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From: "Tom-Lynn Koftinoff" <tomk@telus.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-2784622@logan.com>
Subject: Re: [FlyRotary] Coolant leak - the teardown
Date: Tue, 11 Mar 2008 01:44:51 -0700
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Someone probably has mentioned this before, but in the 13B engine, if the 
needle bearings, spacers, thrust washers, etc are all installed correctly 
(see page 70 of Haynes Automotive Repair Manual, Mazda RX-7, 1986 thru 
1991), then the pulley hub protrusion (maximum) shouldn't exceed 0.0961 
inches (2.44 mm).    Just my two cents, I am probably not a great source of 
information, since I am still trying to work the bugs out of my 
rebuild/conversion.

Tom

----- Original Message ----- 
From: "David Staten" <Dastaten@earthlink.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, March 09, 2008 6:29 PM
Subject: [FlyRotary] Coolant leak - the teardown


> Well.. today we tore the engine apart.. the short and sweet of it is there 
> is no obvious source of a coolant leak.
>
> Took the engine apart without too much trouble..
>
> As we pulled off all the housings we checked the rotor faces, the grooves, 
> the seals and the intake ports for any sign of a leak or blowout. None was 
> forthcoming. I had expected to see a blown out coolant o-ring groove, but 
> all were intact. Felt the intake ports, no sign of a problem there either. 
> I had only ported the center iron, so the other two end irons were stock. 
> So as it stands, we have an engine that is giving us no obvious reason for 
> a coolant leak. The bolts werent loose at all.. they were so snug from 
> tape and silicone it took a hammer and vise grips to extract them once 
> they were untightened.. So thats the semi good news..... nothing obvious.
>
> Now the bad news..
>
> When we took the engine apart, I was concerned about how the rebuild 
> itself went.. and how things held up to our first attempt at building the 
> engine. I examined things as we took them apart and paid particular 
> attention to the front end.
>
> I was even showing Chris how the front bearings can be a problem if you 
> loosen the front bolt and cause a bearing to get pinched.. well the front 
> bearing on the outside of the thrust plate looked fine. Took off the 
> thrust plate and discovered that the other bearing had destroyed itself. 
> At this point, Chis chimed in that there was metal bits in the oil when he 
> drained it, and lo and behold the bits resembled the roller pins in the 
> bearing..
>
> The spacer had welded itself with the inner ring on the destroyed bearing, 
> forming a spoked wheel, and the inside of the thrust plate had wear damage 
> to it as well.
>
> I am certain i know when this happened. During assembly, everything went 
> as it should. end play was ok. I had installed the stock pulley on the 
> front at the time of rebuild. After we added the PSRU I was no longer able 
> to check end play, as it secured the engine's flywheel travel.
>
> At some point, we purchased and I added a double pulley, and while i took 
> care not to let things shift around, I am suspecting that this is when it 
> happened. The lesson: don't remove the front nut if you cant check end 
> play or put the engine vertical.
>
> The remainder of things looked great - no missing pieces, nothing burnt, 
> no gouges... 10 hours of use on the ground and thats what weve found.
>
> Dave
>
> --
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