Moparts Tech Archive
Small Block
changing oil pump ??'s
changing oil pump ??'sultrajosh
Moparts Member
Posts: 1466
From: Somerville, MA
Registered: Apr 2000
posted 06-07-2002 04:46 PM
I've heard I should pack the new pump with grease. What kind? What's the best way to do this? Or should I just stick it in some oil and crank it manually to prime it?
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Original Wedge
Moparts Member
Posts: 505
From: Winnipeg, MB, CANADA
Registered: Feb 2001
posted 06-07-2002 04:52 PM
Follow the manufacturer's instructions that come with the pump. If they say to use grease, it should be petroleum jelly (Vaseline) as it is soluble in oil.
BTW, I prefer the Sealed Power HV pump over Melling or MP (Melling) as it has a different rotor design and in my experience provides more oil pressure at idle.
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Wayne M
New Member
Posts: 87
From: Staten Island, NY
Registered: Apr 2001
posted 06-07-2002 04:53 PM
I don't believe in packing oil pumps. I've always had good luck in just spinning them with a drill and a piece of hex stock. I once made do with a stock type oil pump drive (pressed on gear- not pinned) with the gear taken off. I drove it with a cheap large flat bladed screwdriver cut off at the handle and chucked in a drill.
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Fury_Us
Moparts Member
Posts: 618
From: OKC, OK
Registered: Jan 2002
posted 06-07-2002 04:53 PM
Moly lube is good--it'll disolve right into the oil. And the best way to prime the pump would be with a priming tool after it's installed. That way, the whole engine is primed.
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carl
Moderator
Posts: 6973
From: Ohio
Registered: Nov 1999
posted 06-07-2002 04:56 PM
Some assembly lube or 90 weight gear oil will be just fine.
Prime before firing and you'll have no problems.
carl
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ultrajosh
Moparts Member
Posts: 1466
From: Somerville, MA
Registered: Apr 2000
posted 06-07-2002 05:00 PM
Changing it because I am having low pressure problems on my new 340. Mechanical gauge shows nearly 0 at idle when hot. Never gets above 50 psi except at high rpms when cold. So far I have tried changing to thicker oil and a new filter, no change.
I've also heard I should check the front of the block for a diamond stamp, indicating an oversize lifter bore; that it might be cam bearings went out of alignment; that it's gunk in the pickup screen or tube; that I might have a bad relief spring... Uh, I forget the rest of the possibilities.
I bought a melling pump at Autozone. Figure I can check the pickup once I pull the pan, then change the pump.
Any easier stuff i should try first?
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boxcar
Moparts Member
Posts: 139
From: Mason MI USA
Registered: Mar 2001
posted 06-07-2002 05:00 PM
You should take the cover off the new pump to check for debris from machining or assembly. As far as priming goes, pour a little oil into the pump to coat the rotors and housing before you install the pump. Maybe crank your engine with no spark for a few seconds to watch the guage move before you fire it.
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Wayne M
New Member
Posts: 87
From: Staten Island, NY
Registered: Apr 2001
posted 06-07-2002 05:20 PM
Ultrajosh, I'm sorry to hear about your 340. everything you said is possible, and more. I would really consider pulling it back out for a real thorough going over (checking galley plugs, lifter bores, bearing clearances, etc) at the end of the year if this dosen't work.
If you want to check 2 out of 5 cam bearings, you can do it with 2 men. One man runs the drill while the other man bars the engine over real slow. The left bank rockers will oil when the passage in #2 cam journal lines up, and the right will oil when #4 journal lines up. All this will happen in 2 turns of the crank.
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origcharger
Moparts Member
Posts: 1737
From: Fort DODGE, Ioway
Registered: Feb 2000
posted 06-08-2002 12:26 AM
Now I am no smallblock expert but I do seem to remember an easy to overlook oil galley plug that is in a hard to see location on a smallblock. I believe if it is left out you will experiance low oil pressures. I also remember reading that you can verify if it is in place without engine disassembly, to do this you remove the oil sender and insert a straight wire as far as you can, mark the wire and pull it out and measure. At this point I should tell you what the measurement should be and I would if I could remember where I read it. Does any one else have this information at hand, if not I can check the manuals at work tomorrow.
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EricMU
Moparts Member
Posts: 140
From: Delaware, USA
Registered: Jan 2002
posted 06-08-2002 09:17 AM
If he changes to a HV pump will he need a diferent distributer drive shaft?
I ask, because I'm doing the same thing.
Eric
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origcharger
Moparts Member
Posts: 1737
From: Fort DODGE, Ioway
Registered: Feb 2000
posted 06-08-2002 09:20 AM
This information may or may not pertain to your oil pressure problem, I found it in a 1988 factory truck service manual in the 318/360 section;
OIL LINE PLUG
The oil line plug is located in the vertical passage in the block between the oil to filter and oil from filter passages. Misinstallation or absence could cause erratic, low or no oil pressure.
Inspection
1. Remove oil pressure sending unit from back of block.
2. insert a 1/8" wire into passage.
3. Plug should be 7 1/2" to 7 11/16" from machined surface of block.
4. If plug is off location. Remove pan and no. 5 main cap. Use suitable flat dowel to remove plug and position plug properly. Plug should be 2 1/8" to 2 5/16" from bottom of the block. Coat outside diameter of plug with Mopar stud and bearing mount adhesive to assure retention of position.
5. Reassemble engine and check oil presssure.
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Wayne M
New Member
Posts: 87
From: Staten Island, NY
Registered: Apr 2001
posted 06-08-2002 12:35 PM
YES, there is a special hidden plug. I think is in the galley that starts under the main cap, where the oilpump output is going to. I believe this plug seperates the galley in order to force oil through the filter among other things. I think the last post is real accurate. Usually, if you're starting off with a new block, this must be checked. they are hard to remove.
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ultrajosh
Moparts Member
Posts: 1466
From: Somerville, MA
Registered: Apr 2000
posted 06-10-2002 11:24 AM
I will check for this plug before I pull the pan. Thanks so much for the detailed instructions!
Since this is a refurbished block, though, I wonder if the machine shop would have gone to the trouble to find and pull this plug?
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74DartSport
Moparts Member
Posts: 361
From: Boonton, N.J. U.S.A.
Registered: Nov 2001
posted 06-10-2002 11:30 AM
Since this is a refurbished block, they may have removed the plug to facilitate cleaning and forgotten to re-install one.
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