The PO installed an oil filter in my 8BA Flathead. It looks like he used the oil pressure sending point on the block for the filter feed (am I correct? Isn't the pressure sensor is supposed to be on the rear top of the block, down behind the driver's side head?)

I found the sensor lying in the debris in the bed.

Anyway, is there a way to add the sensor back into the oil line? Can I add a brass "T" fitting in the oil filter feed line? Could I add the "T" fitting to the oil filter return line, or would that register as low pressure?

Thanks...chico

 

The flatheads used a "sidestream" filter. Only a portion of the oil flow goes thru the filter, but it gets filtered more finely than a modern full-flow. It does normally use the sensor connection on the block. The sensor is usually in a Tee right ahead of the filter.

Be aware that there needs to be an orifice inside the inlet to the filter to restrict flow properly, or the engine will be starved for oil. It is usually pressed into the inlet fitting on the filter.

 

Thanks for the info. I'll look for the orifice you described. Will it be obvious?

Based on your reply, I'll go get a brass "T" filling to add the oil sensor to the oil filter line. Just to be clear, that's normally the way it's done, right?

Thanks...chico

 

The inlet restrictor (orifice) isn't that obvious, other than it is a smaller hole than you'd expect if you look into the filter. I mentioned it because I've heard of people thinking it would work better if they hogged it out -- bad idea!

I went out and looked at mine a little closer; the Tee is actually kind of special on the factory fitment; it's a female flare fitting where the oil line enters the Tee; the branch that the sensor is in is a female pipe thread; and it has a male pipe thread that goes into the filter nozzle (directly). If your line goes directly to the filter, they must have used an adapter to mate the flare on the tubing to the FPT inlet?

I'm kind of leery of using compression fittings on steel pressure lines, so I wouldn't use that to splice a Tee into the line. You might want to check around for a stock fitting, there must be millions laying around, or they may still be available from some of the vendors.

 

Thanks. I got the proper fittings, I'll try it next week when I'm up at the ranch with the truck.

Question: Will the inlet to the oil filter reduce the pressure in the line where the sensor is enough to give a low reading? I assume that the inlet restrictor is small enough to not have a big impact on oil pressure, but I was just wondering if it causes a noticeable drop in the gauge reading...

 

Well, because it's a sidestream filter, which essentially sends oil back to the pan after filtering, it does lower the pressure of the entire system, but (when fitted with the orifice) it is allowed for in the design. If the sensor is located right at the filter inlet, like factory, I would say that your gauge readings are the lowest pressure in the system. There are several flathead forums on the web that have excellent oiling schematics and pictures, and there is some good reference material here on FTE member's pages.

 

Cool. As long as it was an approved factory add-on, I'm satisfied.

Thanks for the help. I've got a lot more questions, but I'll dribble them out over enough time to avoid being a pest...

chico