V-Twin 12-9931 oil pump: no pressure

[jim50EL]

Has anyone used a V-Twin 12-9931 oil pump? I have the infamous no pressure when hot and only drooling on the return into the oil tank on my 50 EL. I can see nothing obvious with original pump-gears and check balls and springs and ball seats look good. There is something underneath the welch plug on top of the pump body I am curious about that is visible through the pressure by-pass port. The pistons were siezing in the cylinders. They were '74s. I don't know if this was from lack of oil pressure/volume and when the jugs got overheated the oil did too but the oil never got real hot as the pressure would drop in 10 minutes. I have the engine on an engine stand and the only issues are .012" end play on the flywheels and the plug in the end of the pinion shaft interfeers with oil flow as it is screwed in a little too far and I will take care of that. I have a '72 Shovel pump I could try but I like the stock look.
I haven't had this bike very long and the learning curve is killing me. The previous owner didn't know much about the bike other than what he'd done to it-paint and front piston replacement.
thanks jim

[Cotten]

Jim!

I think the funny thing beneath the welch plug is just a bubble-busting baffle, "T"-shaped with two holes in it. It hangs in a little groove beneath the plug.

If your motor problems were simply a matter of oiling, your lower end would have suffered as well as the cylinders. Cylinders are oiled from below by splash and the vacuum of the pistons moving upward. Very little oil is required or even desired, as excess would be forced up past the rings.
Pistons seize because of heat. There can be more than one cause of heat at a time, but the most common and most devastating are vacuum leaks.

....Cotten

[jim50EL]

Thanks for the reply Cotten

[VT]

I don't know if this was from lack of oil pressure/volume and when the jugs got overheated the oil did too but the oil never got real hot as the pressure would drop in 10 minutes. I have the engine on an engine stand and the only issues are .012" end play on the flywheels and the plug in the end of the pinion shaft interfers with oil flow as it is screwed in a little too far and I will take care of that.

Box the motor up and send it to Accurate Engineering. My experience has been that many people can try and build a "swiss-clock precision" Harley Knuckle or Pan motor and if they get one thing wrong, the motor self-destructs before you put 5,000 miles on it. I had a motor like that....once.
Because of the "one thing wrong factor" these Panhead (or Knuckle) motorcycles become Ferrari expensive-on-the-installment-plan very quickly. The unfortunates that get caught up in a downward spiral of motor failure, either spend even more money to get the motor finally built right, or they chase the problems until they can't afford it anymore and the motorcycle ends up on the selling block.
My advise is always to send the motor to Stett's, or send the motor to Accurate Engineering.
If you can't afford it, then you have to get another job on top of the job you already have, and you need at least one other motorcycle to ride until you get your Pan running (sounds like you already have that covered Jim, so I'm advising anyone else that might read this). Keep your sanity and your family together as a functioning unit, neglecting no one.
The foundation of the "build-hobby" is a correctly built motor. Only a motorcycle machinist or better can build one. Don't let anyone tell you that you can fix the problem yourself. If you had that ability, then you wouldn't be asking us what to do. Since you are, then send your motor to one of those shops mentioned above (or to anyone that's a member of this "front street" site), with a laundry list of symptoms and your credit card number.
Don't mess around with these Harley motors. Every time you do something wrong it costs you ten-fold in time and money.

[51Hog]

Working on these old bikes is not rocket science. The only thing I had done for me when I complete rebuilt my whole bike was to have the crank assembled and balanced. (The next time I will do that myself.) I have never in my adult life touched the innards of an old Harley until I rebuilt this 51. This site with all of the great knowledgeable people was a great help.
All you need to do is to be able to read from reliable sources, understand and be able to apply what you read . IE Service manual, Climers, Palmers. These are the books that I used. When you run into something that you can't do yourself-----you will probably recognize it before you start.
Of course there are people that know that they do not have the ability to work on their bikes---Those are the people that would need to send out their parts, or even their bikes for repair.
VT
We have all been guilty of asking questions here. We all can learn something, and apply it. It does not mean that we are incapable of fixing a problem just because we cannot immediately diagnose that problem.
Dale

[VT]

the only issues are .012" end play on the flywheels and the plug in the end of the pinion shaft interferes with oil flow as it is screwed in a little too far

Nobody that knows how to build a Pan motor would ever allow anything to be installed in that motor that wasn't spec.
Anytime you open a motor and find there are items out of spec. and don't know who built the motor (so that you can go back to them and ask what's up) and yet you're going to try and "fix" what they allowed to happen.....look out. You're going to invest more time and energy for what? A few thousand miles and more problems?
We can help people with minor stuff like wiring, etc. but to lead someone into "re-building a motor online"....I think not and warn against it.
Ask all the questions you want, that's what we're here for, but expect to hear answers.
Low oil pressure can be a handful of reasons. Loose fitting pinion shaft to cam cover bushings can be a reason. Line-boring/honing cases is rocket science that some builders don't think is necessary. What your doing having to "guess and fix" your problem which leads to what? You already know somethings mechanically wrong in there. Now what? Your at the same "crossroads" we've all been to (my initials should be carved into the sign post somewhere), in the process of putting a Big Twin back on the road. How much is your time and misery worth vs. how much will you actually retain that you can apply later in life (before you forget what you've had to learn through the process of getting there.). Pay the money now and get a guaranteed motor the e-z way.

http://www.stettsironhorseranch.com/" onclick="window.open(this.href);return false;
or
http://www.accurateengineering.com/" onclick="window.open(this.href);return false;

These bikes were built and maintained over the years with very basic tools, skill and sometimes, yes, knowledge.

And that's the problem that Harley un-intentionally created. Harley-Davidson wrote the 1940-1947 Service Manual with great detail, with side-note corrections on many of the mistakes and improvements they incurred with the first 1936-1939 OHV design. It was so hard to "write" the 1940-1947 Service Manual and not have a mountain of Shop Dopes that would need to follow-up after field testing the machines, that the factory called a halt and never produced a 1948-1957 Service Manual. During this period between 1936 and 1959, the majority of the world population worked with their hands. Harley motors were made to be re-built. The factory had a vast audience to teach to back then. (i.e; Farmers were instructed by the 1951-1953 (216 c.i.) service manual to carve-to-fit babbit bearings for crank journals, if necessary). Everyone worked on their own machines in those days. Service manuals were written for the procedures.
After 1947 OHV Harley-Davidson's (side valves always had problems) began to get a bad reputation for unreliability, because, in fact, the HD service manuals told the ordinary undisciplined owner/mechanic how to rebuild their motors, and the "mechanics" that lacked the knowledge or the tools to follow the Service Manual instructions grew frustrated and started following their own and other "helpers" suggestions - and that's when the Milwaukee Swiss Clock OHV's started to fail. Rather than take the blame for the bad builds throughout history, the "mechanics" blamed Harley-Davidson for their problems and their opinions stuck with the public. False opinions though, because we all know, that built by the book (or better), the 1948-1964 OHV runs for many miles - trouble free.
Nowadays, the the people who work with their hands are fewer. The do-it-every-day-for-a-living OHV motor knowledge is concentrated to certain regions of the country. If (if were a ship, we'd all go sailing) we had true replica 3.5 gallon tanks that would all change in large part.

[51Hog]

Hummm....
Wonder what the next generation of Pan owners would do when last generations Pan mechanics die off,
if this generation takes their Pans to mechanics, because they cannot figure out how to work on 50 and 60+... year old rocket science technology.
Modern technology is a great thing and can be used for building/repairing our old bikes although not necessary.
These bikes were built and maintained over the years with very basic tools, skill and sometimes, yes, knowledge.
I imagine that some owners even took them to qualified repair shops but I am willing to bet that most of them were re-built and maintained in the back yard.---Without books or the cumulative knowledge of thousands of people on forums.

[awander]

The do-it-every-day-for-a-living OHV motor knowledge is concentrated to certain regions of the country. If (if were a ship, we'd all go sailing) we had true replica 3.5 gallon tanks that would all change in large part.

OK-VT-I gotta' ask-how the heck would having a good set of repro tanks available change anything about anybody's knowledge of motors?

[VT]

More people would build them. The more people that build them and make them look like OEM the better. The benefits are manifold, but the tanks need to be made first. I'm waiting to hear any word on them. If I don't hear a peep by next week, I'm building my own and be happy. It's still fun, but less so without 3.5 tanks for the masses - worldwide.

[jim50EL]

10/27/08 update...original question un-answered-any one have any experience with the VTwin 12-9931 oil pump?
...and back to the engine...
I split the cases to find the crankpin worn out and the oil passage through the pinion shaft into the flywheel blocked at the crankpin. There was a light coating of oil through-out the internals. The cases had been sealed with what looked like Permatex #1. The valve cover felts had also come un-glued. I would not use that type sealant for this application and have no idea on the felts..old age or bad glue... Improper sealant and adhesive application reacting to motor oil appears to have done the engine in.
thanks for the responses so far..jim

[VT]

Yeah get all of that goop-string material out of there. Yamabond for the case halves. V-Twin might have it.
3-M (black) weatherstripping for the felt glue (available at NAPA).