M38A1 wadeing plug caution plate

[Phil4280]

Hi there!

At what stage of production ffor the M38A1 was the brass caution plate above the gauges, to do with the bell houseing wadding plug used?

Thanks!
Phil...

[wesk]

I believe the brass plates were installed in the field no at Willys or Kaiser. The original notice was a decal. The IPL lists no cutoff serial for the decal. It's safe to assume that the plug was never meant to be installed during normal over the road operation since oil leaks would then puddle inside the bell housing. I would assume all M38A1's left willys with the decal. But none left with a brass plate for that purpose.

[Phil4280]

Thanks Wes!

Phil...

[timjuhl]

Hijacking the thread slightly.... I have an oil leak that I believe originates with the engine, specifically the oil pan. I haven't pinned it down exactly and of course the oil moves around a lot when I'm going down the road. Would I be correct that if the leak was associated with the rear engine shaft seal that I could expect oil to drip out of the bell housing if the plug was removed?

Not knowing any better, I've left the plug in. When I did pull it awhile back to check for leaks, it was dry.

Tim

[wesk]

The rear seal is composed of three pieces. Two vertical tubular seals and a crushing type rope seal or garlock seal. If the oil from the rear vertical seals can get past the pan gasket it will leak from the rear edge of the pan. If it can get past the inner edge of the rope seal or the inner lip of the garlock type seal it will run down the back of the block into the bell housing lower area. If the last two type seals were not installed properly they could leak into both areas.

[timjuhl]

Thanks Wes. As I said, nothing dripped out when I pulled the plug awhile back. I'm going to remove it (and leave it out) and see if that is still the case.

I looked at TM9-8014 and couldn't find where it went into any detail concerning the seals you discussed. That said, I suspect that the only way to inspect or replace the seals would be to pull the engine.

You said "If the oil from the rear vertical seals can get past the pan gasket it will leak from the rear edge of the pan." Does that mean that if oil appears to be coming from this area that carefully resealing the pan might stop or at least diminish the leak?

Finally, are the aforementioned seals ever known to fail in a catastrophic manner or do they just slowly increase to the point where they can't be ignored?

I'm a retired teacher so I know what it is like to be asked the same questions over and over.... I appreciate your patience and willingness to share your knowledge and experience.

Tim

[wesk]

Look in my photo albums in the album L134 & F134 Crank rear seals:
http://www.willysmjeeps.com/v2/modules. ... _album.php

The seals can be changed (often unsuccessfully) with the engine installed, oil pan removed and tranny lowered, but trust me when I say you only want to do this once so removing the engine will insure you do a good job the first time. Also the removal opens the rest of it all to a thorough inspection, again saving another recent removal requirement.

If the oil is getting past the flat cork or composition pan gasket then yes you may be able to stop it but you must do a good job on the pan gasket and correcting the dimpled effect of the bolts on the pan's bolt hole areas.

The leak will become very noticeable before a catastrophic failure occurs where they seals have been there a long time. Where the seal was replaced in the last year I would be cautious since there are bad seals being sold (from stocks produced late 80's thru the 90's) that are too tight on the crank journal and overheat and cause failure of the rear most bearing.

[timjuhl]

Wes,
My engine was rebuilt probably around 2008-9 by a mechanic who worked for a Jeep dealership. Looking at the pan, I think he sealed it using permatex ultra grey oil resistant silicone... at least that's what I think I see around the lip. I'm going to contact him and see what he did with the rear seal.

The Jeep starts and runs good and has great oil pressure. I've put close to 4000 miles on it since I got it in mid 2011. During that time it was down for 11 months while I restored it, except for the engine which I thought was good to go. I've been keeping a close eye on fluids and if I fill the oil to the top it uses a quart of oil every 200 miles or so, although the drip matt under the engine only shows a few small spots after each run.

I suspect the pan may be dimpled around the bolt holes and who knows what else is going on... until I pull it off I'm just guessing.

I know it's been asked before but what would you recommend for a gasket and sealer for the pan?

Also, in researching the subject I came across this on the CJ3B site. Are these items that need to be replaced when the pan gasket is replaced or are they parts of the seals we've been discussing?
http://www.film.queensu.ca/cj3b/Photos/ ... Leaks3.jpg

Thanks for any advice you can give or any sites you can point me to that would help.

Tim

[wesk]

Most of the young techs today are just like the young doctors (young means 50 and under) whatever the media salesman shoves in their face they have a tendency to use and pass on to the customer. I have been installing gaskets on engines and components since about 1960 and the only time I use any sealers or adhesives is when the manufacturer of the gaskets recommends it. If no directions to add any additional sealers comes with the gaskets or in the jeep service manual then they go on dry. 95% of the gaskets produced on this planet require no extra goodies to help them seal any better. In most long or complex gaskets installs the tech uses the extra sealant or adhesive to hold the gasket still because it's easier than farting with the gasket or using thread to tie the gasket still at a few bolt holes and then cutting the thread. As a basic rule RTV's have no business anywhere on an engine where they can creep into the oil system.

1 quart per 200 miles and you are making 1000 miles a year means you do a proxy oil change every 800 miles!! Your rings should be seated by now and your oil consumption should be much better than 200 miles.

Any quality US made gasket is fine.

They are the two tubular vertical seals I mentioned that come with the rear main seal. They seal the sides of the bearing cap to the block.

Rear seal leaks are under pressure leaks and they do their serious dripping at highway cruise RPM's and drip very little in the driveway while sitting.