MTFCA Forum

If you were going to try to make a stock T engine and transmission as leak proof as possible, what items would you attend to? I'll list some. If I miss any, add them. All oil pan bolts (engine and hogshead), Oil pan inspection cover bolts, Transmission pedal shafts, Camshaft front cover seal, Front crank seal. I didn't list places like the starter, generator, or hogshead inspection cover because assuming the gaskets are OK, they seldom leak. Not part of the engine or transmission, of course are the rear axle seals. What did I miss?

Clutch fork shaft, engine side plates and pan inspection plate.

Allan from down under

I would add the starter to the list. Mine leaks an incredible amount of oil, mostly after engine shutdown, through the shaft bushing. The oil flows along the inside of the starter and drips out through the drain hole at the commutator end of the housing.

This is a fix for that leak:

Allan wrote: ↑

Thu Apr 17, 2025 3:33 am

Clutch fork shaft, engine side plates and pan inspection plate.

Allan from down under

You are correct, Allan. I did forget the clutch fork shaft, but I did mention the oil pan inspection cover.

I would say the biggest culprit is 4th main. Hogshead to block felt is close second.

You have to remember that even a new Ford T at the dealerships had small leaks on the showroom floors. If you drive a T fairly often they are going to leak a little. The worst culprit is the transmission cover area. If it’s an all new rebuild and it doesn’t leak you haven’t been driving it much.

Even though the starter, generator, oil pan/block and access panels have gaskets, anywhere the bolt threads enter the crankcase or are exposed to oil, the bolts can still leak over time around the bolt heads by the oil seeping out through the threads. It is always a good idea to clean the threads of old oil and seal the threads of all bolts with something like the Right Stuff. The Right Stuff should also be used on all gaskets. oil can also run out through the square hole of the drive plate if the universal does not fit tightly.

I think both of my cars leak on the garage floor even when they have sat all winter without being started.

Ok, I'll say it. If your T isn't leaking oil, you better check the oil level.

Here’s a dealership photo that shows the drip pan under a new T. Yes a new T didn’t leak but very little but after a while———————>.
It’s something we should do and to try to use the right sealers and gaskets in the right places on rebuilds.

I used to run a PCV valve on my speedster, worked waaaaay better than any gasket sealer. The 4th main is a tough one tho

[quote=
I used to run a PCV valve on my speedster, worked waaaaay better than any gasket sealer.
[/quote]

Just curious..... how did you run the PCV valve?

Speedster, so everything is different. Basically I tried to seal the crankcase the best I could. Hardest part on a T is the valve galley where the throttle rod passes thru, but I run a ‘19 block with 2 side covers so easier to seal. Made up an aluminum oil fill cap with o-ring seal and stuck a PCV check valve in the top. All that is left is a pipe fitting in the manifold near the carb flange, and a short length of hose to connect

There are two paces where attention may be warranted in 100 year old parts. The pan arms are riveted and bronze welded to the pans. The bronze weld is not necessarily entirely consistent all over the contact area, and it is possible for il to leak past the rivets. It is not too difficult to solder the rivets on the inside of the pan when doing a rebuild. The front dam in the pan is also riveted in, and soldered around the outside to make a seal. Often this solder is cracked at the pan rail ends of the dam. If you really want to seal this, it can also be soldered on the inside of the pan.

Allan from down under.

I'll start by stating I have used various gasket sealers over the years and Aviation Permatex is my gasket sealer of choice. If applied liberally to both gaskets and bolt threads during assembly, it does a great job of reducing oil leaks. After assembly, clean the excess off with a rag and gasoline. Let it set up and your golden.

Regarding leak proofing or modifications. All those mentioned above are great suggestions and recommended as well. One area often overlooked and very prone to leaking oil is the area of the pan where the frame arms are located. When using a pan straightening table, it is impossible to access the flats as the arms are in the way. A straight edge across this area will show a significant dip between the front and rear bolt holes. You have two options to minimize the likelihood of leakage in this area. The first option (my preferred method) is to drill two 3/8" holes is the arm to allow access with a punch. Heat the area with a torch and flatten with a round punch. Once satisfactory, weld the holes up and finish grind. The other option is to double up the gasket material in the area and apply a very liberal amount of Aviation Permatex on all mating surfaces. Install the transmission cover bolts as usual. Wire off excess with a rag and gasoline. Let dry for 24 hours.

Lastly, when installing the transmission cover felt seal, I have had excellent results by soaking the felt seal in Shelac prior to assembly. When installing the laminated shims for the field coil, I place the narrow portion of the teardrop in the upward position. This helps hold the felt in position when installing the transmission cover.

Just a few tricks learned from dad, the master Model T Mechanic, over the years. I'm sure you will also find these suggestions useful.

Shellac on the felt makes sense. New to me.
I thought about the " right stuff" like China walls on a Chevy, but it is not very friendly removing later.

I use 'threebond' grey - the Japanese sealant. Probably a close relation to aviation permatex?

The wrinkle I was taught is to do up bolts on the mating surfaces firmly only, leave to set up for 24 hours then return and tighten up fully. I was taught doing up tightly right away squeezes most of the sealant out defeating the advantage of it.

On a motor where authenticity is not a must, has anyone had success using nylon washers under the head of bolts and nuts?

My 4 dip inspection plate has steel/ rubber washers like for tin roofing. They work great.

Terry - I used the nylon washers under the bolts on the inspection pan when I rebuilt the engine on my 1919 Speedster in 2012. I also used the standard paper gasket that is included in the gasket kits from the vendors, and "The Right Stuff" as a sealant. For the first several years, I didn't notice much leakage around those bolts, but over time, it's increased a little. No significant leakage but they do seep a little now 13 years later. Still very acceptable and expected for a 13 year old rebuild. Here's a photo of the pan; hard to tell but there's a light oil film on several of the bolt heads and around them.

My grandfather put together an engine with the goal to eliminate leaks. He cut groves for o-rings in the pedal shafts ect. Problem was it worked well but would cause the pedals to stick and he would have to oil them!

babychadwick wrote: ↑

Mon Apr 21, 2025 2:27 pm

My grandfather put together an engine with the goal to eliminate leaks. He cut groves for o-rings in the pedal shafts etc. Problem was it worked well but would cause the pedals to stick and he would have to oil them!

Chad, I saw that remedy, mentioned decades ago, I think in "The Vintage Ford" magazine. However, later, I saw people advising against that method, saying the the O ring grooves could weaken the shafts.

Cutting an O-ring groove in the shaft Is a bad idea. That weakens the shaft. One hard emergency stop can break the shaft. Better to O-ring or install seals under the cams.
Either way, a completely sealed shaft will require manual oiling of the low, clutch shaft & outside cams.
When they get dry, the effected pedals will get stuck.

I used hard plastic washers for my inspection, valve and transmission cover plate bolts with Yamabond applied to both sides of the gaskets and the threads, and no leaks found.
Did the starter shaft seal trick as above and used flat washers and hex bolts, sealant on the gasket and bottom threads.
I cleaned the hogshead areas around the rearward two pedal shafts and put ultrablack around the shafts and minimized the shaft leaks. The two forward ones dont leak much but I may add a mat to contain those drips.
I use oil absorbent matting cut to size and held with binder clips for areas yet to be sealed and it helps with keeping the oil from dripping onto the undercarriage and garage floor. A piece of mat wired around the 4th main keeps the excess grease and oil contained.
I have an oil filler snout with a strip of mat wrapped around it to hold the oil mist coming from the filler cap. I may add a vac line with pcv to help in that area. Adding the snout stopped alot of oil from escaping the cap.
I dont have a problem with oil dripping from the throttle rod holes, just a little misting.