Running a 3/8-16 cutting tap to repair the rear main seal retainer with a new stud
Problem
Way back in 2007 I stumbled across the deal of a lifetime. Fliteline Engines, an engine remanufacturing company at the time, had listed a C2AE 292 long block on eBay of all places. What flabbergasted me back then was the price, roughly $800 and no core charge. After some questions and some back and forth I learned that the engine had ECZ-G heads and 1.54 ratio rockers. The explanation on the price was that the company was liquidating some of their inventory that did not move well.
Without much hesitation I purchased the long block and had it shipped to me in Winchester, Virginia for $130. There were just a couple of odd things that gave me pause, but they were slight. The hold-down hardware for the rocker arm assmeblies did not match, the bung for the temperature sender was at the front of the head on the passenger side, and I had to ask Flite Line to ship the rear main seal retainer after the fact since it was missing when the engine arrived on a pallet. While I paid attention to things such as clearances and other details, I did miss the problem that one of the threaded holes in the rear main seal retainer was "wallowed" ever so slightly. Y Block retainers are aluminum, and the studs can very easily strip the threads if you are not careful.
The C2AE 292 Ford engine has been one of the best purchases made on this 1955 Ford.
Back then, it was not too much of an issue and things sealed up fine. Over the years, however, with repeated removal and installation of the oil pan, the problem has only grown worse and was causing a nuisance oil leak. It was time to bite the bullet and take care of things.
Solution
There are a number of ways to handle a stripped set of threads in your block or in a rear main seal retainer. I thought about removing the retainer and installing another one along with new seals, etc. However, the rear main does not leak in this engine and the side seals are just fine. No sense in going through that hassle unless it is really needed.
I considered a Heli-coil. Having used this method in the past to repair threaded holes in various places I knew this would be easy to do. When I examined the width of the rear main seal retainer in the area where the oil pan stud holes are located I did not have much confidence on having enough "meat" left to thread the insert.
I decided I would use a specialty stud, Dorman part number 695-097. This stud has a 3/8-16 size on one end and a 5/16-24 end on the other. Even with having to purchase a box of ten on Amazon the cost was much cheaper than the Heli-coil. I gathered the parts I would need - a tap size 3/8-16, the new stud, a wing nut and another nut to "lock" the wing nut onto the stud, an oil pan gasket set, sealant, and all the hand tools to match. I chucked a 5/16" bit in my 20V drill and went over to the 55 Ford.
The wing nut served to get the stud finger tight in the rear main seal retainer.
The new stud had to be "trimmed" to size - I got pretty close.
To accomplish this repair, I put the car on ramps, rotated to the crankshaft to TDC, removed the sway bar, and drained the oil from the pan. Taking these first steps of moving the crank to top dead center and getting the sway bar out of the way makes sliding the oil pan out from underneath of a mid-fifties Ford passenger car a piece of cake.
Next up was to clean all of the surfaces, use a razor blade to remove all of the old gasket material, and spray some brake clean on the rear main seal retainer.
It is imperative that the oil pan rails and surfaces be as clean and dry as possible.
After drilling the 5/16 hole, the 3/8 tap cut through the aluminum nicely. It was really a good feeling to see all of the shavings drop to the garage floor since the tap was essentially upside down. Just for good measure, I sprayed some brake clean from the top of the hole I made so that any debris could drain back down to the garage floor.
The arrow points to the space above the hole enabling a safe pass through with bit and tap.
Be sure to use sealer on those studs! The threaded holes are open to the crankcase.
The rest of the work is straightforward. Ensure that the studs are sealed off from oil, clean up your oil pan and double check that the rails are true, get your "best" gasket and away you go. If you use RTV please do not overdo it, and do wait to fill the crankcase with oil until the silicone has dried. Your Y Block will thank you later.
Be sure to read the "More Problems" section below. However, take a quick peek at the results of both the oil pump and rear main seal retainer repair. Here in triple digit heat in Calfifornia I am very happy with how it turned out.
More Problems
While I was under the car I recalled that I wanted to increase my oil pressure just a bit. So, after getting the oil pan out and letting the engine drip oil on the large mat I have, I unscrewed the threaded plug that retains the pressure relief valve. If you put a washer or two inside the plug, you essentially increase the pressure of the spring, thereby increasing the maximum pressure your oil pump will put out.
The threaded plug keeps spring pressure on the relief valve.
I located a couple of small washers, put them in the plug, and then put the plug back in making sure it was sealed up well. For some reason I also decided to remove the oil pump cover plate and replace the O ring seal. It "looked" like the plate was leaking a bit (come to find out, this was the oil pan leaking down that side). The problem here was that I did not replace the O ring with an original. I had an O ring that some helpful soul had shipped to me that "was better than stock." This O ring was thicker in diameter than the original. That all sounds good, but just the few thousandths of extra room between the driven gear and the cover plate will really make your oil pressure take a dive at idle.
BUT! Before we get to that, check out this photo...
The 1/4" hex drive socket had fallen into the oil pan!
A trying moment took place in the garage when it was time to prime the oil pump. Everything was sealed up, the sway bar reinstalled, the car taken off the ramps, and the crankcase filled. When I ran the drill CCW with a 1/4" extension and a taped socket on the end, I had a hard time getting oil to flow. For about 45 seconds I ran the drill with no movement on oil pressure. And then it happened. Not paying attention, I pulled the socket and extension out of the distributor boss, hearing a plink on hard cast iron as I did so. The socket! Yep, it had fallen into the engine. I tried to fish it out of the valley of the block but could not see it and my magnet never grabbed anything.
I sighed and started removing the air cleaner, intake manifold, and valley pan. It took a few minutes to drain the radiator, disconnect everything and finally open up to the lifter valley. However, no socket was to be found! I groaned out loud and began the walk back to remove the oil pan - again. I have to say that this was very frustrating. Honest mistake, but one I have never made in my history of turning wrenches on Y Blocks. I guess I should be glad I did not lose hardware or a small socket into a passage in one of the heads!
I got everything buttoned up one more time, the oil pump primed, and it was time to start it up. I hit the key and the Y Block came to life but I was only at 23 psi. Cold, 10w40 oil. I let the engine warm up and went for a drive. I stabbed the gas and the tachometer went up to 3500 rpm or so, and the oil pressure gauge read 70 psi. Welp, that's good.
After driving 3 or 4 miles, I rolled into a parking lot, mashed the clutch pedal, and the engine went down to an idle. I watched the oil pressure gauge. It went down to 13 psi! The dash light never came on. (I believe that light only activates when the pressure gets to 7 psi.) I went home, put the car back up and just decided to remove the oil pump in total and replace it with one I had rebuilt myself on the bench. This time, I made sure that the clearances were tight, the O ring was correct, etc. I did put only one washer in the threaded plug though. The video above gives the final results. After a full week of driving the car every day in temperatures that stay at 105, 106 degrees for much of the day, I can tell you that the oil pressure is the best it has been for quite some time.
One more item to add - I did remove the main cap nearest the timing cover just to see what the wear was like. I was very happy with it!
The Hot Rod Reverend
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