Oil pump shaft
 

I did a mild rebuild on my 8ba. Nothing too in depth as the engine looked in excellent shape. I also installed a new Melling m15 high volume oil pump. The engine has been run for 2 hours and showed good oil pressure, 20 at idle, 50 at 2000 rpm. During tuning the oil pressure dropped to zero. I shut it off and did problem diagnosis which showed nothing coming in to main oil gallery. I dropped the pan and removed the oil pump only to find the shaft had snapped about 2 inches up from the drive gear. The shaft was not twisted, the gears looked good and there was no sign of a jam in the housing. I am an engineer but not a metalergist so to my eye the break looked clean and somewhat concave at the break. I am putting it down to a flaw in the metal itself. I would think the drive gear pin would fail first if there was in fact a jam. Anyone had this happen??? Thanks...Doug

Re: Oil pump shaft
 

It's probably good that it failed. If yours is a 'street engine' the high volume Melling 15 oil pump is overkill and can cause problems with excessive oil pressure. The Melling 19 is more than adequate for a street engine. The M15 is usually used in race engines....

Re: Oil pump shaft
 

Is your M15 pump a real Melling or Mac's/ Drakes/Speedway wantabe ?
I use M15 pumps in all of my flatheads, stock & modified with no ill effects.

Re: Oil pump shaft
 

The pump is a genuine melling stamped M15. I have had it a while but it is new. This sheered off drive shaft is a mystery. I see no other reason than metal failure.

Re: Oil pump shaft
 

Spitballing here. Something was drilled off-center to cause the shaft to wobble. Drive gear or idler.

Lonnie

Re: Oil pump shaft
 

Call Melling and have a chat with the tech people that is what they are there for.

R

Re: Oil pump shaft
 

This is a very unusual situation. I have never seen it happen with the large driveshaft diameter of our Flatheads. I have seen several instances on the newer V-8 Fords which use the tiny hexagon drive, from the distributor, but the Flathead shaft is 1/2" diameter(as I recall) and it seems like the lowest level of hot rolled steel could easily withstand the stress. I would chalk this one up to a defect in the shaft if no other evidence is there. However, I agree with Ronnie about a call to the manufacturer. They SHOULD want to look it over and, perhaps, provide a replacement.

Re: Oil pump shaft
 

Here is a shaft from a ford small block that has failed.(looks like a barber pole)Most of these were from foreign objects jamming the pump.Not uncommon in those applications.
JWL is correct about the shaft in an 8ba being unusual.

http://i64.tinypic.com/29lmni9.jpg

R

Re: Oil pump shaft
 

Never use Mellings "STUFF"