melling m328 high volume oil pump

has anyone used the m328 hv oil pump or one like it?

Stay away from high volume oil pumps unless you plan on turning consistently high rpms for normal use. That is what they are designed for and inefficient for "normal" driving.

wouldn't oil pressure increase naturaly with high rpms. I've heard stay away from them with motors that allready run 60 to 70psi but the 4.0 maxes out at 45.I think I've got some pretty big clearnces on my crank so thought this would help
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also this pump onli increases pressure by 10psi and flow by 20% so its not that much
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jd4242 said:

wouldn't oil pressure increase naturaly with high rpms. I've heard stay away from them with motors that allready run 60 to 70psi but the 4.0 maxes out at 45.I think I've got some pretty big clearnces on my crank so thought this would help
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That's exactly it. Pressure increases with rpms. I've been taught all my life that unless it's a race motor, stick with stock oil pump. I went against that advice a few years ago and put a high volume pump in my 351 I had built for my Mustang. It actually didn't build great pressure at idle and low rpms. Not good for the street. So, in my experience as well, I'm never using them again.

any race motor ive built i run stock oil pumps, hv pumps rob hp!i talked to melling and they said this pump should help at idle and low rpms.but i agree ive always been taught to stay away from them too,but ive also never seen a motor run 19 lbs at idle and in the 30s wile driving!thats really low too me and my rockers are tapping like something else,this is a built motor and i do run pretty high rpms and really dont do any "normal driving" im either tearing up rice burners or in the mud!o and man you got a really nice truck that 351 still running strong?

ok i just recalled milling and they assured me that this pump was made just for the 4.0 and that it will work and was made for a stock motor.they said that a stock oil pump runs(new motor and in spec with recommended oil) 25 idle and 54 at bypass and the new pump runs 34 at idle and 63 at bypass so it 9psi more and 20% increase in flow.they said this pump and numbers where made for a stock replacement and would work fine with stock bearings and clearances,so with that said im going to be putting this pump in next week when i tear my motor down again,ill post some updates and hopefully i dont run into any problems

just an update this pump works great!!no problems at all!!

Adverse results?

I have recently read a posted comment on the internet by a SOHC V6 engine remanufacturer that the camshafts and valvetrain have a tendency to lack adequate lubrication. The remanufacturer replaces the standard oil pump with a high volume (not racing) oil pump.

The only possible adverse results I can think of with a high volume oil pump is a slightly increased load on the engine and increased oil consumption at valve seals and piston rings. There should not be any increased leakage at front or rear crankshaft seals or oil pan gaskets because the crankcase pressure does not increase with oil pressure. Crankcase pressure is controlled by the PCV valve.

I'm considering purchasing a Melling M328 high volume oil pump for my future engine rebuild. Has anyone experienced adverse results from using this pump?

I'm not sure about the sohc motor but I know the ohv lack adequate oiling in the valve train.as far as I know I'm the only one running the 328 and I have had no problems with it.I would highly recommend it.

any links on tutorials for replacing an oil pump would be grand preferably with out taking the motor out

notes oil pan alignment critical, first two nuts? electric oil pump?

I have built many engines in my life, Ford, chevy, dodge, olds, Pontiac and ALWAYS use high volume pumps, ALWAYS. Did I mention I always use hv pumps. Never had any issues at all. MHO, will never build without using one.

Yea this has been years ago..i have built many and others have too using this pump..i think its a critical upgrade for the poor oiling design of the ohv