I finally had enough time to get Earl's engine all installed and tuned up. It runs like a top - very smooth, starts immediately, runs great. I'm really happy, except ...

I got a little drip of oil from the road tube (expected) but a bit more of a drip from the center-rear of the engine. Right below the rear main seal . I've checked this twice, but I'm going to clean everything up one more time and see if the oil really is coming from the seal for sure.

Assuming the seal is leaking, I'd like to fix it properly, but I'd also like to avoid taking the whole darn engine back apart if at all possible. It was easy to clean everything and get the seal just right (well, we though it was just right) on an engine stand with the crank out. I'm trying to imagine doing this job with the engine in the truck and the crank in place. My imagination is coming up with mostly nightmares. Any suggestions or ideas would be greatly appreciated.

One other (perhaps related) point. We put gages in during the breakin period to measure vacuum pressure, coolant temperature, and oil pressure. The oil pressure was about 60 psi at idle and about 80-90 psi at 2000 RPM with the engine hot. That seems pretty high to me after reading the specs (45-50 psi at 2000 RPM, hot). Is it possible we blew the seal out with too much oil pressure?

 

George

Hey that sounds like one of my rebuilt engines. My 302 is dripping a bit and I assembled it very meticulously too. As you know I am far from a Y-block guru but have a couple questions anyway. Are you fairly certain your guage is correct? Did you use a stock oil pump? I usually cause my excessive oil pressure with high volume pumps and my tendency to build them on the tight side of the bearing clearance tolerances. In any event, I would run it a good while before I disassembled it. A tiny leak is not going to harm the engine. Once in a while they will seal themselves back up, but not usually. You are right, it is not nearly as easy or pleasant when laying on your back.

 

Yeah, I checked the gage immediately after seeing the high numbers. We are measuring the pressure in the oil gallery plug just in front of the oil pump. The original oil pressure switch location is the plug just behind the oil pump. Since the gallery is a pretty good sized hole straight through, I doubt the pressure is much different at two locations only a few inches apart.

The oil pump is a brand new Federal-Mogul unit that the engine shop bought as part of the overall rebuild. We are running 5W-30 oil and the pressure does go down a little as the engine warms up - but not more than 5 -10 psi.

I was just wondering if there were more than one type of oil pump used on those engines or if anybody has had this high oil pressure experience? Other than the high oil pressure and the main seal leak, the engine runs absolutely perfectly.

 

Hi, George. My oil pressure runs right up there around 60psi all the time. There are no traces of oil under the truck but the block seems to maintain a light coating of oil from seepage. The cast valve covers seep, oil pan seeps, and no doubt the rear main seal adds its seepage to the mix. Desert dust and grime seem to hold the oil to the block just fine. No dripping. I use 30w Castrol and am satisfied that all old engines have a certain amount of oil on the outside... a patination, if you will... to clearly set their owners apart from the guy in a new truck who never has to worry about such things. BTW, I found a torque spec for a Buick oilpan 6-15ft/lbs. Could this be right for our pans? Hope its not the rear main. Best. Peter

 

George, I don't remember if you're using the rope seal or the neoprene seal. I think the rope seal can be changed while it's in the vehicle. If it is the rope seal, then I wonder if it got scorched at start-up.

I've been cranking my engine with the spark plugs out just to get oil distributed around the engine before I try to start it. I have the neoprene seal, so I don't have the dry-scorched rope seal problem to deal with.

Good luck with Earl.

Edit; are you using the old style cartridge filter system, or the new canister filter? I assume that you went through the oil by-pass system if you've got the older system.

 

Paul,

I'm using a neoprene rear seal and a spin-on canister (new style) FL-1A oil filter. Prior to starting the engine, I removed the distributor and spun up the oil pump using a cordless drill (with a hex-drive extension) on the hex oil pump drive shaft.

 

George-

Where is the oil collecting? Does it come out of the hole in the bottom of the clutch cover? Sometimes the early pot metal EBU seal retainers warp, causing a pan leak at the rear which can be confused with a seal leak. If it's comming out the cover hole, it probably is the seal.

Was the seal surface on the crank polished? The rope type seal was designed to work on a crank surface that had minute hash marks to help retain a litttle oil to keep the seal swelled. The newer neoprene seal likes a smoother finish.

Did you stagger the ends of the seal (not lined up with the parting surface of the retainer and block)? This helps to keep things dry.

Did you lube the seal at the time of installation?

You mention a road draft tube. If you were to install a PCV system, the negative pressure can help reduce leakage.

I just rebuilt my 292 (check my gallery!) and after it was all together and running, I had to pull it all apart again due to a mis-ground camshaft. You know what that involves I'm sure! I'm not suggesting that you do that, but if you do decide to fix the seal (after waiting 2,000 miles to see if it seats better), at least you don't have to pull the whole engine apart again like I had to. The new Clay Smith cam in there now is great by he way.

Give the PCV system a try- it really can help.

Danny

 

Danny, George is doing a 100% restoration right down to every nut and bolt. A PCV system is nice but not stock. Flatheads worked fine with out a PCV system so why not a Y-block.

 

what is the best way and place to install a pcv valve in a 56 f500 272?

 

Old-Uhaul-

You will need a later (post 1962 I think) valley cover which has the pcv hole/baffle at the back, or a hole in a valve cover that will take a grommet and pcv. PCV's vary in their flow rate and spring rate, so you can experiment. I am simply using one from a 60's 289.

You then need to route a hose from the pcv to a vacuum source. Ideally, this comes from either a spacer plate under the carb that has a hose connection, or if using a later model carb, use the big pcv connection already provided (usually). Try not to connect to just anywhere on the manifold- the blowby gasses will be distributed more evenly among all 8 cylinders if the vacuum comes from right under the throttle plates.

I use a vented oil filler cap and run a hose to a later model air cleaner for a fresh air source.

Danny

 

Danny thanks for the info,i will start hunting around for a later cover.i am running a stock 2 barrel,getting it rebuilt because the truck wont stay running unless i mess with the choke all the time and idle very high.
by the way,i love your truck,really nice.
just a side question,How did you make your gallery,i cant find any way to add photos to my album i created
thanks

 

Thanks for all the input Danny.

 

George,

Sorry to dig up this old post but after installing my front cover I learned something new about the front seal and the front cover; the front cover needs to be aligned when it is installed or it might well leak.

The Eichman book was absolutely no help on this subject. The service repair manual was only sightly better. Here's my experience.

I broke the pulley on my original damper when I pulled it off. So I used a brake hone and a die grinder with some sandpaper rolls to hone the inside of the damper so that it would slip on easily but snugly. I used that to align the front cover.

Just thought I'd toss that one in to try to save somebody some grief with a leaking front seal.

 

George, did you ever find the leak? I had a drip on my 272 and it turned out to be the back of the pass side valve cover. John

 

Good golly, i have yet to rebuild any engine that didnt have some type of oil leak for the first couple of months. you have to seat the rings in a break in period especially one using a draft tube rather than a pcv system. i did change a rear seal in an old 390 in the rtuck that had a split neoprean shaft seal and two fiber seals on the sides of the lower shaft bearing surface. i had to lower the pan, slide the tranny back on allthread till it disengaged the crank after removing the shift stick and lowering and supporting the trany, then loosening all the main bearing caps and prying down the crank near the rear a bit. not fun but i figure it beat removing the engine.