Oil pump failure

[rcsteuer]

New to this blog.  Been doing a full restore on a 49 - 3A.

Just wrapping up a full year of complete teardown and rebuild of everything.  Yesterday, got the engine (full rebuild) started. I don't have timing marks, so relied on approximating TDC. Started immediately, but needed adjustments to purr like a kitten.  As I was adjusting timing to max out vacuum and adjusting carb, I started hearing a noise that wasn't making me very happy.  Looked at the oil pressure gauge in the dash and it was reading 0 after having been at about 30 lbs. Shut it down immediately.

Before I started it, I pressure loaded the system so that it wasn't starving for oil. I had been checking pressure to be sure it was staying where it was supposed to be - too many stories of bad pumps - and everything looked great for the first 20 minutes or so.

I've put an inline gauge in to rule out the dash gauge - still no pressure. Tied into a different spot on the block to rule out a plugged galley at the back of the block. No good. Took the pressure relief valve out of the pump to make sure it wasn't an issue. Also took the bottom plate off to check tolerances, which is next to impossible with the pump installed. Put everything back together and still no pressure.

Anyone have any other ideas that I may have missed  Anyone know if there's enough clearance to get the pump out with the engine still installed? y guess is I'll be replacing it.  It's a Melling pump, so this wasn't supposed to happen.

This is discouraging as hell!

Thanks

[Rus Curtis]

rcsteuer,
Welcome!  Bummer about the oil pump.  It's possible to have a failure (nowadays on just about any component) on replacement parts.   I've not had issues with mine (knock on wood) so hopefully, you'll get some guidance on what else to do that may include replacement.

I want to say that there should be enough clearance to pull the pump.  Does the vendor have a return policy?

[1955CJ-5]

I remember all those oil pump failures. Made me just a little paranoid. But, like you I had a Melling and fortunately had no issues, it's been nearly 10 years and still shows 40 psi.

Now I don't remember exactly, but there is a float in the oil pan through which the pump draws it's oil.......now if this float were to separate from the pump input, would the pump still draw oil from the sump?

Worth a look maybe.

[rcsteuer]

Thanks for the replies, Rus and 1955CJ-5

CJ-5, yes the float separation would cause an issue.  The float needs to maintain a tight connection to the bottom of the block in order to pull oil from the pan and feed the journals/oil pump in the block.  A bad gasket or loosened bolts could cause the issue.  But I've torqued all bolts on this engine and don't think it's that (although it is a possibility), given the number of complaints about pump failures.

Rus, I've replaced a bunch of these over the years and this is the first that's failed.  Specifically stayed with Melling because they've always been reliable.  Maybe that's changed.  I've always changed them with the motor out while rebuilding - never while in the vehicle.  Hoping someone has had experience with pulling while the motor is installed. Doesn't look like there's enough clearance to get the pump out without hitting the frame just in from of the steering box. Would hate to get it 3/4 of the way out, screw up the timing, etc., only to find I need to lift, drop, or pull the engine.

[tow hook]

to join in. when i built my engine, i primed the pump and the block with a hand pump oil can,and after 3 months of no psi at start up ( no fuel ) just cranked the starter..... i had 2 bad oil pumps. in the process tore down the engine twice, and replaced the pick up. in the service manual there is specs for the pump if you have feeler gauges.  so i know what you are feeling

[rcsteuer]

Thanks for the reply.  just got back to this yesterday. Replaced the replacement pump with a new USA made unit that I thought was incorrect at first, given the body looked like it fit the older, 134s with chain driven timing gears, where the relief valve was on the cover rather than the body.  However, on comparing, they used a similar body but the gear was the correct orientation so I installed it (after filling it with oil), primed the engine with fresh oil through the oil pressure gauge fitting in the block and verifying I had oil flowing to the pan and the filter canister (a good indicator that the engine has seen oil).

I cranked without plugs and had "0" lbs of pressure again.   Put a separate gauge inline and had 2 - 4 lbs.  Started the engine, ran it for less than a minute because I could not get more than the 4 lbs, which is less than the min. spec.

I don't like taking the cover off, as the gasket is not available and it's spec'd at 0.004", which can't be made out of available gasket materials, so checking the clearances hasn't been done.

The likelihood of two pumps from two manufacturers is pretty slim, although not zero.

I'm stumped on this one.

[1955CJ-5]

Do you have the bypass canister oil filter installed? Did it fill with oil after the initial startup?

Have you tried to remove one of the other pipe plugs in the oil gallery? Was just thinking maybe the rearmost plug where the oil gauge is usually connected is somehow blocked. Did you use the same oil line that goes to the dash gauge to hook up the in-line gauge, or plumb it somewhere else? You might be able to attach the in-line gauge to the input hose at the oil filter.

Just looking for something that might be in common to both your test runs, rather than the oil pump itself. Did you take the first pump apart to see if there were any problems with it? They are so simple it's hard imagine that they would fail, other than a sheared shaft or or a drive gear that had come loose, but they do fail. Since the distributor is turning the pump must be turning also. I have an old pump, I'm gonna dig it out and see what I can learn.

I don't remember if anyone has posted a reason for their pump failing.

Randy

[Chuck W.]

perhaps the rebuilder forgot to install the oil spray jet that goes under the timing gear cover.

[rcsteuer]

Thank you 1955CJ-5 and Chuck.

Chuck, the oiler is definitely in place. I checked the orientation before putting the cover on. But thanks for the heads-up and consideration.

Thanks CJ-5.  With the first replacement pump in place, I added the 2nd gauge in-line with the dash gauge to test the dash gauge and had no pressure.  I then moved the test gauge to the front port just behind the fuel pump and still no pressure.  I then pulled the pan and removed the pick-up (which is brand new) to look for either a plugged up pick-up or port where it bolts to the bottom of the block - both were clear, so reinstalled.  Then removed the first pump and replaced it with a 2nd (neither first or second refer to the original pump) after filling the pump with oil. Preloaded the engine with oil and got approx 5 lbs on test gauge with preload. Cranked the engine with plugs removed and had no pressure in either the test or dash gauges.  Because I'd preloaded it, I started the engine and ran for less than a minute (so pump and distributor shafts are ok and the engine starts) to test actual running results. With the engine running, the test gauge bounced between 2 - 4 lbs. 

The first pump is the newer type body with the check valve in the body, which was identical to the original.  The second replacement has the check valve in the cover, similar to the older versions. But the gear was oriented with left spiral gears so it works.  It also has two gears in the body rather than the newer type with a gear and rotor.

All of that said, I am stuck.  I cannot come up with a scenario where the pressure would be 0 unless the blockage was at the pick-up, given that I've moved the test gauge to a different port in the journal. The oil canister gets oil when I pressurize the system manually, so oil is moving through the journals.

I fear I have no choice but to pull the engine, but very reluctant to do so without a diagnosis. A lot of work without a game plan.

[rcsteuer]

Chuck, found an image of the engine while reassembling that shows the oiler in place.

[1955CJ-5]

I read a little about oil pump failures over in the cj2a forum.

One had broken teeth on the pump drive gear as the second internal pump gear had frozen to the shaft. Another fellow had made a gasket that went between the oil pickup tube and the block, and he had forgotten to punch the center hole so no oil flow...it would seem that just about anything is possible.

It sure seems that if the pump is turning, there would be flow and pressure, as long as the pump is pulling oil from the sump.

I do not know how you would check that without at least removing the pan.

When you take the pump out, the oil passages should be visible in the mating surface.

Could you then either blow air into the sump, via the pump's supply passageway, or maybe slowly pressurize the sump and force oil through the float/oil pickup and send it out the passage that goes to the pump( or the floor in this case...)? This might at least show you that oil is available to the pump.

I'm sure you will figure it out.

I have a Model A pickup, and the engine is a similar L-head four cylinder. The oil system is non-pressurized. Oil is pumped directly into the valve/lifter gallery and from there is distributed via drilled passages to the main bearings. The rods are oiled through a dipper tray and scoops, and the cam gear gets oil as it overflows the front of the gallery and spills onto the gears.

So the point is there is plenty of flow, but if you have an accessory pressure gauge it will show very little pressure (I'm told less that 5 pounds) as there is no restriction to the flow.

Good luck.

When you figure it out please let us know.

Randy

[Rus Curtis]

rcsteuer,
Frustrated yet?  Your first post indicated you had pressure.  Then the noise and no pressure.  So, for a brief period, you were pumping oil.  It sounds like you've replaced the pump with no change.

I wonder if tracing (similar to a wire short) would be effective?  I'm imagining something failing or coming loose to abruptly lose all pressure.  I've never been inside an L-head but I suspect the block is similar to the F-head.  There's a rebuild article on the 3B Page that points out two galley plugs inside.

https://cj3b.info/Engine/Rebuild2.html

Have you had the pan off during your troubleshooting?  If you choose to pull the pan before removing the engine, you might be able to check several things, possibly including the passage from the pickup to the pump.

Piggy backing on Randy's comment about the teeth missing.  You can check to see if the pump is being spun by the cam if you watch the rotor in the distributor.  It couldn't hurt to verify.

[Chuck W.]

Just some random thoughts that might help; do you have oil flow? If the pump is moving oil but not building pressure, you may not have enough restrictions in the lube system to build pressure. I'd take the gauge off the line, crank the engine and see if you have oil flowing from the open line. If so, I'd drop the oil pan and pressure lube the system and see if you have any major oil leaks, cam bearing, main, rod bearings, missing galley plugs, etc. Maybe a good time to plastigauge the rod and main bearings and make sure there are no excessive clearances. FWIW...

[tow hook]

i assume you primed the pump before install ? i used a milk jug, filled it half full of the engine oil, and spun the pump with a drill.

 the other thing i did well having two bad pumps was i got a hand pump oil can. and filled the engine oil galleys with oil. i pulled the oil pressure sender unit.( driver side at rear of the block ) an pumped my oil in there. my can was small so it took 2 or 3 cans to fill the system. when its right you will see oil going into the oil filter can. with the pan off you will see come from the mains etc.

 i had the fuel system off the engine and would bump the starter to get pressure, and would crank for more then 10 seconds at a clip. i have my engine apart 2 or 3 times before i got a working pump. and lighty  heated up the oil pick up to remove sludge

[Gunslinger]

Just a shot in the dark here but I think Rus is on to something, when I first rebuilt Triple X I had the same issue.  Pressure for about 5 minutes then zippo.  Turned out the rear main seal disintegrated, went through the lube system and wiped out the main bearings.  Had Plenty of flow, no pressure.  I hope that's not the case for you.  We pulled the pan, started the engine and watched oil gush out of the bearings. 
Good luck
Gun