Zero oil pressure to head

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murraycod0

murraycod0

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Hi all,
just finished putting my new project together and fired it up and have no oil pressure to the head.I have a MK 3 timing cover on a '74 engine.I changed the oil pressure valve .Just hoping it was that.No . Then I took the cover off and checked the seal, spring & piston and they were all in place.While the cover was off I put a new large gear oil pump on as the engine is all rebuilt I don't want to damage it.The oil is returning to the tank ok. The engine sounds great for the short time I have run it.The last one I built there were no problems with the same setup.The oilways are all clear and I have a gauge set up off the cover.With the new pump it still just spits oil out but will not build up pressure??????????
 
The Mk3 timing cover will have an extra hole in it. It is in the passage between the relief side of pressure regulator and the gasket surface. That passage lines up with a hole in the engine case that goes to the passage leading to the inlet side of the pump.

To use the Mk3 cover you must screw a setscrew in the hole in the case that lines up with the passage. If that passage is not blocked then the pump will draw air through the extra hole and the engine will get very little oil. If you need more assistance with this I can take pictures tomorrow. Jim
 
comnoz said:
The Mk3 timing cover will have an extra hole in it. It is in the passage between the relief side of pressure regulator and the gasket surface. That passage lines up with a hole in the engine case that goes to the passage leading to the inlet side of the pump.

To use the Mk3 cover you must screw a setscrew in the hole in the case that lines up with the passage. If that passage is not blocked then the pump will draw air through the extra hole and the engine will get very little oil. If you need more assistance with this I can take pictures tomorrow. Jim
Click to expand...

Sorry, Jim, but that information isn't correct.

The 850 MkIII timing cover is the one that does not have the OPRV return drilling at the gasket face, and as far as I'm aware, there's no need to blank off the oil gallery in a pre-MkIII crankcase in order to use a MkIII timing cover as the MkIII timing side crankcase still has that gallery open at the gasket face even though it is not actually used.

850 MkIII cover:
grandpaul said:
Zero oil pressure to head
Click to expand...

breather-valve-problem-t7562-15.html#p79006
 
As well as previous, disconnect the oil feed to the head, and see if it will build oil pressure just in the bottom end. ?
Should be OK if not done for long.
 
murraycod0 said:
Hi all,
The oilways are all clear and I have a gauge set up off the cover....?????????
Click to expand...

I'd try a gauge on the feed lines themselves. I'm not sure you get any pressure on the cover.
Jaydee
 
jaydee75 said:
murraycod0 said:
Hi all,
The oilways are all clear and I have a gauge set up off the cover....?????????
Click to expand...

I'd try a gauge on the feed lines themselves. I'm not sure you get any pressure on the cover.
Click to expand...

A gauge should normally show full oil pressure when connected to the timing cover outlet.
 
I have the correct washer on the pump and a gauge hooked up down at the cover.The seal in the cover is the right way round on the crank.I will need to take off the cover again and see what I can find .
 
L.A.B. said:
comnoz said:
The Mk3 timing cover will have an extra hole in it. It is in the passage between the relief side of pressure regulator and the gasket surface. That passage lines up with a hole in the engine case that goes to the passage leading to the inlet side of the pump.

To use the Mk3 cover you must screw a setscrew in the hole in the case that lines up with the passage. If that passage is not blocked then the pump will draw air through the extra hole and the engine will get very little oil. If you need more assistance with this I can take pictures tomorrow. Jim
Click to expand...

Sorry, Jim, but that information isn't correct.

The 850 MkIII timing cover is the one that does not have the OPRV return drilling at the gasket face, and as far as I'm aware, there's no need to blank off the oil gallery in a pre-MkIII crankcase in order to use a MkIII timing cover as the MkIII timing side crankcase still has that gallery open at the gasket face even though it is not actually used.

850 MkIII cover:
grandpaul said:
Zero oil pressure to head
Click to expand...

breather-valve-problem-t7562-15.html#p79006
Click to expand...

Some timing covers have the hole drilled and others do not. I have both here. If the hole is drilled and the relief hole is in the passage then a plug must be used in the case. The cover that was on my MK3 when I got it has both holes drilled. Jim
 
comnoz said:
Some timing covers have the hole drilled and others do not.
Click to expand...

I've never seen or heard of such on a MkIII timing cover (what would be the point)?



comnoz said:
I have both here. If the hole is drilled and the relief hole is in the passage then a plug must be used in the case. The cover that was on my MK3 when I got it has both holes drilled.
Click to expand...

You don't mention anything about that here? : breather-valve-problem-t7562-15.html#p79006

My MkIII cover certainly hasn't got the joint face hole.
 
L.A.B. said:
comnoz said:
Some timing covers have the hole drilled and others do not.
Click to expand...

I've never seen or heard of such on a MkIII timing cover (what would be the point)?



comnoz said:
I have both here. If the hole is drilled and the relief hole is in the passage then a plug must be used in the case. The cover that was on my MK3 when I got it has both holes drilled.
Click to expand...

You don't mention anything about that here? : breather-valve-problem-t7562-15.html#p79006

My MkIII cover certainly hasn't got that hole.
Click to expand...

Good question. But I assure you some do. Then there is a plug in the matching hole in the case. Jim
 
comnoz said:
Good question. But I assure you some do. Then there is a plug in the matching hole in the case. Jim
Click to expand...

Yes, but, even if the second hole was there, if the gallery is drilled the same as the pre-MkIII timing cover then the oil would still have to blow from the OPRV to reach it, so there would be no pressure loss (to the crank and valve gear) and no need for a blanking plug in the case. The oil from the OPRV would simply be recirculated back to the pump inlet same as the pre-MkIII arrangement.
 
Here is a mk3 cover with both holes.

Zero oil pressure to head


If both holes are left open then the suction side of the pump will be connected to an open hole in the timing chest. That will cause the engine to wet sup immediately and the oil pump will draw air from the open hole. I believe I have seen this mentioned in the INOA list tech also.
 
comnoz said:
If both holes are left open then the suction side of the pump will be connected to an open hole in the timing chest. That will cause the engine to wet sup immediately and the oil pump will draw air from the open hole. I believe I have seen this mentioned in the INOA list tech also.
Click to expand...

OK, never seen a MkIII cover like that :shock: [Edit] However from murraycod0's description the oil is circulating normally, and no immediate wet sumping problem mentioned so far.

I do see what you mean about a back bleed problem from the oil supply if both blow hole galleries are connected. I think I'd want to blank off the "second" hole in the case if it were mine, or find another MkIII cover. Hopefully, murraycod0 will be able to tell us if his MkIII cover has this extra hole or not?
 
My bike originally had a slotted head screw in the case. I removed it and put a ball bearing in the hole in the cover so the oil bypass would be directed to the intake of the pump as on the 74 model. I can't say it made any real difference. The oil pump doesn't produce enough pressure to overcome the pressure relief valve once the engine is hot anyway.

Norton supposedly made the change to avoid heating the oil by running it through the pump over and over. Jim
 
Hi I have my cover off again and it does not have the hole like Jims .I am priming the crank to make sure it has some lube and putting the gauge on the cover .Will try to prime it there to bleed it free of air back shortly.
 
Checked the oil pressure valve , shimmed it . Took the srm one off,put an original type on, removed the anti wetsump spring and piston.Measured the seal measured the end of the shaft interference and protrusions all ok.Seal on pump is pushing on cover alright .Light her up and still no pressure.Ugghh!
 
murraycod0 said:
Checked the oil pressure valve , shimmed it . Took the srm one off,put an original type on, removed the anti wetsump spring and piston.Measured the seal measured the end of the shaft interference and protrusions all ok.Seal on pump is pushing on cover alright .Light her up and still no pressure.Ugghh!
Click to expand...

Have you checked for FLOW to the head? banjo off, oil squirts out of feed line from timing chest? Could be a Foreign object blockage. How is you gage rigged? On the opposite end from the feed? Rocker spindles all oriented properly? You verified the gage with shop air?
 
Murray,
I'm not sure if you have done this, but ignore the pressure gauge for the time being. Is there oil returning to the tank? It will be intermittent squirts at low pressure. If so that means the feed side is pumping into the motor. Next, disconnect the rocker feed pipe and see how much oil is actually getting pumped, as that is part of the feed. If that is stream of oil, not just a dribble, then the feed is working OK. I would then suspect your pressure gauge is faulty. If that gauge is proven to be OK, I would then remove and strip the pump and examine the gears and end face clearance.
 
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