Pulling the Pin

[REAR]

Started a rebuild on a Mc 91 and the first thing I was met with was a bad rod. The rod problem is nothing new and it just backs up the thought that these old engines need to be taken apart and given a close inspection before they are run. You don't know what you got till you take a look inside.



Now here is where it got interesting. The piston, bore and rings were in great shape and could be saved so I needed to get the piston off the rod but the style of the piston was the solid bearing pocket out at the exhaust side and I had no access to pull the pin so I had two options, push the pin and the bearing out of the piston on the exhaust side, then re-install the bearing or try and tap the wrist pin and pull it out on the open end.





I didn't want to mess with the pushing the bearing out and then having to re-install it so I decided to pull the wrist pin out on the open end bearing and to do this I was going to tap the wrist pin to allow me to thread in a jack screw set-up.

First thing I did I measured the I.D. of the wrist pin and it was a good candidate for a 3/8" thread diameter. I knew the pin was going to be pretty tough just because of the nature of its use so if I was going to tap it I would need a good name brand hi-speed or cobalt tap and luckily I worked at a tooling distributor in the past and they were able to provide me with a 'Cleveland' brand 3/8"X24 4 flute tap. I went with High Speed Steel because they were out of cobalt, same with the 4 flute instead of 2 but I figured what the hell.

Next thing I did was pack some tin foil down in the wrist pin because I didn't want any metal chips getting into the closed wrist pin bearing as I was tapping, then I tracked down my trusty bottle of Castor Oil tapping fluid from a tech article from days gone by and I was ready to go.

Tap lubed, wrist pin lubed, give the tap a twist. When tapping you can tell right away if your cutting or rubbing and I was met with a nice cut. As I was cutting into the pin I kept very close attention to the flex of the tap and made sure I took small cuts that were very well lubricated.

The tapping procedure went very well and gave me over a 1/2" of nice thread to screw my jack down into.





O.K. first hurdle cleared now its on to building a 'jack' mechanism and I knew the easiest way to build the jack would be to utilize my existing wrist pin push-puller.

My wrist pin puller has a 1/2" inner diameter thread but my wrist pin was tapped to 3/8" so I wanted to sleeve down the inner diameter so I had a better fit on my jack screw so I found a old 3/8" pipe flare nut that had 1/2" OD thread and my needed 3/8" I.D. Next I found a 3/8X24 bolt and nut which would be the jack nut and I threw a washer in between just for good measure.





I heated the whole assembly in my second hand store toaster oven before I tried to pull the pin. Heavy gloves on, I pulled the piston assembly from the oven, threaded the jack screw into the assembly till it stopped turning then I started to turn the jack nut and it pulled the pin right out of the rod. Success !



There you have it, a low buck technique that worked very well however I would not suggest using the tapped wrist again.

See you at THE BIG ONE.

R.E.A.R.

[ted johnson]

Really cool procedure, Bob! Ted

[Scott Kneisel]

NICE
I will also adapt this method as it saves one press of that closed end bearing and provides a more reliable solution!!!
Thanks Bob

[REAR]

Scott,

I kind of had this idea in my head and after bouncing it off of You and Rob you guys gave me the push I needed so I figured I would give it a shot. Besides if it failed I could always blame you and Rob just as easily.

Bob

[Rob Voska]

^^^ Ever so humble.......

[Kurt Bogerman]

Bob,

Your procedure for pulling that pin was beautiful to behold.

I don't intend to hijack your thread, but I also have to agree that going over a new-to-you engine is mandatory. Maybe this topic should become a thread all its own.

Last season alone, I observed two newly rebuilt engines try to run away due to vacuum leaks. One was a freshly built MC92 with a modified Reed sloper intake manifold that didn't have enough sealing surface left to support the reed cage gasket, and the other was a fresh MC101 that was missing one of the side cover bolts. Pressure testing is relatively easy, and saves lot of time and heartache on track day.

Here's a scenario that wouldn't be identified by a pressure test:

I acquired an engine last week that appears to have been assembled from about 75% NOS parts and the remainder very lightly used parts. When I unpacked it, it was immediately obvious that the styrofoam packing material had taken a beating. There were pills of foam everywhere. Between the cooling fins, inside the shrouds. The engine was shipped with the piston down, exposing the cylinder, so there was foam inside the cylinder and crankcase. I was able to vacuum up 98% of that crap. I pulled the stuffer to see what was what inside and found a pea sized glob of silicone sealant, pushed in from a bolt hole, as well as the last half teaspoon of styrofoam effluvia. I'm not sure if the styrofoam bits or that silicone glob would have caused damage or not, but I felt a lot better knowing where it wasn't.

Order restored, it was finally time to observe the wonders of reciprocation, so I amused myself by cranking the engine back and forth, round and round, by hand, over and over. Uh, oh... Something didn't feel right. Besides the compression, the suction, the notchy pull of the flywheel magnets, and the tick over of the connecting rod at TDC & BDC, there was an intermittent binding in the course of rotation. I looked, listened, and felt what was going on, and then I saw it! The needles in the rod journal were tilting to an unusual degree and binding! I grabbed a toothpick and shoved all of the needles together, and, sure enough, there was a gap that could fit one more needle. I removed the rod cap and collected 23 needles from the journal. I counted them a dozen times if I counted them once, and then I spent an unreasonable amount of time staring into the crankcase with a flashlight, looking to see if the builder or myself dropped one in the case. Nope. I'm convinced that the builder got distracted and forgot to put the 24th needle in, or trusted that they were all in the envelope. Who knows? I'm just glad I didn't have to pick it all up off the pavement on it's maiden voyage.

Kurt

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[Kurt Bogerman]

[ted johnson]

Hey, Kurt, BE SURE that rod needle isn't lodged in a back port. Pop and I got one of the very first Mc6's East of the Mississippi in '60. We didn't realize that with a thin ring piston, a little break-in was needed, so I seized it right away. I was sixteen, and not as careful as I am now, so, when I rebuilt it, I dropped a needle. Could not find it anywhere, even after turning the engine stuffer side down and hitting it gently on a folded up rag on the bench. I got a new needle and assembled the rod with the correct number of needles. It actually ran a couple of laps before the extra needle came loose from wherever it was and found its way between piston and bore. Here's a new engine with ten minutes total time, lunched! We figured that the needle had gotten wedged in the back side port passage, and only came out when it could do the most damage!
BTW, the gasket goop is a pet peeve. I just got a Libberton from my buddy. I don't know what kind of goo he used to install that V-12 base, but it took over an hour to remove the gasket half that was firmly glued to the block. Saturating it with spray carb cleaner and scrubbing with a Scotchbrite pad FINALLY got it off. K&W Copper Coat for always. I've never had one air leak with the stuff, and the gaskets peel away easily when rebuild time comes along. TJ

[Rob Voska]

I've used both WD40 or a shallow tray of oil to soak the gasket in before assembly. Copper stuff cleans up nicely.
If you want to use a sealer Yamabond is grey & works well and is easily removeable.

[REAR]

Great posts from both Kurt and Teddy. Teddy's illustrates that you can never be too careful when assembling a engine and though I can't say for sure what created Kurt's situation because I'm not sure if he viewed the engine before purchase or if it was a ebay deal. Kurt's engine does in some ways bring to light that a buyer needs to beware when purchasing a engine. Not saying Kurt got screwed but if Kurt noticed the engine turned over poorly the seller should have noticed that also.

A sad reality of this hobby is that many think that since most involved enjoy old karts and that we are one big happy family looking out for our fellow brothers and sisters but you have to keep in mind that every family has a bad apple or two and this hobby is no different and it surely has its share of bad ones. The fact is that there are many who are just interested in making a quick buck off of old kart parts and who possess little to no knowledge what so ever about what they are selling.

A good way to keep a used engine purchase in perspective is to purchase from people you know personally so you can get some history to what you are buying or realize that when you buy a used engine you basically bought somebody else's junk and always keep in mind that it will take some time and or some money to bring it back to a good running condition.

Bottom line is that 'safe or sorry' is the best way to go and Kurt's engine and mine proved that.

R.E.A.R.