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Ford Bronco Parts - Classic Vintage Early Bronco Parts

Threaded Oil Dipstick Tube

Tech article by rob wilson and filed under Engine

Tech article by Rob Wilson

After replacing my motor with a brand new one, I was bummed to find that it still leaked oil. I had hoped that one of the benefits would be that I would spend less time wiping up oil from the garage floor.

While I was building the new motor, I thoroughly cleaned the stock oil pan including the dipstick tube mounting hole. When I installed the dipstick tube, I used a generous quantity of RTV to seal the tube into the oil pan. I had expected that this would eliminate one of my previous sources of oil leaks.

Well, turns out the dipstick tube sealed just fine. The oil was now leaking from between the dipstick mounting plate and the oil pan itself. I had not expected a leak from this location and had done nothing to prevent it.

Ok, time for a fix. Ordered a Miladon threaded stainless dipstick assembly (P/N 22040). My oil pan was already off the motor (for unrelated reasons… LONG story). I drilled out the rivets that secured the dipstick mount to the oil pan. Turns out that there is an inner and an outer plate that make up the mount.

Threaded Dipstick
Inner Plate removed from Oil Pan

The outer plate just has an oval slot, the inner plate actually has the dipstick tube mount at about a 45 degree angle. The two sandwich the oil pan and have gasket material between them and the pan. In my case, the material was hard, cracked and missing some pieces.

Sooo, how to mount a screwed in tube? Well, first a trip to the local Ace Hardware for a 3/8” female to 1/2” male flare adapter. Turns out the Milodon threads are not pipe threads but fit well into a flare fitting. A little Teflon tape or RTV would help guarantee a good seal.

Threaded DipstickThreaded Dipstick

Threaded Dipstick
Milodon P/N 22040 Billet Dipstick and tube

Next step is to remove material on opposite sides of the ½ inch side of the adapter. Reduce the width by just enough to fit completely through the Oval Hole part of the original dipstick mount.

Threaded Dipstick
Opposite sides of adapter with material removed to fit in outer plate oval slot

I then soldered (brazed would have been better but don’t have the gear) the adapter into the Oval Slotted plate at a 45 degree angle. The adapter fills almost the entire oval when at a 45 degree angle so soldering with a torch was easy.

Threaded Dipstick

I then used some # 10 screws, nuts and star washers to secure the modified Oval Hole part to the Oil Pan. I installed the screw heads inside the pan so I could tack weld them in place. Thinking here is:

  1. If a nut comes off, I won’t have a screw bouncing around inside the pan
  2. I can remove and replace the outside piece without removing the oil pan
Threaded Dipstick
Inside Oil Pan viewI originally considered soldering the whole thing into the pan but that would have prevented removal should it still leak.
Threaded Dipstick
Screws tack welded in place (NO, I’m not a welder by profession)

Once the screws were tacked in place, I removed the Oval Hole part, applied RTV to the screw threads and the back of the plate, then reinstalled it with the nuts and star washers.

Threaded Dipstick

Now I have a threaded insert that is properly angled and allows me to use the Milodon dipstick assembly. I just need to finish building the motor so I can add oil and test this out!

Threaded Dipstick
Installed Dipstick Tube

Tech article by Rob Wilson

One Response to “Threaded Oil Dipstick Tube”

  1. Billsboat Says:

    Does the oil pan have to b out to do this fix. The rivets r already out and plate is bolted back in on my 302. It bolted plate looked to be a factor job, but from what u r saying it is not. I’m just wondering if I can un bolt this from the outside, re-seal, and bolt back in. Thanks!

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