Oil leak at fuel pump

[rob love]

I believe that the reason for the bypass was to protect the engine in the event of a plugged oil filter or crimped cooler line. If that situation occurred then it would simply bypass the cooler/oil system and still lubricate the engine. Your system would not do that. Rather the oil would just dump through the filler/breather tube back into the pan, doing nothing for the bearings.

Is there any chance your filter or cooler lines are partially blocked? Can you get a mechanical oil gauge on the return side, just before the engine, and confirm what the oil pressure is coming back into the engine?

80 psi at the relief would indicate to me that there is a flow problem either coming back to the engine. The flatheads generally would not generate that much pressure.

[Michael R.]

Could a faulty spring or adjustment in the oil relief valve also contribute to the high oil pressure?

[rob love]

You are right Micheal. The relief valve in the block (front of the valve gallery, ford group 6666) should regulate the oil pressure to about 30 psi or so. I can't seem to find the answer right away as to whether the oil relief valve comes into play after the oil exits the engine through the cooler/filter and then back into the engine, or if it regulates it before the oil leaves the block. If it is after, then the problem could still be with a filtration/cooler blockage. Does anyone have a good illustration of the path of flow on a Flathead lubrication system?

Adjustment or repair of the relief requires the removal of the intake manifold.

[Richard Farrant]

Hi Andrew,

From what you were telling me when we met yesterday, I have worked out a possible explanation. The oil will not flow to the cooler if it is cold, it will lift the relief valve in the remote valve block and return to sump, via dipstick tube. This might explain why when you drove the carrier, it did not show signs of leaking through the lift pump hole under the diaphragm, as it was hot oil and not flowing back via the tube. If I could find my T16 book I might be more sure but looking at a Windsor book at present.

[andrew honychurch]

Originally Posted by Richard Farrant

Hi Andrew,

From what you were telling me when we met yesterday, I have worked out a possible explanation. The oil will not flow to the cooler if it is cold, it will lift the relief valve in the remote valve block and return to sump, via dipstick tube. This might explain why when you drove the carrier, it did not show signs of leaking through the lift pump hole under the diaphragm, as it was hot oil and not flowing back via the tube. If I could find my T16 book I might be more sure but looking at a Windsor book at present.

thanks Richard. It has been very hot since the leak started so I think either the thermostat in the cooler has stuck, and reduced the flow causing the relief valve to operate, or as mentioned in my last post maybe I followed the schematic and hooked up the cooler pipe correct for the TM diagram, but the wrong way for my system which as you can see it exactly the oppostite way around.

Very odd!! On top of the Dingo playing up, I am not having a good few days!

[Richard Farrant]

Originally Posted by andrew honychurch

thanks Richard. It has been very hot since the leak started so I think either the thermostat in the cooler has stuck, and reduced the flow causing the relief valve to operate, or as mentioned in my last post maybe I followed the schematic and hooked up the cooler pipe correct for the TM diagram, but the wrong way for my system which as you can see it exactly the oppostite way around.

Very odd!! On top of the Dingo playing up, I am not having a good few days!

Andrew,
Are you positive there is a thermostat in the cooler? Not one in a Windsor, although that means nothing. The way it works is when oil is cold, it has higher viscosity and lifts the relief valve in the t-piece, then as the oil warms and thins, goes straight through the cooler.

[Michael R.]

Is there a cross section view of the relief valve in the T-16 Manual ?

Attached is the cross section view found in UC-F1, which shows the input flow direction and return. The second image is a standard set-up with an electronic oil pressure sending unit attached in the normal fashion for the Ford Canada UC Mk. I* and Mk. II*.

Note that for correct installation in the Canadian Carrier, the high pressure would be on the left side when facing forward, which is as you (Andrew) have it positioned on your block. Your oil cooler plumbing appears to have a direct connection to the return side of the engine block from your cooler.

[ajmac]

Great photos chaps, always nice to see detail.
Here is my take on the PRV: Originally Flathead V8s only had one PRV, that in the valley of the block. Oil passed up from the pump then turned right just under the tappings in the top of the bell housing and went into the valley on it's way to oil the bearings etc.. (not the rear main though), pressure was controlled by the PRV at the front on the valley. When you break into the oil system before the PRV, (which you do when you utilise the bell housing tappings) that oil pressure is unregulated. When they fitted the oil cooler, the additional PRV was added to protect the cooler from bursting due to over pressure in the event of a cooler / pipe blockage and possibly as a form of cooler bypass when the oil was cold and more viscous (not on Yours Andrew, that is just for safety) However on later wartime Flatheads ford came up with a proper PRV system as part of the pump, thus oil at the bell housing is regulated.
What pump did you fit Andrew? If you have the later one you can disable the cooler PRV as you are already protected. If not then I bet your main PRV at the front on the valley is set higher than the PRV in the cooler line causing the cooler PRV to be permanently off it's seat, it shouldn't be relieving in normal operating conditions. To be honest, the pressure transmitter should be mounted on the return from the cooler to give the true engine oil pressure, I would change yours asap if I were you. As it stands at the moment your engine oil pressure could be on it's knees and you wouldn't know a thing about it!
If your cooler never gets hot, remove the aforementioned pressure transmitter and use a thin screwdriver to check that your oil gallery blanking plug is installed. When you poke through the tapping you should bottom out after 1.5" or so, if it goes in much more then oil can travel up from the pump and right into the engine, it will have no interest in investigating the cooler :-)
Ps. Any more photos your your beautiful engine?