Why am I dropping coolant?
 

I'm hoping there's someone out there with an extensive knowledge of our coolant system. I'm having a major issue with my 93 rx7. Can anyone tell me why I'm losing coolant out of my overflow? I replaced the thermostat today and that didn't change anything. Iv'e checked all hoses for leaks and I don't see anything. when the car gets warm enough I see water coming out of the overflow. What can cause this? Please help me...

How much time is on the engine? Do a search on coolant seals. :(

your water seals on your motor are broke. rebuild time.

it works like this. when your seals fail, combustion gases get into the water jackets pushing water out of the motor into your overflow.
happened to me :)

things to look for: bubbles in your coolant while car is running
also, if gas leaks out while its running, then water leaks in when its parked. car will have trouble starting, only start with one rotor, and kick out white smoke.

i went a while before rebuilding. to do this, every time before you drive, top off at the water cap.

it got to the point when i couldnt drive 30min before my coolant level sensor would go off.

The engine has about 800 miles on it. I just rebuilt the motor.
@ Futile I don't see any smoke except for the normal early morning fog. There's no white smoke at all and it seems to be running really well, slightly rich, but that's only at idle and it's probably because it hasn't been tuned since the rebuild. I also added a OMP adapter and have a reservoir too so that could make it run a little rich.

I followed the break-in instructions to a "T" and it never overheated.
also I just found out I put the thermostat with the jiggle pin down instead of up.

Opps sorry that's 800 kilometers not miles and I should mention that I am running water only right now until I figure out why it's leaking. This may be a stupid question, but could using just distilled water w/o coolant cause it to boil over or something out of the overflow? Also, it's not coming out in bubbles its just coming out straight water out of the little black hole on top and only when it gets warm enough.

well earlier I checked the coolant system again to see what it was doing and now I'm getting a lot of smoke when it's cold. Wayyyy more than I thought was coming out. And unfortunately its looking pretty white.... I'm gonna post up a video for you guys to see shortly.

Get a pressure tester and test both your fill cap and pressure cap. Pressure cap should "crack" at approximately the indicated psi, but should hold pressure fairly close to the crack pressure as well. If not, you've got a bad cap. It's possible that your rebuilder "pinched" a coolant o-ring when they rebuilt your engine. A friend of mine here in Phoenix just experienced the same thing.

P.S. How cold is it getting in Vancouver now at night? I'd be a little concerned with straight water in your engine from a freezing perspective. Is your garage heated?

I was the rebuilder, so I'm hoping it wasn't me lol. What do you mean by crack? Would a bad cap cause water to come out of the overflow? Could this be a faulty ast too? If I test my coolant system and it's not holding pressure would that point to coolant seal if I can't locate any exterior leaks? It's not getting cold enough here just yet, still raining.

Here's a video of it running from a cold start to warm-up and a little driving after. Didi this last night.

http://www.youtube.com/watch?v=nRzDEu7oTXk

http://www.youtube.com/watch?v=ubMAbWvRKi8

definitely do a pressure test. In my case, I was using a small amount of coolant, and had a *very* small amount of smoke at startup that would go away once warmed up.

One neat thing that worked for me was to use pressurize the system using the pressure tester, leave it overnight. Pull the egi fuse, and crank the engine with the spark plugs out. For me, coolant spit out of the plug bores, which was a pretty definitive sign that I was getting coolant into the combustion chamber.

Also, did you do a coolant pressure test after you put the shortblock back together?

Don't take offense but this is why I paid someone to rebuild my motor.

Hopefully you get it handled.

Do not go by the stock temp gauge in the car !! When the stock gauge moves past center, it's already to hot.
Get a aftermarket temp gauge, so you will know exactly what the temps are doing.
Yes, it looks like coolant seals, but check it with a tester.

Also, don't "push" the car hard when you're on fumes. Put some gas in that tank.

A better description than "crack" is pop. I have a better idea...

Rent a coolant system pressure test and pressure test the coolant system itself (not just the caps) by attaching it to the thermostat inlet and applying vacuum. If you don't see any visible leaks, it is possible that it is a coolant seal.

Go to the 3rd gen FAQ thread stickied in this forum and look under the "C" section for coolant to learn more about the cooling system.

A bad cap would not cause coolant to come out of the overflow.

Remove the radiator cap with the car stone cold and start the car. If coolant is shooting out, you've got a bad coolant seal and the engine is pushing air/fuel into the coolant system.

Easy test to know for sure.

I built an engine once with the aftermarket coolant seals that are basically O-rings. One of them JUST slipped out of the groove and was pinched by the iron. Engine DRANK coolant. Also, it didn't show up after assembly when I pressurized the cooling system with the Pineapple pressure tester. Had to tear the motor back down, redid it with Mazda seals that STAY PUT like they should. Never touched the aftermarket ones again.

I disagree with the "this is why I let a pro build my engine" - yes, it's complicated to build an engine, but you have to go into it knowing you could mess something up that requires you to tear it down again. That's how you learn. If we all took that attitude this would be like the BMW forums where everyone just talks about writing a check to some shop and doesn't do anything themselves.

Anyhow, sorry for the bad news. Only other possibility would be a hole in the line going from the overflow tank to the radiator cap neck - a hole there would keep the engine from pulling coolant from the overflow tank back into the cooling system. But, that typically takes many cycles to push enough coolant into the tank to overflow.

Dale

Thanks Dale. I always learn from threads like these.

Thanks Dale, and I agree, I bought this car because I wanted to enjoy it. I love to build and I am also willing to pay the consequences of making mistakes. I'm going to do what you said and take the cap off and start it. I'll also check the line from the overflow tank and get a pressure tester. It did take a while for me to see anything coming out of the overflow so I wonder if it's not being sucked back in. I'll keep you guys posted on the results.

I can get the mazda seals from Atkins and Mazdatrix if needed right?

Yeah I'm very familiar with this fact because of all the horror stories about it on this forum. I just figured I would get by until I figured out the leaking. I went and got some more fuel for it so we are sittin at 3/4 now :nod:. Any recommendations on a decent WP gauge? I kinda wanna go digital. I've heard Defi is good, but I don't think they have digital gauges. I also saw this video (http://www.youtube.com/watch?v=YjRTQapbz0s) where this guy had a digital temp readout in his dash.

so far looking good, no bubbles. I'm getting the pressure tester next wednesday. Right now I'm flushing the coolant system ad I also replaced my AST cap just for the heck of it. How do I get coolant out of my overflow? is there a drain plug or anything?

I always use a turkey baster haha.

Dale mentioned the coolant line going to the overflow from the ast make sure it is a good hose if it is weak it wont function properly and cause the overflow problem your having. I also had this problem on my car and I replaced the hose and never happened again.

As I thought about my problem Ive remembered a key difference between my situation and yours, mine overflowed after I had driven it awhile and after it was off for a few minutes it would start to overflow.

Alright I took the overflow tank out and then drained the water from the radiator. I inspected the line that's coming from the top of the AST to the top of the overflow I also did a visual on the other two lines as well. I don't have a way to test for vacuum yet, but I did blow and suck on the hose and the plastic tube in the overflow tank. I didn't hear any air releasing. I filled the car with coolant as per the FSM and am currently waiting for it to cool down so I can burp it.

so the overflow tank is sitting outside the car but still hooked up. I heated the car up and drew a line with a marker where it was when I filled it cold and where it stopped once it got hot. The water hasn't moved at all and its been about an hour and a half since I did that. I did this after my last post. What happens if you pull the cap off the fill neck and the pressure releases?

If you pull the cap off the fill neck it'll burn you really bad and you'll never do it again.

I know that, I waited about 40 minutes before I touched it and even then I used a rag and went slow. My question was whether it would make the system unable to suck coolant back in from the overflow.

Update

So last night I went back out and checked and sure enough the water still didn't drop down from the line I drew. So that tells me it's still not sucking it back in, or maybe there's just a ton of air. I put the excess coolant from the overflow into the fill neck and warmed it up again. I still can't tell if the thermostat was opening but I did warm it up for a while and again watched the overflow slowly fill to almost the top. I shut it off again and let it sit overnight.

Its now just after noon and I checked the overflow again. Nothing was sucked back in at all! Bad AST? Still has air in it? This time when I popped the fill neck cap there was no pressure whatsoever and after squeezing the upper rad hose I was able to dump most of the coolant from the overflow in using a funnel. I also pulled the TB hose. I warmed it up and there was a lot of smoke but it smelled normal to me.

I'm not sure if it smokes more because of the 2 stroked OMP or not. After it got up to normal temp. I brought the rpms to 25 hundred and held it for about 20 secs. Checked the overflow, and repeated this cycle until I finally saw the temp fall way down and then get back up to normal temp again. When this happened the add coolant light came on for about 5 secs then stopped. Also bubbles were coming out of the overflow.

Just to add I should let you guys know that when I changed the T-stat I used an OEM one but not from mazda. It does have the pin at 12 o'clock and is rated for 82C. Today when I warmed it up I turned the A/C and fan on hot so the rad fan would blow.