L134 Lubrication System Simply Explained by TONY NORTON

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
dinof
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Re: L134 Lubrication System Simply Explained by TONY NORTON

Post by dinof » Tue Jul 04, 2023 3:53 pm

SCORPIO wrote:
Tue Jul 04, 2023 2:15 pm
dinof wrote:
Mon Feb 19, 2018 7:13 pm
I get what Tony was saying, but I still don't understand (and it's really never explained here much) what oil pressure readings should be at when you have driven the jeep a good distance. In the summer, driven a good distance I can get only around 15-18 psi at idle, but it will also shoot up to 50-55psi the minute you start driving. So, what is to be expected when the engine is hot & driven in the heat??? I'm using 30wt oil.

Tony's explanation says it should be 25psi at idle. Is this with a cold engine or what?

Thanks in advance,
Dino
I know this is an old post, but my l134 has the exact same pressure as yours. I inherited a Jeep with 60k original miles. I use 30 w oil. Starts cold at 50+ psi warms up to 15psi at idle at 190*f. My opinion is that our engines run fine and Tony’s 25 psi is wrong.
I agree. 25lbs @ idle with a hot motor is a bit off. 15lbs is just fine. With 60,000 miles on yours, that's darn good pressure!
Dino Falabrino
On the "G" since 1998.
1943 GPW 102310 DOD 3-3-43
1928 Model A Roadster Pickup
1930 Model A Tudor
1968 Taco Minibike


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Re: L134 Lubrication System Simply Explained by TONY NORTON

Post by outlaw21 » Tue Jul 04, 2023 8:40 pm

A couple thoughts on this discussion: blocking off and removing the oil filter does not starve the timing chain as the number 1 main bearing has a hole and passage to feed the drilled crank to two holes in the crankshaft timing gear for chain lubrication- on the gear drive camshaft engines the oil squirt nozzle does this same function. If you wanted to remove the oil filter you would be better off plugging the oil galley at the fuel pump rather than plumbing the hose from the galley directly to the timing cover, otherwise you are replacing the .055 orifice in the filter with the hose ID diameter and you will wonder where your oil pressure went. As far as worn cam bearings causing lower oil pressure it seems to me that a couple of restrictor orifices installed in the galleys feeding the #2 and #3 cam to limit the flow to original would be an easier option than the machining for Ford bearings. All of the writing on boring the block for Ford bearings has been third or fourth hand pie in the sky type.

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Re: L134 Lubrication System Simply Explained by TONY NORTON

Post by Wolfman » Wed Jul 05, 2023 4:33 am

Oil pressure is all about oil pump volume and the restriction to flow created by the bearing clearances and the restriction to flow through the oil filter.
Decrease flow, increase in pressure. Increase flow, decrease in pressure. Hydraulics 101.
When there is more leakage than volume of oil the oil pump is pumping, the oil pressure drops.
As pump volume increases, oil pressure increases, up to the oil pressure relief valve setting.
If there is more leakage than the volume of flow the oil pump can produce, you have low oil pressure. And shimming the oil pressure relief valve spring won't help. The shim increases the maximum oil pressure point, but you never get there. The relief valve never opens.
At this point, you either need to tighten up the bearing clearance or install a pump with more output volume. As you would get with a Melling gear pump.
As for an L-134 oil filter. Better than nothing. Part of the oil going through the lube system is diverted to the filter and then dumped back into the oil pan by way of the timing cover.
Most of the oil goes to the bearings unfiltered. At least not directly.
Restricting or partially blocking the oil filter is one way to direct more oil to the bearings and get better oil pressure.
Restricting the oil flow to the cam bearings ?? :shock:
Can't go along with that one.
Worn cam bearings are already in trouble lube wise because of excessive wear and the ability to maintain lube oil on the bearings. Reducing the oil flow to the bearings is going to cause major grief, soon!!
Mike Wolford
CJ-2A
VEP GPW
Comm./Inst. SEL
AOPA ( 50 yrs)
EAA ( 49 yrs)
4th Inf. Div. - 5th Inf. Div. - 2nd Armor Div. - CIB

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Re: L134 Lubrication System Simply Explained by TONY NORTON

Post by YLG80 » Wed Jul 05, 2023 4:49 am

Not to speak about the fact that a blocked filter in an engine can increase the oil temperature which is not good for the viscosity and then for the engine :wink: .
These are not modern vehicles and I would leave the oil filter as it is and as it was installed in almost 600K WWII jeeps, civilian and Hotchkiss/WOF after WWII.
Yves
Ford GPW 1943 - Louisville - DoD 12-7-43
serial 164794

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Re: L134 Lubrication System Simply Explained by TONY NORTON

Post by dinof » Wed Jul 05, 2023 6:44 am

For the 4 million Model A's made,
Ford specified changing the oil at 500 miles because there was no filtration
system. So, I guess you could do that without a filter, but the motor
still had unfiltered oil running around. Keep the filter on your jeep,
but monitor your oil pressure at idle. TM manual says you should have
at least 10 lbs @ idle . Next time your at a car show, you will see many
Model A's with aftermarket filtration systems installed.
Dino Falabrino
On the "G" since 1998.
1943 GPW 102310 DOD 3-3-43
1928 Model A Roadster Pickup
1930 Model A Tudor
1968 Taco Minibike


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