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Really baffled by this and thinking about it often.
What about a situation with an oil line delivering oil to the pump is partially obstructed or delaminated?
In this case when oil is delivered much slower than being sucked up from the system pressure could collapse during engine revving I think.

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Waiting for the intelligent minds to wake up and read this....see if we are on the right track.

Intelligent minds from the past and present: As a rule when John Healy speaks...pay attention!

http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=236206

Last edited by Semper Gumby; 08/12/20 12:30 am.
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Here's my experience with Trident oil pressures which I've gathered is fairly typical.
New to me bike with no history. Installed an oil pressure gauge and started to ride
The before:
Start the bike and cold pressure is over 100 psi, ride it for a mile or two and pressure drops to about 60 psi, ride for about 10 miles and get engine up to temp and drops to consistent 40 psi at 4000 rpm and 10 psi at idle, oil light is flickering at idle. Oil pressure responds to revving the engine about 10 psi/1000 rpm.
At this point I tore the engine down, crank had ridges and bearings were worn. Had crank ground and replaced bearings, along with a NOS oil pump and new OPRV. Note: I did not increase the size of the oil feed to t160 spec.
The after:
Start bike and cold pressure is over 100 psi, stays at over 100 psi for the first ten miles or so then drops into the 80 to 90 range at 4000 rpm. Idle is around 35 psi. On a really warm day may drop in the 70 psi range and 30 idle.
Two things about your bike that seem strange is the low initial cold oil pressure and the fact that revving the engine has no effect. Even on an engine with worn bearing clearances you should see higher cold pressures and a response to revving. To me this suggest that the problem is upstream from the pump in the supply. There is no anti-sump valve in the feed line? I would replace the hoses as matter of course.
IMHO enlarging the feed to t160 spec might be a good idea but the t150 spec works fine for me and tons of others and I don't think I would tear an engine down just to do it. Also, I can't see cold oil somehow creating an "air gap" or loss of prime unless your riding at -50 or something.


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1971 Norton Commando
1972 Norton Commando
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Semper, my racer has a Virago chain drive that spins the pump about 20% faster with the original R3 5/16" inlet pipe. I never had a problem with oil starvation and I run 20W/50 oil.

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Mine only hits 85psi on cold start, but it stays there regardless of RPM until the oil warms a bit. After about ten miles pressure is at 60psi at 4-5000 RPM. Once I get home the pressure at idle is a little over 10psi, used to light the light until I replaced the switch. Now it no longer lights at hot idle. Oil temperature is usually 180 degrees at this point.
htown: yes there is an anti-drain valve. It lives in the bottom of the case where the oil inlet goes in.
I just received a new OPRV. Oddly enough the screen on the Harris valve is the same fine screen found on the twins. Next oil change I'll remove the oil lines and see if I can manage to get a socket on the old one to change it.
Richrd: You might benefit from replacing the feed line to the engine. As mentioned by others, old lines can partially collapse or shed internally.


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Originally Posted by DMadigan
Semper, my racer has a Virago chain drive that spins the pump about 20% faster with the original R3 5/16" inlet pipe. I never had a problem with oil starvation and I run 20W/50 oil.

Yep. I think a new feed hose is going in. Makes sense. I can change that one thing easy and see if it makes a difference. Thanks.

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I'm aware of the internal check ball, those work quite well because the full output of the pump pushes the ball off the seat. What I was referring to is the aftermarket anti-sump valve that people install in the feed line between the tank and engine. Those have a history of failing because you are relying on the suction of the pump to move the valve and if you lose prime they may not open. There are lots of documented cases of blown engines due to those. However, some people run them with no problem. Are you feeling lucky? Just checking that Richard didn't have one of these.


1978 Bonneville T140E
1974 Trident
1970 BSA Thunderbolt
1971 Norton Commando
1972 Norton Commando
1973 Norton Commando
1974 Norton Commando
2018 Kawasaki Z900RS


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Rich would never use a che k valve in an oil line!


Rich
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new feed hose, started on lift. start up 60 quickly dropped to 40. blip drops it to 38, then comes back to 40.


roll it out and ride 4 miles around town in 2nd and 3rd gear 2500 to 3000 rpms. pressure sits at 35.

back home pressure at idle 25, blipping throttle RISES to 30 then settles back to 25.

oil temp in tank 125 degrees radiator fins 153

I think I'll take it down the road and see it pressur will hold at 20 - 30. last time i tried it did not.

So really not gaining anything. whwen do I go looking for another pump?


Rich
"It's not always about going fast. Sometimes it's nice to slow down" (Wendy E.2016)

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Perhaps It would be possible to borrow different pump?

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Richrd must be losing patience over this problem.
Just reading the last few posts I realized that I had lost track of the various happenings on this thread.
So I went back to the beginning and noted the significant developments.
It goes something like this:
a) An incident happened which took out the crank shells.
b) The crank big end and main journals were ground and new shells fitted.
c) At start it gave 70 psi then after a few miles this went down to 40 and then 30.
d) Increasing the revs do not increase the pressure.
e) The OPRV was stripped and examined and found to be OK.
f) Another gage was tried in case the original gage was faulty. The second gage broadly agreed with the first gage.
g) The back of the oil pump was lapped smooth.
h) The pump was tightened back tio the mating surface.
i) It was suggested that the oil feed pipe at the standard T150 5/16" is under sized compared with the later T160 3/8".
j) A new oil feed hose was fitted. At start up it gave 60 psi which then went down to 40. With a blip of the throttle it went down to 30 and then back up to 40. At 2500/3000 rpm the pressure was 35 with idle at 25. With the throttle blipped it went to 30 and then back down to 25.

Having gone through all the above the original problem remains.

What might the problem be?
Some thoughts:
a) What was the problem that "took out" the crank shells? Are we sure we know the cause(s)? Is there debris still lying around in the engine?
b) The oil feed size can be disregarded IMHO. While it is desirable to enlarge the inlet to 3/8" as Triumph did on the later T160s it is not essential to do so. There are literally thousands of T150s running around quite satisfactorily with the 5/16" oil feed pipe size.
c) The OPRV and oil pump seem to have passed inspection so at this stage at least we should I guess rule them out of suspicion.
d) The very strange reduction of pressure with increase in revs (assuming that the pump and OPRV are working OK) points to a supply side restriction causing cavitation within the pump. The fact that the latest test showed an increase in pressure with an increase in revs STARTING AT IDLE is IMHO very significant as cavitation generally starts and gets worse at higher revs-- so the expected behavior of increased pressure with increased revs starting at low revs but not at higher revs is a pointer towards cavitation.
It has been known for hoses to delaminate but this has been ruled out by replacing the oil feed hose. However looking at the supply side of the pump the following questions come to mind:
a) Is the oil tank clean?
b) Is the oil tank oil filter clean?
c) Are there any obstructions within the oil pump on the inlet side?

That is about as far as my analysis takes me.
However answers to the questions posed might help us to move forwards and solve the problem.
HTH

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If it matters I'm using heavy duty transmission oil cooler hose rated for lots of pressure for the feed line.
In either case I will still be gentile till the engine warms up.

And Richard I know you have looked but I would inspect the OPRV again..
If there is any trash in the system the OPRV comes after the pump of course but before the filter (why?)

I beginning to think any old BSA/Triumph I come in contact with must have it oil bag goto a radiator shop. Every time i get into one there is sludge and rust in the damn things. And that includes OIF's.

Last edited by Semper Gumby; 08/14/20 1:26 am.
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Oil tank was boiled at the radiator shop. Just sop here
After first incident engine was stripped and scrubbed in the kitchen sink and flushed with a case of spray cleaner tile spotless.

Checked oil tank filter when i changed hose

Wheni get back from Georgia I'm going to try a different pump


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Reading back you never actually checked the shell clearance, just took the mechanic's word. Were the shells marked -XXX or just the box? Possible the wrong shells were put in the box. You said that you were going to check a main but did but did not because the machinist thought it unnecessary.
Going through the journal bearing calculations, given oil inlet temp 125F, SAE50, 1000 RPM, 38 PSI, one bearing would have to be about 0.004" clearance with the rest at 0.0015" to balance the oil flow required with the pump output. Alternatively, all the bearings would have to be about 0.0023" clearance to balance.

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Thanks for answering my questions, Richrd.
Seems to me the only thing still in question is the oil pump.
Suggest that you remove it and strip it down--looking carefully for any obstruction, scoring etc etc.
May be worth taking photos of the dismantling step by step and posting them here?
HTH

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I have been discussing this problem with Rich for weeks and share his pain. One possibility which has not been mentioned, I believe, is the oil passageway in the case into which the oil pressure sensor is screwed. If there was debris in that channel just upstream of the sensor, could this manifest the symptoms his bike shows? I remember cleaning out my T160 cases as thoroughly as I could with pipe-cleaners and wires but never felt convinced I got them pristine.
Paul.


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I'd drop the center rod bearing through the sump plate and plastigauge it. As mention maybe bearings were mis-marked.


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I did, but it didn't help much. Just more work and money spent smile

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Paul has graciously offered to install a new pump while I'm out east.

Don't k ow if that's a good idea or not.


Rich
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Originally Posted by Dick Page
I might have set it on fire by now

...from a distance with an Anti-Aircraft Gun.

That is the way of it. wink

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Originally Posted by Tridentman
The.......reduction of pressure with increase in revs ......points to a supply side restriction causing cavitation within the pump.
a) Is the oil tank clean?
b) Is the oil tank oil filter clean?
c) Are there any obstructions within the oil pump on the inlet side?
I agree 100% with these suggestions. Most any pressure lubed engine should show OP that rises with revs, especially when cold. If cold OP doesn't rise with revs, there is likely a supply problem. I just got done repairing an '63 Alvis automobile with low OP. It was a fresh engine in a stalled out restoration. An internal galley plug had been left out and even IT had rising cold OP when revved. It rose to 20psi, consistently! (but showed 70 cold once the plug was in place)

Anyway, I would be pulling the tank and any feed fittings. The tank has to be cleaned out with petroleum based solvent or gasoline, focusing like a laser on any sludgy muck laying in the bottom. Who knows, maybe someone poured a bottle of motor honey or STP in there to help out the OP, and that is what is plugging the lines.

Next, I would put on my Inspector Clouseau hat and have a close look at any feed line fittings at the tank ie: banjos, banjo bolts, strainer screens, anything that could reduce flow. Make sure there are no half drilled holes or blobs of braze or anything else blocking things up. I run drills through all the holes if possible and chamfer the end ID of any tubes or fittings I find. On less simple fittings and drillways, I even figure out where the fluids have to flow and then run fluid through them to satisfy myself that it in fact does what I think it should. Blow everything out with compressed air. Consider that Triumph was going through some very low morale around the time our bikes were built (I've got a survivor '73 T150V by the VIN that better matches the "74 parts book.) so all sorts of quality problems are possible. Maybe someone neglected to drill a hole somewhere in a feed fitting. I hope this helps.

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I would be studying that oil flow diagram and thinking about where air can get sucked into the intake side. Aerated oil and shell bearings don’t mix.
It might account for both that weird drop in pressure and the knackered bearings. Small leak that only passes air when intake pressure drops to a certain point? Stranger things have happened... but just a guess. If the pressure drops with the blip of the throttle, then that suggests to me that “if” there is air getting in, it’s close to the pump or the pump itself.


I’ll add the caveat..... I know nothing about triples or their pumps.

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just wondering out loud here,,,

does the pump impart any vaccumm or syphoning on the feed hose?

the oil drains very slowly to the pump under gravity. the strainer, fittings and passages are all clear. I even fitted a larger 3/8 inch hose.

I will be installing a different pump this weekend


Rich
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Originally Posted by Richrd
does the pump impart any vaccumm or syphoning on the feed hose?
Yes. The pump will create a vacuum in the feed line which helps draw oil from the tank, but the vacuum will be reduced when there is insufficient oil in the pump gears themselves. That is why a relatively unimpeded supply is so important. The head pressure from the tank being higher than the pump helps too.

Originally Posted by Richrd
the oil drains very slowly to the pump under gravity. the strainer, fittings and passages are all clear. I even fitted a larger 3/8 inch hose.
This all sounds promising, and I apologize for belaboring the point, but I still must ask if you have physically removed those fittings and inspected them closely, and if you have cleaned out the oil tank of all sludgy muck that may be in the bottom of it. This is so vitally important in a case like yours. I would also run it and do an OP check when I was satisfied that all lines and fittings were nice and clear. BTW, are you using a 20-50 oil?

Originally Posted by Richrd
I will be installing a different pump this weekend
If you do go ahead and install a new pump, everything mentioned above still applies but I just thought of another possibility. On my '73('74?) T150V, the oil pump drive gear is not keyed to the taper shaft. There is no key slot for any woodruff key! So, any slipping on that taper would tend to loosen the thin nut that holds the gear onto the pump shaft. This could slow the pump down, or even make it not turn at all. It is a really sketchy setup IMO but that's how mine is. Loctite, the locktab and careful tightening are all important. When I had the pump out to do my clutch some time back, that nut was NOT very tight and the threads on the pump shaft were quite rough, making proper tightening harder to judge. I spent quite some time cleaning up those threads so the nut would thread on easily by hand. That shaft is hardened so a diamond file works best. Harbor freight here in Cali has them pretty cheap. Not sure about your area, Grizzly or Northern maybe. Best of luck. Let us know how it turns out.

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I am on vacation so don’t have my technical info, photos, bikes etc with me to check it out but——-
Just as a very way out suggestion ——
Have you got the oil pipe connections to the engine the wrong way around?
I know it sounds unlikely— but the symptoms are so strange that perhaps the cause is strange too.
HTH

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