360 oil pan gaskets….One piece, 4 piece??

[Kern Dog]

I’m curious about the differences in oil pan gaskets for the 360 engines.
A friend here is building a 408 based on a 2001 casting 5.9 that was a Mopar Performance crate 360/380. The oil pan on it is center sump for use in cars.
The gasket kit he bought is the Fel Pro 260-1723 which translates to the following..

The oil pan gasket is a light blue rubber or silicone one piece design…

That looks really slick. I didn’t tear down the engine so I don’t remember what the old gasket looked like but this looks great.

Does anyone know if these one piece gaskets fit older 360 blocks and pans?
I remember that the 360 pans have a smaller rear oil seal than the 273-318-340 which I find to be strange.

 

[Kern Dog]

This one seems to fit this pan.

It does do away with 4 potential leak points.

Since this was an MP “Crate motor”, I don’t know if the oil pan was an in house MP reproduction or another aftermarket manufacturer like Milodon.

The steel liner and embossed rings are a nice touch

The big question is… have we stumbled onto a great discovery that you already knew about ? Is this gasket already a common fix for leaky 360 pans?

 

[abodyjoe]

i used a one piece on my 360.. holy crap did that thing leak.

 

[67Dart273]

My memory is foggy. What I THOUGHT those magnum gaskets did, when used with an LA pan/ timing cover, was left a gap in the cutout near the pan rails that had to be stuffed with silicone.

EDIT. Now I remember. Look at the right side of the photo, the front of the pan. See the "steps" at the cutout where it meets the pan rail? That is an LA pan and the Magnum gasket will not seal there--without silicone

 

[Kern Dog]

Ooof. That sucks!
I guess we will find out tomorrow when he comes back. I wonder what is different compared to a genuine Magnum pan. I know the sump is at the rear but is there something different at the gasket point?

 

[67Dart273]

I'm sure I have some Magnum pans..........."somewhere," but they are completely not accessible. I'm pretty sure it has to do with those "steps" at the front of the pan half moon cutout.

Somebody posted a long while back, you can use the Mag pan if you pump that gap full of sealer. I have never yet installed the engine, (house fire) and I believe I used "right stuff." Not sayin' that is the "right stuff," LOL

 

[Professor Fate]

Yes, the pans are different at the end seal. the Magnum pans do not have those "steps" that 67Dart273 is referring to.
To use the one-piece gasket, you need to pump those "steps" full of RTV (gray or black) and then install the gasket. Or just use the LA 360 gasket set. Not a biggie either way.

 

[Mike69cuda]

I tried the one piece gasket with no success and gave up. Seemed like I couldn’t get it to fit everywhere at the same time. Maybe it was just me.

 

[Kern Dog]

I’ve been there too, Mike.
Most of the time when I have trouble with a part, I wonder what the heck i am doing wrong.

 

[Desoto291hemi]

The 1 piece gasket is the best thing Chrysler ever did,,,(,at least as far as pan gaskets go .)
You put a dab of sealer in all 4 corners , and it will seal perfectly.
Yes,,,,,the 360 /Magnum engines are different than the LA 318/340 pans .
The rear main cap was changed when the 360 was introduced .
And all Magnums use the same rear pan seal size,,,so the 1 piece fits all Magnums .
Tommy

 

[Demonx2]

This one seems to fit this pan.

View attachment 1716408161

View attachment 1716408162

It does do away with 4 potential leak points.

View attachment 1716408163

Since this was an MP “Crate motor”, I don’t know if the oil pan was an in house MP reproduction or another aftermarket manufacturer like Milodon.

View attachment 1716408164

View attachment 1716408165

The steel liner and embossed rings are a nice touch

View attachment 1716408166

The big question is… have we stumbled onto a great discovery that you already knew about ? Is this gasket already a common fix for leaky 360 pans?

The "embossed rings" are compression limiters to get the correct compression on the RTV/silicon portion of the gasket.

 

[remytherat]

I'm using the one piece gasket on my 5.9 with a 360 oil pan and early timing cover. Just filled the gaps with silicone and it hasn't leaked a drop.

 

[67Dart273]

AN ANNOYING STORY FROM the old days

Back sometime in the late 70's I stupidly decided to sell the 70RR. I had swapped in a 340, but wanted to drop that in my beat up old FJ-40 Landcruiser, which at the time had a 360

No pan? No problem. I had a 360 rear sump pan which I needed for the 340--to--be in the FJ-40, and I needed a front sump pan for the 360-to-be in the RR

So I made a jig to bolt to the rear of the pans and produce a cut line around the rear cut out areas of both pans, and then bolted them, one at a time to the spare block. Swapped the pieces cut out of the rears of both pans, gas welded them back in. Used a little silicone, and off we went.

This of course is in a small N Idaho town, and no internet then, so parts were not really plentiful, least of all a 360 front sump pan!!!!

 

[Bobzilla]

Here is a thread with some good pictures and descriptions of the differences.

Magnum Oil pan/gasket fitment issues

 

[jbc426]

If your pan has the steps at the timing cover seal, you can flatten them out with a hammer and dolly to allow seal with the one-piece Magnum gasket on the LA oil pans. Verify the size of your rear cutout. I still use Ultra Seal on the corners.

 

[Kern Dog]

Thanks, John.
That oil pan looks like it still has the notches in it.

 

[Uncle Bob]

I used one of these on a 360. I siliconed the living daylights out of it. No leaks.

Milodon #41007 One-Piece Oil Pan Gasket

 

[autoxcuda]

Magnum 360 one piece gasket will not fit an older block and pan. I learned the hard way.
Like was said the corners are way off.

And the rear does not accept the older pan profile correctly. It just pushes out.

Mine leaked like the Exxon Valdez for years until I took it apart and put the original style in.

If you got your heart set on it, just cut the side rails to mimic the cork ones. Of course that’s back to a 4 piece.

 

[1969reddart]

I used one of these on a 360. I siliconed the living daylights out of it. No leaks.

http://[URL][URL]https://www.manciniracing.com/mionoilpanga.html

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I used one as well. 360 LA - No leaks…

 

[hollywood hig]

I used one as well. 360 LA - No leaks…

View attachment 1716409409

I used a one piece fel pro gasket meant for a 2000 Dodge 360 magnum like the one kerndog had on my 75 360 la, fit perfectly, no leaks.
This solved an ongoing problem I had finding the traditional gasket with the proper rear rubber seal, all the ones I encountered the rubber seal was a quarter inch too long and would squeeze out when tightening down the pan. Problem solved
Thanks for the info guys!

 

[YY1]

Just an aside, but-

The four piece Fel-Pro gasket I used for my 318 had the holes for the first two bolts in the front, off by about 1/8 and then 1/4.

If I had assembled them without reaming them, it would have made the gasket bunch up (I dry fitted it) right where the rubber seal overlaps.

IMO it would have been sure to leak.

Easy fix, if you catch it, though.