The mystery of the 308 oil leak

[usgrant7]

It's been a while since I've looked at this, but I have a pretty good oil leak. I'm running a 308 / 6. The leak does not seem to be coming from the frone main bearing (shaft comes out the timing chain cover). Rather, the leak seems to be coming from the front of the oil pan. Why this is the case seems strange. Why would there be a seal there, apart from the pan gasket?

I seem to recall that there are 2 larger bolts right up in front, next to the pan bolts. When removed, oil comes out.

How do I fix this? What is causing this leak? I'm trying to imagine why there would be oil in the bolt holes.

Can someone point me to a drawing?

Thanks;
-Chris

[`Hudsonator]

Those two bigger bolts are actually your front main bearing cap bolts. Why Hudson placed those outside of the oil pan - I'll never know. My Super Wasp also leaks out the front. Since I'm building a new 308 for the '49, I thought I'd do a little looking around. If you loosen them, be sure to torque them back to specs.

The front camshaft bearing has a groove cut into it that sprays pressurized oil towards the timing chain that is in addition to the oil that would normally weep from the bearing circumference. This is fine and dandy, but if you have good oil pressure, you are spraying alot of oil into the timing cover. The drainback hole from the timing cover back into the oil pain is kind of small, and located a tad high. I was given a tech article by Terraplane Kelly that addressed this by drilling an additional hole in the front main to help drain more oil back into the oil pan. This new hole is to the right of the main centerline and further down.

I'm pretty sure my Wasp is leaking oil from between the engine block and the front engine plate (motor mount plate). Or, from between the plate and timing cover. However, I'm going to say that its due to an excess of oil staying pooled in the bottom of the timing cover.

There is a dang good chance that a stepdown engine could leak from around the main cap bolts also. May want to retorque those and see if it helps.

That's my 2 cents.

Mark

[Billy K.TN.]

Mark and USgrant. Mark if you have pulled the main caps notice the drilled holes In between the caps and block both front and rear and also holed from front to rear on each. These holes must be packed with something. I use string from a cotton floor mop and drive the string into the holes really pack it in after tightening the caps to specks. Hope to see you in Murfreeboro. BK.TN.

[`Hudsonator]

Mark and USgrant. Mark if you have pulled the main caps notice the drilled holes In between the caps and block both front and rear and also holed from front to rear on each. These holes must be packed with something. I use string from a cotton floor mop and drive the string into the holes really pack it in after tightening the caps to specks. Hope to see you in Murfreeboro. BK.TN.

I know the packing you are talking about, and that may very well be the problem with the Wasp's oily front end. I hadn't thought of that, Thanks!

BK is the voice of experiance, and I listen.

See ya in Murfreesboro - its on the calendar.

Mark

[usgrant7]

Mark and USgrant. Mark if you have pulled the main caps notice the drilled holes In between the caps and block both front and rear and also holed from front to rear on each. These holes must be packed with something. I use string from a cotton floor mop and drive the string into the holes really pack it in after tightening the caps to specks. Hope to see you in Murfreeboro. BK.TN.

Wow, excellent! I don't have to buy a seal or drop the pan? Sounds good to me. :-) My Hudson leaks so much oil, Dick Cheney sends me a love letter every time I turn the key.

So what torque should I tighten the bolts to? I seem to recall an old Hudson manual talking about driving wooden dowells into these holes. I guess now I know what that book was talking about.

I'll check the rear as well. I'll bet its been leaking for years too.

-Chris

[Ron P]

I have a 29 Hudson with the same problem of leaking oil from the same place. Do you know if the 29 has the same set up with the holes that need packing ?? Thanks Ron

[Billy K.TN.]

Dont know about the 29. But you will have to pull the pan to pack the holes in caps.

[russmaas]

Filling the holes with RTV is a better solution than the string. Also when you put the string in it has to be pounded in and some people believe it causes stress to the bearing and may change the line bore ever so slightly

[usgrant7]

Filling the holes with RTV is a better solution than the string. Also when you put the string in it has to be pounded in and some people believe it causes stress to the bearing and may change the line bore ever so slightly

Excuse my ignorance; RTV? What? Where? :-)
Also, will I have to drop the pan on a 308?

-Chris

[mars55]

RTV is silicone adhesive sealant. Made by Permatex and every other sealant manufacturer.

[TwinH]

OK,here's a pic of a 308 front main cap for a visual. (upside down)


http://i15.photobucket.com/albums/a353/Ramblur/Hudsonjan06017.jpg

[usgrant7]

Filling the holes with RTV is a better solution than the string. Also when you put the string in it has to be pounded in and some people believe it causes stress to the bearing and may change the line bore ever so slightly

I wonder why the holes are there to begin with. Does the thing you shove into the holes form part of the bearing?

-Chris

[TwinH]

I believe the "holes" actually keystone shaped slots in the main cap are
there to keep oil from seeping between the main cap and block any farther than
the timing cover. There are two more packings (not seen in the above pic) that
are under the oil pan rail and run vertically on the sides of the main cap and
intersect the packing slots seen in the pic. Between the two of them they seal
the crankcase from the exposed part of the front main cap. Hope that helps.

[alexa]

Wildrick builds a lot of these engines and he told me not to use RTV by itself in this area, it will start leaking in a short time. He said to put a small amount of permatex ultra in the slots, then pound in the yarn from the gasket set until you saw the permatex coming out. I did as directed and it seemed to work.