regasketing 454

Ok, still on my first pass through the 89 gmc 454/th400 i bought, 124K on it. Running real good now, next on my list is leaks. It's leaking oil, and from what I've been able to tell it looks like it's coming
from either the oil pan gasket or rear main seal. From the book I have to lift the engine to do the oil pan, and might as well do the rear main while I'm in there. My question is, if I'm going to go to that much trouble, should I just drop the 120 bucks and get the master gasket set, and do the TBI, intake, heads, valve covers, waterpump, etc etc etc.
My other leak is the front diff, from what i've read it isn't worth the trouble, but i'm gonna attempt it anyway, as i can't stand a truck that leaks anything....
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pulling the engine, or dropping the transfer case and then the tranny. In rare cases you may be able to drop the drive shaft, unbolt cross member for frame, tranny from engine and then with a floor jack adding support slide the tranny/transfer case back far enough to get access to the rear main seal. If its the rear main you should being seeing pretty hefty oil loss. I have seen valve covers leak down the rear of an engine as well. If you pull the engine, along with the oil pan and rear main, might as well replace the freeze plugs as well.
Whitelightning
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Ditto the above. Look hard at the rear of the valve cover gaskets.
Al
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Thanks guys, will definitely take a look, i got under there today with some degreaser so hopefully i'll get a better idea where it's coming from when it leaks again, i'll go check the valve cover gaskets too.
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Don't see any oil coming from the valve cover gaskets, on the driver side, the oil filter adapter may be leaking where it goes into the engine, the other place with oil all over it is the starter and the torque converter cover, that's where it seems to be dripping from, so it looks like it's leaking on both sides... the front of the oil pan definitely looks like its leaking too.
Instead of raising the engine wouldn't it be easier to just drop the front diff/tube? My factory man says to raise the engine, but that seems like a lot more work. I have to do the seals on that anyway, so I guess I may as well just do it all one shot. I actually had a parts guy pull the rear main for me and it's definitely one piece so I guess at least that's good news.
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How long since u Changed the PCV valve.. if it is Defective, Presure builds in the Crankcase and The pressure is releaved thru the GASKETS..
Also Check The Distributor GASKET . I donnot Remember if the OIL SENDING unit is in By the distributoe,, The Sending units on the older 350/327 used to Develope leaks due to age
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PCV valve was changed about 1000 miles ago. Oil sending unit on this is on the front drivers side of the engine...looks ok.
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Ok took a look at the front diff last night, looks to me in my very amateur opinion that I can take out the flange bolts on each side, take out the bolts that hold the case to the frame...and drop the case tubes and all, maybe have to take out the swaybar first. Am I way off here? Looks like after that the oil pan should come out pretty easily. And while I have the case out I can replace the seals right?
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If I just pull that shaft out to replace the seal, am I gonna lose all the parts that it goes through? Or is this as easy as it looks?
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