On oil temperature

Well, since the Beetle is back in service, I decided to waste no time on getting back to work on the bus. And, as this is valuable Fallout 4 time on my day off, I took it seriously.

I had purchased an oil temp sender and oil temp gauge for the bus. Since I like the one I got for the beetle very much, I just re-ordered the same sender/gauge set again. Unfortunately, I ran into a snag. You see, the beetle oil temp sender I bought is M18x1.5, which is the size of the Oil Pressure Relief Valve bolt hole (on the picture below, it’s the gigantic flathead bolt right in the middle). On the beetle, the sender replaces the bolt, and reads oil temperature coming off of the pump. On the Type 4 engine that the bus has, however, the pressure relief hole is M22x1.5.

I had already purchased the sender, and started thinking of where I could mount it. I came to the conclusion that the oil sump is a good place for an oil temp probe, as it gives you a hybrid oil bath/case temperature, which is good enough for my purposes. Since no bolts on the bus are M18, I decided to purchase a weld-on bung to weld into the inspection plate cover (one of two plates on the bottom of the engine: one is the strainer plate familiar to anybody who has ever had an ACVW, and the other is a round inspection plate that resides on the sump right where the oil filler goes). In the following image, the plate I’m using is the black one to the far right. The engine pictured has an aftermarket deep sump, but that’s not what I’m talking about:


O2 sensors are also M18x1.5 in many applications, and weld-on O2 sensor bungs are a dime a dozen, so I purchased one. Total cost: $4.

First step, remove the inspection plate:




That’s probably not good.



No idea what it is


Now, I have driven the bus for the past few weeks without issue (even average 10PSI oil pressure when hot and idling, even!), so I’m not too concerned. Of course, there is a requisite level of concern a person is legally required to have when they discover a large chunk of metal in their oil pan, and I will admit that my current level of concern is measurably higher than that minimum. For now, I’m just stuck wondering what it is (was). Regardless, I pressed on.

I used a pilot bit, and then a large Milwaukee step bit, to drill the hole in the plate out to the proper size. Following the drilling and many test fits, I proceeded to “weld” the bung into place.

Why is “weld” in quotation marks? Well, I’ll let the pictures explain:




It goes without saying, but I’ll say it anyway: I am not a good welder. Hell, I’m not a welder by any means. But by hook or by crook these two pieces of metal are now attached to each other, and I can’t really see or detect any leaks. The oil temp sender fits in there snugly, and I will be sealing it off with some Aviation Form-A-Gasket. The silicon O-ring that goes around the inspection plate was clearly damaged on installation by whoever used it last, and there has always been a slow seep there. I’ll also use form-a-gasket to help seal that up until I can get a new O-ring ordered.


One thought on “On oil temperature

  1. Try to find two 6mm copper crush washers # N012803-2, one gasket that goes between the two plates (I didn’t see the second sub-plate in the photos?) # 039-101-287 and o-ring # 021-101-269A that goes between the taco plate and engine case. Porsche parts (for 914) are interchangeable, and sometimes I have better luck finding parts that way than for late buses.

    Remember not to over tighten. The slight crush of the red/orange o-ring should prevent leaks if installed on clean metal with no RTV or sealant. If you must use sealants, try Curil, Hylomar, or other sealants that do not change the properties of crush joints like RTV does.



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