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#634592 01/10/16 4:53 pm
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I have a 1972 T100. This weekend I decided to see what the oil pressure was looking like. I used a proper oil pressure kit with the correct fittings etc. Now, it should be 20 odd psi at tickover and 70 odd at running revs.
All I can get is 18 psi max regardless of revs. First thing I did was to replace the spring in the pressure relief valve with a new one, same result.
I then borrowed a complete valve from a T140, same result. Out of desperation I tried a trick with putting a spacer on the end of the spring hence it would never release even at a BIG pressure. Still 18 psi.
I checked the gauge with an air line, this worked, it went up to 90 plus.
The oil is returning at a very good rate and with some pressure. Oil is also going to the rockers at a slow but regular pace.It has done over 1500 miles since the rebuild and has not gone bang.
Next step is to try the gauge on a known bike with good oil return, but one is not yet available.
Any clues where and what to look for if or when I rip it apart?

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Boo #634596 01/10/16 5:17 pm
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Does the 1972 500 have a crankshaft oil seal in the timing cover?


Amateur Loctite enthusiast.
Boo #634597 01/10/16 5:19 pm
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Originally Posted by Boo
Any clues where and what to look for if or when I rip it apart?


Check if the lip of the crankshaft oil seal in the timing cover has inverted or split?

L.A.B. #634600 01/10/16 5:43 pm
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Originally Posted by L.A.B.
Originally Posted by Boo
Any clues where and what to look for if or when I rip it apart?


Check if the lip of the crankshaft oil seal in the timing cover has inverted or split?


Or has been fitted backwards by some dope.


Amateur Loctite enthusiast.
Boo #634636 01/10/16 8:43 pm
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And if it did or was, replace with Pioneer-Weston brand.

Steve


'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
Boo #634990 01/13/16 5:12 pm
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I had a mate with a T140 recently with very poor returning oil supply. That was a split oil seal. So I am not expecting a split seal but will look at it anyway as it is on the way in to the pump.
Anyone had experience with crap oil pressure gauges? I hope to borrow a mates bike to test the gauge on at the weekend.

Boo #635075 01/14/16 6:58 am
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Hi,

Originally Posted by Boo
1972 T100. This weekend I decided to see what the oil pressure was looking like. I used a proper oil pressure kit with the correct fittings etc.

Just as a matter of interest:-

. Where are you connecting the gauge; in place of the oil pressure switch in the front edge of the timing cover?

. The thread in the cover is 1/8"NPS (National Pipe Straight); it's uncommon so the usual substitute on a gauge is 1/8"NPT (National Pipe Tapered).

Originally Posted by Boo
70 odd at running revs.

All twin owners wish. The workshop Manual says 55/60 psi when hot (and above about 3,000~3,500 rpm), same as any twin using the plunger pump.

Hth.

Regards,

Boo #635087 01/14/16 8:27 am
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Originally Posted by Boo
I had a mate with a T140 recently with very poor returning oil supply. That was a split oil seal.



Timing side crank seal cannot cause "poor returning oil."


Amateur Loctite enthusiast.
Stuart #635136 01/14/16 4:36 pm
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Originally Posted by Stuart
Hi,

Originally Posted by Boo
1972 T100. This weekend I decided to see what the oil pressure was looking like. I used a proper oil pressure kit with the correct fittings etc.

Just as a matter of interest:-

. Where are you connecting the gauge; in place of the oil pressure switch in the front edge of the timing cover?

. The thread in the cover is 1/8"NPS (National Pipe Straight); it's uncommon so the usual substitute on a gauge is 1/8"NPT (National Pipe Tapered).

Originally Posted by Boo
70 odd at running revs.

Still pretty short of the mark.
All twin owners wish. The workshop Manual says 55/60 psi when hot (and above about 3,000~3,500 rpm), same as any twin using the plunger pump.

Hth.

Regards,

Boo #635138 01/14/16 4:40 pm
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I have the correct BSP fitting and a load of other types in the universal kit.
Originally Posted by Boo
Originally Posted by Stuart
Hi,

Originally Posted by Boo
1972 T100. This weekend I decided to see what the oil pressure was looking like. I used a proper oil pressure kit with the correct fittings etc.

Just as a matter of interest:-

. Where are you connecting the gauge; in place of the oil pressure switch in the front edge of the timing cover?

. The thread in the cover is 1/8"NPS (National Pipe Straight); it's uncommon so the usual substitute on a gauge is 1/8"NPT (National Pipe Tapered).

Originally Posted by Boo
70 odd at running revs.

Still pretty short of the mark.
All twin owners wish. The workshop Manual says 55/60 psi when hot (and above about 3,000~3,500 rpm), same as any twin using the plunger pump.

Hth.

Regards,

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Oil seal looks like a possible fault. However, it would surely be low pressure on the return pipe and this is returning under very good pressure. I will take a look after I have tried the pressure gauge for working properly.

Boo #635145 01/14/16 4:59 pm
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Originally Posted by Boo
Oil seal looks like a possible fault. However, it would surely be low pressure on the return pipe and this is returning under very good pressure. I will take a look after I have tried the pressure gauge for working properly.


The feed side of the pump forces oil towards the crankshaft, via the pressure relief valve and the oil seal. The amount of oil it pumps is proportional to rpm. All that oil ends up in the bottom of the crankcase, some through the big ends and a lot from the relief valve. If the seal is bad, most escapes through the seal.

The scavenge side of the pump sucks all the oil out of the bottom of the crankcase, no matter how it got there.

Last edited by triton thrasher; 01/14/16 5:11 pm.

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Boo #635201 01/15/16 2:45 am
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If the oil being returned is churned up and full of air then a higher return capacity can be overwhelmed, but then there will be more than one fault eg excessive ring blow by or breahter to provide the air.

Boo #635206 01/15/16 4:57 am
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Hi,

Originally Posted by Boo
I have the correct BSP fitting

BSP is NOT "correct". Triumph and BSA never used BSP for the oil pressure switch. As I posted previously:-

Originally Posted by Stuart
The thread in the cover is 1/8"NPS (National Pipe Straight)

BSP and NPS (or NPT) are not interchangeable.

Hth.

Regards,

Stuart #635291 01/15/16 4:54 pm
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Originally Posted by Stuart
Hi,

Originally Posted by Boo
I have the correct BSP fitting

BSP is NOT "correct". Triumph and BSA never used BSP for the oil pressure switch. As I posted previously:-

Originally Posted by Stuart
The thread in the cover is 1/8"NPS (National Pipe Straight)

BSP and NPS (or NPT) are not interchangeable.

Hth.

Regards,
Doh! 1/8 NPS not bsp. I did match the threads but not my typing skills.

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Good point. This does look like o possibility. I will test the gauge first anyway then it's just a case of pulling the case off and taking a look. That's my weekend taken care of. Many thanks.
Originally Posted by Boo
Oil seal looks like a possible fault. However, it would surely be low pressure on the return pipe and this is returning under very good pressure. I will take a look after I have tried the pressure gauge for working properly.

Boo #635555 01/17/16 3:36 pm
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I took the timing cover of this afternoon. YES it is a split seal. Only a small split but a split all the same. I will order some seals tomorrow and give it a go next weekend. Thanks all for your help. I will keep you informed on my progress.

Boo #636491 01/22/16 6:38 pm
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Started up the T100 today with the new oil seal after replacing and removing then replacing again just to make sure all was well.
First 80 psi on start up, went down to 40 when warm. Tried again later with a luke warm engine, went up to 55 then gradually went down to 15 at hot idle. Add a few revs and it went up to 45 then down again to sod all.
What sort of pressure should I get and at what temperature?

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To help with the replies, What oil/weight are you using?

Boo #636500 01/22/16 7:29 pm
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10 psi per 1000 rpm is sort of a rule of thumb on these old crates when the engine is warmed up thoroughly. So if you are getting 40-50 at 4000 rpm and 15 at idle on a hot engine, I wouldn't worry about it. 80 on cold startup sounds about right. Oil pressure is mainly function of wear on rod bearings, so an engine with some miles on it can be a bit lower but still in the "healthy" range. 20w/50? Air temps?

Last edited by htown; 01/22/16 7:30 pm.

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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htown #636527 01/22/16 10:54 pm
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Hi,

Originally Posted by htown
10 psi per 1000 rpm is sort of a rule of thumb on these old crates when the engine is warmed up thoroughly.

Fwiw, not my experience (three Triumphs with o.p. gauges, fourth fitted temporarily with a gauge every now-and-then). My experience is: warm - idle, pressure shown in the workshop Manual or a little (5 psi?) less; above about 3,000~3,500 rpm, at worst, lower end of "Normal" pressure range shown in the workshop Manual. Anything much lower, especially "sod all", is a fault either with the gauge (not rare) or something within the engine. frown

Hth.

Regards,

Stuart #636538 01/22/16 11:56 pm
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God bless you Stuart,
If it's getting some oil and it's still running, that's it. These old turds are not Swiss watches. They are Singer Sewing Machines. Designed to run any where under any conditions. Well maybe not designed, but that's the way it worked out. Way before FAX and email Triumph had an address for telegrams " trusty coventry". After a zillion miles on Triumphs I can can only remember two times not making it home.
TRUSTY


1968 T120R
1972 T120RV
Any advice given is without a warranty expressed or implied.
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10psi per 1000rpm is often quoted, mainly as I recall in automotive engine tuning books. These engines are much larger than our motorcycle engines where moving parts are further apart.

It therefore does seem reasonable to expect smaller older engines to manage with less. This is why it's important to use a thicker oil in our classics. Very few of our engines will run comfortably on for example 10w40 oil, unless you have an upgraded pump and accept faster potential wear on cam followers for example. You only need to compare the surface area of cam followers on a parallel twin and the BMC 'A' series engine (mini). These cam followers also rotate to spread the wear.


BSA: '71 B175; '68 B25; '71 A65; '71 A75
Triumph: '87 T140; '72 T150v
desco #636581 01/23/16 8:46 am
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Originally Posted by desco
God bless you Stuart,
If it's getting some oil and it's still running, that's it. These old turds are not Swiss watches. They are Singer Sewing Machines. Designed to run any where under any conditions. Well maybe not designed, but that's the way it worked out. Way before FAX and email Triumph had an address for telegrams " trusty coventry". After a zillion miles on Triumphs I can can only remember two times not making it home.
TRUSTY


God bless you Desco. You have a capacity to cut through all the B/S and generally summing up issues pretty well. RR smile


'72 Bonneville
"He who praises you for what you lack wishes to take from you what you have." - Don Juan Manuel
RetroRod #636683 01/23/16 4:46 pm
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UPDATE. Started up this morning, smoking like a Jawa, oil pressure lower than a snakes belly button. Took the case off again, torn oil seal. WHY? I took my time putting on the case yesterday and even took it off again to check. All was ok, yet today, this. I have now fitted yet another seal, again double checking all is well. Only time will tell. I even measured the distance of the seal from the crank end, 8mm gap.Spot on. Running on classic 20/50. Should not be a problem, I hope.

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