Series 2 Oil Pressure Problem

[LarryN]

I'm back! My Series 2 Alpine is now running a new Series 5 oil pump and a new distributor. A new fuel filter cured the rough running/loss of power that has plagued the car for the past months during the rare intervals when it was driveabl e. In the course of replacing the oil pump, the pressure relief valve was removed and cleaned and the leaking oil pressure gauge line was replaced.

The problem now is that the maximum oil pressure is right around 25 psig. I pulled the PRV and made sure the piston will move freely with about the same force as the comparable valve from an old full-flow filter set-up (I haven't measured the force, just pushed the thing open a dozen or so times). I also cross-checked the oil pressure gauge against another mechanical gauge I have laying around - close enough to make me believe the problem is real.

So, with fresh oil and a new filter, a clean PRV, a new oil pump, and an OK gauge all accounted for, I'm running out of ideas. The Workshop Manual says that one possible cause for low oil pressure is a loose timing chain feed pipe - has anybody encountered this and is it a common problem? The engine only has about 12K miles on a professional rebuild, so I'm not sure worn bearings would be likely. Any thoughts?

larry

 

[RootesRacer]

whats the idle pressure (hot)?

 

[LarryN]

Nicely warmed up, the oil pressure is between 15-20 psig. Yesterday, after about 15 miles in 107F ambient air, it was down around 10.

 

[RootesRacer]

Nicely warmed up, the oil pressure is between 15-20 psig. Yesterday, after about 15 miles in 107F ambient air, it was down around 10.

You just gave two numbers.
If the pressure is 10psi hot idle then the engine is either very loose (clearances) , or the rubbing block oil feed is loose, missing its ball and spring or not there at all.

Its also possible that your gauge is reading low.

If the pressure wont increase above above 25psi even if you rev to 5000rpm then the OPR spring is too loose (or your gauge is reading low).


I'd start with the gauge.

 

[mikephillips]

Since you said you checked with another gauge I'll assume the reading is reasonably accurate. A cople things come to mind. First, was the professional familiar with the Alpine engine?? As pointed out the chain oil feed could be a problem. There's supposed to be a small ball and spring trapped inside it. If he didn't know any beeter it's possible this was left out allowing pressure from the gallery to run out. Second. In fitting a new pump, how tight was it in the block?? Since the pump passage cuts through the oil gallery a loose fit can allow pressure to leak out around the pump body. Third, the connection from the pump to the block. If you're still running the 1592 engine then the pipe would require different size ends. How was this handled and is it leaking at any joints.

 

[LarryN]

OK - just back from the driveway. I warmed the car up and the oil pressure at 800 rpm idle is just below the 25 mark on the stock gauge - call it 20 psi. It rises to 25 psi at about 2000 rpm and creeps up to about 30 when revved to 3500-4000 rpm. The changes I'm seeing in pressure are about one needle width on either side of the 25 psi mark.

The gauge in the vehicle was replaced with another gauge which showed oil pressure at idle to be about 20 psi - I didn't go any further with that gauge, but the two gauges compare reasonably well at 20 psi.

I'll pull the pressure relief valve tomorrow and measure the force required to open the valve.

 

[RootesRacer]

Knowing what pressure that the piston spring has at the point where the piston cracks the dump orifice is what you are after.

Your idle pressure is too high for it to be a massive internal leak.

Probably just a weak spring on the OPR.

Which filter and filter base are you running (early or late)?

 

[LarryN]

Mike:

The mechanic got familiar with the Sunbeam engine when he overhauled it - otherwise, he mostly does German stuff with a smattering of Alfas, FIATs, Triumph, etc. The engine ran fine for 12K miles before he replaced the pump and distributor - not to say that the timing chain oiler was properly installed, but that's a long time for a problem to develop that essentially took the oil pressure from 60 psi down to 25 psi overnight.

The feed pipes from a Series 2 and a Series 5 were cut and tack welded with the Series 2 pipe on the inside of the joint. The joint was then soldered.

I don't know how well the Series 5 pump fit into the passage - is there an O-ring or other seal required?

Thanks
Larry

 

[RootesRooter]

Series V pump on a 1592? Isn't there a question of the cam gears not meshing right?

I'm not sure what you mean by "comparable valve from an old full-flow filter setup." Do you have access to another PRV of the same style you could temporarily install, even one you know is a 'sticker?' The initial pressure before it heats up and starts sticking might give a clue.

Do you remember what the pressure was like before you had all the work done?

 

[mikephillips]

As long as either the V camshaft went in or the earlier gear was swapped onto the pump should work fine. I'd guess they did one of these since if not timing would become an issue very quickly, not to mention possible damage.

There's no O-ring or other seal at the pump/block interface, it relies solely on being a snug fit.

 

[LarryN]

I'll try to answer all of the open questions:

1. The camshaft is Series 2, the Series 5 pump was fitted with the Series 2 oil pump drive gear

2. The oil pressure was in the 20 psi range at warm idle and 50-60 psi at highway speeds - this was after the rebuild until the pump replacement, so about 2 years and 12K miles

3. The relief valve from the "full-flow filter" or "renewable filter" (both terms are used in the Workshop Manual will not fit the adapter for the disposable cartridge filter. It might be possible to swap the adapters and use the older style filter if I can find a filter element. However:

4. I removed the relief valve this morning and very scientifically measured the opening force by placing the valve on an electronic kitchen scale (note that this particular valve has a stub sticking out of the head which I believe indicates it is the later valve which was replaced by Rootes with the earlier valve due to problems with sticking). I then used a small bolt to press down on the piston and recorded the force when the piston just came off the seat and the force required to push it down to the point where the orifice opens. Those values were 7.6# to lift it off the seat and 9.6# to open the orifice. Since the valve is not easily disassembled, I measured the OD of the cylinder and the depth through the orifice to the piston to determine the piston diameter (0.42 inch). So, the piston area is 0.14 square inches, giving pressures of 55.0 psi when the piston lifts and 69.5 psi when the orifice opens. It appears the valve is opening properly and consistently with the pressure before the problem appeared.

At this point, the most likely culprit appears to be the timing chain feed pipe: it is close enough to the pressure gauge tap (I think) that the gauge would read the pressure in the galley rather than the pressure out of the pump/filter, a loose/missing/broken pipe or fitting would be of sufficient size to significantly reduce the system pressure. I can't think of any way to check this short of pulling the timing chain cover.

 

[RootesRooter]

If installing a modified Series V oil pump was the ONLY change you made before the oil pressure suddenly dropped, I'd pull the pan next instead of the timing cover. It's gotta be the pump. I'll bet you've got a bad weld on the feed pipe that's sucking air.

Mike:

The mechanic got familiar with the Sunbeam engine when he overhauled it - otherwise, he mostly does German stuff with a smattering of Alfas, FIATs, Triumph, etc. The engine ran fine for 12K miles before he replaced the pump and distributor - not to say that the timing chain oiler was properly installed, but that's a long time for a problem to develop that essentially took the oil pressure from 60 psi down to 25 psi overnight.

The feed pipes from a Series 2 and a Series 5 were cut and tack welded with the Series 2 pipe on the inside of the joint. The joint was then soldered.

I don't know how well the Series 5 pump fit into the passage - is there an O-ring or other seal required?

Thanks
Larry

 

[Alpine Addict]

Just out of curiosity what aws the reason to change to the series 5 oil pump?

 

[LarryN]

Alpine Addict:

The switch to a Series 5 pump was necessitated by a bent shaft in the Series 2 pump and a complete lack of replacement pumps or rebuild parts. The saga is documented in a couple of other threads - and the folks on the Forum were incredibly helpful both in trying to locate a replacement pump and in tips on how to make the switch. The Series 5 pump was purchased from Sunbeam Specialties.

larry

 

[LarryN]

Rootes Rooter:

Good suggestion on the feed pipe - could be cracked or loose on either the suction side sucking air or on the pressure side blowing most of the oil back into the sump.

Larry

 

[Tom H]

Larry, you said

(note that this particular valve has a stub sticking out of the head which I believe indicates it is the later valve which was replaced by Rootes with the earlier valve due to problems with sticking

I think this means you have a valve that has been modified by someone to make it an adjustable PRV and the "stub" is the adjustment device. I have never heard of any factory PRV with a stub sticking out of the head. That's why the pressure ( before your pump change) was higher than the more normal 45 or so. I am not suggesting this is a problem, just alerting you to what you have.

Tom

 

[Ken Ellis]

If the "stub" of which you speak could also be described as a "pip" -- a small 1/16" dia, 1/16" high protrusion on the center of the head -- then that's just a identifier to the mechanic to differentiate it from other bolts of the same size.

A modified OPR valve, when in place, generally looks like a bolt with another bolt sticking out of it.

 

[todd reid]

I agree with RootesRooter's previous comments. If dropping the pan is a hassle for you, another option would be to make your PRV adjustable (effectively making the spring tension on the plunger adjustable). If increasing the pressure on the plunger doesn't increase your oil pressure, then you know you have to dig deeper.

 

[LarryN]

If I had to choose, I think dropping the pan would be a whole lot easier than modifying the PRV. As I understand the modification, the solder joint holding the valve assembly togther has to be un-soldered. Then the large end (essentially a pipe plug) needs to be drilled and tapped and a small disk made which fits inside the tube. The valve is then reassembled and soldered. The adjusting screw is fitted with a jam nut and screwed in to the plug. The installed PRV is then adjusted to give the proper pressure and the jam nut is locked down. I may have missed a small O-ring being installed at some point, but without a proper place to seal it doesn't seem necessary.

At this point, having verified that the PRV opens and closes freely and that the pressure required to overcome the spring force is in the 55-70 psi range, I think I'm having to dig deeper. If the pump is sucking air due to something loose or broken on the suction side, then it is unlikely to be generating the correct pressure so this is worth checking. If the outlet pipe is loose or broken, then much of the flow out of the pump is returning to the sump before it gets to the filter and PRV - it seems, however, that the pressure would rise with increasing flow and that would show on the gauge even though it might not get high enough to trip the PRV. If everything between the pump intake and the filter outlet is solid, then the pump will be making full flow, the PRV will be regulating the pressure to 55-60 psi, and the oil flow out of the filter would be sufficient under normal circumstances to cause the gauge to indicate 50-60 psi. A significant leak (as in a broken pipe or loose fitting) would significantly reduce the pressure in the engine despite the fact that the PRV is maintinaing the correct pressure at the inlet to the filter. While the pump might be capable of producing enough flow to maintain the system pressure, the use of the relief valve as a pressure regulator diverts the oil back into the sump.

Ken & Tom: The PRV is just the one with the "pip", not a modified valve. Somewhere in this Forum or TEAE there is a post with a Rootes service memo which indicates these valves were to be replaced with the older version because the newer ones stick.

 

[RootesRooter]

Just one thought before you pull the pan. When did you switch oil filter assemblies? If it was during the rebuild some time back, nevermind. If it happened at the same time you did the oil pump swap, is there any chance you installed the filter base gasket backwards/upside down?