warning: melling oil pumps...

[BerniniCaCO3]

So, a year ago I rebuilt my engine.
Two of the oil galley plugs popped out shortly after startup.

Not long thereafter, I also found a divet in my oil pan that turned into a slowly seeping crack.
Punched from the inside, I reasoned, that it must have been one of those galley plugs: if it had been spun up by the timing gear, it would have hit with enough velocity to crack the pan from the inside.

This past week I pulled the engine again, to finally replace that pan, and some other things.

Well, I dropped the engine in and was putting in the mount bolts when I discover, the same exact dent in the exact same spot... in the brand new pan.
I grab the old pan back out of the dumpster and take a closer look, and that dent that I presumed to be from a galley plug, is hexagonal.
Turns out, the melling oil pump from napa that I had purchased, is just slightly larger than OE, and one of the four bolts that holds that plate over the gears, runs into the oil pan!

I don't have time to get another pan and pull the engine out again to install it... it looks like maybe this one, this time, hasn't quite opened a crack, and merely reforged the steel pan. I'm hoping that it doesn't turn into a leaking crack with time and heat and vibration from the oil pump contacting it.

Well darn.
And a warning to all of you about melling oil pumps! At least, take the driver front bolt and grind it down just a little bit.

[turbo2256b]

Yea basicly one of the oil pump cover bolts hits. Best to set cover on the engine with a few bolts no gasket. Tap with a hanmmer around the area to mark inside the pan. Remove pan then work around the area wit ha ball peen hammer and a hollow spacer of some sort to dimpple the pan in that area. Releaving the area so it dosent crack during final install

[pantera77]

Wouldn't you have noticed putting the pan on it's hitting something?

[gadget73]

Hm, can't say I've run into that one before, but I don't remember what oil pump I'm using either. Good to know though.

[t65neon5]

did you use a standard or high volume oil pump?....the melling high volume pump carries a warning that it may require minor oil pan modification •High Volume Pump
•25% Additional Volume Of Oil Than Stock Pump
•Heavy Duty Shaft Support
•Protective Coating
•Screw In Valve
•Includes Intermediate Shaft
•Uses 5/8 Inch Bolt On Screen
•May Require Minor Oil Pan Modification
•Quantity Per Vehicle: 1 (this is for a f code 302)i also found 5 different pumps listed,part #s M68,M68A,M68HV,10687 and 10688.....M68HV and 10688 require modification and are both high volume pumps....also the sealed power high volume oil pump also lists that you need to check for clearance also

[BerniniCaCO3]

no, this was a normal one.
And no, I didn't notice: it cinches down on the gasket, anyway, so there's that resistance. Lots of little bolts can easily put enough pressure on that one spot without you noticing it.

If it didn't crack this time, is it likely to start to crack in the future, or might I be safe?

[Southern_Pride]

I've had one in my car for a year with no issues. I'm using a trick flow metal impregnated rubber gasket though. It may be thicker than what your using.

[86VickyLX]

I've never had any issues with melling oil pumps. Ran one in the old lopo and now in the explorer. No issues. You just got a fucked up pump.

[t65neon5]

no, this was a normal one.
And no, I didn't notice: it cinches down on the gasket, anyway, so there's that resistance. Lots of little bolts can easily put enough pressure on that one spot without you noticing it.

If it didn't crack this time, is it likely to start to crack in the future, or might I be safe?

ok,cool....just checking,ive had customers buy the HV pumps before and bring them back because of the clearence issue with the high volume pumps......

[BerniniCaCO3]

I almost bought a high volume pump, and I wouldn't have known about clearance, but I reconsidered: on a near-stock engine with stock clearances, what would be the need for it?
I think the HV pump from melling, was additionally advertised as higher pressure, too.

Now, a race engine that runs thicker oil through looser clearances, would call for a HV pump, right?
Or, a worn out engine [that ended up with loose clearances through age]

[turbo2256b]

I base pressure on RPM strive for 10 PSI per 1000 RPM. there are std pumps, HV, HP, HV & HP. I perfer a bit extra pressure with hyd roller lifters. HV pumps should be used with extra capacity oil pans for shure if turning high RPM Std Pan could be sucked dry.

[zoomie]

unless you rrunning a 7 qt pan forget the hv or HO pumps the stock pump is perfectly fine, if you need somethinge extra invest in a windage tray........

[gadget73]

Have to be careful with those high volume pumps in a stock pan. You can actually suck it dry, especially if the oil returns aren't improved to make sure the oil gets back to the pan quick enough.

[BerniniCaCO3]

good warning.
I suspect stock meets my needs just fine.
I have a guage hooked up, and have 40psi at all times, even idle, with the stock-spec melling pump. I don't think I'd even need the high pressure (how high, btw, would start ballooning filters, etc.?)