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Discussion Starter · #1 · (Edited)
Finished big bore build yesterday and fired up engine. Started right up and oil light went out after a few seconds. Let it run for 3-4 minutes and noted a high pitched scraping noise. Shut it down, let it cool. Fired it back up, same issue. Pulled the cam chest and inspected the cam gears, bearings and oil pump. All seemed fine, so I pulled the jugs and found light scoring on the cylinder walls and on the intake sides of the piston skirts.

When assembling motor, used plenty of oil and assembly lube on the jugs, wrist pins, pistons and rings. Installed all new o-rings and gaskets as applicable. Installed new lifters that had soaked in oil. Confirmed that oil had been pumping up push rods and oil return O-ring in top of lifter box/plate was present. Cylinders and pistons skirts had oil film on both. Some oil also on top of pistons...maybe assembly lube? Plugs indicate mixture was very rich, black in color. All timing marks correct on cam gears and push rods installed in correct positions. Also confirmed that all rings installed correctly with ring gap to spec.

Had not actually removed oil pump during build but recall when pulling cam plate for gear drive install, feed pump rotors pulled out/fell out. I simply reinstalled. Upon disassembly and inspection of the pump as possible cause I noted that when the rotors were reinstalled, the punch marks where facing inward. My manual reflects a note that indicates the rotors should be installed with punch marks lined up and facing outward. Looks the same to me, either way, based on the way the gears are cut. Could this have been cause? If so, why would the oil pressure light go out when pressure was sufficient and oil present on piston skirts?

Any suggestions appreciated. Trying to find cause before reassembly of new or reconditioned parts.

Thanks!
 

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I am assuming that because oil was on top of the pistons when you pulled the heads the oil pump was indeed working. Just figuring that if the pump was not there would be no oil on top of them. Now as to why oil was on top....were the rings put in correctly? Proper ring in proper place and lined up the way the book says? Another thought is fuel wash.

Hastings article:

http://www.hastingsmfg.com/Service Tips/fuel_wash.htm

Keith Black articel:

http://kb-silvolite.com/feature.php?action=read&F_id=52
 

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If it was a ring problem,i.e. second ring upside down, a tremendous amount of heat would be produced expanding the dome first. A fuel wash like Dave said sounds right.
Panman
 

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Did you take a look at your wrist pin clip?

I really have no idea, just giving an example of what I would look for.

darrell
 

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Man I am so sorry your having the problem.....terrible disapointment. I am no expert but I have had a very simular problem you are having. Mine turned out to be a bad ignition timing and incorrect carb jetting issue combined that resulted in cylinder wash. The intake side of my pistons and cylinders on both were scored on the skirt area below the rings. I also now on new builds run oil with the gas for a few hundred miles....Marvel Mystery Oil for upper cylinder lube. Also any left over assemblers lube on top of pistons and combustion area I would figure would burn off almost immediately when you fired it up. I am guessing that the oil in top is blow by caused from the scored area of cylinder walls that once scored the rings would not seal anymore and oil would get by the rings and end up on top.

There are some very smart TC guys on here and I hope they can help you as the damage is done but not repeating it by understanding what happened I know is your thought right now.
 

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Discussion Starter · #8 ·
Dave,

Have confirmed that timing marks on cam gear drives correct. This is an MM EFI bike.

To add to my original post, I did download a Power Commander MAP closest to my biuld just before firing up. Do not know what impact this has to the fuel/timing issue you suggest may have occured.
 

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As an add to this post, Is there a way to "pressure lube" the oiling system on a TC88 motor prior to firing for the first time after a rebuild?

DLR
 

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I will be honest with you I am getting way over my head here as I am not a TC wrench......almost afraid I have said too much already. Years ago I was an A&P mech who worked on Helo and piston driven aircraft which many of the engines were air cooled also. Thats the extend of my knowledge. I just do not want to lead you down a path of listening to me when some of the true wrenches can better help you.
 

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DLRVelocity1 said:
As an add to this post, Is there a way to "pressure lube" the oiling system on a TC88 motor prior to firing for the first time after a rebuild?

DLR
Don't know about pressure lubing the pump but like I said above on new builds I always put a little MMO in the gas for a few hundred miles.
 

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Dave,
Roger the A&P. Appreciate your straight forwardness. I too am an A&P, (Site assigned FAA Airworthiness Inspector), heavy maintenance commercial aircraft, D5, C17, and P3's. Understand. Educated guesses are always appreciated. Hopefully one of the guys that have been down this road will chime in.
Dave
 

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Hi, I understand you found the issue, do you mind sharing with us. The thread will eventually make it to archive and someone may run into the same issue.

Thanks, its not about making fun of your issue, just helping some others doing a build and might benefit from what you found.
 

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dmeals:
A new set of .010 over pistons and a fresh bore and hone, you should be back in business. I would say .005 over but give yourself a little wiggle room on the re-bore just in case the cylinder score is deeper than .005. I would re-map the bike back to the mildest map you can find for your build. If I remember right there usually isn't much metal with a scuffed piston and wall floating around in the case but I would flush it out to be safe.

Curious as to which cams you are running, head work, plugs, and exhaust. If you get a chance please post some pics of the damage.
 

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I too would like to see picts.
Sometimes what some call scoring are just lines / marks, no depth to them.
Just a long shot but were you messing with anything else? Did anything else change while you did this round of repairs?
 

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Thank you to whoever un-deleted this thread, I am also curious as to what was the eventual cause to your problem. Could you enlighten me/us?

darrell
 

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This will not solve the scrapping issue but if you can feel the score mark with your finger nail then it is deep enough for a re-hone or rebore. Ring ends can be a cause of this scoring.

I see where you checked the cams for clearance but were they clearanced enough? Any scrapping marks on the cam plate??



All the best, Ozzie
 

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Discussion Starter · #19 ·
After close examination of the oil pump, clearly the pump was installed incorrectly and took a dump causing the scoring due to lack of lubrication.
 

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dmeals said:
After close examination of the oil pump, clearly the pump was installed incorrectly and took a dump causing the scoring due to lack of lubrication.

Thanks for sharing, we all learn from our mistakes. The instructions in the manual as to the oil pump reassembly are not particularly clear, don't ask how I know.......

I am really surprised that a few minutes of running with low oil pressure and lots of installation lube can do this.
 
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