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Added appropriate low pressure elec fuel pump to my stock 1950 6400 235. Starts runs perfectly now, but suddenly I’ve got milkshake oil. Wondering if fuel pump could cause this? Or if it’s just coincidence and head gasket went? Oil doesn’t smell like gas - but the coolant isn’t down noticeably either. I left the mechanical pump in place. Appreciate any thoughts.

"Oil Milkshake" is normal associated with water in the oil, not fuel. Unfortunate condition for sure.

If you confirmed your not losing coolant (it doesn't take much to contaminate the oil), it's possible you could have water entering somewhere else. A prime other possible source is the upper cab cowl vent drain discharging onto the top of the valve cover instead of off to the side and behind the engine.

Does your early 235 have the two bolt valve cover with vents like this? Water from the cowl drain pipe, if cracked or installed and pointing in a straight down position, can drain onto the valve cover rear central flat area and trickle down into the vent, collecting inside your engine. It will mix with the oil when running and create the milkshake effect.

Let us know what you figure out.

When installing that cowl vent drain, consult with your tailor whether you”dress” right or left!
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Great input! Had no idea that vent was there in the valve cover- just came off a 4” rainstorm ( unheard of for us). I keep my cowl vent wide open for the summer and have no idea if the drain for it is oriented correctly or even there after 76 yrs. This is fresh oil so it makes sense - will let you know what I find out. Thanks for the advice!

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Getting a little water in the oil from the cowl vent is sure better than the alternate. I had an engine with a crack in the cylinder wall that developed what I called chocolate pudding. That required a replacement engine. You should be able to deal with it by draining the milkshake out and doing a couple short duration oil changes. Be sure to get the engine nice and warm a few times to help evaporate the water.

Oh, and don't stand out in the rain with your mouth open so to speak.

I’m hoping this is the answer- rarely does the simple one work out for me - but if it’s this and not a head gasket I’ll be overjoyed!

Some people choose to weld that rear vent slot closed, and install a vented oil filler cap instead.
Jerry

Exactly what I was thinking of doing!

You can use JBweld to close those slots also. Just sand the area where the epoxy is going to sit really well followed up by some type of solvent prior to the application.

I was thinking about doing that to get me through the summer.

Just remember if you seal them all up, it's wise to install a vented valve cover cap. You need to have some form of ventilation on the top end. Otherwise when you run the engine, you're likely to get condensation build up under the valve cover from trapped air/moisture. Which of course leads to rust formation under the valve cover and on your valve train components.

Well looky there - exactly as described! That drain tube is original and hard as a rock. I had no idea this was configured this way. Closed and siliconed the vent will modify valve cover next. Thanks for the great advice all - I’d have the head off by by now for no reason.

Looks like the culprit has been found and a solution is up next!

Very glad you didn't start tearing your engine down!

This (first pic) is how the drain vent hose is supposed to be installed, but it being rubber, they tend to succumb to gravity and wind up straight down like mine was when I originally got the truck (second pic.)

Glad you found the issue and it wasn't as serious as a coolant leak.

The quick fix would be to extend the drain tube about a foot and tuck it behind the valve cover.
Jerry

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That would seem to make more sense than mutilating that valve cover.

I would like to say, "You guys always amaze me!" 🙂

If you replace the drain hose with a new piece, you can install a piece of soft copper tubing into the hose. Then bend it with the needed offset to make it look like a factory molded hose! This also keeps the hose from kinking...

Mike B

We found the same while oil. Ran and changed it 5 times, but did not know about the cowl, and it's rained since the oil change. Going out to check it out tomorrow. thanks for