Oil pressure at head

A good amount of oil up there indicates the returnside is keeping up. Now with that antisump and what this all means for the crank side of the pump opinions abound. Try a different gage =get a different number. It's not likley that the return side would work perfect and the crank side would not.

norbsa48503 said:

A good amount of oil up there indicates the returnside is keeping up. Now with that antisump and what this all means for the crank side of the pump opinions abound. Try a different gage =get a different number. It's not likley that the return side would work perfect and the crank side would not.

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norbsa,

Why all these references to the return side? The valvegear is fed from the feed side.

Fourperf,

Adding shims to the pressure relief valve will not increase your overall oil pressure only raise the pressure that the valve opens.

norbsa48503 said:

A good amount of oil up there indicates the returnside is keeping up. Now with that antisump and what this all means for the crank side of the pump opinions abound. Try a different gage =get a different number. It's not likley that the return side would work perfect and the crank side would not.

Click to expand...

thanks a lot.

I took it for a good rump and what I found was 30 lbs at 4000 rpm and 20 lbs at 3000 rpm. I checked in the oil tank when I got home with the bike running and there was plenty of oil returning into the oil tank (I am not sure if that means anything). I pulled the left rocker cover and there was oil on the back side of the cover and the rocker was moist with oil. Its hard to tell how much oil there was around ther (its subjective I suppose). Does this all sound correct?

maybe I should add a shim which would make 4 total. The oil pressure would be over 100lbs at idle when cold but maybe that would get me closer when hot. On another note one of the tapped holes in the timing cover for the boyer pickup plate is stripped. Do you know if those holes are blind or do they go all the way through? I forgot. If they are blind I can helicoil it without pulling the timing cover.

Thanks again for all your help.

this forum is great.

Mark

fourperf said:

maybe I should add a shim which would make 4 total. The oil pressure would be over 100lbs at idle when cold but maybe that would get me closer when hot.

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No it won't.

You have it set too high now (80lbs)

Once the oil pressure drops below the release pressure then the relief valve does nothing at all.

When I had one less shim in it the pressure read about 20 lbs at 4000 rpm

do you set the oil pressure with the shims based on the engine being hot or cold?

Mark

Then you have a problem with the release valve.

If the valve is set to open at 60 (or 80lb) then it should not be letting oil through at 20 (or 40 lb).

Basically it should not matter what the oil temperature is just that when the oil is warm it is unlikely to reach a pressure that will operate the release valve.

L.A.B. said:

Then you have a problem with the release valve.

If the valve is set to open at 60 (or 80lb) then it should not be letting oil through at 20 (or 40 lb).

Basically it should not matter what the oil temperature is just that when the oil is warm it is unlikely to reach a pressure that will operate the release valve.

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how can that be tested?

Mark

Probaby easier to buy a new one!

By the way what oil grade are you using?

L.A.B. said:

Probaby easier to buy a new one!

By the way what oil grade are you using?

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castrol gtx 20w50

would I buy the piston,spring and body and the cap. The whole assembly?

what can go wrong with that thing, it seems so basic?

mark

I cannot see how it could be affecting the pressure that much below the relief pressure that it is set to.
Perhaps others here could comment?
Possibly the piston isn't seating properly in the housing?

You could strip it and check it closely. You may find a way to pressure test it.

You can buy the parts separately.

Or the assembly.

20/50 should be OK, although the 'experts' still recommend using monograde oil.

L.A.B. said:

I cannot see how it could be affecting the pressure that much below the relief pressure that it is set to.
Perhaps others here could comment?
Possibly the piston isn't seating properly in the housing?

You could strip it and check it closely. You may find a way to pressure test it.

You can buy the parts separately.

Or the assembly.

20/50 should be OK, although the 'experts' still recommend using monograde oil.

Click to expand...

Thanks L.A.B

I`ll might pull it out and have another look. There was oil on the back of the rocker cover when I pulled it off to have a look after my last ride. Is it safe to assume that the oil pressure is the same at the guage (being fed from the double banjo bolt on the rocker oil feed) as it is at the bottom end?

Thanks

I am sorry for the ignorance, as I stated in an earlier this is the first motor I have done.

Mark

I did wonder if the distance the gauge is from the oil pump could possibly make a difference to the pressure reading.

fourperf said:

I am sorry for the ignorance, as I stated in an earlier this is the first motor I have done.

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No need for any apologies! We are all learning things here!

thanks a lot, maybe I should run a second guage off the bottom banjo bolt (the one underneath the relief valve) and see. I could have them both at the same time to see.

Mark

L.A.B., I AM LOOKING AT FIG. C29 IN THE WORKSHOP MANUAL FOR 850'S IT'S THE NICE THREE COLOR DIAGRAM SHOWING OIL FLOW. IN THE DRAWING IT SHOWS THE CRANK BEING FED OUT THE FRONT OF THE PUMP AND THE TOP END FED OUT THE BACK OF THE PUMP VIA THE SPIGIOT. THERE IS NO WRITING EXPLAINING HOW THE CHAMBERS ARE LINKED. MOST BSA'S AND TRIUMPH'S TAKE THIER TOP END OIL OFF A REDUCING TEE IN THE RETURN LINE. SO I COULD HAVE AN ERROR IN MY THINKING. BUT FROM WHAT I HAVE BEEN TOLD THERE IS A BREAK BETWEEN THE HIGH PRESSURE CIRCUTS GOING TO THE BOTTOM AND TOP END. THIS WOULD MAKE SENCE TO ME BECAUSE YOU WOULDN'T WANT YOUR BOTTOM END PRESSURE AFFECTED BY WHATEVER RESISISTANACE THERE WAS IN THE TOP END OR VICE VERSA. BUT IN TRYING TO EXPLAIN THIS I FELL INTO THE OLD HABIT OF TALKING AS IF IT WERE A BSA AND THAT ISN'T RIGHT. THANKYOU FOR POINTING THAT OUT. THE TRUTH OF IT WILL BE HARDER TO EXPLAIN. MANY OLD HANDS AT THIS HAVE TOLD ME NOT TO WORRY TOO MUCH OVER OIL GAGES READING LESS THAN IDEAL PRESSURES. IT MAY BE THAT THE SIZING OF THE INTERNAL CHAMBERS PRODUCES A DIFFERENSIAL NEEDED BETWEEN THE TOP AND BOTTOM THEY BOTH ARE PUMPED FROM THE SAME SIDE UNLIKE THE BSA SET UP. I will post more later have to go eat.

does that mean that the lower oil pressure at the thead would be expected?

thanks

Mark

norbsa48503 said:

L.A.B., I AM LOOKING AT FIG. C29 IN THE WORKSHOP MANUAL FOR 850'S IT'S THE NICE THREE COLOR DIAGRAM SHOWING OIL FLOW. IN THE DRAWING IT SHOWS THE CRANK BEING FED OUT THE FRONT OF THE PUMP AND THE TOP END FED OUT THE BACK OF THE PUMP VIA THE SPIGIOT.

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There's no feed from the back of the pump!

If you take a quick look at your timing cover you should see that the rocker feed is taken off the timing cover.

The feed from the pump passes into the timing cover gallery. One end of the gallery (forward) goes to the crankshaft the rear part goes to the rocker feed banjo and relief valve.

And please: THERE'S NO NEED TO SHOUT!

L.A.B. Sorry for the caps I was using my word program to spell check and the settings there are wrong. No need to shout.

sorry to be such a numbskull fellows but what does all this mean. Would it be expected to have lower oil pressure at the head? I think maybe I will run the second oil pressure guage off the bottom feed.

Mark

If you have a second gauge then it's worth a try, but I have no idea what difference (if any) to expect. As I said: we are all learning!

I will give it a shot tomorrow and post the results.

Thanks

Mark