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Discussion Starter · #1 ·
I had forgotten just how much of a challange it is to change the rear main seal of a SB with the engine still in the car. The rear main seal on my son's virgin 68 307 has been leaking severely. The mounts must be unbolted and the engine raised as far as possible (and then some more) to get the pan removed. I placed the car on stands, then used a hoist to lift the engine from the front. It has been many years since I have changed one in the car. Be sure the crank is rotated so that the forward counter weight is in the up position. Otherwise, the front of the pan will not clear the counter weight. The way to tell if the crank is in the correct position is to have the timing mark pointing down. After lifting the front of the engine with a hoist, I also had to place a bottle jack under the balancer to raise it just a tiny bit more for the pan to clear. Once the pan, pump and rear cap were removed, I loosened the other main caps to allow the crank to drop just a little to make it easier to remove the seal. When a seal has been in an engine MANY years, the upper half may be stuck pretty good, as this one was. It took some digging and persuading with a long thin screwdriver to get the upper half to break loose and then slide it around the crank.
As I recall, this cannot be done with a BB in the car. The engine must be removed. Has anyone been able to remove a BB pan with the engine in the car?

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Tom Parsons
 

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Tom, I had an awful vision of wallowing around under that chevelle doing the job you described. Maybe it's just me, but I have enough trouble sealing the bottom of engines with 'em on the engine stand upside down right in front of me. I'd be afraid of making more leaks. Backing off main caps and letting the crank drop down some is scary to me too--hope all the bearing shells stay put. I ran some kind of seal softener magic fixer goo in the oil in a 350 in an old Monte that was leaking bad that had sat for a long time. I'm not sure if it was the softener or just the running stopped it, but it's still pretty dry. Might be a few things you could spiffy up if pulled the engine and resealed it.
 

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I've never pulled the pan on a BB Chevelle with it in the car, but have done it on the 68 427 Biscayne and one of the 69 427 Corvettes. The Biscayne required dropping the drag link. It was a barrel of laughs just trying to find a pan that would work. The one with the car was too rough to use when I bought it. The one GM says will work wouldn't, assuming I wanted a stock drag link. A call to Milodon's tech line produced another one that wouldn't clear and finally a BB Nova pan was required. THEN, after all this pan changing, I've got an oil leak, so off again. Fel Pro now makes a one piece oil pan gasket that I'm sticking on this time to be through with it.
 

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Discussion Starter · #4 ·
My son and I are off the rest of the rest of the week. We have some errands to do this morning, including getting parts. I've never had a problem getting a pan sealed in the car, but sometimes the new rear seal doesn't seal good. We've pulled the pan and replaced the rear seal in a 400 in another son's 66 pickup 3 times, still leaks!
We may have it done tonight or tomorrow, and I'll let you know how it turns out.

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Tom Parsons
 

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if it helps,fel-pro makes a double lip seal to help those leaky problems i don't remember the number but advance auto carries them in stock!
JIMK
 

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Tom . BTDT on SB but not on BB !!!
As for the Frequent Leak'rs. A trick I learned many years ago is.
After you rotate the top seal into position
do not push it flush with the block, let it extend 1/4 in. below the block. On the cap side let it prodtrud the same amount on the
oposite side.
I then install the cap making sure the seal is not damaged or tore.

Have fun

Wayne
 

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Discussion Starter · #7 ·
Well, it's a done deal. Everything went back together just fine. We ran the engine for a while and no visible leaks. Tomorrow we'll road test it.

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Tom Parsons
 

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Tom. Chilton's 64-71 repair manual says for oil pan removal - inline engines - 64-68 Chevelle, 1969 Chevelle w/standard transmission. Step 1 - Remove engine from car.

For 64-68 V8 Chevelle (no distinction between sbc and bbc), "This procedure is the same as that for 1964-68 Chevelle models with inline engines.

Sounds like you just did what Chilton's says can't be done (or at least recommended)
On 69-70 it says you can drop the steering, yada, yada, yada, and "Rotate crankshaft until timing mark on torsional damper is at 6:00 o'clock position." I would think if you can get the engine up high enough, drop the steering linkage, and set the crank correctly one should be able to pull the pan on 64-68's as well. (?)


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Dale McIntosh
TC Gold #92/ACES #1709
67SS & 67 Elky
Dale's Place
Team 67
Integrity: If you have it, it doesn't matter - If you don't have it, it doesn't matter.

[This message has been edited by Dale McIntosh (edited 12-27-2001).]
 

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Discussion Starter · #9 ·
Dale,
I knew this could be done in the car, because I have done it before, although, the last time was several years ago-----------and ALWAYS on SB engines. As far as I know, engine removal is necessary with a BB.

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Tom Parsons
 

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Discussion Starter · #10 ·
It has about 60mi on it now and its as dry as a bone.

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Tom Parsons
 

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Tom, I know I had to remove the engine from my 71 to get the pan off (big block) and I tried every trick in the book to get it moved around enough...no good, all that time pushing and pulling, I could have just had the engine out in half the time. I think you're right about that. But congrats on the "no more leak" John
 

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Thanks Tom.

I just did a TC search on "rear main" and found your story. I didn't think it was realistic to replace the rear main on the car, even though the factory Chevy service manual says you can. You've given me the inspiration to try this on my '70 Malibu when the weather warms up a little. (20 degrees outside right now
) It does look like alot of work though.

Can you please share a little more about the prep work you did to raise the engine? For example, did you have to unbolt the transmission mount? Linkages? Fuel pump? Mine's a 4spd so I also have to worry about the zbar.

Thanks,
Tom K

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TC Member #59
'70 Malibu 350/4speed
'90 John Deere SS165
 

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Discussion Starter · #13 ·
Tom,
You need to let the car sit for 2-3 days so that as much oil as possible will drain down from the upper engine. Otherwise, you will continually have to deal with dripping oil when you remove the pan. This gets old in a hurry.
BEFORE YOU DO ANYTHING------------turn the engine so that the timing mark on the balancer is straight down-----------this places the counterweight on the front of the crank up into the engine for pan clearance.
Yes, I did have to remove the fuel pump, but only because the long engine mount bolt had been installed from the front (on the right side, the long bolt should be installed from the rear).
I unbolted the ex pipes from the manifolds because the right side pipe hit the floor pan before I could raise the engine high enough.
In the past, I have always removed the dist so that it didn't hit the firewall. This time I ONLY removed the cap, PLENTY of room!
Make SURE the rubber PS hose has enough slack, otherwise, you may need to undo it from the steering box.
Yes, for a manual tranny car, you will need to undo the Z-bar.
I placed the car on 4 stands. I have an overhead hoist which I used to lift the front of the engine. I lifted with a chain across the 2 front manifold bolts (used longer bolts). When I lifted the engine until the car began to lift off of the stands, it was not quite enough to clear the pan. I placed a bottle jack under the harmonic balancer, and got just enough more lift for the pan to slide out (actually it surprised me and almost hit me in the face).
I have always loosened ALL the main caps to let the crank drop just a little extra so that pressure is reduced on the upper seal half. If you have the original seal in the engine it may take a little persuasion with a long, very thin screwdriver to jiggle the upper seal loose so that it will slide around the crank. Once you get it to move a little, you can grasp it with needle nose pliars. After removing the seal, I used compressed air to blow away any particles which may have remained above the crank (you just cross your fingers on this one). I'm sure you know it is recommended to place the seal halves so that the parting lines of the seal are offset from the block/cap.

LAST OF ALL, TRIPPLE CHECK 16 TIMES TO BE SURE THAT THE SEAL LIP IS IN THE RIGHT DIRECTION!!!!!

While your're there, you might want to replace the motor mounts.
I DID NOT undo the tranny mount.

TAKE YOUR TIME GOING BACK TOGETHER. CLEAN, CLEAN, CLEAN THE GASKET SURFACES. Something like lacquer thinner or brake cleaner is good to use. I glued the new side gaskets to the bottom of the block. I used a LITTLE Ultra Copper RTV on the ENGINE side of the front/rear pan seals, then, I used a heavy bead of RTV on the pan side of the front/rear seals and at the corners. If you are bothered by an excess of RTV squeezing out, you can trim it off a few hours later after it sets up.
On this engine, the only real problem that I encountered was getting the second motor mount long bolt through the mount holes. Finally got it. This was all done in one day with my 16yr son as a helper/gofor.
The engine probably has 200-300mi on it since my first post and it is still bone dry!

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Tom Parsons
 

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Tom,

You are great. Thanks for taking the time to explain things in such detail. I'm much more comfortable with it now. Yes, I am aware of installing the seal with the parting lines are offset. And your advice about letting the car sit for a few days to let the oil drain is excellent.

I'm glad it worked out for you. Hopefully it will for me too.

Thanks again.
Tom K
 

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The one piece gasket 2blueLS6"s describes is excelllent, and really easy to use. I don't know how it would be putting it on in the car but I would not use anything else on a new motor. Just too simple.
 

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I did it on a V8 Vega once without pulling the engine. I hit a pothole that busted the oilpan, so I had to pull the pan to straighten and weld it. That was lots of fun!
 
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