oil pump change help

[nheller76]

Ok so I'm changing the oil pump in my 78 and I'm not pulling the motor. I know that it can be difficult so has anyone done it? And what are some important things to do. Plus high volume or just a regular pump?
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[75chev4x4]

Is it 2wd or 4x4 truck? I would just go with the standard oil oump if its just a stock motor.

[nheller76]

It's a 2wd c20. I had to replace the heads and found some 202-150 valve heads. I also put a demon Jr 625 and a new egr intake on it. Still think I should go stock? I also herd that I have to prime it before u get it to work, how do u do that.
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[INSIDIOUS '86]

You had to replace heads and you now changing the oil pump? Why put a bundle if cash next to a stick of dynamite?
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[Krwright]

Not a hard job at all. Changed many pumps and bearings from underneath. Go high volume same price most of the time.
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[piecesparts]

My question would be, if you had the heads off, why did you not do the rest of the rebuild at that time?

[KQQL IT]

You don't have to loosen motor mounts. Unbolt the pan. Easy easy
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[Krwright]

The proper way to prime is down through the distributor. You can make one from an old distributor shaft just grind the teeth off of the gear and use a drill. If you don't want to pull the distributor and go that way pull the cover off the new pump and pack the cavity around the gears with lubraplate or Vaseline just crank the engine a bit with the power wire off the distributor. You'll be fine the pump just needs an initial lubricant to start suction. Don't use grease!!! Vaseline dissolves in oil grease won't.
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[nheller76]

Originally Posted by INSIDIOUS '86

You had to replace heads and you now changing the oil pump? Why put a bundle if cash next to a stick of dynamite?
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They were heads I had laying around, I don't need to put a new one in but the truck is 35yrs old and hasn't had a oil pump change plus the heads had to have cracked some how why not pour cooling and lubrication. It's not that spendy plus its a good learning experience and the rotating assembly still looks in good shape. We all know that this type if truck last a long time, why not take care of it now when I have the time.
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[rs74]

I will second the vaseline in the pump cavity. I have always done this when putting a new pump in to get a good initial prime. Make sure you put in a new pump shaft with the steel sleeve and not the plastic sleeve. I usually use a Melling pump and shaft.

[nheller76]

Originally Posted by piecesparts

My question would be, if you had the heads off, why did you not do the rest of the rebuild at that time?

Thats what I'm doing, I got a new 6 al system put in at the mechanics and then barely got it home! Tuns if white smoke, so I thought blown head gasket. But nope cracked head so its got a new top end, plus I'm putting a new water pump in as well. So the oil.pump is the next step in the rebuild.
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[rs74]

I never had any issues but I have heard people say that if you rebuild the top end then it takes a toll on the rings later. I don't know if there is truth in that or not but I have never had an issue like that.

If you are short on money then do what you have to. Otherwise you could pull the engine and see about honing the cylinders, and have the block work done. New cam bearings, freeze plugs etc. Then have the crank polished with a set of new bearing and throw in a new cam, lifter and timing chain.

I don't rebuild my own engines anymore. I just send them up to the machine shop and just for a basic rebuild it can cost around $1000 but that is redoing the heads too. Generally oil pumps don't just go out but it can happen. Do what you think you need to and go from there. We can't all do things the way we would always like them do be done. Sometimes you just have to do what you have to do.

[74 stepside]

Considering the top-end replacing and the oil pump, plus new pan gasket..Its alot easier to just pull the motor. Then you could wash off all the grease and give it some new paint too.

[nheller76]

Trust me I considered replacing the engine, I even have a 350 that's board.30 overbut its not finished yet and I need my daily driver until I get it put together. Thank u all for your information it is so helpful.
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[chrly1492]

just my two cents...if you are planning to do this by yourself and the budget allows, get the one-piece pan gasket from fel-pro #OS34510T. Comes with corner clips that makes hanging this on upside down a lot easier. Good luck

[75chev4x4]

Yea I would second pulling the motor to get a look at your bottom end just to be sure its not something else. If u do it on a day off you can have it in and out in a day if nothing major is wrong.

[INSIDIOUS '86]

Get a standard volume pump. I've run many engines this way and never had an issue with standard volume. A standard pump with a high pressure spring is good for everything. A big block pump doesn't kill power like one would think but it keeps pressure more stable at lower rpm and uses less power to turn than a high volume. One peice gaskets are very nice. Make sure to run all the surfaces down with shop towels and isopropyl alcohol to make th clean and rtv the corners of the gasket underneath and above for good measure.
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[LONGHAIR]

Why? What makes you think it needs to be replaced?

[nheller76]

Two things, its 35 years old and before I started everything with it my oil gauge said I had no oil pressure. I replaced the sending unit and it still was really low so I might as well try and change it. I got the new pump today but have had the hardest time getting the pan off. All the bolts are out but the thing is just staying fried on their! I'm gona do my best to get the pan off tomorrow and get it changed.
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[INSIDIOUS '86]

Are you using a mech gauge? If the pressure reading is accurate and your oil press is low then the engine is tired. No pressure isn't bad since there is still flow but it shows that the clearances are worn down.
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[nheller76]

Originally Posted by Krwright

The proper way to prime is down through the distributor. You can make one from an old distributor shaft just grind the teeth off of the gear and use a drill. If you don't want to pull the distributor and go that way pull the cover off the new pump and pack the cavity around the gears with lubraplate or Vaseline just crank the engine a bit with the power wire off the distributor. You'll be fine the pump just needs an initial lubricant to start suction. Don't use grease!!! Vaseline dissolves in oil grease won't.
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I want to say thank u again for the advice I stuffed my new oil pump with Vaseline and am hopefully installing it tomorrow.
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[LONGHAIR]

INSIDIOUS 86 is hitting on my point of asking why.
The oil pump may indeed be worn, but so is everything else. And I would bet that the pump wear is less.
The main and rod bearings are worn enough that the pressure is being lost there from the extra clearance. A new pump will have the same problem. It can't overcome the loss, so the pressure will still be low.
I would be willing to bet that your "worn" old pump could make good pressure in a fresh,tight motor...... the pump is not your problem.

[79Betty]

I'll add my .02. My origional 350 was a 2 bolt with god know's how many miles. Said i had no oil pressure. Dropped the oan put a new timing chain water pump belts while at it. 3 weeks later both #8 cylinder lifters went down and i spun the #2 rod bearing. Now i have anlther 350 in my truck with "0" lbs of oil pressure. Until it starts knocking (or i get my other motor done) i'm not touchin it. I'd just drive it but that's my .02
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[nheller76]

Ok so pulled the pan today, it took me an hr to do it! The gasket was so fried on their I had to use chisels and screw drivers to pry it off. But got the new pump installed and got a good look at everything under their and looks like its in good shape. Next I put the water pump back on and tighten it all down.
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