Triumphrat

Ahobie17 · 07-05-2008, 11:30 PM

I have a couple of ?'s concerning the oil pressure on a 1970 T100C, I have a new oil pressure light and when cold the light stays off even at a fast idle, 1,200 rpms, but when hot the light comes on dimly at 3,400 rmps and gets brighter at lower rpms. The engine is newly rebuilt but the oil pump wasn't replace (low mile engine). I'm running Mobile synthetic 20w50. Is this normal behavior? Should I replace the oil pump if so will the check balls need to be seated or will this already be done? What about a high volume oil pump as I seem to recall seeing that one is offered somewhere (if you know where tell me)?

Thanks

htown16 · 07-06-2008, 01:19 PM

This is not normal behavior and you should not ride the bike until you correct it. First possibility is that the oil light is bad. Replace the sender with a guage and see what the pressures really are at idle, and mid rpm, cold and hot. Since the motor has recently been rebuilt a prime suspect is the crank seal on the timing side. There have been a lot of reports of early failure of the seals due to inverting. A lot of people recommend replacement with the Pioneer brand. I believe Mitch Klemp carries them. The pumps them selves rarely fail since they run in oil.
Good luck
Htown

Ahobie17 · 07-06-2008, 09:42 PM

Where can I find an oil gauge that fits??

htown16 · 07-06-2008, 11:59 PM

A cheap automotive oil pressure gauge will work. Remove the sending unit for the light and fit the gauge. I'm not sure what the thread size is for a 500. Anyone else out there know?

Ahobie17 · 07-07-2008, 09:10 AM

I have a SW gauge, but finding the right fittings, might prove difficult.

Thanks

htown16 · 07-07-2008, 12:19 PM

The fitting on a 1970 650 would be a 1/8 " 27 tpi straight pipe thread. I'm guessing the 500 has the same. It only needs to be seated lightly, to avoid cracking timing cover.
You could skip the gauge step and just pull the timing cover and check the seal because that would be the next step. Only tricky bit is retiming engine. Have you checked to see if oil lines are attached correctly and are not blocked. The oil light only comes when the pressure drops to about 5 psi. This definitely not what you want at 3500 rpm.
Good Luck
Htown

Ahobie17 · 07-07-2008, 01:28 PM

I found some fittings and it'll be good to know what it is exactly, threads are 1/8x27 as you said. Just light seepage at the points, but are you referring to the triangular cover for the seal?? I suppose you are.
Re-timing the motor doesn't other me, as much as resetting the timing, neither is that bad though.

htown16 · 07-07-2008, 07:29 PM

Yes, the triangular cover. On the crank seal the clip should be on the side away from the crankcase and on the points seal toward the crankcase. It'll also give you a chance to check oil pump.

Ahobie17 · 07-08-2008, 08:45 PM

I connected the oil gauge and the pressure was low, sub 20psi, I do get a steady stream out of the line, then I removed the oil tank cap and was getting a steady stream of oil there too. Guess I'll be looking behind the timing cover, what signs am I looking for if the seal is bad? I highly doubt it is, but what do I look for?

Thanks

htown16 · 07-08-2008, 09:20 PM

Suggest you go over to the Triumph section on Britbike Forum and do a search on seals or low oil pressure. Lots of posts on there describing the problem.