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Low Oil Pressure 1968 TR6c #732076
04/16/18 4:54 pm
04/16/18 4:54 pm
Joined: Mar 2018
Posts: 7
Baytown, TX, USA
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Gary Walentoski Offline OP
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Gary Walentoski  Offline OP
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Joined: Mar 2018
Posts: 7
Baytown, TX, USA
Having trouble with low oil pressure on my 1968 TR6c 650. The engine was completely rebuilt last year by a shop down here near Houston. All seemed well after the rebuild and I put about 350 miles on it. I took it back to the rebuilder to have him inspect everything, change oil, and to have Boyer ignition added in lieu of the points. Got the bike back and noticed I had an oil light on after the engine was hot and at idle, after a 10 mile ride. I fitted a gauge and found I had 20 PSI cold and 7 PSI at hot & idle. I took the bike back to the shop and they've checked the screens, replaced the timing cover crank seal (Pioneer), replaced the new OPRV with another new one, checked the new oil pump, made sure that timed tappets were fitted. All this made no difference to the oil pressure. The oil is correct grade. Outside of the big end bearings, what else is left? I'm concerned that the pressure is not nearly high enough when it's cold. The shop is stumped at this point and I'm ready to look elsewhere for help, since riding season is here!

THANKS!

Gary

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Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #732077
04/16/18 5:00 pm
04/16/18 5:00 pm
Joined: Aug 2001
Posts: 7,668
scotland
triton thrasher Online content
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scotland
There is probably a slightly big big-end clearance.


Amateur Loctite enthusiast.
Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #732088
04/16/18 6:41 pm
04/16/18 6:41 pm
Joined: Mar 2018
Posts: 7
Baytown, TX, USA
G
Gary Walentoski Offline OP
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Joined: Mar 2018
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Baytown, TX, USA
TT, That is what I'm thinking, but I want to make sure that maybe they did not miss something else.

Thank you!

Gary

Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #732101
04/16/18 8:27 pm
04/16/18 8:27 pm
Joined: Nov 2012
Posts: 745
Isle of Wight, UK
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koan58 Online content
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The most obvious thing to check is the oil seal in the timing cover, then the feed side of the pump (ball seating), and that the OPRV is working freeely.
After these, if the pressure is still very low, can you not hear any knocking from the engine?
If the big ends were worn enough to give 20psi cold, I'd expect them to be saying hello to you very soon.
Hopefully, this is a pump or seal problem, don't tear it down just yet.

Re: Low Oil Pressure 1968 TR6c [Re: koan58] #732106
04/16/18 9:32 pm
04/16/18 9:32 pm
Joined: Mar 2018
Posts: 7
Baytown, TX, USA
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Gary Walentoski Offline OP
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Baytown, TX, USA
The engine was running fine, no knocking at all. I did not trust the low pressure light, I assumed the sending unit was bad, so I fitted the gauge. OPRV and pump seem fine (old units were refitted, to be sure, with no change). Seal was replaced, just in case. Still no joy.

Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #732109
04/16/18 10:06 pm
04/16/18 10:06 pm
Joined: Nov 2012
Posts: 745
Isle of Wight, UK
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koan58 Online content
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I'm not familiar with the units, is the feed to the exhaust tappet block still necessary? If you block that off, what difference does it make to the oil pressure?
The pressures you have been reporting are not adequate for reasonable engine life, so it needs to be sorted.

Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #732117
04/16/18 11:07 pm
04/16/18 11:07 pm
Joined: Sep 2001
Posts: 662
Great Southern Land
tridentt150v Offline
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Take the head and barrels off.............then grab a piston and see what movement you have. Up and down or rocking side to side = big end issues.....note that there will be a small amount of sliding side to side movement, this is OK.

Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #732134
04/17/18 2:28 am
04/17/18 2:28 am
Joined: Feb 2014
Posts: 1,218
Lancaster, California
C.B.S Offline

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Lancaster, California
How about taking the timing cover off and seeing if the oil feed seal is installed the correct way? It could be backwards or it could be inverted? Everyone always wants to jump to the big end.... troubleshoot other areas first

Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #732148
04/17/18 7:17 am
04/17/18 7:17 am
Joined: Jan 2017
Posts: 546
Pleasant Hill, California USA
T
TR7RVMan Offline
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Pleasant Hill, California USA
Hi Gary, That's too bad.

To be clear, it was ok so far as you know until shop changed oil? Is that correct?

Exactly what oil did it have before during break in? Exactly what oil does it have now?

7 psi might be on the cusp of turning on the light. It could have been nearly too low prior to oil change but didn't turn on light with break in oil?? The new oil might be just enough to push it under the limit you were almost at??

Sounds to me like your bases have been pretty well covered other than the tappets. You say they are correct. How do you know?

Generally speaking a smoking hot motor after 2 hrs. riding 82f day, will idle about 17-20# at about 900-1000 rpm. Even 50 rpm more will raise oil pressure a few PSI hot.The type oil & RPM will effect pressure. Raising idle to 1300 will often add 15# on gauge. Reving hot 4000 RPM will be about 70#. So you are indeed too low.

When you say timed tappets, which timed tappets? Early with wide grooves or late with narrow grooves?

Are you running tappet feed restrictor or hollow dowel? A mistake here very well could account for this much loss.

Ran into this recently on motor overhaul while doing ,69 Bonnie motor. Removing the restrictor that should have been a hollow dowel on '69 bonnie lowered idle pressure about 12-15#. Prior owner installed it at some point. Why?? I always wondered why pressure was so high at idle. It also restricted bore to PRV so 4000 rpm hot was 90#. Had correct narrow groove tappets. Changing to correct hollow dowel correct pressure idle & reving. This bike has gauge installed on it. Original oil pump & PRV were reused.

The rod clearance was .0015" using plastigauge. Has correct for this year narrow groove timed tappets. Hollow dowel. The idle pressure hot is 17-20. Interestingly break in oil was Torco TBO 40w. After 400 miles changed to Mobil1 20-50 v-twin. On pressure increased by a good 2# hot. I expected a loss as V-twin feels thinner coming out of bottle, but I guess not hot.

Back to your bike, I expect the shop would have verified correct seal installation when they replaced it again. I hope they tested oil pump like manual says pulling plungers & watching for oil drop in ports. This test is very effective. I have a repro pump nearly new that failed the test & gave low oil pressure. The ball seat is out of round & not sealing well. Plainly showed fail during the test.

With timing cover off you can test PRV for being stuck open by pumping oil into front dowel. If valve is stuck open oil will readily exit the bleed off bore that points towards the exhaust cam gear. More often the timing cover is not off, so you must do careful inspection of PRV. If at all possible we want to actually see the problem.

I remove OPR valve & very carefully look at plunger position to see if it's stuck open. Even if it's stuck partially open 99% of the time you can see it's stuck.

A broken spring in valve can look like stuck open. We'll take apart later & inspect spring visually in any case.

If dirt or something gets beside piston or between piston & port edge it can jam piston open. A broken spring will allow piston to move back & uncover port. .

Occasionally a stuck open piston will free itself as you remove valve. In this case you won't know what happened. 99% of time a stuck valve will stay stuck. Usually a metal chip or gasket chip is seen holding piston back. In every case I separate valve, remove piston & verify no dirt is behind piston. You want to visually inspect spring anyway. Again try to see a fault if there is one.

Since you tried a known good valve, we'll rule PRV out, but now you know for next time.

I've tried to get a feel of pumping oil into tappet feed dowel to see if I could tell if had wrong tappets. I could not get a feel for that. So visual inspection is what I have to do, which means pulling cyl & tappets. Cly will have to come off to split cases anyway so check this before removing motor.

I've tried to pump oil into crank feed bore & see if I could feel for worn bearings by feeling if oil pumped in too easy. I could not.

I have pumped oil into crank feed & watched oil exit rod bearigs & see if I could tell wear that way. I could not.

I cannot feel if a rod bearing has .001 or .003" play. I doubt you can either. If bearing is wasted & knocking bad you can feel that if you have practice.

I have to measure bearing clearance with micrometer & bore gauge or use plastigauge. That is really the only way.

Another source of low oil pressure in leaks at the sludge tube plug & possibly the flywheel bolt. This should have been checked before assembly.

I always pump oil into crank hard & visually check bolt, plug, crank oil way plug for any signs of leakage after assembly with crank on bench. There should be none.

Be sure to pump oil into crank with rods still on & test for leaks before you remove rods. Look for oil coming out anywhere it shouldn't. Like a crack in crank even.

Since you don't have a base line with pressure gauge after overhaul, you don't really know what happened. It is most important on teardown everything that could effect pressure is examined most carefully.

I most strongly recommend using plastigauge to measure actual rod bearing clearance. Make sure the plastigauge is not aged. It should still be soft & pliable, not hard/brittle or it doesn't read accurately.

No guess work, you need to find the fault(s). Then correct all faults & verify all is well at each step during assembly.

Good luck on your journey. Hope the solution is readily found.
Don






1973 Tiger 750
Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #732149
04/17/18 7:18 am
04/17/18 7:18 am
Joined: Jun 2002
Posts: 10,262
Scotland
S
Stuart Offline
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Stuart  Offline
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Joined: Jun 2002
Posts: 10,262
Scotland
Hi Gary,

Originally Posted by Gary Walentoski
I fitted a gauge and found I had 20 PSI cold and 7 PSI at hot & idle.

What's the pressure above about 3,500 rpm when hot?

Regards,

Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #732164
04/17/18 11:51 am
04/17/18 11:51 am
Joined: Sep 2008
Posts: 896
Skudeneshavn Norway
S
Stein Roger Offline

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Posts: 896
Skudeneshavn Norway
Lot's of good suggestions already, perhaps no need for more, but I have a couple anyway:

A friend of mine, not too familiar with these plunger pumps, asked me the same question. Looking over the pump, I found the feed plunger ball valve seat had never been cut. This was also on a ca 68 engine, and the bike had seen some use in those years. Must have run with low oil pressure it's whole life. I cut a new seat and all was fine. My point is, the seat may look good, but may still be damaged. Another friend has a ball welded to a rod that he grinds the seats with. I haven't done that yet but will if I have to.

Other suggestion, I recently had issues with oil seeping from the exhaust tappet guide block on a T140. Since it was otherwise oil tight and running great, I cheated a little by plugging the tappet oil feed drill-way behind the OPRV. It's easily done by removing the timing cover and OPRV. I made a solid dowel of ca 5,1 mm in diameter and 12 mm long, and pushed it in with a suitable drift. I cleaned as well as I could and used a spot of Loctite on it, but also peened some aluminium over it.
I got the result I looked for, no leak, but must also have gained a few psi more in oil pressure. I haven't measured the OP but the warning light extinguishes sooner and stays out for longer, when kicking the engine over.

Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #732171
04/17/18 1:30 pm
04/17/18 1:30 pm
Joined: Dec 2004
Posts: 9,662
Scotland
kommando Offline
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Its ok to block the tappet oil feed off on any 650/750 with Nitrided cams, but a 68 did not have nitrided fitted at the factory so unless you know the cams have been changed to nitrided then leave the tappet oil feed in place but in the correct configuration for a 68.

Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #732174
04/17/18 2:22 pm
04/17/18 2:22 pm
Joined: Sep 2008
Posts: 896
Skudeneshavn Norway
S
Stein Roger Offline

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Skudeneshavn Norway
Good catch kommando, thanks.

Re: Low Oil Pressure 1968 TR6c [Re: Stuart] #732197
04/17/18 4:58 pm
04/17/18 4:58 pm
Joined: Mar 2018
Posts: 7
Baytown, TX, USA
G
Gary Walentoski Offline OP
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Joined: Mar 2018
Posts: 7
Baytown, TX, USA
Stuart, The best the pressure was maybe 10 PSI at higher RPM. I noticed the longer the engine is run, the lower the pressure goes. I'm assuming that had to do with oil thinning at temperature.
Gary


Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #732199
04/17/18 5:06 pm
04/17/18 5:06 pm
Joined: Mar 2018
Posts: 7
Baytown, TX, USA
G
Gary Walentoski Offline OP
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Joined: Mar 2018
Posts: 7
Baytown, TX, USA
A lot of good suggestions from everyone. Thank you! I'm making a list for the engine guy and I'll see him in the next day or so. I want this fixed. I enjoy this bike way too much and I want it back on the road SOON!
Gary

Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #732200
04/17/18 5:10 pm
04/17/18 5:10 pm
Joined: Nov 2012
Posts: 745
Isle of Wight, UK
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koan58 Online content
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Pretty much all the possibillities from the feed side of the pump have been suggested in previous posts (barring something truly exceptional like a breaking crank etc).
If you are satisfied that all the obvious pre-teardown options suggested so far are not responsible, and have double checked with another gauge that the situation is definitely real (or checked your gauge in some other way), I have one other long-shot suggestion worth a try before teardown.

With a normal amount of cold oil in the tank, remove the oil pump. Is there a steady flow of oil from the supply port in the crankcase that continues for several minutes?
What I'm getting at is that if the pump can't receive enough oil in the first place, it will not deliver the necessary flow to the crank. This could be due to a restriction caused by a gunged up gauze in the tank or maybe a sliver of rubber pipe somewhere in the feed to the pump.
Something that I've experienced myself, that showed up as I was cruising along a motorway, was gradually diminishing oil pressure. From the usual hot oil 60 or so psi, it dropped to ~40 over a few miles (I'm sure you can imagine that my attention was not on the road, but the gauge). Expecting the worst, I slowed to ~45 mph to tickle it along gently to the next service stop, pressure now frighteningly low, 15 and falling.
The guy in the petrol station couldn't have been more helpful, as my investigation was a very messy oily one, I needed catch trays (he got some plastic food containers from a bin), frequent hand washing (gave me a bottle of liquid soap to use with an outside tap) and a whole blue roll. He was only 20 something, ran a 70's CB500/4, and loved older bikes, thanks be to some of the oft criticised younger generation!

After getting this organised, I returned to the bike, to find a significant pool of oil on the ground. This was unusual, and it reminded me of my friend's comment that morning of drips on her garage floor. So before taking the timing cover off, I just lay next to the bike with a ciggy, watching. The drips were from the bottom of the crankcase (pre-unit). So I started from there with the blue roll and found that the oil was leaking from a split in the feed pipe from the tank.
Only then did I understand that the draw of the pump was taking in what was most easily available to it (air), and as the split developed, air became an increasing part of the mix. I suspect the crank survived because of the end feed/centrifuge nature of the design, but I wouldn't want to push that too far!

Ended up blocking the oil tank outlet with blue roll, so I could remove the pipe and clean it with petrol, allowing insulating tape to stick, and several hundred more miles before getting home and sorting it properly.

Please forgive such a lengthy story, the essence of it is that the supply to the pump may be worth checking as well.

Re: Low Oil Pressure 1968 TR6c [Re: koan58] #732204
04/17/18 6:17 pm
04/17/18 6:17 pm
Joined: Mar 2018
Posts: 7
Baytown, TX, USA
G
Gary Walentoski Offline OP
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Gary Walentoski  Offline OP
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Joined: Mar 2018
Posts: 7
Baytown, TX, USA
koan, Good story and worth looking into. The engine was rebuilt as I had holed a piston. Tank, hoses, lines, screens were washed out multiple times and blown dry. That said, everything has been open and that means something may have found its way into the tank or lines. I certainly will make sure we have a good flow.
Thank you.
Gary

Re: Low Oil Pressure 1968 TR6c [Re: Gary Walentoski] #753936
10/25/18 3:25 am
10/25/18 3:25 am
Joined: Oct 2009
Posts: 292
Diamond Springs, Kalifornia
Buckshot1 Offline

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Diamond Springs, Kalifornia
How does this end? Or has it?


Michael

currently owned by a 72 T120R
'02 Sprint ST
maker of plunger conversion jig
Re: Low Oil Pressure 1968 TR6c [Re: Buckshot1] #754526
10/30/18 1:56 am
10/30/18 1:56 am
Joined: Mar 2018
Posts: 7
Baytown, TX, USA
G
Gary Walentoski Offline OP
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Joined: Mar 2018
Posts: 7
Baytown, TX, USA
Buckshot1,

Interesting you should ask...
The engine was taken completely down to the crank by the re-builder. It's supposed to be back together and he's putting a few miles on it to make sure all is good. I'm going over there Thursday to get the rest of the story and to hopefully pick it up. Since the temps are out of the 90's here finally, we're into some good biking weather and I'm more than ready (hope the Trophy is too.)

GaryW


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