T140e Oil Pressure

[Dashfixer]

I have a T140E 1979 that has had a total rebuild about 4 years ago. As I have been working away from home I've done very little work and no riding on the bike since finishing the rebuild.
I recently, about 3 months ago, fitted an oil pressure gauge by tapping off from the Pressure relief valve. I now have a problem which I would like advice on.
The oil pressure should read approx 20 - 25 psi on idle increasing up to 60-65psi on full throttle. My bike is going straight to 60 psi as soon as it's started. It is also dumping loads of oil into the crankcase. So much oil that the pump can't scavenge it out fast enough and so slowly the oil tank is emptied into the crankcase, or would be if I kept the engine running. Originally after fitting the pressure gauge I had the correct readings.
My thinking is that a blockage has developed somewhere and the pump has nowhere to send the oil so I get instant high pressure and the Relief Valve is straight away porting oil into the crankcase to try and control that pressure.
Before I strip the engine down to access the crank shaft does anyone have any other ideas? I will be very grateful for anything. Thanks.

 

[Rudie]

oil pressure should read approx 20 - 25 psi on idle increasing up to 60-65psi on full throttle. My bike is going straight to 60 psi as soon as it's started.

"as soon as it's started" means the oil is cold. "20 - 25 psi on idle increasing up to 60-65psi" (the latter ideally above 3,500 rpm) are hot oil pressures.

Damhikt but, cold oil, injudicious right hand, good oil pump on a twin is quite capable of exceeding 100 psi.

also dumping loads of oil into the crankcase. So much oil that the pump can't scavenge it out fast enough and so slowly the oil tank is emptied into the crankcase, or would be if I kept the engine running.

The oil pump, or something in the scavenging system, is not functioning correctly. All oil pumps' scavenge always have a greater capacity than the feed. The only other possibility is large quantities of oil are leaking past the pump into the timing chest, draining from there into the bottom of the crankcase.

When you rebuilt the engine, did you fit a new crankshaft seal in the timing cover? If you did, did you measure the crankshaft/have it measured accurately to determine whether the undersize ID seal was required? Did you fit a Pioneer Weston seal?

A check you should make is remove the timing cover and check the seal to the crankshaft. The only seal make I trust is Pioneer Weston, other have been known to invert and/or split given the aforementioned cold oil and injudicious right hand. You will need to remove the seal from the timing cover to check for splits.

fitted an oil pressure gauge by tapping off from the Pressure relief valve.

Please post more detail how you did this, I have never heard of this, pressure gauges on Triumph twins are normally connected in place of the warning light switch in the timing cover.

 

[Dashfixer]

"as soon as it's started" means the oil is cold. "20 - 25 psi on idle increasing up to 60-65psi" (the latter ideally above 3,500 rpm) are hot oil pressures.

Damhikt but, cold oil, injudicious right hand, good oil pump on a twin is quite capable of exceeding 100 psi.


The oil pump, or something in the scavenging system, is not functioning correctly. All oil pumps' scavenge always have a greater capacity than the feed. The only other possibility is large quantities of oil are leaking past the pump into the timing chest, draining from there into the bottom of the crankcase.

When you rebuilt the engine, did you fit a new crankshaft seal in the timing cover? If you did, did you measure the crankshaft/have it measured accurately to determine whether the undersize ID seal was required? Did you fit a Pioneer Weston seal?

A check you should make is remove the timing cover and check the seal to the crankshaft. The only seal make I trust is Pioneer Weston, other have been known to invert and/or split given the aforementioned cold oil and injudicious right hand. You will need to remove the seal from the timing cover to check for splits.


Please post more detail how you did this, I have never heard of this, pressure gauges on Triumph twins are normally connected in place of the warning light switch in the timing cover.

My mistake on posting, I didn't tap from the pressure relief valve but from the pressure switch. After I had fitted the gauge I was getting the correct indications of oil pressure 20-25 at idle 60 at high throttle settings, so I don't think it's cold oil.
I had measured the crankshaft end and used the correct 10 thou undersized oil seal on rebuild. I have now replaced the seal 3 times as I thought the same as you. I've checked the suction line for leaks, none apparent. Tomorrow I will take the timing cover off and the sump drain plug out and see if I can squirt oil through the crank shaft. I've now tried 2 different oil pumps to see if there was a lack of scavenge with no change.

 

[Dashfixer]

My mistake on posting, I didn't tap from the pressure relief valve but from the pressure switch. After I had fitted the gauge I was getting the correct indications of oil pressure 20-25 at idle 60 at high throttle settings, so I don't think it's cold oil.
I had measured the crankshaft end and used the correct 10 thou undersized oil seal on rebuild. I have now replaced the seal 3 times as I thought the same as you. I've checked the suction line for leaks, none apparent. Tomorrow I will take the timing cover off and the sump drain plug out and see if I can squirt oil through the crank shaft. I've now tried 2 different oil pumps to see if there was a lack of scavenge with no change.

Pioneer Weston are just up the road from me so I'll be nipping over to them for a new seal or two tomorrow.

 

[Dashfixer]

Well I took the timing cover off and tried to push some oil down the crank shaft using a syringe with no joy. As soon as I tried to push the syringe plunger it was solid. So I'm now starting the strip down it will be interesting to see what is causing the blockage.

Just for info, I checked the crankshaft oil seal and I had fitted a Pioneer and weston seal and it looked fine.

 

[Rudie]

Well I took the timing cover off and tried to push some oil down the crank shaft using a syringe with no joy. As soon as I tried to push the syringe plunger it was solid. So I'm now starting the strip down it will be interesting to see what is causing the blockage.

One place you should check, if you did not during the rebuild, is the sludge trap exit hole aligns precisely with the hole in the crank ... some sludge trap makers are not as fastidious about accuracy as they should be ...

However, do not be surprised if you do not find any actual "blockage". The big end clearances are a few thousandths of an inch, it is very unlikely your thumb on any syringe plunger could generate sufficient pressure to push a noticeable quantity of oil through those gaps.

After I had fitted the gauge I was getting the correct indications of oil pressure 20-25 at idle 60 at high throttle settings, so I don't think it's cold oil.

Not clear from this is whether the "20-25 at idle 60 at high throttle settings" was with cold or hot oil. If with cold oil, any plunger pump that fits a Triumph twin engine is not capable of maintaining the same pressures with both cold and hot oil.

The pressures quoted in the Triumph workshop manual are for hot oil - thin and flows easily. Cold oil is thicker and does not flow so easily - is why the oil pressure relief valve has a higher pressure than the "60 [psi] at high throttle settings".

If the pressures in the manual are seen when the oil is cold, the pressure at all rpm will fall dramatically as the oil warms up.