BLUE TII

When I was driving to the hillclimb breaking in the rebuild I had detonation so bad the car just hesitated in the midrange. I had left the boost at the 8.5:1 15psi on the new 9;1 rotors- doh.



Once the boost was turned down to 13psi the motor felt good on the low end, but a little soft on top and WAY too quiet w/ the wastegate open to the atmosphere.



When I checked my plugs after the race (doh!) I found the front leading plug had lost its ground stap due to erosion/vaporization from the detonation at break in.



Fixed that and the motor felt good on the bottom and the top end was back to its former glory and ear splitting charm.



Then my oil pressure suddenly dropped to stock levels despite my 120psi regulator after a few 9,000rpm runs.



There was little bits of hard metal and larger shreds of soft metal in the oil filter (bearings? and ?? I thought) but adding oil thickener did NOT raise oil pressure as I would expect if it was over clearanced bearings dropping pressure.



I removed the front cover expecting to find a blown out o-ring that caused low pressure that caused metal to metal contact, but it was intact.



Removed the oil pump and found half a dowel pin between the pump stages. Checked the pan and there was the other half.



It was the front side housing stationary gear locating dowel pin that was vibrated out? during earlier rotor rocking detonation? or high RPM operation? and sheared between the front housing oil pump cavity and pumps first stage. Luckily the front side housing pump land is in good shape still.



I would not have sucked the dowel pin up if the oil pick up had the bug strainer on it still (it is velocity stacked), but then I am thinking the rotor may have gone out of phase at some point with only the higher clearance bolts holding it in place - so maybe it is a good thing it failed as it did in an obvious manner?



The soft metal in the filter appears to be the aluminum oil pump body and stage divider the hard metal bits the dowel pin and oil pump- phew.



I guess a new dowel pin will go in with permanent lock tight.

j9fd3s

wow thats a weird one! we've sheared that pin off before, but ive never heard of it falling out... lucky you

BLUE TII

The dowel pin hole was still very tight, but either side of the starionary gear slot was beat up a bit from impacting the dowel.



Now that I think about it I think the cause of the failure WAS the fact that the front leading spark plug was missing its ground strap.



I believe that since the whole front half of the engine was down on power there was a lot of force put upon the front stationary gear as the rear rotor was driving the front rotor around the gear through the e-shaft.



I drove it like that for several races and lots of daily driving- I just thought this rebuild was soft on the top end :P



Sound plausable?

j9fd3s

yeah, if the timing was off or there were misfires or something, i could see extra stress on the stat gear and bolts. speaking of that were the bolts loose or damaged at all?

BLUE TII

Hmm, I am thinking just firing the trailing spark on the front rotor could have been hard on the stat gear from combustion forces as well.



The stat gear bolts were all tight and looked normal.



I am thinking the pin just came out and I sucked it into the oil pump almost instantaneously. As soon as I saw oil pressure drop I was very easy on RPMs and power. I was trying out the new found power of having all four spark plugs working and actually saw the pull the oil pressure dropped on.



There was an indent the shape of the whole dowel pin's side on the leading counter weight face where it slapped the pin out of the air and into the oil pan!

j9fd3s

so it sounds like that pin just fell out? dumb luck?



i wonder how badly the oil flow is affected if you put a little wire over the opening, so it cant suck up any bolts?



all in all though its not too bad, didnt damage much

BLUE TII

so it sounds like that pin just fell out? dumb luck?



Well, visually it looks like the stat gear was vibrating the pin out by unusual back and forth forces on it. I think it had to do with the missing spark plug ground strap on the front leading plug.



I have never heard of someone having this failure and I have never heard of someone dumb enough to race a rotary w/ out a leading plug working- so they probably go together



i wonder how badly the oil flow is affected if you put a little wire over the opening, so it cant suck up any bolts?



If the bug screen was on there I wouldn't have known there was a problem until the rotor got out of phase at high rpm and contacted the rotor housing. I have seen scary pics of housings broken open when this happens.



A screen would help if I dropped something into the engine and was too lazy to flush/fish it out ( I have had to do this), but if parts are falling out the engine's internals into the oil pan, I don't mind finding out about it from a trashed oil pump.



all in all though its not too bad, didnt damage much



Exactly!



Can you tell I am bumping this thread so that someone who knows can give me some insight :P



I know- what this thread needs is pics. Gotta get those off the camera!

j9fd3s

yesh! if theres no pics it did nt happen!

BLUE TII

Sorry for the poor pic quality. You are looking at a sheared stat gear dowel pin, the stat gear slot, front housing dowel pin bore damage and oil pump inlet damage.



I didn't get a pic of the pin imprint on the counterweight

Barry Bordes

The roll pin is really only for indexing the oil port between the stationary gear and front housing. The six bolts take the load.



You can flare the pick-up tube to aid flow, but I reinstall the screen.



It would probably still be running with the roll-pin in the sump if you had had a screen.



Barry