Author Topic: Oil Pressure  (Read 1589 times)

have parts

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Oil Pressure
« on: May 14, 2008, 10:21:23 PM »
I was helping a friend with his 29U. We got it started but we can't get any oil pressure. We tried a couple different gauges. He had the engine rebuilt at a local shop. Any help would be greatly apperciated. He doesn't have a repair manual so we're shooting in the dark. Thanks

chetbrz

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Re: Oil Pressure
« Reply #1 on: May 14, 2008, 10:38:01 PM »
On the U engine the oil pump is external and is located under the intake and exhaust manifold.  If you remove the front cover crank the engine for a short time to ensure that the eccentric is turning.   I believe there is a little gear that commonly wears out.  If your engine was rebuilt I would assume that this was checked but who knows.

Also there is a pressure relief valve that might be creating some problem.   I know that with modern oil pumps you should always prime them prior to installing them.  I am not sure about the U pump but it can't hurt.  There is a pipe that goes from the oil pump to the engine.  Check that for oil content and if the pump is turning then maybe get some oil in it to prime the pump.

My 2 cents, 

Chetů  & Welcome to this web site.!!

PS... If you are not sure you are getting oil pressure then I wouldn't run the engine. 
« Last Edit: May 14, 2008, 10:41:55 PM by chetbrz »
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Doug

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Re: Oil Pressure
« Reply #2 on: May 15, 2008, 01:27:45 AM »
My 30 U has lost it's prime a few times, I just take the line lose that goes from the oil pump to the fule pump and with an oil squrit can fill it up with oil hook everything back up and all is fine.

have parts

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Re: Oil Pressure
« Reply #3 on: May 15, 2008, 04:26:48 AM »
Thanks for the info. I'll check it out tomorrow & let
you know how we make out. Thanks for the welcome.

have parts

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Re: Oil Pressure
« Reply #4 on: May 15, 2008, 04:43:07 AM »
I was just thinking about the info. Does anyone have a diagram
of the oiling system they could send us?  Thanks

chetbrz

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Re: Oil Pressure
« Reply #5 on: May 15, 2008, 05:43:40 AM »
I was just thinking about the info. Does anyone have a diagram
of the oiling system they could send us?  Thanks

This is the best I can do.  The attached file is a cut view of the Modal U engine.

Chet...

Open the PDF file below the line.
« Last Edit: May 15, 2008, 05:46:36 AM by chetbrz »
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Re: Oil Pressure
« Reply #6 on: May 15, 2008, 06:45:52 PM »
Thanks Chet,   At least we have some idea of how the oil flows.

29UJohn

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Re: Oil Pressure
« Reply #7 on: May 18, 2008, 05:01:44 AM »
The pump draws oil from the sump via the long copper pipe that attaches to the top of the pump - this pipe goes thru the engine block just abov ethe oil pand and then to a vertical pipe to the sump filter screen.

The oil pump pushes oil out the smaller forward side U-shaped copper pipe that attaches to an oil galley port in front of the pump. 

Here are a few tips for priming a 1929 Plymouth (I have used them all):

1)  Remove all the spark plugs.
2)  Remove carb.
3)  Remove Oil Pump and put oil in it by either:
     a) Use some 90 weight gear oil that comes in a tube and put oil in the intake port (top of pump), squeezing tube slightly while turning oil pump by hand.  This is messy, but works well, and you can tell right away if the pump works, or,
    b) Remove cover and pour oil in it and replace cover (while cover is removed, check that the vanes and springs are in good shape), or,
    c) Remove cover and pack with vasaline and replace cover.  The theory is that when the oil gets hot, it will wash out all the vasaline.  (This works well, but I was surprised to find vasiline in a "nook and cranny" of the pump when I disassembled it many miles later.)
4)  Using some 90 weight gear oil in a tube, put some oil into the draw tube. (The long upper tube)  Squirt it in under a little pressure.  This way you can also tell if the line is free to the sump.  You may find it helpfull to remove the crankcase vent for easy access.
5) Reinstall pump.
6) Using starter, turn engine over with the spark plugs removed untill you notice oil pressure on the gage.  This may take a few minutes.  If no pressure appears after 60 seconds, stop, let the starter cool a few minutes, and try again.  You should get 10-20 lbs of pressure when it primes.

Now regarding trouble shooting - if no luck on pressure, try:

1) Remove U-shaped copper pipe from front of pump.  With spark plugs removed, one person turn engine over with hand crank while the other watches to see if any oil comes out of the pump.  If oil comes out, pump is OK.

2) Remove oil pressure gage line and check that it is clear (not obstructed). 

3) If the above checks out, and you still cannot get a prime or oil pressure, even with a new gage, then you may need to use a device that will externally pressurize the oil system.  I made one using a new one gallon pressure sprayer from the hardware store.  I removed the spray nozzel and installed a presure gage, shut off valve, a flare fitting.  I put a couple of quarts of oil in the hand pump, then attached the hose to the galley port on the engine (bypassing the engine's oil pump).  I then pressurized the tank (with the attached hand pump).  If the oil galleys are free, oil will flow from the tank through the system and drain into the oil pan.  (It is best to empty the oil from the engine oil pan completely before you start this test.)  Also, this test will tell you if there is an opening to the engine oil gally that is preventing the oil from building up pressure.  If so, you will notice the oil rush out of the tank and quickly fill the engine's oil pan.  If everything is working properly, oil pressure should build up, and the external oil tank should slowing empty into the engine.

If you want, I can take a picture of this test device.

Good luck.
« Last Edit: May 18, 2008, 05:28:53 AM by 29UJohn »
John
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