Drain plug seal/gasket questions

[andymac0035]

My car's oil pan drain plugs, especially the front one, are not sealing properly.

A little background:

-Plugs that were in the car when I got it were overtightened/messed up. They turned hard all the way out.

-Pan threads looked good, so I went and got new plugs. Computer system at said parts store lists a metric-thread plug for a 91' full-size ford.
I did not realize this (or look at the #'s) and just assumed I had the right part. Looking back, I'm thinking since the 4.6 was used in the 91' TC, that might account for the error in the system.

-So, obviously, when I tried the new plugs they didn't fit.

-Stumped (and not realizing my error) I decided to put the old drain plugs back in (stripped as they were, at least they fit) and bring it to the garage around the corner from me.

-They "chased" the threads out and put new drain plugs in, and also let me know that the right size was 1/2" x 20. The also went on to say that my pan was "messed-up" and that they had to tighten the plugs more than they liked to get a good seal, (and they did get a good seal BTW).

-Well I changed the oil early thinking there was probably lots of crap still in the engine from years of sitting. Plugs came out okay and went back in okay.

-I snugged them up real good, being careful not to overtighten.

-Got oil seeping ever so slowly out the front one. The rear one seeped ever so slightly and has since sealed.

-I have tightened the plugs as much as I dare to. The threads do feel a tad sloppy/loose, but they are not stripping, I can "feel" the tension on the bolt head as I snug it down onto the gasket.



Okay.......sorry for the novel.......back to my question.

These are the "help" brand drain plugs and they use a large wide plastic washer with tiny ribs/lines on it.

Garage suggested switching to fiber gaskets/washers and replacing every time I change the oil. (that seems ridiculious to me) (but who knows?).

I picked up a gasket assortment.......AND..... also an assortment of o-rings.
The o-rings are the real fat ones, and I found a size that seams to fit perfect (I brought the metric plugs back for some 1/2x20's for spares).

My Question:

Will O-rings hold up or will they melt??

[1987cp]

Some newer cars do use an O-ring type seal on the oil drain plug. Depending on the composition or the rubber (don't suppose they're Viton? ) and the thickness of the O-rings, I imagine they could very well help.

[Glen]

The O-Rings will work, but, the fiber gaskets will be better.

[Lincolnmania]

yucatechs 89 has metric drain plugs.....skips 90 has std plugs.......really gotta watch the 89 up 302 drain plugs for the right thread

[andymac0035]

I did not know that about some 302's having metric plugs. (good to know)

I don't know what brand these o-rings I got were. I got them at Bonds, which is "parts-master".
They are black in color (I think I've seen red/orange one's somewhere).
Is there like a color-coded heat range for o-rings or something?

As for fiber vs o-ring....the assortment I got has fiber gaskets.....but not as thick/wide as the o-rings are.
So while the fiber (I guess) is tougher, the o-ring seems to fit better.

Which would be the better trade-off?

[gadget73]

I'd take one of those O rings and put it in a small cup with a little bit of oil covering it. Let it sit there a couple weeks and see if it distintegrates or if it remains a normal rubber compound. If it holds up, I'd say use that. Not all rubbers are oil safe, read the warnings on a condom about lubricants sometime.

[andymac0035]

I'd take one of those O rings and put it in a small cup with a little bit of oil covering it. Let it sit there a couple weeks and see if it distintegrates or if it remains a normal rubber compound. If it holds up, I'd say use that. Not all rubbers are oil safe, read the warnings on a condom about lubricants sometime.

I havn't used a condom in years.

Seriously though, thanks, I'll try that.

[gadget73]

I havn't used a condom in years.

sorry for your luck????

[andymac0035]

Haha.....I was waiting for that.

Nope, happily married.....and "snipped".
......Don't miss having to wear those.

[andymac0035]

Okay.......back on topic.....

I've got a couple of those o-rings sitting submerged in a small container of used motor oil.
Be interesting to see if they break down or not.

My father in law also pointed out that if those o-rings were to split apart it most likely would end very badly.....

On a different note.....
I put some teflon tape at the base of the threads of the front plug as well as using a fiber gasket today and so far.....no more leak.

[gadget73]

If the teflon tape seals it, spectacular. If it doesn't, you might consider going to a single oversize drain plug. Sounds like the threads in the pan itself are getting tired if a new standard sized plug feels loose in there.

[andymac0035]

One more thing I forgot to mention.

I was told that the drain plugs weren't going in "straight" and that was why the old ones were messed up, they were overtighening them to get a good seal.

Personally, I thought the guy was mistaken, as it looked alright to me.
But....looking at the old gasket....for being such a large (and wide) one....it was kinda' messed up and out of shape. (probably why it wasn't sealing well).

Time will tell on this one.

[andymac0035]

I'd take one of those O rings and put it in a small cup with a little bit of oil covering it. Let it sit there a couple weeks and see if it distintegrates or if it remains a normal rubber compound. If it holds up, I'd say use that.

I checked on my little O-ring experiment today. (oil change coming up soon).
They were fine. Probably will try them out when I change the oil.

[Smokestacklightnin]

A few years back when my mom had her 86 TC, the front drain plug got stripped out. It was replaced with a rubber plug. Dont know if those are still around, this was several years ago. Cant go wrong with teflon tape.

[andymac0035]

Well, did my oil change today. I tried out the o-rings. I didn't like what I saw and put the gaskets I had been using back in. The o-rings squished out a lot more than I expected. front one was okay, but the back one was odd. It verified for me that the rear drain hole is not perfectly straight. I could see the o-ring being squished out more on one side.

I think the drain plugs out there that use a rubber seal use a harder compound and have a recessed area to hold it in place.