Moparts Tech Archive
changing oil pump ??'schanging oil pump ??'s
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?
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.
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.
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.
Some assembly lube or 90 weight gear oil will be just fine.
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 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?
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.
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.
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.
If he changes to a HV pump will he need a diferent distributer drive shaft?
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;
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.
1. Remove oil pressure sending unit from back of block.
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.
I will check for this plug before I pull the pan. Thanks so much for the detailed instructions!
Since this is a refurbished block, they may have removed the plug to facilitate cleaning and forgotten to re-install one.
info provided by members listed above