How Much Pressure/Heat Is In The Oil Pan When Engine Is Running

[lumina]

Hi All,,,

Symptom: Very small oil leak from the port engine oil pan drain plug, maybe 4 drops a day.

Cause: Port engine oil pan drain plug was cross threaded when work was done. (Believe me it's an ugly story and you don't want to know).

I can remove it but was wondering what my options would be.

1. I could try and re-thread the pan and put a new plug in.

2. I could re-thread the pan and try and re-thread the plug with a whatchacallit and try re-insert it.

Thinking about it I was wondering if there is minimal pressure and moderate heat, maybe I could use plumbers tape on the plug ?

[Avenger]

Watchacallit = HeliCoil. That's the best possible fix, but difficult to do in situ.

I'd avoid the plumber's tape if possible. If any of it gets loose, and it has a tendency to do that, you don't want it getting into the oil system. Probably your most practical option is a new plug and carefully chasing the threads in the pan with a tap or thread chasing tool.

FWIW, sealing isn't accomplished by the threads, it's the surface of the plug head and the surface of the pan. Usually there's a copper washer between there. If copper doesn't work I'd try to find a softer gasket material like a nylon washer.

Oil in the pan should be near coolant temperature and the pressure would be crankcase pressure (should be minimal) plus the column of oil in the pan. IOW, not much.

[rsmith]

Watchacallit = HeliCoil. That's the best possible fix, but difficult to do in situ.

I'd avoid the plumber's tape if possible. If any of it gets loose, and it has a tendency to do that, you don't want it getting into the oil system. Probably your most practical option is a new plug and carefully chasing the threads in the pan with a tap or thread chasing tool.

FWIW, sealing isn't accomplished by the threads, it's the surface of the plug head and the surface of the pan. Usually there's a copper washer between there. If copper doesn't work I'd try to find a softer gasket material like a nylon washer.

Oil in the pan should be near coolant temperature and the pressure would be crankcase pressure (should be minimal) plus the column of oil in the pan. IOW, not much.

Most Detroits are NPT drainplugs

[Boatsb]

they are right. The seal is the copper washer. Sometimes the flat part of the pan where it seals is gouged and needs to be cleaned up.

[sandspur1966]

they are right. The seal is the copper washer. Sometimes the flat part of the pan where it seals is gouged and needs to be cleaned up.

What he said... If it were me I would live with it using diapers until the next oil change and then carefully work the plug in and out a few times. I would use some emery paper to clean the face of the pan around the plug and install a new plug and washer.

I would definitely NOT use Teflon tape... perhaps some Loctite 565 course thread sealant, they make it in a low-strength formula (link below) that wont lock the threads but will give you a better seal.

http://useloctite.com/products/produ...ealing4c67.php

[Avenger]

Most Detroits are NPT drainplugs

If that's the case, then Gene can chase the threads and use some liquid thread sealer or Loctite.

Can't say I've seen a lot of pipe plugs on steel pans, but a cast pan or a pipe thread bung welded in....

So Gene, pipe or straight thread?

[rsmith]

I just changed my oil mine are NPT although I have a oil change system I found when I rebuilt the engines there's a forward plug that holds almost a gallon of oil ahead of a divider in the upper pan. I would bet the 8/71s are the same.

[lumina]

Hi All,

Thanks so much for the quick feedback everyone.

I will check tomorrow, I haven't taken it out yet. It's attached to the oil changing unit.

I gotta tell you guys what happened......I was in a pinch and let someone else replace the ss hose clamp between the plug and the oil changer. I had an oil change planned and the clamp was on the maint list.

A week later I noticed a little puddle of oil under the port engine. Both engines are, believe it or not, pretty tight for old DD's, so it stood out.

I got my old arthritis laden spine down in there with a flashlight and you will NEVER guess what I saw. The drain plug was completely covered in gobs of marine-tex. I freaked out. Called the guy, had a "discussion". Seems he thought he cross threaded it so he "sealed" it to prevent leaks. There was no reason to remove the plug at all, but he did...... ahhhhhhhh.

Thank god he didn't prepare the pan well (left some oil) so it didn't bond to it, hence the drip. It took 3 days to slowly carefully remove the marine-tex using dremels, blunt chisels, from the plug, nipple etc etc.....

That'll teach me to let family do me a small favor.

[Paul Gwiz]

Now some good news , I have heard if a Detroit isn't leaking oil , It's not running Right.........

[lumina]

Hi All,

Oh they weep, but in comparison to several of my friends motors (who keep big rectangular pans under them to catch the oil) we're pretty pretty tight !!