Oil leak cause

[DanOlson]

My 53 B-4-C has always had an annoying oil leak which I assume is from the rear main. Maybe a tablespoon a week. Last week I was in a homecoming parade and had 11 7th grade girls in the back throwing candy. When I got home and parked, within 15 minutes I had an oil puddle about a foot across under the rear of the motor. To be honest, I've not driven is since to see if the leak has changed. If I figure 100 pounds/girl and two adults in the cab, I had about 1500 pounds on the truck. Could the increased load lead to an increase in the oil leak? Short term increased crankcase pressure?

Thoughts?

Dan

[Don Coatney]

The additional payload should have nothing to do with the oil leak. Take a look under the truck and see whare the oil is coming from. Is your dipstick reading low oil?

[ChrisCoccia]

Dan;

I used to have an F250 with a 302 that wouldn't drip while driving, but when I'd park a bunch of oil would drain out of the bell housing. Long story short I replaced the rear main seal a couple of times and it still did it, so I learned to live with it. I didn't lose that much oil from it. In rebuilding my B1D all the mechanical parts were well preserved under half an inch of oily crud, leading me to believe that a constant-flow external oiling system is par for the course in these trucks.

[grey beard]

Dan,

The good news is that your later style (53) truck motor has the newer - and likely better - neoprene rear main oil seal. These are much better than the earlier style rope seal many of us have.

The really bad news is that in order to replace the top half, it is necessary to pull the flywheel, cause' it is retained with cap screws horizontally into the block, around the crank flange. Earlier style used a rope seal that one could finesse into place - even the top half - with the crank and flywheel all in place. Can't swap seal types cause' the block is machined differently in that area, or I would have used the neoprene seal when mine was down for the rebuild.

[DanOlson]

Thanks for the info. That is good and bad news and another item to add to the winter to-do list.

[MBF]

Just something else to consider-parade use is hard on a vehicle (constant stops and starts at idle speed for a prolonged period of time). I'd almost suspect that what you're seeing is the accumulation of stuff that was collecting in the road tube during the parade that ejected during the ride home. I think you've got to see where the puddle is coming from, and how much oil you actually lost. A few drops after it creeps on a floor will look like a whole lot more than it actually is. Being 50+ years old entitles anyone to a little drip and smoke. Mike

[DanOlson]

By the road tube, do mean the inch or so tube that hangs on the passenger side of the motor south of the carb? I guess I don't understand its function.

Dan

[Allen I.]

As I understand, it creates ventilation to the crankcase. As you tool down the road, air passes past the angled end and creates a vacuum. This draws air through the crank case through the vent on your oil cap. Some oil mist can escape through there too. This is might also be why the center of the road used to be so much darker than the "tire lanes". Parade speeds do not provide for this airflow and some oil can build up to be dumped on the driveway.

[Don Coatney]

This is might also be why the center of the road used to be so much darker than the "tire lanes".

Good observation. Even today if you see an area in the center of the road that is noticably darker than the rest of the road you will feel a "dip" as you drive over this darkened area. The dip in the road causes the external oil build up under all vehicles to fall off.

[DanOlson]

You know, that explanation sounds just crazy enough to be true. 50's version of a PCV system. I remember when I was ~8 helping my dad with fencing by driving in the ditch by turning the key on and pushing the starter and shutting it off when I moved enough. I wonder if the truck spewed oil.

Dan

[MBF]

Dan-I made up a crude but working PCV system on my 52 1 ton w the 218. It uses a modified road tube housing with a nipple welded on the housing that the bolt goes through. To this I installed a short piece of rubber hose with a PCV valve in it, then another piece of rubber hose up to a vacuum port on the side of the intake. To filter the air coming into the block, I used a later model oil vent cap with the mesh filter inside (this needs to be re-engineered to draw filtered air on up on the air cleaner. I always had problems with this vehicle sludging up-and it had a lot of crud in the pan. Since my last oil change early this season I've put close to a 1000 miles on this, and the oil is still clear! Only problem I see is that she's a little more cold tempered than she used to be due to the calculated vacuum leak from this system. When she's warmed up no difference. The whole setup cost less than $15. Mike