Rear Main Seal question

[rcmaniac791]

So of course, I have an oil leak. Seems normal of a car this old with most original gaskets. I've been milking it for 3 or so years, so I'm used to it. It ain't that bad, so whatever. But I'll fix it one day. I believe it's the Rear main leaking, as the drip comes off the bottom of the trans bell housing, and it's clearly engine oil.

So I started looking at gaskets and seals to see how much they are, and I saw that the rear main on a 318 is 2 piece? Do I have to pull the trans to get to it, or just the oil pan?

Also, when I do this I might as well change the oil pan gasket. Is cork the best option for that? I put cork under the new valve covers and they have been fine.

 

[AJ/FormS]

Before you get all psyched up to drop that pan, you really ought to be 100% sure it's the main-seal. Oil migrating from a leaky oil sender up by the distributor, will find it's way to the very same place. So will oil leaking from the rear china-wall, and so will oil migrating from underneath the dizzy flange. And these are all common leakers.
So the test for this is easy. You just pressurize the crankcase and spray very soapy water on all the suspect areas. When you see bubbles, that is the proof. To pressurize, you need a source of regulated air pressure down to 4PSI-MAX. You also need to plug the valve cover openings. I inject through the dipstick tube.
So once you have proven the main-seal is leaking;
Yes you can change that seal by dropping the the oilpan and then the rear main cap, rolling out the top half and then rolling in the new part. HOWEVER, and this is important, if you are not careful, you may cut that top part during the rolling-in process. To make this easier, I coat the block side of that half-seal with silicon O-ring lube. Then as the seal enters the groove, I keep pressing it onto the crank for as long as possible. If you get it right, it rolls right in. If it stops rolling, STOP! ,back up and start over with more lube. Don't worry about too much silicon-lube. You can wipe off the excess when you are done.And whatever is left over will not mix with the oil. It will end up in the filter before long.
Do NOT lube the block-side of the lower half.You don't want that seal to start spinning in there.Very lightly oil the sealing lip. I mean just a light smear.
The silicon-lube I use comes from Eaton/Fuller. It is used in the rebuilding of RoadRanger Hi-way Tractor transmissions.It is the best!
I am not a fan of old-style cork gaskets. But the newer impregnated stuff seems to work OK. They are a one-time-use gasket tho, so if you have to go back in at a later date,you are buying another.The corners have to be glued on,(3M Weatherstrip glue) and the interfaces have to be daubed with RTV sealer. For these reasons I installed, in my personal vehicle, one of those One-Piece Re-usable gaskets. They are not cheap until about the third install. But no-glue, no-RTV, and re-usable; and a bonus is the torque limiters. Hooray.

 

[BudW]

I might have missed it in the above posts, but the back gasket to intake manifold has a tendency to blow out which can leak oil.

Do as AJ.FormS said and find out, for sure, where the leak is coming from, before tearing things down!

I recommend removing the transmission dust plate. It is not fun for starter and those two struts are in the way, and possibly the engine filter (depending if your car uses the 90’ adaptor, or not).

Once dust plate is removed, look for oil leak trails.

The rear main seal, depending on how bad of leak it is, can coat the torque converter as well as inside part of dust plate, if there is a dark oily powder or tacky like substance in bell housing, then the rear main seal is not the source of oil leak.

A dry paper towel helps. Major oil leaks will appear (somewhat) gold in color on the paper towel.

A leaky engine oil pan will rarely get oil into the bell housing.
A leaky rear intake gasket will rarely get oil into the bell housing, as well will coat the outside of transmission with oil (which also applies to oil pressure senders and distributor O-ring and maybe from a valve cover gasket(s).

I have seen some 1-piece replacement oil pan gaskets for these – but a quick search didn’t find anything.
I am a believer of the “re-useable” gaskets, when they are available. Like this one https://www.summitracing.com/parts/mil-40600/overview/make/dodge
Not a 1-piece, but sill (so) much better than Cork.

BudW

 

[rcmaniac791]

Awesome. Thanks guys.

I was doing some further inspection today (After adding 1/3 a quart. But 1/3 a quart in 1500 miles ain't bad)

There is the drip on the bottom of the trans bell housing. There are also a couple of drips on the transmission pan. It is engine oil, none of the fluid is ATF for sure. Looking at the top of the trans from above, from what I can see, the trans is coated in oil. Now that I'm thinking about it, it seems that the drip on the bell housing runs down from the side of the transmission. I'll have to get the car up in the air to get a better look.

I know it's not the valve covers because I replaced those.

I know it's not the distributor because I replaced that.

I'm leaning more towards the intake, because the intake itself is dry up front from when I cleaned it last year, but the back end of it as well as the brand new wiring for my MSD distributor has a good coating of oil on it.
So if I replace the intake gaskets (which I might do regardless simply because of age) Do I need a certain type of gasket because I still have the EGR, or will something like this work: Fel-Pro Performance Intake Manifold Gasket Sets 1213


I'll still pull the trans dust cover too.

Also, I'll try to get pictures up so y'all can see what I'm working with.

 

[AJ/FormS]

When you had the dizzy out, did you notice an embossed,sorta-flat, metal-ring gasket in addition to the O-ring?

And you are running a PCV, right?
And you are not running an AirGap with Aluminum Valvecovers, right?

 

[BudW]

Sounds like the rear intake gasket. I have seen those in cork, rubber, felt, foam and in other materials.
I don’t think any of them are quite up to the job (IMO).

There are two dowel pins in the middle of front & rear intake pad. If missing one of those dowels, the intake gasket will either blow out or get sucked in. In either case will cause a significant oil leak. I have seen new engines without those dowel pins. I’ve even seen engines come back from machine shop with pins missing.

The gasket needs that pin, for gasket to stay in place!

Also, there are two little fingers on lower edge of metal cylinder head gaskets that need bent into place of the end gaskets, which also tie the end gaskets in place.

On top of that, instructions ask you to place a small bead of sealant on corners of intake gaskets, which also help tie the gaskets in place.

You can see the finger (red circles) holes in both end gaskets (red arrows).

This last one has both the dist. O-ring and gasket (yea!). That gasket is hard to find and recommended to use.
Note: all pictures were swiped from internet.

BudW

 

[rcmaniac791]

AJ, When I had the dizzy out, all I remember was a rubber o-ring. That was on both the new and the original dizzy.

I am running PCV
I am not running an airgap or aluminum valve covers. Chrome, but not aluminum.
Besides the ignition system, the engine is stock.

Pictures to come (hopefully)

 

[rcmaniac791]

Here's what I'm looking at. I will say that I need to replace the choke spring. Mine has seen better days haha.

 

[AJ/FormS]

Is the vacuum advance defeated?

 

[BudW]

Have you performed a Lean Burn conversion? In other words, installed a distributor that has both mechanical and vacuum advance, as well as a bolt on ignition module?
If so, where did you put your module at?


The oil on intake is from valve cover gaskets. When I get a chance, I will add another post on tips for valve cover leak prevention.
I'm not sure if all of the oil leakage is from valve cover gaskets, though.

 

[BudW]

A great video!

Stamped steel valve covers are not very strong. Some valve cover gaskets (cork and others) are soft. What happens to most valve covers is over tightening the valve cover screws will squish and squeeze out the cork material. When that happens, it also bends the valve cover rail.

About 9 times out of every 10 valve coves I remove, the bolt hole area is bent inwards (towards the cylinder head). When that happens, is without straightening the valve cover, the new gaskets will also get squished out and there is nothing on the rails, between bolts, to hold the gasket down.

I recommend to inspect the valve cover gasket surface each time it is removed and using a block of wood and a ball peen hammer, to tap the gasket surface flat the entire gasket area (the bolt holes are the big issue areas). Matter of fact, I like to tap the covers a bit the opposite direction at bolt holes (it will straighten out when tightened).

Next I recommend using valve cover bolts with a triangle shape washer on them (or get triangle shaped washers for existing bolts. This spreads the force around and makes for a better (ie: non-crushed) gasket seal. I have seen washers in chrome before. Most of the newer (pre-magnum) 318’s already use them.

Pic swiped from eBay. Ad said these are from a /6.

Also I recommend using a high quality gasket. Many newer gaskets come steel core and have stoppers that keep a person from over tightening the gasket. Not sure about 318 fitment. Many of the re-usable gaskets which are worth their weight, to use.

Lastly, DO NOT OVER TIGHTEN the bolts! The bolts should be NO TIGHTER than 90 inch pounds tight (about 7.5 foot pounds). My sneezes will over tighten a valve cover bolt!


Aluminum valve covers don’t have this problem – but it is hard to fit aluminum covers on driver’s side because of the brake booster (if you could reach the rear most bolt to begin with).

 

[AJ/FormS]

A great video!

Stamped steel valve covers are not very strong. Some valve cover gaskets (cork and others) are soft. What happens to most valve covers is over tightening the valve cover screws will squish and squeeze out the cork material. When that happens, it also bends the valve cover rail.

About 9 times out of every 10 valve coves I remove, the bolt hole area is bent inwards (towards the cylinder head). When that happens, is without straightening the valve cover, the new gaskets will also get squished out and there is nothing on the rails, between bolts, to hold the gasket down.
View attachment 18924


I recommend to inspect the valve cover gasket surface each time it is removed and using a block of wood and a ball peen hammer, to tap the gasket surface flat the entire gasket area (the bolt holes are the big issue areas). Matter of fact, I like to tap the covers a bit the opposite direction at bolt holes (it will straighten out when tightened).

Next I recommend using valve cover bolts with a triangle shape washer on them (or get triangle shaped washers for existing bolts. This spreads the force around and makes for a better (ie: non-crushed) gasket seal. I have seen washers in chrome before. Most of the newer (pre-magnum) 318’s already use them.
View attachment 18926
Pic swiped from eBay. Ad said these are from a /6.

Also I recommend using a high quality gasket. Many newer gaskets come steel core and have stoppers that keep a person from over tightening the gasket. Not sure about 318 fitment. Many of the re-usable gaskets which are worth their weight, to use.

Lastly, DO NOT OVER TIGHTEN the bolts! The bolts should be NO TIGHTER than 90 inch pounds tight (about 7.5 foot pounds). My sneezes will over tighten a valve cover bolt!


Aluminum valve covers don’t have this problem – but it is hard to fit aluminum covers on driver’s side because of the brake booster (if you could reach the rear most bolt to begin with).

I use those 4 inch long wing-nut MR.Gasket type bolts. I throw a couple of those tacky wingnuts in the tool box, a couple in the car, and the rest go into the back shed,lol. In a pinch, you can put a plier on the splines. Those bolts cum studs, are great anchor points for stuff.

 

[rcmaniac791]

Is the vacuum advance defeated?

If you are talking about the ESA computer vacuum advance, yes, because the computer is not functioning anymore. The new Dizzy has vacuum advance on it.

Have you performed a Lean Burn conversion? In other words, installed a distributor that has both mechanical and vacuum advance, as well as a bolt on ignition module?
If so, where did you put your module at?

I did convert the Lean Burn. I used an MSD Ready-to-Run distributor. It's a 3 wire hook up, so no external module. It has mechanical and vacuum advance though, and it comes with other springs and bushings to change the curve for higher power engines. I'll attach the document of the wiring diagram here: http://documents.msdperformance.com/8388.pdf
It was expensive, but worth it in my mind.

Distributor: MSD 8388 Chrysler 318-360, Ready-to-Run Distributor - MSD Performance Products

I'll also mention that I replaced the feedback carb with a non-feedback Carter BBD. The original one needed a rebuild anyway.

Back to the leaks, I'll have to address the valve covers. I've certainly got seepage from there. Would y'all say that I shouldn't be concerned with the intake right now?

 

[BudW]

Just making sure you have a distributor with vacuum and mechanical advance on it.
You do, so great!
I saw the non-feedback BBD on there, so thought you did is all - but couldn't see enough about the distributor, to know.

I can’t rule out the possibility of intake gasket yet.
Need to fix the “known” leaks, so we can rule out the “unknown” leaks.

I would highly recommend giving the car a good washing before working on it.
BudW

 

[rcmaniac791]

Need to fix the “known” leaks, so we can rule out the “unknown” leaks.

I would highly recommend giving the car a good washing before working on it.

Completely agree.
Also, Oil filter is leaking. Stupid K&N filter is almost 12 bucks. Darn thing shouldn't leak. This is probably why the leak has seemed worse. And I know for a fact that I installed the filter properly.

Might try the Mopar filter next time...

 

[AJ/FormS]

What oil viscosity

My hi-vol pump created a leak at or near the filter with 20w50.With 15w40 it happened at a higher rpm. 10W30 cured it.To this day I cannot say with certainty what exactly was leaking.The filter was never damaged.

 

[rcmaniac791]

Regular old 10W30. Nothing fancy.

More inspection tonight:

- The filter has a drip on it and a run down the bottom. It does have the 90 degree adapter, and that adapter is coated in oil. Gasket in that may be bad.

- Bolts on the dust cover for the bell housing on the tranny are greasy, but do not have active drips. There are visible runs down the passenger side of the tranny, not much dirt build up, only some.

- Driver's side of the tranny is greasy, lots of road grime stuck to it. No visible runs, overall much dirtier.

- up top, the oil pressure sender wires have a good coating of clean oil on them. The plug for my dizzy is oily, but only the side facing the sender. when it was wired, the plug ended up right next to the sender between it and the firewall.

- There is a pipe running on the back of the engine (seems for the air-pump?) The part right under the sender has a thick layer of grease on it and looks wet, like a leak that has been happening awhile. Closer to the driver's side and the brakes booster, the pipe is greasy, but not nearly as coated. This pipe attaches to the back of the cylinder heads I believe.

- Back of oil pan is greasy, front is dry


Final thoughts:
- if the intake was leaking, my distributor would be coated. Everything is clean though. Only oil on intake is from a slight leak from valve covers

- Leak seems to be concentrated on passenger side, closer to where the sender is.

- The leak goes away if the car sits awhile.


Sound like the pressure sender?, Between that and the filter adapter, Those may be it.

 

[AJ/FormS]

It sure does.
The senders for the gauges seem to develop leaks much ,much,more often than the senders for the lamps.It's almost common for them to leak.

 

[rcmaniac791]

Ordered a new sender, Filter adapter gasket kit, and new rubber valve cover gaskets. Hopefully this should do the trick. I'll do some cleaning while I'm at it. Anyone got a good deal on a case of Gunk de-greaser? lol.

 

[BudW]

- There is a pipe running on the back of the engine (seems for the air-pump?) The part right under the sender has a thick layer of grease on it and looks wet, like a leak that has been happening awhile. Closer to the driver's side and the brakes booster, the pipe is greasy, but not nearly as coated. This pipe attaches to the back of the cylinder heads I believe.

They bolt to back side of both exhaust manifolds.

It sounds like valve cover gasket(s), oil pressure sender and oil filter housing seals might fix all of your leaks.

Hard to believe, but even on today’s car, oil pressure senders are still known to leak oil.
In some cases, they come apart which then runs engine out of oil in no time (a potentially very bad and very quick death of an engine – in some cases before you can stop it).
BudW