I have a 88 n/a vert. My add coolant light and buzzer has been coming on. I add coolant and for a few hours its ok but then the light and buzzer return. My reservoir is now over the full mark. My guess is that it is not getting back into the cooling system. Could this possibly be the problem? Does anyone know how to fix this? I searched for a similar problem but I could not find any. Thanks in advance.

 

If you have a crack in your coolant reservoir cap pressure will bleed off and wont be able to return the coolant back into the rad while the engine cools down. I had a similar problem and the cracked cap turned out to be my problem. Good luck.

 

The cap does not look like it is cracked. I inspected all the hoses and they all seemed ok. There is no sign of any leaks. My filler cap does not have a psi rating but my radiator cap says 13 psi. It is the kind with the red lever that you pull up to remove and push down to lock it in. Any other ideas? I am completely stumped.

 

Are you adding coolant to the reservoir or removing the pressure cap and filling through the the water outlet? Try the latter.

Leave the cap off and run the engine until it gets hot enough to open the thermostat. If you see a couple bubbles it could just be air in the system. If you see a continuous stream of bubbles you have a coolant leak.

 

I have been adding through the filler neck. When I run the engine coolant rises and begins to spill out of the filler neck so I replace the cap. Up until that point I do not see any bubbles. My bleeder plug is completely stripped so I don't know if the air is completely out of the system. Also the coolant in the reservoir is completely a different color than the coolant I am adding. I add green and the coolant in the reservoir is a dirty reddish brown. Rebuild time?

 

Replace the small-diameter hose between the rad and the overflow bottle. It may have a small air leak in it that is preventing the coolant from being sucked back into the rad when the engine cools down. If that is the case, the coolant would flow out of the rad when the engine gets to operating temp and the coolant expands, but when the engine cools down and tries to suck the coolant back into the rad, it can't because of the air leak.

 

I replaced the hose from the radiator to the reservoir and it still is not returning to the radiator after it cools. I also replaced the radiator cap just to be safe. The upper radiator hose was also replaced about a week ago, and the lower hose looks like new. The thermostat seems to be working ok, I feel the coolant in the upper hose. I ran it for about an hour to see if the light and buzzer would come on and it didn't but the temp guage went to half. I read that they are supposed to be closer to 1/3 of the way up so I am a little worried about that. Any other ideas? If not then I am going to take it to the Rx7 store here in Columbus. Thanks again

 

Did the overflow tank fill up this time?

Just a thought, the cap on the overflow tank has an internal hose attached to it. Is that hose present? If not, there is no way the coolant can be sucked back into the rad. Otherwise, I would recommend that you get a aftermarket coolant temperature gauge. The OEM gauge doesn't really give you the numbers you need to determine temps.

 

There is a hose on the inside of the reservoir. I will give it a few days and see if the light and buzzer return. I siphoned out the reservoir to the full mark so it wil be easier to tell if it gets stuck in there again. Thanks for the help.

 

Next time you get the buzzer, let the car cool down so you can work on it. Remove the cap on the thermostat housing and confirm there's no water there. Then remove the cap on your radiator. Fill the radiator til full. Put the cap back on the radiator.

Now pour water into the filler on the thermostat housing till full. Now unscrew the cap on the radiator just enough til water starts to come out. When water starts coming out around the cap, screw that cap back on. Now go to the filler on the thermostat housing and fill it up til full. All the air should now be out.

But I bet there's a leak somewhere and the problem will recurr.

Oh yeah, put the cap that says 13lbs on to the filler on the thermostat housing and the other thing on the radiator.

EDIT: Let me take that last sentence back. Put the 13lb cap whereever the overflow tube is that goes to the overflow tank. I'm not familiar with series five.

 

try bleeding your coolent system you could have air bubbles that wont come out so what you do is have the car running and on the passanger side of the radiator is a petcock turn it open a little bit till it starts bubbleing lets it bleed for a few mins and then close it shut off engine and then that might solve your problem

 

did you say you replaced the radiator? if so did you get a cross flow or a straight flow?

 

Did you use a lisle funnel when you bled the system?

 

I have not replaced the radiator. I just used a regular funnel when filling it up. I ran the engine for a minute or so, but then it would start to overflow out of the filler neck so I would replace the cap. Should I let it all spill out instead to make sure there is no more air? I didnt want to spill coolant all over the engine.

 

Google this. ^

 

After driving home from work today I popped the hood and heard hiss from the radiator cap. I am guessing this is where my problem is. It is a brand new cap so I think it might be coming from the radiator neck. I am going to take it apart and inspect it when it cools off. Does anyone know I can even find that part anywhere? Maybe just needs a gasket?

 

Your **** needs a gasket all right.

If your coolant reservoir isn't functioning anymore, there is only 1 problem.

 

I know only a couple of things in this area on S5's. There is an o-ring where the thermostat cover/pipe attaches to the water pump, and this plastic assembly likes to crack so maybe one of these is the source of your leak.

Also, since you were asking...let the car warm up with the highest cap in the system (thermostat cap, right?) off, let the thermostat open, let fluid leak out as it expands. Now the coolant is circulating, letting any trapped bubbles out. **Make sure the heater is on hot** so air comes out there too. Wait some time until you're sure there are no air bubbles (15 min. after warm). Also, my bleeder is also stripped, but a big enough flat head turns it now - so get the bleeder loose until just fluid comes out, then tighten it back.

Also, you mentioned the color of the coolant is different in the tank. Probably the pink redish 'long life' coolant in there - regular green stuff is the 2 year 48,000km coolant.

Last note is guys here swear by using a Mazda Cap and Thermostat. I concur.

 

It was fine for a day or so and the buzzer came back today . Yesterday I took off the radiator neck and looked at it and the o ring looked fine. Today I didn't hear a hiss so that's good. I will try to bleed the system of air one more time and then I am taking it to the rx7 store. Thanks for all the help

 

ok dose your car smoke at all when start up???

 

There is no smoke at all. Sometimes I do smell antifreeze after I shut it off, but there are no drips or signs of a leak anywhere.

 

After a few more tests, I have pretty much figured out my engine is toast. I ran the engine longer than I did the last few times and I got lots of bubbles. Does anyone know of a good sealant that will get me by for a few weeks until I get the money together for a rebuild? I really appreciate everyones help.

 

my buddy has this same problem and it came out to be blown water seals no smoke just overflow and the buzzer...but he still drives it, just adds water all the time he just removed the termo to avoid pressure...

 

hey there! I currently have the exact same problem with my 1987 rx7 n/a! I am very shocked that you claim that the "engine is toast"! Can you please elaborate on why you came to this conclusion? I really dont want to replace my cars engine

 

you can try the Bar's leak copper radiator sealer but it likely won't work since it sounds like you're only pushing air into the cooling system and not water into the engine.

the coolant sealer needs to bake from combustion gases to seal, so if it can't work it's way into the joint it simply won't work.

it has worked well for me in the past on some personal projects but it's only temporary and only ever worked on engines that were burning coolant inside the engine.