jon88se

Sunday was a beautiful day and I decided to park my new daily driver and take the FC out for a spin. It's been about 3 weeks since I drove her last...

After about 10 minutes of driving, I noticed that my temps were almost at the halfway mark on the factory gauge...I turn around and go home without incident. Once I shut the car off, I opened the hood and noticed coolant coming from the overflow bottle and a lot of gurgling. The upper rad hose was also pretty hard and it seemed to have a lot of pressure. The top of the radiator was hot so I don't think there is a clog and while driving home I was able to get heat in the interior so I don't think the heater is clogged either.

The thermostat has maybe 800 miles on it and the motor has about 3500 miles on it. The next morning, I filled the car with coolant/water and pulled the EGI fuse to crank with the rad cap off. While cranking, no water spewed or gushed out of the thermostat housing where my rad cap goes (no cap on my radiator, this is how some FC cooling systems are designed).

I haven't played around with it since. Should I try taking the thermostat out and see what happens? I put another rad cap on - I had a spare. Now, as I said before, my rad cap goes on my thermostat housing. There is NO hose that connects that housing the the overflow bottle. The way my system works is that a hose runs from the top of the radiator to the overflow bottle. There is a pill/restrictor about an inch from the top of the rad in this line that you can feel and I believe this is how the system reaches pressure.

I was under the impression that modern thermostats only get stuck open, not closed. Any ideas?

Aaron Cake

iTrader: (1)

Taking the thermostat out won't solve your problem, and could cause several others.

First, do a coolant system pressure test to make sure your engine isn't pushing exhaust into the system.

What's with the odd cooling configuration you have? There are many variations on stock, but that is not one of them. I would eliminate it and use a proper pressure cap before you troubleshoot further.

nopistons

Mine ('88 SE) has a non-sprung cap on the t'stat housing, and a regular, sprung- radiator cap on the rad. The overflow tube sits beneath the cap on the rad, and goes to the bottle. The cap on the t'stat housing is not a pressure-relief cap. (It has no spring underneath) It's just a cap. The cap on the radiator does all of the pressure releasing - That's why the overflow tube is there. That tube has got to be wherever the spring-loaded cap is, otherwise the overflow/reintake system won't work properly. Is that how your's is? It sounds like perhaps you've got the tube where the unsprung cap is. Have the two caps switched places? That would make a difference.
EDIT - I just reread and saw you have NO cap at all on the rad. You have to have that overflow tube under the sprung cap. Doesn't one of the setups come like that?

jon88se

My car has been this way since the day I bought it in 1997 - before and after the turbo swap without any problems. Here is a pic of the engine bay so you can get an idea of what I'm talking about:

Aaron Cake

iTrader: (1)

That's a cooling config I have not seen on an FC. It certainly doesn't resemble any factory install. In this case, I would first suspect that check valve. Your car is demonstrating the symptoms of a bad pressure cap, so that valve would be the first place I would look.

ilike2eatricers

It looks like someone threaded a fitting onto where the coolant level sensor would be.

jon88se

I know there are other people who have this configuration - the stock level sensor is still hooked up.

skatingsamurai

i had this same problem.... although i shouldnt advise it because its really dangerous... every time you drive the car open up the hood. then unscrew the bottom cap about 1/4 to 1/3 turn. just enough to hear girgling in the rad....this should allow excess press to release and you shold see some spray out the overflow tube...and continue to do this untill you stop having the problem.... and make sure you check to see that you have enough coolant in the over flow tank cuz on cool down it should suck some back up.

i have had success with this method anyways. seems like it might help! oh and if anyone objects to this idea please feel free to tell me im stupid and shouldnt do it because im always looking for new ideas

jon88se

That is def. not the right way to bleed air in the system Tonight I bled the system and filled it and put the OEM unsprung cap on the t-stat neck. I took her for a drive for 10 minutes and let it idle for 5 minutes. Temp was normal and there was no excess pressure, nor any leakage from the overflow.

The one thing I DID notice during the drive is that my voltage was low - it wouldn't go above the 12 volt mark. After the drive when I let it idle it was down to 9-10 volts. It still idled and ran but the alternator wasn't charging the battery when I gave it some throttle.

Could this have something to do with what happened the other day since the same belt runs the water-pump? That wouldn't make sense. I've got a good spare alternator that I'll put in on Sat. and see what happens then.

jon88se

bump

So as I said earlier, after re-filling the system and replacing the sprung cap I had on the T-stat neck with the OEM un-sprung cap, the car seemed fine. It ran for about 10 minutes and idled for more than 5 minutes with good temps and pressure on the gauge.

While filling, I did squeeze the upper pipe with the bleed screw out to get rid of any air bubbles - could that have been my problem?

nopistons

Jon - I see in your photo that there's a bolt-on adapter on the top of the t'stat housing neck to hold the cap. My rad has the same adapter on the rad to hold the pressure cap, but it also has the overflow tube neck built into it. Perhaps you can find a used adapter like that and put it on your t'stat housing in place of the one on there now. Then you could run the overflow tube from there to the bottle. That'd be a more "normal" set up, and would eliminate that check-valve thing.
Pete

jon88se

Thanks guys - as I said before, this setup has worked for years and years without incident. I'm wondering what could have caused my problem the other day that has now seemed to be fixed.

Could it have something to do with the fact that during last nights drive my alternator stopped charging? Air in the system?

Syonyk

If the belt is the problem, you'd see it when looking at it. It would have to be really quite loose (and would probably be squealing badly) to be not driving things properly. Poke at it. If it deflects more than half an inch or so on the long side, tighten it up. A slipping belt could definitely cause problems.

-=Russ=-

xtremeskier97

That is EXACTLY like mine. It IS STOCK.

jon88se

Ok, so you have ONE cap on the thermostat housing that is UNSPRUNG, correct?

And your radiator connects directly to the overflow bottle with a restrictor in that line, correct?

I just want to make sure we're talking about the same exact thing because I thought this setup was stock as well.

What year/model is your car?

jon88se

bump

Aaron Cake

iTrader: (1)

I've never seen that configuration before, and I've seen all the various factory configurations. If it's stock, then it's news to me.

Still, that "restrictor" is likely the problem. I assume that it is a check valve which serves the same purpose as a pressure cap.

RotaryEvolution

iTrader: (30)

it is stock, as i said a while earlier the pressure cap is located next to the RF headlight. i would double check your pressure cap, maybe even throw your spare one in that position.

Aaron Cake

iTrader: (1)

Well, then that's news to me. That would be one configuratoin that I have not seen.

RotaryEvolution

iTrader: (30)

i have seen it on a few n/a's in wrecking yards, i actually pulled one of the pressure cap assemblies and used it on my car for a while to control the pressure i had when i was having coolant seal problems.

RotaryEvolution

iTrader: (30)

you can see what i am talking about in this picture of my car.




notice the extra pressure cap assembly to the left of the coolant reservoir?

jon88se

I don't have a configuration like that...there is no pressure cap down there on my car. I only have ONE cap, unsprung on the t-stat housing. I do feel a restrictor of some sort about an inch into the line that runs directly from the radiator to the overflow bottle.

I'll call mazda and get the t-stat housing with a pressure cap and overflow outlet and connect it correctly. I would need a t-stat housing from what year? Anyone know the part #?

jreynish

iTrader: (2)

Just buy a Koyo or Fluidyne Rat and just use a Rad cap. Probably be the same than buying all of that stuff from The Dealer.

xtremeskier97

Ill verify when I get home this evening and let you know, though I am almost POSITIVE that it is EXACTLY the same.

RotaryEvolution

iTrader: (30)

then something is wacky with your system, there has to be a pressure limiting device between the top of the radiator and the overflow bottle or your car is not right.