weak rear mains

wingski

wingski

Senior Member
After learning how to drive in model A’s, my first road car was a’54 Merc 2 door hrdtp. My folks had owned Mercurys and had a beautiful red and white “55 Montclair 4 door. Before that, they had a green ’51 4 door that we took on trips across the U.S. Those cars were exceptionally good cars and ran great. When I told my Dad that I was going to buy a ’54 Merc, he warned me about buying the first production year of any car. “They haven’t got all the bugs out yet” was his reasoning. As you all know ’54 was the first year of the overhead valve V-8.

Anyway, I bought my Merc and after a very short time it started throwing oil out the rear main. Mom and Dad insisted that I take the car to an auto shop instead of trying to fix it myself. Boy, did they see me coming and took advantage of my inexperience. That shop charged me $329 to repair the rear main, and it started throwing oil again a month and two days after I’d paid the bill. $329 was an enormous amount of money in 1960, and Dad and I went back to the shop to have them fix what they hadn’t fixed before. They told us we were out of luck because their work was only guarenteed for thirty days and it was two days past that. We tried everything to get them to honor what they hadn’t done and repair it with no luck. When we left, Dad and I were soo mad that we vowed to make sure everyone we knew found out about how I had been treated. We later found out that the shop already had a bad reputation and I was just the latest to get screwed.

Dad didn’t rub it in that he had warned me about first year production models, but he didn’t let me forget it either. I sold the Merc for almost nothing and bought a TR-3 that didn’t leak or throw oil.

My querstion is: Did all ’54 Mercurys have a weak rear main? If so, did the ’54 Ford V-8’s have the same problem? I think they were all the same 239 cubic inch engine which was the same displacement as the ’53 flathead V-8.

Thanks for reading,
Mike
 
First, '54 Mercs were 254 cu. in., almost the same as '49-'53 Merc flatheads (255"). As I remember, this rear main situation was fairly common with all Y-blocks, not just the first year. When overhauling one, the crankshaft almost always needed to be reground and the most wear was usually on the rear main. I blame a combination of poor crankcase ventilation (there was a filter on the road draft tube that sludged up and didn't get cleaned/replaced often enough) and lack of oil changes. This led to oil dilution, especially in cold parts of the country. Most people lived close to work and didn't take long trips in the winter, so engines seldom got warm enough to evaporate the unburned fuel and acids that formed. Plus, oil wasn't as good then.
If you changed oil, kept the road draft filter clean, and ran the engine long enough get thoroughly warm you kept the sludge level down and the engine didn't leak oil (much). I've put a lot of miles on Y-blocks without rear main leaks (including a first-year 1954 Ford).
 
$329 should have have bought you another car in 1960 and probably something better than the Merc.
I had the same idea that 40 deluxe mentioned. Y-blocks need to breathe and the rear main is the weakest place in the pan when it comes to holding back any pressure.
 
The rear seal was made of a rope type material that I've been told was supposed to absorb oil in order to not "burn" as it rubbed against the crankshaft. Makes sense if you think about it. You mentioned it was throwing oil so if that was the case it was definitely not weeping oil. Location of the side draft tube is an issue as it has to control the oil being whipped around in the crankcase. The cap on the oil fill tube was also part of the engines vent system.

Sounds like the repair was unlikely done properly. Surface where the cap meets the block were as cast so likely not flat, the side seals are a pain to install and if not seated all the way down without a gap oil would leak there and cause you to think it was the rear main seal, also without pulling the engine to offset the parting lines of the seal in the groove is impossible. So, yeah you likely got hosed by the shop.
But, in the Y blocks defense, most engines of the day all used the same material for seals, Ford, Chevy and Mopar. So the all had issues..

There are rubber type seals available for the Y today and if they are not installed correctly they too will leak.

Just a little more info for ya.

Dave
 
Mr. Covey has a very good point. When compared to other cars of the era, the Fords did not leak as much or more than other cars. I remember Olds, Poncho, and Chev leaving puddles, when Fords only left spots.
 
"There are rubber type seals available for the Y today and if they are not installed correctly they too will leak. "

True. I've had better results lately using tediously installed rope seals.
 
On some of the Y blocks I have taken apart, the seal itself was OK. They leaked from the side triangles, at the top. At reassembly, I used a drop of sealer on top, and on the threads of the holding bolts. On one engine, the oil was leaking from the rear cam bearing plug.
 
x2 Ole Don. All that, plus clocking the rope seal 1/8 to 3/16 inch, sealer on every surface, soaking the seals before install and brushing aviation sealer on the inside and outside mating surfaces.
 
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