Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board A65: another oil pressure thread....

Paul,
I've been reading all the comments pertaining to your problem and it seems that whatever you try leaves you with the same result. I know it can be very frustrating. I've been thinking about this for sometime and would like to make a few comments that may help you figure this problem out.

You advised that you rebuilt the motor. I assume that you had a machinist do the crank & rod journals. It sounds like you currently have .040" over pistons, ,020" under rod journals and a .040" under bush journal. I also assume that you actually put the motor together after the machine work was done. You advised that all the clearences were good but didn't state what they are. Did you actually check all the clearences when you put the motor back together or did you rely on what the machinist told you? Did you have .0015" end float on the crank and .0015" on the rod & bush clearences? As the clearences become greater than that on a BSA, your are going to have lower & lower oil pressure as the parts wear, even if your oil pump & OPV are perfect.

Did you use good quality rod bearings or Tiawanese copies?

You advised that at one time you got 7 psi at idle & 40psi while riding. Then you advised that you got up to 50psi while riding. Then you advised that you "flogged the [***] out of it and rode it for a good hour & both gauge & switch read ZERO oil pressure through almost all but fairly high rev's". You then advised that you shimmed the OPV, got 70 psi at idle and rode around and then got zero psi at idle but you didn't advise what oil pressure you were getting while riding.

If you "flogged the [***] out of it & rode for a hour with no oil pressure then the engine would be toast or you have a bad oil pressure gauge. If I were you, I would invest in a good liquid filled oil pressure gauge that goes to at least 60psi. Get a piece of 1/8" threaded pipe x 1 1/2" & a double ended female coupler to attach the pressure gauge so you can see it while riding. Instead of bending the OPV spring, you can shim it between the spring & plunger using 8mm flat washers or 1/4" AN type washers and get whatever release pressure you want.

I suspect that the gauge you are using my not be all that accurate, is it a 45 or more like a 320 degree sweep? I suspect that most of these gauges are probably more accurate on the higher end than on the lower end.

I don't think that the idle pressure is as important as yor crusing pressure. As long as you are getting approx. 10psi per 1000rpm, you should be fine. If you still don't get close to that while crusing, after shimming the OPV then you have either a clearence problem or an oil pump problem.

I hope I didn't come off as condesending in anyway, just trying to help out as best I could.
Best of Luck,
Ken

sorry, i try to include as much information as possible, but it's easy to miss some. at night, it is difficult to read the gauge while riding home. also, i don't have a tach, so telling you where 3000 RPM is will be a guess, but i'd guess 15 PSI.

1) yes, i did put the piece back in, and it had no noticeable effect. zero oil pressure at idle hot.

2) i really trust(ed.. he died a couple weeks ago) my machinist, and he did lots of these engines through the years. he knew the proper clearances without me even bringing the specs in. in any case, i know for a fact that the crank bush was set at .0015" clearance, as i double checked with a dial gauge once installed. i trust that the rod bearings were proper, but didn't verify myself. the guy that did them has done it for years and years and is an old man.

3) when i checked my dwell (what should it be, by the way? i think it was around 35...), the idle was right at 1000 RPM. again, i don't have a tach so it's a guess. if someone has a cheap tach to sell me, please let me know.

ken-

thanks for responding. if i didn't want critical questions, i wouldn't have asked, so fire away.

now, to answer some of your questions: i did rebuild the engine (.060" over pistons, .030" under rods journals, and .050" under bush). as i told mike above, the clearances were set properly (i think you meant to type .0015", not .015"... that would be a disaster...). end float at .001", and both crank and rod clearances at .0015".

as for the quality of the bearings, i'll have to double check with my supplier, but he usually prefers to order the good stuff.

ok, so i've posted a lot of different conditions regarding the operating pressures. the bottom line is this: whether the OPRV opens at 50, 70, or 80 PSI, once warm the pressure gets to 5-7 PSI at idle and 15-20 above say 4000 RPM. once really hot, these numbers drop to 0 indicated at idle and only reached 10-15 PSI when revved fairly high.

the quality of my gauge is definitely suspect (yes, 320 degree or so dial) and there is a lag between pressure changes and its reading, but i'm wary to blame the whole thing on the gauge since the switch corroborates its tale at idle. they both could be bad i suppose, my gut just tells me there's something else going on. the gauge is mounted at the handle bar.

as i stated before, i didn't stretch the spring, but rather shimmed it between the spring and piston to preload the spring. the results are easy to determine.


also, i have finally concluded that the engine is in fact a little noisier once hot and the PSI has dropped. with stright 50W oil in and cool, the engine was noticeably quieter and smoother with the higher PSI. without seals to worry about blowing out, i'd be much happier to err on the side of higher pressures.

Paul,
Thanks for catching my error, I went back & corrected it. Anyway, what you have there is really strange. If all your clearences are correct as you advised, it seems that either the gauge is not reading correctly or there is some problem with the oil pump when the motor gets warmed up. Is it possible that when the motor gets hot, the oil pump body distorts enough to cause it to leak into the timing cover & sump? Just for the hell of it, did you ever check the return flow back into the tank during any of your tests? It won't necessarlly tell you if the rods & main bush are getting oil but at least the pressure side of the pump is working if you are getting a good steady flow of oil into the tank, or the suction side wouldn't have anything to pump. Unless you find something else amiss, I don't know what to suggest.
Best Regards,
Ken

Paul,
Tiger, myself and you all agree on clearances etc. I don't know what else to add that would be helpful. I pulled my A65 out of the back of my shed to do tests similar to yours, but the battery was about dead so I am charging it up as we speak. Maybe tomorrow I'll get at it. Your problem is not uncommon as there are lots of threads that have started just like yours.

Mr Mike

Where are we coming up with the .0015 rod clearance figure? Was this a solid bush or at least a steel backed copy? Was the crank reground on the main journal this last time? Remember the pressure switch is calibrated to a falling pressure and may need a few more psi than the falling pressure rating to open the contacts again. Get a quality 0-30 gauge and use that once you are up to temp. to measure this "Zero" idle pressure. Try not to peg the gauge revving it up....

Sorry to hear your Machinist has passed on.

Paul,
I have been reading the posts here concerning your dilemma and one thing that is never mentioned is if you checked whether your pump was leaking at its mating surfaces when you assembled your engine. This is something I learned a long time ago to do using a short piece of 1/4" rubber hose clamped onto the tach drive on the pump with a 1/4" stud in the other end held in place with another clamp then using an electric drill spin the pump while feeding oil into the pump port with a squirt can or a funnel, when doing this watch for leakage where the drive snout attaches to the main body of the pump, if you are going to have a leak this is it, you will also be able to see how much oil is bleeding off of the RH main bushing and rod bearings. My guess is you have a leak at the pump if everything else is as it should be.
I am now putting an engine together that I rollerized and when I checked the DD pump it leaked quite badly at this joint so I took it apart and surfaced all sealing surfaces then rechecked it and I had no leaks.
Another thing is you can check your OPR valve while doing this test.
Ed

ken- yes, the return is happy and constant. perhaps that is some consolation...

to be honest, i'd have to re-read my BSA manual to confirm the rod bearing clearances. the point i intended to make was that all clearances were set to factory specs.

in regards to my friend/machinist: he was truly a source of knowledge that has passed without an heir. he raced (cars) and built for over 50 years, and helped me through several oddball projects, including more than doubling the horsepower and torque in a '76 cb550 by using cb650 and cb750 engine internals, with a lot of custom fabrication. if i had wanted to do a roller bearing conversion locally, he would have been the guy to help me figure it out.

Ed V sez:

"when I checked the DD pump it leaked quite badly at this joint so I took it apart and surfaced all sealing surfaces then rechecked it and I had no leaks."

I did forget to mention the oil pump sections. I have read somewhere that BSA used a varnish type sealant on the pump body sections. For a long time, in addition to making sure the mating surfaces are smooth, I use Permatex Hytack on both sides of the pump body. It only takes a very thin coat to do wonders.

I think he also needs to check the fit of the pump to the cases. The gasket he used, if typical, probably has lousy alignment with the various holes. There is also a possibility that he has one of those gaskets that show up from time to time that are rock hard and won't seal.

Rich,
Loctite 518 gasket eliminator works for a pump sealant and may be similar to what the factory used way back when although if all surfaces are flat no sealant is required. I do agree with you on the pump gasket as almost all that we use need to be modified to be sure all ports are clear. The ones we have been getting lately are of the Klinger material and work well other than the trimming needed.

Ed

Paul,
Well I got my A65 cranked this afternoon. Had to clean up the carbs as the ethanol that we now get in all our gasoline will gum up a carb quickly. Any way when I got the bike where it would idle properly, I ran it for about 20 minutes till it was good and warm. I installed my test presssure gauge setup and cranked it. I had good pressure. I let it idle for another 30 minutes and the idle pressure at about 1000 rpms never dropped below 20 psi. At 2500 rpms it would peg my 0-60 test gauge. These pressures were on a breezy day about 55-60 degrees. The transmission case was too hot to touch, but I do not know if the oil ever reached max temperature. I can't ride it with the test setup as I have no pressure relief. I need a dipstick gauge. Twol years ago I had a little less pressure.... 17-18 psi at idle but that was on a hot summer day about 90 degrees when I tested it. It has been about 4 years since I rebuilt the motor which has only about 8000-9000 miles since rebuild. Anyway my point is I have a stock pump and it does make pressure that seems ok.

E webster: On bearing clearance, the manual does not specify clearance for the bush. I made my own bush and pressed it into the steel sleeve and doweled it. It was then pressed into the case and it was bored to .0015" clearance over the crank which was ground and polished. I only grind the crank till it is true and cleans up, then I measure it and have the bush bored for the .0015" clearance. I chose .0015" clearance from the macninery handbook. ...about .001" for each inch of journal diameter is a good rule of thumb. The guy who ground my crank agreed that .0015" was just about right.

Good Luck Paul, I will surely use Ed's oil pump test if i ever have to redo my motor again.

Mr Mike

Lots of ideas and thoughts and worries, no action! You won't be convinced that all is well til take the inner and outer cases off, remove the crank worm gear and spin the oil pump with a drill. Leaking pump or excess clearance??? You won't have peace of mind til you do it.
I've taken sidecovers off hot engines to test as in running condition this way, it's a simple job.
However, it's not a job to do in the dining room at night when the wife is off to Bingo. Cheers Rick

i can assure you, i've taken as much action as my busy schedule has allowed thus far. i like your idea of spinning the oil pump manually. this is the type of test i've been trying to come up with. where do you attach the drill? at the tach drive? at this point, i have to suspect leakage at the pump or terrible readings, but the sound of the engine hot leads me towards something still being faulty.

could someone clarify what ed v's test is? ed? is it the aforementioned oil pump test? when i installed the gasket i made sure the holes were clear, as they were stamped poorly, and if i remember right i used some threebond on the gasket surfaces.

To clarify
"using a short piece of 1/4" rubber hose clamped onto the tach drive on the pump with a 1/4" stud in the other end held in place with another clamp then using an electric drill spin the pump while feeding oil into the pump port with a squirt can or a funnel, when doing this watch for leakage where the drive snout attaches to the main body of the pump, if you are going to have a leak this is it, "

This is a makeshift flexy drive arrangement to spin the oil pump from an electric pistol drill using two hose clamps ( jubilee clips in the UK) a short stud to fit in the drill chuck and a piece of 1/4" Inside diameter rubber hose, the crank drive worm gear needs to be removed but the pump can remain in situ.Or alternatively remove the pump and set up a test feed as Ed suggests.
Mark Parker has posted pics in the past showing leaks at pump body joints.
To make the test even better preheat the oil to normal running temp, spin the drill and watch for leaks.

I believe pump joints were coated with shellac at the factory, nowadays far better sealants are available.

If your pump checks out OK then it looks like new crank time, ouch.
Did the pump get a rebuild when the motor was refreshed?
Cheers
pod

I have an 1969 A65 with a similar oil pressure problem. My problem started right after I did an oil change. Normally I complete the process in a short period of time, this time, after I had drained the oil and removed the sump cover I left it open for 5 days. Eventually completing the oil change with Sae 40 racing oil. I started the bike, checked to see oil returning to tank and went for a ride. Rode 10 - 15 miles and just as I returned home my oil light came on. First time light ever came on in 3 years I owned the bike. I checked the tank and there was no oil return flow. I installed an oil pressure gage, started the bike and immediately registered 50 - 60 psi, went for a ride and as engine warmed up I watched the pressure continue to drop even at high RPM,s and at idle the pressure was non existant, looked in tank and no oil flow.

I completed an upper end overhaul 3 yrs ago, pistons 40 over, but did not see need to do lower end. Engine sounds good no unusual noises, after removing pump could not determine any play in crank, inside of pump looked relatively good, some scaring on inside of pump cover.

Questions:

Could delay in refilling oil, thus leaving oil system exposed to air, have anything to do with eventual loss of presure, ie seals and bearings becoming dry and then expanding when new oil at high pressure is forced against them. or

Does it sound like I have a pump problem.

Peter

There's enough oil coating the surfaces in your engine that the delay in refilling wouldn't be a problem. Besides that, all the important surfaces that determine your oil pressure are metal-to-metal; the few rubber seals (like on the points drive) are there to keep oil in, and don't determine pressure.

No oil flow to the tank? But showing pressure at the gauge (presumably at the relief valve cavity)? The oil must have been going through the pump, through the relief system, and hopefully through the main bearing, the crank, and into the sump.

But it sounds like it wasn't being picked up and returned to the tank. Any chance the pickup tube is blocked or fell out? We ran a 441 Victor once that had had the sump plate and sump screen installed 90 degrees out, and the screen was blocking the pickup, same thing happened.

That's one idea anyway, I'm sure others are on the way.

Lannis

Lannis

Thanks for quick reply. The oil was flowing back to tank when i had pressure at start up. With engine running, after gauge showed no pressue, I checked tank and no oil flow. I was able to run bike for 15 or 20 mins. with oil pressure, although somewhat dimimishing over those 15 or 20 minutes, so oil was returning to tank at some point

peter

Moths are blocking the oil return tube.
BSA used highly radioactive steel for the oil return tube, salvaged from the early Windscale reactor years, a hitherto unforseen problem(left out of the manual), dangling camphor balls during a protracted oil change should cure future problems/
Pod

ok guys, i'm finally getting somewhere. first off, i noticed "1/71" scribed on my oil pump, so that explains the lack of an iron pump body.

anyway, i pulled the inner timing cover and spun the pump by the tach drive... voila! oil seeped immediately between the to halves of the pump, not at the mating face. however, upon tightening the four bolts (which were loose) that hold the two halves together, i could no longer spin the pump with the tach drive. i have removed the pump for inspection, but can't work on it anymore tonight.

when i get into it, what should i look for? i'm thinking i might have a wrong-sized o-ring on the spindle housing. until i figure out why it tightens up, i can't further test for leaks here.

at least i'm on to something! also, how much oil should i be seeing seeping towards the timing side from the crank bush?

Paul,

You are into one of the irritating mysteries of the unit twin (and probably pre unit as well). The o-ring was a running change, it wasn't always there.

Most likely you have gears that are less than well matched or you have a tight spot in the body. The pump is going to need to come apart and look for shiny spots where the gears may be rubbing. You can use your pump drive to turn the pump when it is off the bike.

Measure the length of the "matched" gear sets to start with. You may find a gear or 3 that is not close to matching it's mate. I have had luck having gears "skimmed" to match it's mate. Small Heath's "selective" assembly was somewhat lacking IME.

In frustration, I have already used the pump drive to turn a pump until it runs in. It takes time. Run the pump and tighten the body screws a little at a time to run the high spots out of the pump.

Use a sealant on the end sections of the pump. I prefer Permatex HyTack, Ed V has good experience with Loctite 518 in the same application. Either one will do the job.

Since you are into the pump, make sure the gasket is matched to the holes and the opening where the spring/ball fits doesn't tangle the spring.

Get a spare ball bearing for the check valve. Braze it to a piece of rod. Use the modified bearing to lap the seat where the check ball seats. Using a punch to drive the ball into the seat is so crude.....

Make sure after all your effort everything is CLEAN. I pack the gears of the pump with a very light grease during assembly. Makes sure it primes when it starts turning. And also it doesn't turn dry.

Once the bike is back together, remove the switch, gauge, whatever and kick the bike over with no plugs in it. When oil comes out the switch hole, you are primed.

Turning the pump without the engine turning will get a fair amount of oil coming out of the TS bearing. Since the crank is stationary, there is no wedge formed, so most (but not all) oil supplied will come out of the gap from the crank settling in the bearing.

thanks rich!

so should i try omitting the o-rings in favor of the sealant, then?

i did disassemble and inspect the pump when i was rebuilding the engine, but everything looked clean and unworn so i just put it back together. i don't remember any shinies on the gear teeth. i wonder if it would help to use a fine clover on the gear teeth to run in the tight spots? i've used this procedure on trans gears to reduce drag from factory hog-cut teeth.

i did in fact have to trim up the gasket when it was new to make the holes line up well. are there discrepancies between the machining on different years, or is the gasket manufacture really that poor?

1. so should i try omitting the o-rings in favor of the sealant, then?

I always use the o-ring, it provides a seal for leakage up the shaft. The sealant is for the body to end plates

2. i don't remember any shinies on the gear teeth.

The shiny areas would more than likely be on the body or end plates. With end plates being the most likely culprit. With care, they will run in on their own on the bench and avoid using anything to hasten the process. Also less to clean up

3. are there discrepancies between the machining on different years, or is the gasket manufacture really that poor?

I vote for the gasket. I have not seen anything that makes me believe there was variation in hole locations and mounting studs. But I have seen a lot of variation with gaskets, even trying the gaskets on different pumps/cases and seeing the same misalignment. So I blame the gaskets

i dissembled the pump, cleaned it up, and applied a little dye to the mating surfaces/ gear ends. the middle joint has little drag, but the end plate is bad. i applied some gasket sealant, let it tack up, and lightly tightened the assembly up to flatten the goop. once it's set up well enough, i'll tighten it up and hope that the sealant created enough clearance between the gears and endplate. if this doesn't work, i'll try to make a spacer out of .001" shimstock and apply more sealant.

strange design that has the gears turning on the face of the endplate like this...