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I've done my research here on the forum and read several cases of this issue. I purchased a pressure gauge (not cheap junk) and fittings to add to my collection of useful tools for future projects. Here is what I have observed; Cold- Idle @ 1100 rpm- 20 to 22 pounds. Rev to 2000rpm- 35 pounds. Rev above 3000 rpm-runs right up to 80 pounds.
Hot- Idle @ 1500 rpm- 6 to 8 pounds. Rev above 3000 rpm- 45 pounds is best it will read. Examining the OPRV, the spring measures 1.514 inches, book spec is 1.5312. The valve piston appears good, but the walls of the housing are scored toward the rear of the cylinder. This engine was professionally rebuilt before I bought the bike as a basket case. I replaced the timing cover and correctly installed new seals. I did not examine the oil pump. I have 325 miles on the bike and am presently running on my second oil change. I am running Penngrade SAE 40. (Please don't turn this into an oil or break in thread!) I have not thrashed the bike nor have I babied it. Some oil consumption but no smoke. One other thing that REALLY bothers me is periodically I get a baby poo slurry out of the breather when I run at highway speeds,but I think might be a build up from in town riding. (see pic)
What say you?? Thanks, HF
751536
 

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i had a 70 T120R in morocco in the navy, only oil on base was 10-30 oil lite would not go OFF at idle after warming, enter 20-50 + all was good!! morocco was HOT, dont see your location but heavier oils work unless your in a cold climate
 

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Hi Happyfeet, You’re low cold as well. If relief valve spring is not broken & piston is moving & not stuck back with spring compressed unlikely relief valve is root problem. Deep scoring in valve or piston is a problem. Minor scratches usually not. Can you post photos of valve best you can. You could try new PRV, but I wouldn’t hold my breath that’s all it is.

Is screen in oil tank clean? If you disconnect rubber hose at feed pipe does oil flow freely out? Feed hose goes to front steel pipe, meaning in front of the nut that holds pipes to motor

Next step is pull timing cover & inspect seal crank nose. If ok.

Next pull pump & bench test pump. Measure clearance of driving block & inspect bores, pistons & verify gasket looks good & not broken or displaced.


PM me your email & cell # , I’ll send to video on how to bench test pump. What pass looks like & what fail looks like.

The oily condensate from breather is likely normal. If return portion of pump is bad it’ll show on bench test.

I personally like to run vent hose on ‘69 & most others all the way back to tip of rear fender & sticking down 1-1 1/4” farther. Even though you can see it. Tends to keep the area a little cleaner. At least run it back flush rear of fender. At least hose is mostly inside fender.

My observation using 40w break in oil is with 20-50 pressure was slightly lower cold & slight higher hot. Say that your problem doesn’t sound like different oil will cure it.

If pump is good you could check exhaust tappets to verify correct late ones installed.
Next pull rods & check bearing clearance.

Very well could have combination of problems.

On 2 motors now I’ve seen new Hepolite rod bearings have more clearance than old bearings... .0005-.00075” to .001” more. Measured before & after with plastigauge. Crank not turned. The new bearings wear made with more clearance. Both cases lower hot pressure.
Don
 

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Hi Robert,
I am running Penngrade SAE 40.
Triumph only recommended that viscosity for ambient over 90 degrees Fahrenheit. Unless it's that hot most of the day, every day where you are, it's way too thick when it's cold.

Unless the "Penngrade" is specifically a monograde break-in oil, the monograde recommendation is over half-a-century old, and BSA/Triumph was well behind multigrade oil technology even then; use 20w50, cheap quality up to 500(?) miles, good quality after that.

Also consider fitting a proper micropore oil filter - bad practice to let combustion byproducts and wear particles circulating 'round and 'round an engine even for only a few hundred miles. Modern multigrades are designed around just carrying that stuff as far as the aforementioned proper micropore filter.

One other thing that REALLY bothers me is periodically I get a baby poo slurry out of the breather when I run at highway speeds,
Commonly known as "mayonnaise". Nothing to do with "town riding", it's water - condensation - mixed with the oil; you aren't riding the bike hard enough for long enough for the engine to heat up enough to boil off the water, its mixing with the oil.

Also, where's the end of the breather hose for the "mayonnaise" to be dripping in your image? '69 crankcase vent exit is a steel spigot beside the gearbox final-drive sprocket, oil tank vent is from the raised "froth tower" in front of the filler.

If you look in your parts book:-

. "CRANKCASE" illustration (p.10) shows the spigot as part #7 with part #39 "Breather extension pipe" (a length of rubber hose) attached.

. "OIL TANK" illustration (p.54) shows parts #16-#18 but poorly. In reality, part #17 was/should be positioned two-pipes-up-single-pipe-down between the battery and the vertical frame tube in front of it, the crankcase "Breather extension pipe" connects to "single-pipe-down", the oil tank vent hose connects to the smaller-diameter pipe "up", hose #18 connects to the larger-diameter pipe "up" and should be long enough to be routed to the lower rear edge of the rear fender - either inside the edge of the fender if it has the clips, or outside through "Clip" #19 attached to one of the bolts through the rear of the "Lifting handle" and the fender.

. If your bike doesn't have part #17, when you enter the part number into your internet search engine you use, be aware it'll return images of two different parts, only one'll look like the part #17 illustration.

. Another possibility occurs - does your bike's oil tank have a slotted screw visible in the neck and a spigot pointing rearwards from the neck? If so, that's the original chain oiler bleed; the screw was for metering, should have a pointed end and a friction spring to keep it in a set position. In reality, hot engine oil is a truly crap chain lube, I advise tightening the screw as much as possible and never touching it again.

Hth.

Regards,
 

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It's likely the majority of Triumphs never have the pressure checked. The riders motor on in ignorant bliss for years....What is too low for reliable operation for normal riding? Any facts like an engine with known low oil pressure threw the crankshaft onto the pavement...
 

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The only time I ever installed an oil pressure gauge was on my 2001 VMax. After install was when all the problems started to occur. I couldn't take my eyes off the damn thing. When it got hot at idle, it registered almost no oil pressure. Then I was worried about blowing up my engine. Then I just kept staring at it while I was riding, worried to death about what the pressure reading was. Finally took the oil pressure gauge off and have been riding the bike for the last 15 years with no issues. Sometimes I think we look for problems where there aren't any.

Rob'
 

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Discussion Starter #9
The only time I ever installed an oil pressure gauge was on my 2001 VMax. After install was when all the problems started to occur. I couldn't take my eyes off the damn thing. When it got hot at idle, it registered almost no oil pressure. Then I was worried about blowing up my engine. Then I just kept staring at it while I was riding, worried to death about what the pressure reading was. Finally took the oil pressure gauge off and have been riding the bike for the last 15 years with no issues. Sometimes I think we look for problems where there aren't any.

Rob'
I can't disagree with Rob or Truckedup either. My investigation began only because of the dreaded "idiot" light flashing at a hot idle. The bike runs strong and sounds good or at least just like my other 650 and my 750 as far as the usual engine noises. Some of the other issues brought up by Don and StuartMac- I knew what the baby poo was (we'll now call it mayonnaise LOL), I've just never experienced this from my other bikes, I have the crankcase vent system properly plumbed but I decided to cut the hose short of going all the way to the rear of the fender because there is no clamping provided to attach it neatly. I cut it off above the chain guard about even with the rear axle and zip tied it to the rear fender brace that runs to the tail light. I already capped off the chain oiler and screwed the feed adjustment all the way in.
 

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The mayonnaise can also be caused by blowby...Seen it many times in the crankcase ventilation on my worn auto engines....More stuff to worry about....
 

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As far as using SAE 40 during break in- Don states he uses a SAE40 break in oil from Torco. I don't wish to start the "OIL" debate. Many engines thru the ages have been broken in on conventional oils and while the PennGrade I chose isn't specifically a break in oil, I felt it would do the job. Here's a pic of the valve body of my PRV. Heavy scoring 360 degrees and top to bottom of cylinder. Even if a new valve made no improvement in the oil pressure readings, it can't hurt so will likely be replaced.
751586

My plan going forward is to change the oil and clean the tank screen. I plan to run a conventional 20-50. I will reinstall the PRV in its present condition and see if my oil pressure readings change for the better or not. I am going to get a new PRV ordered either way. I'm just taking this one step at a time. As I said in my original post, I installed new seals and am 99.99% sure I did it correctly, so I will consider my options after I have changed oil and cleaned the oil tank screen. I'll keep you posted!
 

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The mayonnaise can also be caused by blowby...Seen it many times in the crankcase ventilation on my worn auto engines....More stuff to worry about....
Yep, that's the gamble I took when I bought a basket case bike with a rebuilt engine done by a shop I don't know personally. Like I said, this bike runs strong, sounds healthy and doesn't blow smoke. This all began with a flashing idiot light at idle with a heat soaked engine....:rolleyes:. Worry changes nothing and this is my hobby!
 

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Hi Happyfeet, Not saying idiot lights are reliable ... But indeed was doing it’s job.

Flashing at idle, indicates it’s seeing low pressure. The next step is testing pressure with gauge. Which you did. Gauge confirms low pressure. Which the motor has.

Some motors can run on very low pressure. With the Hepolite inserts with too much clearance I found heat soaked idle 100f day to be 5-7# lower. Closer to 15-17#. At 975-1000 rpm. There is a world of difference between 6-8 & 15-17#.
I have on dvd Triumph service bulletin stated dealer is to check oil pressure after every motor overhaul. Did they? Who knows. Triumph didn’t get the specs out of a hat.

I doubt the OPV will help much, but it’s worn. Avoid stainless, just get the normal steel. A stainless cap is ok, but the slider body can get sticky.

The PRV works like this. You see the hole on side of bore. That’s the by pass.
As rpm & pressure rises oil starts compressing spring. So in effect no regulation happens until the spring is compressed until spring is compressed enough for piston to uncover bore. Think about that... Weak or short spring generally doesn’t effect pressure at lower rpm. What it does is uncover bore too soon so the pressure plateau starts too low.
If you know what to look for you can see this on gauge. At lower rpm pressure very closely follows rpm. At cut point port begins to be uncovered. Needle slows down. Pressure increases more slowly as spring compresses & progressively uncovers port. Finally fully open. Checking some bikes depending on pump, bearing clearance, oil type the pressure is actually a fair bit higher than book. I’ve seen this on T140 mostly. Again you can see needle action changes when fully open.
You have look for the subtle changes. You’ll see them on after repairs test.

I saw broken spring. Wound on itself.
Pressure was really low like 3#, but linear to 4500 where pressure was near 60 cold. Motor had miles on it. New PRV cured. So piston had moved back enough to uncover by pass.

On problem motor I try to remove PRV valve as a unit. Look at piston position through screen best I can & feel it with a wire. A metal chip can get stuck at corner of bypass & piston. For some reason wedges piston & sticks partly open.

How long will motor last ignoring low pressure? I don’t know. I’ve been afraid to find out. I’ve seen 15# hot idle last ok thousands of miles. All the winking or solid on lights got repaired after gauge verified low.

Morgo claims more pump volume due to larger pistons & other differences this is true. Would this help make up for the extra .0005” bearing clearance?? I’ve wondered that. That’s another subject.
Don
 

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Discussion Starter #14
Don, I saw just what you're describing on my test ride this morning. I cleaned the tank screen (which was not dirty) and put 20w-50 oil in. On cold start up my pressure at idle was in the 40-42 range, much better than when I first hooked up the gauge. When riding the pressure would jump up in the 70-80 range and then with more throttle you could see when the PRV would open. Once the engine was heat soaked the running pressure would be around 50-60 which was better than first test, but idle at 1100 rpm was 10 or below.
Like the other folks have said, how many Triumph owners have rode blissfully along with oil pressures well below spec? Many, I would surmise. On the other hand, I don't want to be the guy who ignored the warning signs and has a numbers matching bike destroyed by a thrown rod. I'm going to take this step by step, eliminating potential causes that are easily accessed before pulling the engine and heading to the machine shop. My investment in the test gauge set up is a good one. I wonder what my 1971 650 and 1979 750 will test out at. The Idiot lights on them never flicker. Maybe I'd better just ride blissfully along without knowing ...LOL
 

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Don, I saw just what you're describing on my test ride this morning. I cleaned the tank screen (which was not dirty) and put 20w-50 oil in. On cold start up my pressure at idle was in the 40-42 range, much better than when I first hooked up the gauge. When riding the pressure would jump up in the 70-80 range and then with more throttle you could see when the PRV would open. Once the engine was heat soaked the running pressure would be around 50-60 which was better than first test, but idle at 1100 rpm was 10 or below.
Like the other folks have said, how many Triumph owners have rode blissfully along with oil pressures well below spec? Many, I would surmise. On the other hand, I don't want to be the guy who ignored the warning signs and has a numbers matching bike destroyed by a thrown rod. I'm going to take this step by step, eliminating potential causes that are easily accessed before pulling the engine and heading to the machine shop. My investment in the test gauge set up is a good one. I wonder what my 1971 650 and 1979 750 will test out at. The Idiot lights on them never flicker. Maybe I'd better just ride blissfully along without knowing ...LOL
Oil pressure worry. One reason i never have a gauge on an old bike. It gets built up and all looks good. I know the condition inside the engine, so just go out and enjoy it. I have a 71 with the red light. It comes on when i start and goes off instantly. It has come on just the once while i was riding at 80 mph when the crank snapped on deceleration.
RIMG0037.JPG
 

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Hi, A gauge is just a gauge. John has one on ‘69 Bonnie. It reads the pressure which is good, because all is to spec.
Knowing what pressure is is simply that. What the pressure currently is. We know what manual says. I’d wager most bikes are near specs. If not, something in motor is not to specs. We each decide what to do about it.
I’ve seen much damage from low oil pressure in my career. Never see much damage from good oil pressure & proper oil changes. Cranks can break. PRV can get stuck on occasion, spring can break. Those are rare really. With proper maintenance the lubrication system is quite trouble free.
Bringing lubrication system to spec is never foolish. 10# at near 1000 rpm is not right.
Don
 

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Hi Happyfeet, For comparison this my PRV I just took out today. You did good job on photo! No so easy.

My screen is very fine. Too fine to stick wire through. The '69 screen wasn't this fine. Anyway here is my wear at 36K miles. I see some scoring. I show both sides of piston & bore. I doesn't wear straight.

My spring is 1.470" ;long. About 1-11/32" Spec is 1-3/8" So I'm about 1/32" short. Hot pressure after 30mi. road test 90f day was 35# at idle about 1000rpm. 75# at 3500. Oil was fully warmed, motor fully heat soaked. I've seen this on other T140. The T140 pump is different though. Mobil1 v-twin 20-50 oil. I was checking pressure due to noises which was from pistons, but I wanted to get base line pressure before motor overhaul.

I installed real oil filter at 19968 miles, 2/10/17. Has 36k on bike now. We'll see how sludge trap looks next week. Has had every oil change on time from new.

Check photo out on cap gasket.... Cap is bottomed on threads, but barely pinched gasket. It's had tiny seep from new. Not enough to bother with. Wrench will force threads & cap will tighten. Should you take new one apart, using sockets in the vise is a safer method. Never clamp hex of PRV in vise. It can distort it.

Going together put body in first & final tighten, not over tightening. Then put in piston & verify free movement. Then spring & cap. Don't over tighten cap. Over tightening can distort the unit. If possible try to avoid installing assembled body by using cap to tighten. That can lead to overtightening cap. The original seals were some sort of plastic. The PRV had never been removed until today. I lightly polished piston & bore with grey (fine) scotch brite pad. Surgically cleaned after. I will reuse valve as pressure test was good.
Don
 

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Hi Robert,
20w-50
Once the engine was heat soaked the running pressure would be around 50-60
(y) Excellent.

As you know, that's about what the Triumph workshop manual says for "Normal running"; fwiw, I bought my triples' oil pressure gauges from Les Williams; in his fitting instructions, he equated that to 3,500rpm and above; if that's what you're seeing, imho don't worry.

idle at 1100 rpm was 10 or below.
Again fwiw, something to keep an eye on but not overly concerning?

As far as using SAE 40 during break in- Don states he uses a SAE40 break in oil from Torco.
Mmmm ... Don's in CA, which I understand has high ambient temps most of the year ... you're a bit further north?

how many Triumph owners have rode blissfully along with oil pressures well below spec?
I don't want to be the guy who ignored the warning signs and has a numbers matching bike destroyed by a thrown rod.
Precisely. Unless you built the engine, you have no idea what compromises the builder made.

E.g. many years ago, I knew a guy who built a bike for another guy, the second guy to finish off the bike, because either was going to pay the same for the remaining parts. Took the second guy a some time and, very shortly after he put it on the road, it started making horrible engine noises and low oil pressure. Turned out, while the first guy who built most of the bike had put in a NOS crank, he hadn't had the big-ends ground; he said he told the second guy to bring it back before he put it on the road, so he could build the engine to work; second guy said he didn't remember the first guy telling him that (but it'd been a couple of years previously) ...

... pressure gauge fitted would've told the second guy immediately something was amiss, "blissful" ignorance made the resulting rebuild far more costly and time-consuming ... and two friends wouldn't have fallen out.

That appears to be a triple OPRV?

have the crankcase vent system properly plumbed
cut the hose short
above the chain guard about even with the rear axle and zip tied it to the rear fender brace that runs to the tail light
because there is no clamping provided to attach it neatly.
There is - if the fender doesn't have the hose clips inside around one or other edge, just get creative with the #19 F3098 "Clip" shown on the parts book "OIL TANK" pages? The list page shows "2", they (should) fit on 1/4" fender bolts, those bolts are used to mount fender bits all the way to the licence plate, just use as many Clips as needed to route the breather hose as neat as you want to the bottom of the fender, either inside or outside?

Hth.

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so, all this talk but it appears no one has an idea of the minimum pressure for safe running...
 
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