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Difficult starting 12A

 
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Solow



Joined: 26 Mar 2006
Posts: 2

PostPosted: Mon Mar 27, 2006 4:47 am    Post subject: Difficult starting 12A Reply with quote

Hi,
I'm new here but have owned two '83 RX 7's. I still have one of them with a carbed 12A rotary engine but have not driven it for several years due to starting issues. I can get it started occasionally but usually flood it trying (plugs get wet with fuel) and running down the battery. If I roll it down the hill and let the clutch out it starts up and runs fine. Actually it runs very well, no smoke etc). Warmed up it will start easily and run normally. Let it cool down though and I am back to hard or impossible starting again. The car has about 80K miles on it and was bought used so I am not sure how well it was maintained. In any case I suspect compression issues may be the cause. I also read about fuel leakage into the rotor housings can wash the oil out causing lower compression during starting. I am wondering also if rotor seals etc can become carboned up and get stuck in the grooves etc? Could this be a problem for me and can it be fixed? I have heard of gas / oil treatments such as "seafoam" that are supposed to unstick seals and such in carboned up engines. Any experience with this stuff?

TIA for any help.
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Blake
Been there, done that


Joined: 12 Jul 2005
Posts: 135
Location: Portland, OR

PostPosted: Sat Apr 01, 2006 9:24 pm    Post subject: Re: Difficult starting 12A Reply with quote

Solow wrote:
Hi,
I'm new here but have owned two '83 RX 7's. I still have one of them with a carbed 12A rotary engine but have not driven it for several years due to starting issues. I can get it started occasionally but usually flood it trying (plugs get wet with fuel) and running down the battery. If I roll it down the hill and let the clutch out it starts up and runs fine. Actually it runs very well, no smoke etc). Warmed up it will start easily and run normally. Let it cool down though and I am back to hard or impossible starting again. The car has about 80K miles on it and was bought used so I am not sure how well it was maintained. In any case I suspect compression issues may be the cause. I also read about fuel leakage into the rotor housings can wash the oil out causing lower compression during starting. I am wondering also if rotor seals etc can become carboned up and get stuck in the grooves etc? Could this be a problem for me and can it be fixed? I have heard of gas / oil treatments such as "seafoam" that are supposed to unstick seals and such in carboned up engines. Any experience with this stuff?

TIA for any help.


A real compression check is in order, I think. Low compression engines run GREAT, just before they give up the ghost, so it's not too suprising that it's hard starting but good running. Low compression could be caused by a number of things. Carbon may be a contributor but the root cause could be weak springs under the seals. This is more likely in a car that has been mildly overheated several times. Anything before 1993 (3rd gen) has really wimpy corner seal springs that flatten just by looking at them wrong. And, as the apex seals wear, the spring pressure diminishes too. Lots of possibilities and it could be a combination of things. This is presuming you have a compression problem...you need a compression check.

I've never used SeaFoam, or whatever it's called. Some people swear by it, but most of them can't really base their enthusiasm on anything objective. I dunno. Probably wouldn't hurt, but you're on your own there. What I *do* recommend for fighting carbon deposits is "steam cleaning" the engine by having it suck in water through a big vacuum line while you hold the revs up to keep it alive. It will drink up the water at a pace that is not dangerous (it won't hydrolock) and the water will flash to steam during combustion, helping disolve the carbon deposits. Very, very effective and minimal risk (minute chance of lodging a sliver of carbon under a seal, but I've never actually heard of that happening). Might want to give it a shot.

Since your car is a carburetted 12A, you can just pop the air cleaner off and pour or squirt the water down the venturis. One or two liters is plenty. Since you have to keep the engine revved up while adding the water, you can drill a hole in the cap of a 2 liter bottle, stick a clear tube in it down to the bottom and just squeeze the bottle to squirt it. That should allow you to sit in the driver's seat. The throttle bell crank is hard to reach in the engine bay, so it would be best to just use the throttle pedal from inside the car. At least, that's how I would do it. Hope that helps.
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Blake Qualley
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Solow



Joined: 26 Mar 2006
Posts: 2

PostPosted: Sun Apr 02, 2006 10:02 am    Post subject: Reply with quote

Thanks Blake,
Very good suggestions and advice. I figured the compression is the culprit and will try to do a check on it soon. I am pretty sure it is just worn out and in need of rebuilding (but the cost of rebuilding rotaries is rather high in my opinion and may not be worth it for this old car). I would go out and check compression right now but I am rebuilding my wifes' Ranger engine right now so it may be a few weeks before I can get to the RX7. The idea of "water injection" is something I learned long ago and have used in the past. I was taught to sprinkle water from a coke bottle into carbs while revving the engine to loosen carbon deposits. The grey smoke produced is evidence it works (as well as a smoother running motor). From what I read on a Full SIze Bronco forum "sea foam" is supposed to unstick lifters, rings, etc as well as clean out carbon. Who knows if it really works as advertised but most of those guys liked the results. Made me think of the old RX7 problems and I figured I would ask the forum here.

Thanks again!
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