a few minutes of warming her up, i took off the rad. cap, and not only did it bubble like all hell, there was exhaust coming out

::too upset right now to continue post, I will return later to give more info::

 

So sorry to hear that. But on the bright side you can pull it and replace the soft seals for $200 and port it while you are in there.

 

or put a 13B in it

 

...it has a 13B, it would like a 13BT

but I think this is the end of the road for me, as I'm nearing the end of my college career (one more year)and I want to get a 3rd gen, as that is the RX-7 I always wanted. So it's time to cut my losses now (which aren't really losses at all, I had a blast with my FC and my FB) and really start to save for the 3rd gen.

I'm not making any decisions right now, but don't be surprised if Shadow gets put on the "for sale" board in the next few months.