Hi,

Since I've owned the truck there has always been a slow ( less than 1/2 qt a month) oil leak that manifests down the back driver side of the block and pools behind the oil pressure sender area.

I've replaced the valve cover gasket, push rod cover & gasket, oil pan & gasket , oil pressure sender, oil filter.

Finally i power washed the thing and slowly but surely it comes back.

the plugs are new and tight and she's firing on all cylinders.

My guess is its coming from where the head meets the gasket or the #6 spark plug? I've replaced the push rod gasket 4 times now

Note: the #6 plug well is always wet?


Note: push rod cover and gasket have since been replaced, but the leak is the same.

 

Looks dry up near the head to me. I think I would be looking farther forward on the engine. Possibly around the front seal or the timing cover. Air blows up from the road in the area you have pictured, so a drip from up front can be thrown back and hit that bellhousing area.

Cheap brake cleaner from the parts store is excellent for this purpose. Just spray it on that oily area and it will instantly clean it off and dry to a dull film. I wonder how long it would take for the leak to show up? If you let it idle in the driveway with a piece of cardboard under it, where it would drip? If you never saw it back there with the truck never moving down the highway, I would be suspicious it is being blown back.

 

The idling idea is great. But first, here are some updated pics. I am pretty sure it is not coming from thr front/timing cover area of the engine.

After I clean the 6th spark plug area the dark liquid always comes back. No drips underneath until it pools for 2 months.


Always gets wet with gas or oil here?



This is where it starts i think.



Possible path. X is where it begins to pool.

 

#6 plug is never oily or fouled on the tip?

 

No fouling to speak of. I'm really stumped.

 

When you have replaced the pushrod inspection cover gasket, "I've replaced the push rod gasket 4 times now ", how tight have you made the fasteners?

 

Gorilla tight the first 2 times. Now about 2 lbs with my new torque wrench.

 

I had a persistent leak from the pushrod inspection cover gasket and had used a quality cork gasket. I recently replaced this with a rubber gasket and the leak has stopped.

 

The way I see it if the spark plug well is wet with oil I would think it most likely is coming from above it.


I guess it could blow up there but.......


I have had a valve cover that leaked not from the gasket but the cover it's self.
The washer under the bolt cut the cover and when tighten down it would open up this" cut/crack" and oil would pour out.


The other thing I would look into is the PCV system. If the valve has not been replaced I would even if it rattles as it maybe the wrong one.
Also replace the hose. Some people use fuel hose and it will not hold up to oil. The inside of the hose falls apart closing the hose from working even if the out side looks good.


I would degrease the motor real good, don't forget to do the under side.
Hit any left over areas with brake or carb cleaner.
Run it for 30 min. checking for leaks. If you cant find any take it for a little drive say 5 to 10 miles and check for leaks.
Keep doing short runs/trips checking for leaks, you need to find this before it pools any where as it is too late and will need to clean all over again.
Dave ----

 

Sometimes, the covers, when over tightened, warp. I replaced one, years ago, with good results.

Ford 4.9L 300 CID Lifter Pushrod Side Cover | eBay

Brand New 4.9L 300 CID Ford Lifter Pushrod Side Covers | eBay

The one I used was from the 2nd source.

 

Hey I'm new to the forum but I was reading this thread ( I know it's a few years old) but I've seen some engines get messy towards the back couple cylinders from the dip stick.

 

If it is coming from the dip stick the PCV needs looking at or the motor has a lot of blow by and needs a over haul.
Dave ----