I have a 400 in a 78 F-250 that I just rebuilt, and the front seal is the last leak I have yet to fix. I replaced it once in hopes the first one was just bad. The leak persisted through the replacement and manifests as a steady drip. There was no groove in the balancer when I changed it out. I can see the oil is leaking out around the balancer shaft where the black part of the seal meets the balancer. I'm using Pennzoil conventional 10w30. I can't figure out why it's leaking! Any help would be appreciated.

 

Did you put the big flat washer between the crank gear and front cover? It helps keep the oil from splashing on the seal. Almost looks like a shim. It should be called a slinger.

 

It could be excess crankcase pressure. Any time I see a leak at front or rear main, timing cover, china wall, or valve cover cap, I look at the PCV setup to see if it's working properly. If the PCV assembly is good, then I start thinking about excessive ring gap, or rings that haven't seated. Did you properly break in the engine, in order to seat the rings?

And like Moose said, if you didn't install the oil slinger, it could leak.

 

Leave the timing cover loose before you stick the balancer on.This centers things with the seal.If you didn't do that,could be the problem.If you installed a roller timing set,no need for a slinger. Does little or nothing to keep the front seal from leaking.

 

Ranger, I've got a PCV valve running from my driver's side valve cover to the back of the carb. We broke the engine in for about 15 minutes, it's a roller so no flat tappet cam. Also a roller timing set, so no oil slinger. I did not loosen the timing cover to install the balancer so that may be my problem! I'm assuming that job requires the water pump to come off too?

 

I never heard of no slinger if using a roller chain?
Where is this posted with the chain?
Dave ----

 

I think the slinger is supposed to lubricate the cam chain no matter what type. Don't know about it's effect on the seal.

 

Yeah, I've got oil slingers in engines with roller camshafts and double roller timing sets. They don't eliminate the need for a slinger, if the timing gear leaves room for it. Some timing covers, like that of all the Windsor covers I've seen, have a little wall that supposedly allows oil to drip onto the seal, instead of hitting it with a lot of velocity. And don't forget the other purpose of an oil slinger...it's there to throw oil onto the fuel pump eccentric, if you're using a mechanical fuel pump.

By break-in, I meant ring seating break-in. That can only be done under a load, or in other words, while driving or on a dyno. If you just run a newly ringed engine, without cycling it through light load, medium load, and heavy load, the rings may never seat, and the cylinder walls will glaze over. There's a gazillion different opinions on how to do it, but all builders agree that it must be done, one way or another. If the rings never properly seat, a lot of the combustion gasses will blow by the rings, and into crankcase. If that's happening, there's no amount of PCV that will help. Even a vacuum pump, or an exhaust pulled evac won't defeat that much blowby.

All that said, your problem is probably nothing more than a misaligned front seal. Like Headloct said, leave the timing cover loose while seating the balancer. Then tighten the timing cover bolts.

 

There's an oil slinger on the cam shaft gear for the timing set, but I definitely didn't have one for the crank. I'll go beat on the motor between medium loads for a bit to make sure those rings seat in. I guess I've gotta order another seal for round three 😂

 

I was told the Slinger was to keep oil from hitting the seal directly with any force, it would get enough oil other ways to lube the seal.
Dave ----

 

I was looking at some technical drawings, and it showed the crankshaft oil slinger as a "car" only part. My f250 may have never had one. Part shown as part # DOAZ6310A

 

The original 351M in my current truck, and the original 351M in my 79 Bronco both had oil slingers. And I've robbed timing covers off junkyard truck 351M and 400, and they had oil slingers. And every 460 I've pulled apart had an oil slinger. the only Ford engines from this era that I have not seen slingers in, are the Windsors.

 

Something I missed earlier. You said there's an oil slinger on the camshaft gear. ??? Are you sure? I've never seen that before. Are you sure that's not the fuel pump eccentric you're thinking about?

 

Yeah I got it wrong, its definitely for the mechanical fuel pump! And so far as I've looked the crank oil slingers are not available anywhere outside of pulling them from junkyard engines!

 

Check ebay. I've seen NOS and used ones there.