On my 3.4L DOHC I have a pair of 'rear' valve covers on either side of the engine, because their not equipped with an oil cap I purchased a push-in style oil plug to install in one of the valve covers. The package specified that the plug required a hole with an ID of 1.25" to fit snug. With my drill press and a 1.25" bi-metal hole saw I drilled a hole in the valve cover and using a fine metal file I brought down the flashing around the hole. I went to push in the plug (which required a bit of force) and found that the fit was far more loose than it should've been. I don't want the plug to 'bleed' oil or any contaminents to enter the hole.

Is there a solvent out there or a fluid I can emerse the rubber plug in that will cause it to swell and make a tighter fit?

Right now I have it sitting in synthetic brake fluid, I've heard that works but I haven't noticed an improvement. Lastly I know that in doing so I risk weakening the rubber, any help would be greatly appreciated.

Thank's!

I know a way to make a rubber swell.

quote I know a way to make a rubber swell.

i just had a good laugh at that :P

why dont you just buy a new plug that is atad bigger? i heard of people using ATF fluid to swell up rubber.
ATF - (Automatic Transmission Fluid)

Brake fluid might make it swell

WD40 will do it for you.

Varsol.

quote Originally posted by Justinbart: Brake fluid might make it swell

brake fluid does not make rubber swell thats why its used in brakes!!...not trying to be a smart ass i'm just sayin

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BLUE BY YOU!
NYFOC

quote Originally posted by Hardpact: brake fluid does not make rubber swell thats why its used in brakes!!...not trying to be a smart ass i'm just sayin

Haha I guess it does. Its the contaminates in brake fluid that make rubber swell

Have you entertained the idea of drilling the existing hole 1 drill size smaller and just @^$#........................ wait a minute let me recheck my math on this one. :

Spoon

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Two yeast spent their entire life "about 2 days" discussing what the purpose of life could be and not once did they even come close to the fact that they were making champagne. Quoted by: Unknown

quote Originally posted by Hardpact: brake fluid does not make rubber swell thats why its used in brakes!!...not trying to be a smart ass i'm just sayin

Brake fluid does not make EPDM swell. EPDM isn't used in fuel or oil applications though...

Anyway you can pull the original O-ring and adding an additional flat type O-ring behind it?

Or, and assuming there is some sort of O-ring on the plug, can you remove the O-ring and wrap string in groove.

[This message has been edited by Danny (edited 12-26-2010).]

Thank's for your replies guy's, ya I let it sit in brake fluid for a solid 2.5 hrs and hadn't noticed any swelling. Now I know why! What your saying make's sense.

I considered buying a larger plug but I couldn't bring myself to do it, I'm just too cheap, lol.

Before trying the atf fluid I dug an o-ring outta one of my parts trays. The plug is tapered and by sliding the o-ring over the plug it allowed it to sit a bit more shallow in the hole, and thus futher down on the taper. It seems to fit rather snuggly now. Hopefully it'll stay that way when I add other factors like heat and vibration.

Thank's again guy's!

BTW even if you find solvent to swell the gum at last, you weak gum badly. In fact, if any plastic or gum serious swell, it mark you TADA! finaly destroyed structure of polymers. So, never do this for car parts, you loose resistance for temperature, oil, gas, or everything For toys, garden, some 'visual' parts, maybe, who cares, but re-work on car (or f.e. pipes in house, or similar high cost/low access seals or parts) is too expensive IMO.

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Fiero 1985 notch 2.5 automatic
http://boni.smutek.pl/auto

Motor oil will swell rubber and some plastic....

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(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

If you put anything on it, soon as it dries out it will shrink back up. Putting it in laquer thinner will def swell it up. Why not put a small bead of automotive engine grade silicone sealant in the groove and install it. It will glue it in and seal any gaps.

on any of the engines I've used the aftermarket "Gromets" to use the push in breather, if you put a smear of GOOP on the valve cover & some on the grommit, then install it, it'll never leak. done it many times.

Before you do anything, did you try pushing the breather in the grommet ? It may just be big enough to push the grommet out for a tight fit in the valve cover

something to "think about". if you try to "swell" the rubber, it not only "grows", but it also gets "floppy" & doesn't really hold the original shape & gets "soft".

Im still thinking if he puts in the push in breather, it will be fine. When I put the new valve covers on my Dodge, the grommet was also loose. Soon as I managed to get the breather started in the hole, it was tite enough it needed a rubber mallet to put it in all the way.

a destinct possability !