Houston, and anyone else who wants to chime in, I have a problem.
I have an 86 RX7 that probably has bad apex seals.
I have not done the champagne test but here are the symptoms.
Stupid low coolant buzzer goes off every 30 miles or so at which point I remove coolant from the reservoir and return it to the system. Temp always stays in the low range on the gauge.
I have replaced the radiator as the original was (invisibly) leaking at the edges. I used dye and found no other evidence of leaks. All hoses, cap (13 psi) and coolant are (relatively) new.
Since putting in the new radiator the coolant has been escaping to the overflow.
So, I ran into two guys who specialize in rotaries and seemed very knowledgeable and legit at an autocross and hit them up for free info. They said that the two choices are rebuild ($2200) or they use a product that seals the apex seal leaks, basically a head gasket repair product. They say that it is effective at sealing the combustion chamber 75% of the time. It costs around $200 and a day of my time as the shop is two hours from my house.
THe car is an 86 Rx7 1:scratch13b normally aspirated. 94000 miles, seems to be pretty well maintained. I have owned it since it had 89k miles (2 years)
My goal for the car is monthly autocrossing.
If this sealant gives me a few thousand miles i.e. at least this season, so i can find a cheap motor to rebuild myself over the winter, I will be happy.

Anyone have any experience with any products of this sort.

 

Are you sure they said apex seals? If they did, stay FAR away from these rotary "specialists". They have no idea what they're talking about, and just want your money. Apex seals have absolutely nothing to do with the cooling system. The apex seals are at the tips of the rotors, and seal the combustion chamber during the intake/compression/exhaust "strokes". On a piston engine, they'd roughly be equivalent to piston rings.

The head gasket equivalent on a rotary would be the coolant seals, which are between each of the "slices" of the engine (front iron, front housing, center iron, rear housing, rear iron). These are paper based gaskets, which some have had success with sealer additives. However before trying anything like this, do the champagne test. Check for bubbles in the coolant. Generally an engine with blown seals will overheat or have trouble starting (due to coolant leaking into the combustion chambers), but yours is apparently not having these problems? Does the coolant overflow tank have a vent to atmosphere (stock form has an open hose from the cap)?

 

what is this champagne test? and did those guys say they were rotary specialists or did u just think they were cause what they said seemed to make sense?

 

Testing for bubbles in the coolant, which could be coming from a blown coolant seal. Gases from the combustion chamber get forced into the water jacket, then make their way up to the radiator filler neck/cap. This is one thread that talks about it: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/champagne-test-coolant-seal-803178/.

 

o alright. never heard it called that.

 

I had a similar issue, but with opposite results. Where you have coolant being pushed out of the radiator, I had coolant being pushed out the exhaust.

I fixed mine with a bottle of Alumaseal radiator sealant. Cost under $4.00 and solved the issue within a half hour of idling.

However, since your flow is in the opposite direction, I'm not sure that this would be a viable option for you. I think the inflow of exhaust gasses might keep the sealant away from the area that requires repair. However, if you added it, and then just idled the car rather than driving it, for say half an hour, then let the car sit overnight, it might work. I'm thinking that as the car sat after shutdown, the pressure in the coolant system would force the sealant through the repair area, since that would be it's only way out at that point.

If this were my car, I'd give it a shot. My repair has held for over two years now, and I've made two trips down to North Carolina and back without issue. I just got back a couple of days ago, and put just over 2,400 miles on the car over the course of 6 days.

If you do try this, just make damn sure you get the right stuff. Alumaseal is what you want, others could have nasty side effects...



.

 

Thanks for the valuable info!
No, I am not sure they meant apex seals. I didn't realize there were other seals on the rotary.

It does have a hard time starting if its been sitting for a while. Generally it does smoke and run a little rough on startup, but it seemed more like an overly rich condition, but there is some gray smoke to it as well as the black smoke.

I will have to do the champagne test. I am assuming that if there are bubbles it is the coolant seals. Could it be anything else in that case?

Alumaseal it will be and then another few seasons of autocross maybe?

We love the autocross. My wife doesn't like the RX7 - says she can't see over the hood. So in order to get her into it we may end up selling the RX7 (cheap) and getting a shorter hooded car CRX, Del Sol.... But I love the rx its a lot more car than I am driver at this point. We are in the Blue Ridge Region SCCA. Its great. The guys in it are all great. Low key, helpful, friendly.

Thanks for the help, keep it coming.

 

Well I tried the ALuma seal yesterday. SO far so good. Put it in topped it off - low level alarm was sounding. Idled for 50 minutes, took for a short drive - 12 miles or so. No alarm, no coolant into overflow tank. Will put on more miles before I declare it "fixed".
It failed the champagne test. That is there were bubbles coming up from the filler neck.
Easy and cheap fix if it holds and I suspect it will as the Alumaseal stays in so it should plug up new pin holes, whatever as they crop up..
Thanks for the help!

 

Keep in mind that the champagne test assumes that you have all air bubbles out of the coolant system. If you don't spend the time to bleed all air out of the system, you can easily mis-diagnose the results of the champagne test. Even a good motor will blow some bubbles during a test.

Here is a good local-ish rotary expert for you:
http://www.pfsupercars.com/

 

Let me know how it works out. There have been 8 or 9 others that have followed this advice (that I know about) and so far, only one failure so far (that I know about).

 

I am not so sure it is holding. Had to transfer fluid from the overflow and bleed the system twice on the (120 mile) trip home from the autocross this weekend. Only 8 runs on the car, in addition to the trip up and back, it has improved but is not fixed.

As far as the champagne test, bubbles were coming from the engine block side of the filler neck, my bleeder is at the radiator as far as I know which is actually lower than this .

So I am thinking its not fixed although it has improved. Looks like I am going to sell it as a project as the car is not worth enough money (and my marriage is worth more than any car) to rebuild the motor.