Oil Pump Problem

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Oil Pump Problem

Post  BigDave65 on January 1st 2011, 4:43 pm

My buddy has a 521 iron headed CJ motor. I did a freshen up on it last winter. It was a typical deal, new rings, bearings, gaskets, timing chain, oil pump, freshen heads, and a new forged Eagle crank to replace the cracked reground cast stroker crank. They re-installed the engine into the car, got it running and everything seemed great. The car actually ran the quickest it ever had after this rebuild, by over a tenth. After several races, they noticed that the oil pressure was acting funny. Only 40-50 psi at idle. It would build pressure when you revved it up. After a run it would fall to about 20 psi coming down the return road. Whent it cooled off it would come back to 40 or 50 psi. My buddies son is just in his scond season driving the car and hadn't been paying attention to the oil pressure, so we had no idea when the problem started.

So I get the engine back in the shop and disassembled, trying to figure out what is going on with this thing. All the bearing clearances were .003-.0035, but the bearings didn't look very good. I take the oil pump apart and this is what I found. Two of the ears broken off the bottom plate of the pump. I'm sure this was allowing pressure to bleed off instead of oiling the engine properly, and I'm guessing would have eventually broken the plate off of the pump. This is a FMS/Melling pump. I have never seen this happen before, and wanted to share so everyone could store this in their memory bank if you get some weird oiling problems.

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Re: Oil Pump Problem

Post  bbf-falcon on January 1st 2011, 7:10 pm

Not sure,but they might have torqued the pump cap bolts too tight after/if they disasembled it. Just a guess of course.

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Re: Oil Pump Problem

Post  Lem Evans on January 1st 2011, 7:23 pm

That's a new one for me Shocked Never seen that condition before....wow.

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Re: Oil Pump Problem

Post  BigDave65 on January 1st 2011, 7:49 pm

Lem Evans wrote:That's a new one for me Shocked Never seen that condition before....wow.

LOL....Lem, that seems to be the story of my whole racing career Rolling Eyes

When I disassembled the pump, the bolts didn't seem overtightened. I just used a regular 7/16" box end wrench.
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Re: Oil Pump Problem

Post  Paul Kane on January 1st 2011, 11:50 pm

We've taken apart countless Melling oil pumps. One thing that has always astonished me is how loose those bolts are on the new pumps.

Tip: Always assume nothing is ready to go out of the box/always check out new componentry just as you would any used componentry. Familiarize yourself with and evaluate everything you use to build an engine.

Paul

p.s.: If you need a replacement gerotor cover for that pump, I'd be happy to send you one, just PM me your address.
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Re: Oil Pump Problem

Post  Paul Kane on January 2nd 2011, 11:21 am

Just realized I didn't offer any advice on evaluating the condition of the pump so as to determine what might have been the cause for such a failure in the first place. Like Lem (and probably everyone), I've never seen a solid iron gerotor cover break so there must have been a reason behind it...such as foreign debris getting lodged between one of the HV gerotor cover's cast-in oil cavities and the rotor vanes, for example. As far as evaluating:

  • Inspect the machined side of the gerotor cover for signs of taking a hit from the inside of the pump (as described above in this post).
  • Check the machined side of the gerotor cover for flatness (make sure it was not stessed by being bolted to the pump body)
  • Check the pump body's machined surface (where the cover mounts) for flatness; be sure to check not only for high spots between cover mounting holes but also check that the mounting holes are not low spots on the pump body.
  • Check that the gerotor mechanism is competely inside the pump body's gerotor cavity (with cover off) and not protruding above the pump body.
  • Visually inspect the gerotor cover against another one to see if there is anything unusual about it dimensionally.
If everything checks out, then this must have been a fluke of some kind. But no-one can be sure without evaluating to some extent. If this were a 2Y 460 crank with a hurt journal, for example, we'd want to check all the mating parts just the same. Lastly, if you opt to just purchase a new pump or don't have the time to investigate the cause, send the pump here I'd be happy to look it over myself and tell you what I think. Cool

Paul
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Re: Oil Pump Problem

Post  BigDave65 on January 2nd 2011, 12:29 pm

Thanks for the info guys. The inside of the pump still looks brand new, and feels very smooth when turning it by hand. The machined surfaces still look perfect. I ran a straight edge across the surfaces and they seem to be OK, and the gerotor is flush with the cavity. I'm going to set it up and run a dial indicator across the bottom of the pump and gerotor to confirm flatness. You're right Paul, I should have inspected the pump before installation. I just spun it by hand and it felt nice and smooth. So I went ahead and bolted it onto the engine. I will be a little more careful next time around.

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Re: Oil Pump Problem

Post  Paul Kane on January 2nd 2011, 1:01 pm

BigDave65 wrote:...I went ahead and bolted it onto the engine. I will be a little more careful next time around.
Don't beat yourself up, Dave! Smile As far as I know, nobody's ever seen this before. Okay maybe the pump assembly was dropped on its head sometime during it's handling/shipping and had a hairline fracture. But in all seriousness stranger things have happened, such as 4340 crankshaft forgings breaking in low hp applilcations and entirely on their own/without any evidence of a culprit other than the crankshaft itself. As you've already noted earlier in this thread....sometimes....that's racin'. Wink

Paul
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Re: Oil Pump Problem

Post  racnrick on January 2nd 2011, 3:03 pm

My first thought was the oil pump shaft was too long and pushed the cover down when dizzy was installed, but then there would have been wear on the cover and gears, which there is not any. Could also be when it was assembled at factory, maybe the assembler was having a bad day and did not tightend down cover evenly??

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Re: Oil Pump Problem

Post  BigDave65 on January 2nd 2011, 3:27 pm

racnrick wrote:My first thought was the oil pump shaft was too long and pushed the cover down when dizzy was installed, but then there would have been wear on the cover and gears, which there is not any. Could also be when it was assembled at factory, maybe the assembler was having a bad day and did not tightend down cover evenly??

Thats kind of what I was thinking, but the way the cover has to slide over the end of the shaft just to get it in place to bolt it down, I don't know if you could get it uneven enough to break the ears off.
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Re: Oil Pump Problem

Post  rmcomprandy on January 2nd 2011, 5:06 pm

I have seen that exact thing.
At that time it was caused by an overzealous person installing the distributor.
After the gear was meshing with the camshaft, the distributor was tightened against the pump shaft; when it was discovered that the distributor still wouldn't seat, they started over ... the damage had already been done.

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Re: Oil Pump Problem

Post  Paul Kane on January 2nd 2011, 9:57 pm

rmcomprandy wrote:...After the gear was meshing with the camshaft, the distributor was tightened against the pump shaft....
Aaaaaah, yes. The distributor gear meshed with the cam gear but the oil pump's hex shaft has not yet been aligned with the female hex in the bottom of the distributor shaft. And instead of turning the crankshaft a few degrees (enables hex shaft to align with female hex--then distributor drops/seats into place), someone tried to force the distributor downward against its will (in your particular case)...which forces the entire drive system against the gerotor cover.

Nice, Randy. I ain't never seen that one before. Idea

Paul
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Re: Oil Pump Problem

Post  cool40 on January 2nd 2011, 10:15 pm

that could also be the cause of some pumps breaking at the block,in the "neck"area.IMO Very Happy
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Re: Oil Pump Problem

Post  BigDave65 on January 2nd 2011, 10:39 pm

rmcomprandy wrote:I have seen that exact thing.
At that time it was caused by an overzealous person installing the distributor.
After the gear was meshing with the camshaft, the distributor was tightened against the pump shaft; when it was discovered that the distributor still wouldn't seat, they started over ... the damage had already been done.

You may be on to something there Randy. That makes sense! Thanks
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Re: Oil Pump Problem

Post  Gregaust on January 3rd 2011, 5:35 am

What about an ARP pump drive??? Sometimes they need trimming for clearance?? I had one that was tight had no endfloat

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Re: Oil Pump Problem

Post  rmcomprandy on January 3rd 2011, 11:54 am

[quote="Paul Kane"]
rmcomprandy wrote:...After the gear was meshing with the camshaft, the distributor was tightened against the pump shaft....
Aaaaaah, yes. The distributor gear meshed with the cam gear but the oil pump's hex shaft has not yet been aligned with the female hex in the bottom of the distributor shaft. And instead of turning the crankshaft a few degrees (enables hex shaft to align with female hex--then distributor drops/seats into place), someone tried to force the distributor downward against its will (in your particular case)...which forces the entire drive system against the gerotor cover.

Nice, Randy. I ain't never seen that one before. Idea

Paul[/quote

Paul, at that time I caught it 'cause it was a new engine and the oil pan hadn't yet been installed.
Helpers are great ... most of the time, lol.
EDIT: Personally, I like to use the FRPP shafts.

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Re: Oil Pump Problem

Post  BigDave65 on March 12th 2011, 9:44 pm

Well I got this 521 finished up on Tuesday. The owner installed the engine in the car and fired it up today. It fired off on the first crank and held 80 psi of oil pressure. Let it run until it reached 200* and it still held 75 psi. So it seems we fixed the pressure problem we had. I did double check the fitment of the pump, driveshaft and distributor. Adjust the valves, set the timing, and this baby is ready to crank out some more 5.80's and maybe even a .70 on a good track, at 2800+ lbs. I'll keep you updated on it.

Thanks to Paul Kane for the parts!

Next project is plumbing and wireing the full chassis '57 Ford that this same guy is building for his son. I'll have pics of it soon hopefully. Going to have an alum. BT headed 521 for it.
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Re: Oil Pump Problem

Post  Lem Evans on March 12th 2011, 9:56 pm

"EDIT: Personally, I like to use the FRPP shafts."
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
And i have no idea why one would not......

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Re: Oil Pump Problem

Post  Paul Kane on March 14th 2011, 9:18 am

BigDave65 wrote:Well I got this 521 finished up on Tuesday. It fired off on the first crank and held 80 psi of oil pressure. Let it run until it reached 200* and it still held 75 psi.

Thanks to Paul Kane for the parts!
Always happy to help. Cool

Paul
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Re: Oil Pump Problem

Post  maxed_out_rpms on January 10th 2012, 2:28 pm

Ive broken 2 oil pumps in my 514, and they both broke just below the mounting bolts (where pump mounts to engine block) BUT...I think I have the reason tracked back down to the suction tube causing me my greifs. The pump is mounted on the front of the engine, but the suction is in the back of the pan. 1/2 way back there is a tab on the suction tube that bolts it to a main stud. I think that there should be a spacer of some kind in between the cap and the tab. Im thinking that when I re torque the main stud nut back into place its putting strain on the pump, then when I cross the line at 7000 RPM its just to much strain on the pump and it ends up breaking off.

Yuppers...now Im changing to a external pump Very Happy

Hi Paul, been awhile huh Buddy

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Re: Oil Pump Problem

Post  dfree383 on January 10th 2012, 2:38 pm

You definetly don't want to stress the pump with forcing the pick-up tube to fit, thats a big no no.

IMO the Kaase pump is a great upgrade.
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Re: Oil Pump Problem

Post  maxed_out_rpms on January 10th 2012, 4:25 pm

, Didnt have to force it to fit. The last time I replaced the bearings, the motor was upside down on the stand, and tab seemed to be right into place with no forcing at all. But with the weight of the sump part pulling it towards the engine block while it was upside down might have been just enough to add the stress to the casting causing it to break off.

Just my thought
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Re: Oil Pump Problem

Post  Paul Kane on January 10th 2012, 10:10 pm

maxed_out_rpms wrote: Ive broken 2 oil pumps in my 514, and they both broke just below the mounting bolts (where pump mounts to engine block) BUT...I think I have the reason tracked back down to the suction tube causing me my greifs. The pump is mounted on the front of the engine, but the suction is in the back of the pan. 1/2 way back there is a tab on the suction tube that bolts it to a main stud. I think that there should be a spacer of some kind in between the cap and the tab. Im thinking that when I re torque the main stud nut back into place its putting strain on the pump, then when I cross the line at 7000 RPM its just to much strain on the pump and it ends up breaking off. Yuppers...now Im changing to a external pump Very Happy

Hi Paul, been awhile huh Buddy

Rick Miron
Wow, hi Rick! Long time. Smile

This is the biggest cause and reason for OEM oil pump breakage. To many people simply throw things together without thinking of the consequences. (Not pointing my finger at you, Rick). Then a lot of people come on the world wide web and mistakenly (obliviously) blame the oil pump.

Installing an oil pump, and then forcing the pickup tube down against the stand-off stud on the main cap stresses the neck of the pump. Add engine harmonics to the equation and it's a recipe for failure. Now take the stress out of the neck of the pump and the engine harmonics are far more tolerable (trying to think of a good analogy but will have to come back to this one).

Adjust the pan-to-pickup clearance with the pickup removed from the assembly, then re-install and check the clearance. Once pan-to-pickup clearance is set, remove the pickup tube again and adjust the pickup brace to rest lightly on the base of the standoff stud (top of the main cap bolt). Reinstall and recheck, adjust if necessary, re-check, etc, etc, etc.

Can OEM pumps break when properly installed? They can under very extreme circumstances, but the majority of the failures noted in high perfornace engines are usually due to negligent intallation techniques. Consider that the OEM front sump engines--which use no brace whatsoever--last hundreds of thousands of miles without trouble. A brace (in the form of a rear-sump pickup tube) should make the setup stronger....unless they are improperly set up during installation.

Paul
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Re: Oil Pump Problem

Post  jbozzelle on January 11th 2012, 11:52 am

I've broken a cover like that on a SBF from a oil pump driveshaft that was too long. And I've also see broken pump mounting ears due to people pulling the pickup tube down onto a main bolt instead of bending it to get it to rest naturally at the desired height.

Glad you got it fixed Dave. The last one I fooled with was cracked about 75% of the way around the base where it bolts to the block. The pickup tube was also "pulled" down onto the main cap. Once the pump finally broke it was evident that it was cracked for a long time.... Had the same oil pressure problems you describe.

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Re: Oil Pump Problem

Post  1fatcat on January 23rd 2012, 6:43 pm

i have also had a oil pump mouting tab failure and was niether a rear sump pan or miss alingned distrib. or oil pump . i think it is a wieght of the oil pump and a stress or vibration issue (over time) . Jon Kasse has an upgraded pump with very long mouting ears, much stronger . i think it is a common problem that has plegged him and others over the years as well ?
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