T140V Low Oil Pressure

[Migsan]

Hi everyone

Just finished rebuilding a 1976 t140V including the motor.
Bike starts and runs fine. but oil light started flickering even when running. That was during testing near the house. Changed the oil and couldn't see any aluminum shraple on the sediment. Ordered some parts and tools. Measured the oil pressure and it's 10 psi at 1000 rpm and 20 psi at 3000 rpm cold engine because I am to scared of let it running to long. Have a strong continues flush of oil in the oil tank feed with no air bubbles. Bought a new PRV and still the same. Removed the oil pump and was super clean had good vacuum and would squirt oil on both sides with good pressure. checked the balls and springs all seemed good and clean with good seat. Also tested directly the feeding hose for negative pressure and it sucks oil. No issues with oil feeding to the pump either. Replaced the oil seal even though the previous one seemed fine. reassembled the pump and when the motor is turned oil comes out the feeding hole to the timing cover.
Already staring to think about the main bearings. I changed the originals and bought news ones on ebay;
70-2879 (Triumph) (NKE Premium Quality)
https://www.ebay.co.uk/itm/253253753851Let me know what you think of these bearings.
Also replaced the guide blocks and I am wondering if I confused the inlet with the exhaust! but in that case would it affect the pressure like that or would increase it instead?

Apart from that bike starts at 1st kick and sounds great!

Don't know what else to test and really don't wanna take the motor apart unless I have to.
Maybe you guys can think of something.
Thank you very much!
Miguel

 

[grandpaul]

That's a head scratcher, if you have good visible oil flow.

I wonder if you have a "weak" sensor, that trips at too low of a setting?

 

[Migsan]

That's a head scratcher, if you have good visible oil flow.

I wonder if you have a "weak" sensor, that trips at too low of a setting?

Hi Grand Paul
I believe so. I tried to follow all the indications to test the pump but would love to see a video just to be sure. Also when I rebuilt the engine the rod sleve bearings seemed fine with no visible scoring so I let them be. plus the main bearings were brand new even though I bought them on ebay. Don´t wanna throw money out of the window on a new pump unless I really have to.
Thanks

 

[Migsan]

Hi Grand Paul
I believe so. I tried to follow all the indications to test the pump but would love to see a video just to be sure. Also when I rebuilt the engine the rod sleve bearings seemed fine with no visible scoring so I let them be. plus the main bearings were brand new even though I bought them on ebay. Don´t wanna throw money out of the window on a new pump unless I really have to.
Thanks

Sorry what I meant is that I believe the oil has a good flow. with sensor you mean the oil pressure switch right?

 

[Josheezpapa]

I'm no expert. Heck, im barely a spurt. But if I understand these oil systems correctly, I'd be sure there's no partial blockage, but I would personally lean towards a worn pump... too much wear, or clearance. I would think if that was the case, a quick diagnosis might me to do an oil change with heavy engine oil... maybe 50 we racing oil,, if the pump is worn, pressure should improve ..
CAVEAT:
a new engine, during break in, may not be served well with that....
However, when I break in a new engine, I use straight 30 for break in... I guess some habits die hard, so 50 might not be so bad.

Thats just my opinion, probably worth exactly what you paid for it

Good luck. Let us know what you find

I discounted the sender, since you had diagnosed, apparently, with a mechanical guage ?

 

[Josheezpapa]

I'm no expert. Heck, im barely a spurt. But if I understand these oil systems correctly, I'd be sure there's no partial blockage, but I would personally lean towards a worn pump... too much wear, or clearance. I would think if that was the case, a quick diagnosis might me to do an oil change with heavy engine oil... maybe 50 we racing oil,, if the pump is worn, pressure should improve ..
CAVEAT:
a new engine, during break in, may not be served well with that....
However, when I break in a new engine, I use straight 30 for break in... I guess some habits die hard, so 50 might not be so bad.

Thats just my opinion, probably worth exactly what you paid for it

Good luck. Let us know what you find

I discounted the sender, since you had diagnosed, apparently, with a mechanical guage ?

One other thought... fresh bike rebuild.... did u change the hoses? They need to be reinforced, if I remember right, for a couple reasons.. reinforced hoses are not likely to kink on bends, and non reinforced, even if rated for oil, the suction could suck the hose shut maybe?

I'll go away now. Lol

 

[grandpaul]

good input.

 

[Migsan]

One other thought... fresh bike rebuild.... did u change the hoses? They need to be reinforced, if I remember right, for a couple reasons.. reinforced hoses are not likely to kink on bends, and non reinforced, even if rated for oil, the suction could suck the hose shut maybe?

I'll go away now. Lol

Thanks for the help!
Yes I changed all the hoses. I believe they are reinforced as well with those white threads within the rubber. Also the feed line has no bends I made sure of it on assembly. I would be more suspicious of the return line because I installed a filter but it has a really strong flow back to the tank.
I loved the idea of the oil change but maybe it's better to order pump straight away then and save the money in oil. I was reading of several other threads and forums that the original pumps are very reliable and all.
Would you guys recommend the morgo replacement (2 valves)?
Cheers

 

[speedrattle]

change the oil seal again. look at it very carefully with a good light before you move it, but change it anyway.

make sure the one you put in is a pioneer weston seal, marked PW. the seal is the same as the one in the points cavity. the inexpensive taiwanese seals sometimes invert, bleeding pressure and giving the symptoms you describe.

dammit, i just now see that you are in portugal. where are yku getting your oil seals?

 

[Migsan]

change the oil seal again. look at it very carefully with a good light before you move it, but change it anyway.

make sure the one you put in is a pioneer weston seal, marked PW. the seal is the same as the one in the points cavity. the inexpensive taiwanese seals sometimes invert, bleeding pressure and giving the symptoms you describe.

dammit, i just now see that you are in portugal. where are yku getting your oil seals?

Hi Kevin

Yes I am in Portugal and I have to order everything from the UK. Like I said the previous oil seal seemed fine I replaced it myself during the rebuild but just in case I replaced it again today. I ordered an extra one so I will check the brand tomorrow. I believe I got the pair from feked
Thank you for the help

 

[Migsan]

Hi Kevin

Yes I am in Portugal and I have to order everything from the UK. Like I said the previous oil seal seemed fine I replaced it myself during the rebuild but just in case I replaced it again today. I ordered an extra one so I will check the brand tomorrow. I believe I got the pair from feked
Thank you for the help

So the previous one I removed was marked PW but the new ones are marked SFK

 

[Rudie]

oil seal
got the pair from feked

previous one I removed was marked PW but the new ones are marked SFK

I would not waste my time or money buying important parts from Feked or Ebay. As you have to buy parts from the UK, I recommend TMS and L.P. Williams, both have been in business longer than Feked.

oil light started flickering even when running.
oil pressure and it's 10 psi at 1000 rpm and 20 psi at 3000 rpm cold
strong continues flush of oil in the oil tank feed with no air bubbles. Bought a new PRV and still the same. Removed the oil pump and was super clean had good vacuum and would squirt oil on both sides with good pressure. checked the balls and springs all seemed good and clean with good seat. Also tested directly the feeding hose for negative pressure and it sucks oil. No issues with oil feeding to the pump either. Replaced the oil seal even though the previous one seemed fine. reassembled the pump and when the motor is turned oil comes out the feeding hole to the timing cover.
Already staring to think about the main bearings.

Why? The main bearings do not have anything to do with the oil pressure.

replaced the guide blocks and I am wondering if I confused the inlet with the exhaust! but in that case would it affect the pressure

No.

don't wanna take the motor apart unless I have to.

In my humble opinion, you have to.

You have tested the pump ("pump and was super clean had good vacuum and would squirt oil on both sides with good pressure") and feed to it, oil also returns to the frame when the engine is running.

"Bought a new PRV".

Oil seal between crankshaft and timing cover: you have replaced it twice.

"oil pressure ... 10 psi at 1000 rpm and 20 psi at 3000 rpm cold": did you connect the gauge in place of the oil pressure switch? If you did, it is the tiny clearance between the crankshaft and the big end shell bearings in the connecting rods that is the restriction that shows as oil "pressure". The larger the clearance, the lower the pressure. As I understand it, you have eliminated all other possibilities, the cause of the low oil pressure is in the big end bearings?

Did you clean out the crankshaft sludge trap during the rebuild? If you did, did you ensure the hole in the side of the new/replaced sludge tube lined up with the hole in the crank?

wonder if you have a "weak" sensor, that trips at too low of a setting?

oil pressure and it's 10 psi at 1000 rpm and 20 psi at 3000 rpm cold

Removed the oil pump and was super clean had good vacuum and would squirt oil on both sides with good pressure. checked the balls and springs all seemed good and clean with good seat. Also tested directly the feeding hose for negative pressure and it sucks oil.

Don´t wanna throw money out of the window on a new pump

maybe it's better to order pump straight away

So why do you keep posting about a new pump?

 

[Migsan]

I would not waste my time or money buying important parts from Feked or Ebay. As you have to buy parts from the UK, I recommend TMS and L.P. Williams, both have been in business longer than Feked.


Why? The main bearings do not have anything to do with the oil pressure.


No.


In my humble opinion, you have to.

You have tested the pump ("pump and was super clean had good vacuum and would squirt oil on both sides with good pressure") and feed to it, oil also returns to the frame when the engine is running.

"Bought a new PRV".

Oil seal between crankshaft and timing cover: you have replaced it twice.

"oil pressure ... 10 psi at 1000 rpm and 20 psi at 3000 rpm cold": did you connect the gauge in place of the oil pressure switch? If you did, it is the tiny clearance between the crankshaft and the big end shell bearings in the connecting rods that is the restriction that shows as oil "pressure". The larger the clearance, the lower the pressure. As I understand it, you have eliminated all other possibilities, the cause of the low oil pressure is in the big end bearings?

Did you clean out the crankshaft sludge trap during the rebuild? If you did, did you ensure the hole in the side of the new/replaced sludge tube lined up with the hole in the crank?







So why do you keep posting about a new pump?

Hi Rudolf
Thanks for your help!
Yes I think I excluded everything else but in regards to the pump it's my first rebuild so that's why I am questioning if I tested the pump properly.
I read a lot of different post about testing the pump but I haven't seen it before with my own eyes. Maybe I am just in denial.
I did placed the pressure gauge in place of the oil pressure switch.
The sludge trap was cleaned and replaced by a professional mechanic back in the UK while I was living there.
If I tested the pump properly then I can't think of anything else. When I rebuilt the motor the big end shell bearings didn't seemed to show any signs of wear but I didn't measure them or anything

 

[Rudie]

I read a lot of different post about testing the pump but I haven't seen it before with my own eyes.

During the rebuild, did you dismantle the pump, check the bores for any damage? If you did not, it would be wise to eliminate this possibility? If you have not dismantled the pump, the bolts can be very tight - the pump should be held in vice with jaws padded very well.

If you check the pump pistons and bores by filling with oil, there should not be any leakage.

If you decide to change the pump, Morgo is a good one - it has a slightly larger capacity than the standard pump but, more importantly, Morgo make all the pump parts.

When I rebuilt the motor the big end shell bearings didn't seemed to show any signs of wear but I didn't measure them

Undersize big end shells are available in increments of ten thousandths of an inch. It is impossible to tell ten thousandths of an inch by eye.

 

[Migsan]

During the rebuild, did you dismantle the pump, check the bores for any damage? If you did not, it would be wise to eliminate this possibility? If you have not dismantled the pump, the bolts can be very tight - the pump should be held in vice with jaws padded very well.

If you check the pump pistons and bores by filling with oil, there should not be any leakage.

If you decide to change the pump, Morgo is a good one - it has a slightly larger capacity than the standard pump but, more importantly, Morgo make all the pump parts.


Undersize big end shells are available in increments of ten thousandths of an inch. It is impossible to tell ten thousandths of an inch by eye.

Hi Rudolf
I did at the time but maybe I will check it again I if I will take the engine apart anyway. So you say if the pump holds the oil inside the pistons while vertical it's enough proof?
yes just dismantled the pump completely before I started the post and the only thing I could see was minor scratches on the feed side but when submerged in oil it seemed to pump ok.
The other test I did to check for the valve seating was to submerge in oil and pump a couple of times. After that, with the pump holes turned up I would cover the feeding holes and would pull the piston. on the feeding side the oil level didn't move on the exit hole but on the scavenger side the oil would be sucked in (the one with the wider piston). Because the scavenger side was functioning properly didn't pay much attention to it.

In regards to the shell bearings the increments are used only when the journals are machined right? Didn't pay attention to the markings on the shell so I don't know if they are standard. felling pretty stupid right now.

 

[Rudie]

if the pump holds the oil inside the pistons while vertical it's enough proof?

Yes, none should leak out.

shell bearings the increments are used only when the journals are machined right?

"Standard", "-0.010" (inches) and "-0.020" big end journal actual diameters are in the Triumph workshop manual - Section B37 (Inspecting The Crankcase Components), manual page B39 or, if you are using the online pdf, page 77.

Journals are ground to "Standard" size (between 1.6235 inches and 1.6240 inches) during building. When a used engine is dismantled, both big end journals should be measured with a micrometer in several places - to ensure they are still round across their widths - and the actual measurements compared to the manual. If either journal is scored or the actual measurements show either journal is worn compared to the big end shells fitted, both journals must be ground to the next undersize (if possible) and the corresponding new shells fitted.

If the big ends require grinding to the next undersize, the grinder must be chosen very carefully, because modern crankshaft journals are parallel across their full width between the crankshaft webs, there is a 90-degree corner between each journal and web. However, if an old Triumph crankshaft is ground in this way, it will break shortly after the rebuilt engine is returned to use, because the 90-degree changes between journals and webs are stress raisers.

Triumph crankshafts must be ground with a radius between each journal and web. Most crankshaft grinders hate doing this because they must first grind the radius on the corners of the grinding tools, which afterwards can only be used for grinding Triumph (and other old motorcycle) crankshafts. The cheapest grinder is likely to be someone who has the special grinding tools already (which might not be in Portugal? ).

If your crankshaft big ends must be ground to the next undersize and you must use a crankshaft grinder who will first alter the grinding tools, the corner radius dimensions are not in the workshop manual. However, they are available, post if you need them.

 

[Migsan]

Yes, none should leak out.


"Standard", "-0.010" (inches) and "-0.020" big end journal actual diameters are in the Triumph workshop manual - Section B37 (Inspecting The Crankcase Components), manual page B39 or, if you are using the online pdf, page 77.

Journals are ground to "Standard" size (between 1.6235 inches and 1.6240 inches) during building. When a used engine is dismantled, both big end journals should be measured with a micrometer in several places - to ensure they are still round across their widths - and the actual measurements compared to the manual. If either journal is scored or the actual measurements show either journal is worn compared to the big end shells fitted, both journals must be ground to the next undersize (if possible) and the corresponding new shells fitted.

If the big ends require grinding to the next undersize, the grinder must be chosen very carefully, because modern crankshaft journals are parallel across their full width between the crankshaft webs, there is a 90-degree corner between each journal and web. However, if an old Triumph crankshaft is ground in this way, it will break shortly after the rebuilt engine is returned to use, because the 90-degree changes between journals and webs are stress raisers.

Triumph crankshafts must be ground with a radius between each journal and web. Most crankshaft grinders hate doing this because they must first grind the radius on the corners of the grinding tools, which afterwards can only be used for grinding Triumph (and other old motorcycle) crankshafts. The cheapest grinder is likely to be someone who has the special grinding tools already (which might not be in Portugal? ).

If your crankshaft big ends must be ground to the next undersize and you must use a crankshaft grinder who will first alter the grinding tools, the corner radius dimensions are not in the workshop manual. However, they are available, post if you need them.

Thanks Rudolf
When I was living in Dorset England I was half an hour drive from Feked and the Bugad workshop wich was great for learning. It was there the sludge trap was changed. And I asked the mechanic what I thought about the journals and he said the it was ok but I am not sure if he measured. HE just recommended cleaning them with the back part of sand paper before installing the rods. I think I tried to measured the journals without knowing quiet well what I was doing and they must of been at least symmetric in measurements. I did all the engine rebuilding guided between the manual and by lunmad videos on youtube so I must of checked more or less according to the guidance.

Definitely would have to send the crank back to the UK if I would need grinding. I would be reluctant to trust my bikes to any mechanic here because you just don't see these bikes around here.
Also with Brexit it's a pain to get parts plus not to mention taxes which are abusive.
Thant's why when I order parts I need to think about two or three different scenarios otherwise I will be stuck waiting for next order.
I will take the pump out again today, submerge it in oil pump the pistons up and down several times and the leave them filled with oil. Whipeout excess oil and see if they dribble!

 

[Josheezpapa]

This is an interesting and informative thread.
I, for one, am enjoying it.

 

[Migsan]

In my humble opinion, you have to.

You have tested the pump ("pump and was super clean had good vacuum and would squirt oil on both sides with good pressure") and feed to it, oil also returns to the frame when the engine is running.

"Bought a new PRV".

Oil seal between crankshaft and timing cover: you have replaced it twice.

"oil pressure ... 10 psi at 1000 rpm and 20 psi at 3000 rpm cold": did you connect the gauge in place of the oil pressure switch? If you did, it is the tiny clearance between the crankshaft and the big end shell bearings in the connecting rods that is the restriction that shows as oil "pressure". The larger the clearance, the lower the pressure. As I understand it, you have eliminated all other possibilities, the cause of the low oil pressure is in the big end bearings?

Did you clean out the crankshaft sludge trap during the rebuild? If you did, did you ensure the hole in the side of the new/replaced sludge tube lined up with the hole in the crank?







So why do you keep posting about a new pump?

Hi everyone

So followed Rudie recommendation and rebuilt the engine. One of the conrod bolts was coming loose. At the time I got new bolts but used the old nuts torqued to spec.
So I got new conrod bolts and nuts. No signs of damage on the journals rechecked with a caliper and placed new big end bearings which weren't replaced last time.
Oil pressure is back up and seems alright for now.
thank you all for the help!
Now I probably start another post on the carbs which I am struggling at the moment

 

[B25bsaboy]

Hi everyone

Just finished rebuilding a 1976 t140V including the motor.
Bike starts and runs fine. but oil light started flickering even when running. That was during testing near the house. Changed the oil and couldn't see any aluminum shraple on the sediment. Ordered some parts and tools. Measured the oil pressure and it's 10 psi at 1000 rpm and 20 psi at 3000 rpm cold engine because I am to scared of let it running to long. Have a strong continues flush of oil in the oil tank feed with no air bubbles. Bought a new PRV and still the same. Removed the oil pump and was super clean had good vacuum and would squirt oil on both sides with good pressure. checked the balls and springs all seemed good and clean with good seat. Also tested directly the feeding hose for negative pressure and it sucks oil. No issues with oil feeding to the pump either. Replaced the oil seal even though the previous one seemed fine. reassembled the pump and when the motor is turned oil comes out the feeding hole to the timing cover.
Already staring to think about the main bearings. I changed the originals and bought news ones on ebay;
70-2879 (Triumph) (NKE Premium Quality)
https://www.ebay.co.uk/itm/253253753851Let me know what you think of these bearings.
Also replaced the guide blocks and I am wondering if I confused the inlet with the exhaust! but in that case would it affect the pressure like that or would increase it instead?

Apart from that bike starts at 1st kick and sounds great!

Don't know what else to test and really don't wanna take the motor apart unless I have to.
Maybe you guys can think of something.
Thank you very much!
Miguel

Migel,

You answered your own question - Removed the oil pump and was super clean had good vacuum and would squirt oil on both sides with good pressure.
When you removed the plunger pump did you dis-assemble and reseat the steel balls into the seating area? This done using a brass drift, seat the ball into its cavity and gently give it a tap. This reseats the ball into the cavity, and do not over tighten the end caps. You will find the oil pressure will rise. Triumph T120/140 engines don't usually have high engine pressure and you can tell by watching the oil return line that comes up from the engine back into the engine oil reservoir. Steady stream is a good sign, sputtering oil return tells you the oil pump needs to be reseated and the crank sludge trap needs servicing.
Just one question about your engine rebuild did you remove the dreaded crank oil sludge trap? This is a must when ever you do an engine rebuild!
Good luck in your quest and you will find these engines are robust if maintained properly and use only 20/50W petroleum oil and not synthetic!
Merry Christmas and may you have a fruitful New Year.