Stop Oil From Leaking from Aluminum Vavle Cover

**keith460** · 12-03-2009, 10:48 PM

OK guys, I was going to start a new thread on this subject but I think everyone has been to this one before including myself. I too have the Alum. Valve Cover and think the oil cap sucks big time and have read the complaints on this forum and others about the oil leakage that seams to happen with these push in type rubber plugs. So, in order to prevent an upcoming oil leak on my nicely powder coated valve cover and engine, I decided to do a little R&D work to fix this problem before it starts.

Some of the submitted ideas are on the right track but I decided to clean them up a bit and keep cost to a minimum. We basically need two items to purchase to solve this leaking problem around the oil fill hole and two suppliers have what we need on the cheap. First, head on out to your local Ace Hardware store and get yourself a rubber expansion plug from the nuts and bolt aisle.

Cost: $3.75 and it is for a 1-1/4" hole

Next, go online to McMaster-Carr.com and purchase a threaded knob with a 5/16-18 threaded hole. I picked out five that will work and are ideal for gripping but the choice is up to you. Here's some pics of what I have picked and the part numbers are located on each drawing in the lower right-hand side.

Cost: Anywhere from $1.00 to $4.00 + shipping.

Most of the knobs shown, if not all of them, have a temperature range from -15° to 200°F. I chose the first one pictured but probably will try the second one and last one pictured as they look more like something you would find under the hood and they have a larger diameter for gripping. Will post later on with pics when I receive them.
We now have our two products and no modifications are need except to remove the 5/16" nut from the rubber plug and use one of the knobs in its place.

Now the new plug is ready to install and the top washer prevents it from falling inside the valve cover. I think it would be a good idea to actually glue the washer onto the rubber so in case you loosen the knob to much, the rubber won't fall below the rim of the valve cover. The threaded stud through the rubber piece has a long square shank like a carriage bolt and doesn't fall out unless you push on it so I don't think that would be a problem. Plus, there is an o-ring at the bottom bolt so no leaks can come from there either.

Here's a pic or two of it installed.

That's it and as always, comments are welcome, both pro and con. Hopefully we can get this problem resolved as I cannot give a review if this works or not as my Jeep is still under construction. But tightening that knob by hand until it stopped sure beats the hell out of popping in a cheesy rubber thingy. I tried to pull it out without loosening and it didn't move at all....that's a good thing.

cruiser54 · 12-07-2009, 07:39 PM

Alot of heavy equipment uses that type of expanding filler to keep dirt out. I wonder if you could get one off the shelf, but it wouldn't look as nice as the one you made.

**Zeep** · 12-08-2009, 05:36 AM

The first pic of the engine, looks like your doing a 100 pt. restoration?

**keith460** · 12-09-2009, 05:39 AM

No, just my hobby and fun for me to do.

fredrok · 11-24-2010, 04:18 PM

I recently got around to doing this mod after remembering it some time ago. Thank you Keith for the idea and information.

FYI. I have 2 things to add: first off, my Ace Hardware also had the exact knobs on their nut/bolt shelves. They were $4.99 so maybe that comes out about the same as ordering them? Dunno, but it's less of a hassle I guess.

Second, at least with my valve cover, the 1 1/4 expansion plug is the correct size but a snug fit even before cranking down on the knob. It was difficult enough just pulling it back out after trial fitting that I imagined after being installed for some time, it's likely the expanded rubber portion may develop a "lip" just under the valve cover and make it quite difficult to remove down the road.

Not sure if it's just my particular valve cover, but I'm going to experiment with slightly tapering the portion of the rubber plug that will be inside the cover to make it less prone to expanding larger than the hole size and thus making it difficult to remove.

**keith460** · 11-24-2010, 04:31 PM

I thought of tapering the rubber plug as well since it makes total sense that it would become oil soaked over time and expand some.
Good idea and I may do the same after my Jeep CJ is up and running next year.

**Cutlass327** · 11-28-2010, 03:20 AM

Check at your local truck stops or heavy equipment supplier. The Caterpillar and Detroit engines all use something similar. It isn't as fancy, and is a little longer so check valve rocker clearance, but it'd work in a pinch or if you have to order the parts listed in the OP's post. I do like his - looks nicer than a T-handle..