i may have found out why the pumps are failing.

[[X]treme R/T]

im not going to post a for sure statement till my snap-on dealer comes out tomorrow and recalibrates my presicion tools so i have a dead on measurment but i have "possibly" found the reason behind these failures.

i'm comparing the melling/sealed power pumps to the FACTORY ORIGNAL pump.

the distance between the the helical gear and the pump output (not the sump side) is slightly off, and the angle in which the gears on the "OEM" (not factory original) pumps are cut is slightly off. which if this is the case, causeing a misalignment not seeable by the naked eye. so it make look splined but it actually off by a few thousanths, maybe even 10's of thousandths

being a helical gear, there basically cant be anything remotly off in the machining of the parts. if it is off slightly, it will cause friction and a large amont of heat causing the i-shaft to "eat" into the oil pump gear and eventually striping it completely.

again, this is not a for sure statement, i will post my findings, late tomorrow morning, early afternoon, depending on when the snap-on truck comes.

[lotashelbys]

I would think that if the Melling pump is off that they would all fail. I have a Melling pump in everyone of my TIIIs and will not ever put a stock Mopar pump back in. I dont like the stock pump because the mounting body is aluminum. I have seen 4 of them crack right at the mounting flange and that scares me. I myself have never had a Melling pump fail in a TIII car. I would also like to know if you can find a measurable difference in the two to compare....

[mopar2ya]

Ive had that suspicion for sometime. I went through something similar with a manual trans rebuild in my dually. Back in the day Dodge wouldnt release the rights to the Getrag G360 trans parts even though they no longer used that trans. So people went aftermarket.

I went through 7 5th gears in 2 months. They would fail within 500 miles. Id get a light clicking sound in 5th then within a few dozen miles, no more gear. The shop finally bought new OEM parts from Dodge and spec'd them out. Sure enough the pitch was a tad off on this and that, so they put the OEM parts in my trans and problem solved.

Has anyone ever used prussian blue to check the contact patch of the gears.

[[X]treme R/T]

the thing is, the differnece between the original pumps and the new oem pumps from melling and sealed ower is that the casing is cast aluminum on the original.

maybe thats why they last longer, cuz there is a very significant difference in weight and maybe when it heats up, its warping the pump casing on the new OEM pumps causing the gear to become off-center.

its very possbile this is the issue because aluminum can disapate heat ALOT faster than cast steel. i think it could be retaining to much heat and warping.

either way, im gonna mic up both the pumps and see if there is any difference's

[[X]treme R/T]

i mic'd up the two pumps and came up with these numbers, all in inches

i did find that some numbers were close, but others were considerbaly different

the ORGINAL FACTORY pump:

gear width: 1.122

Gear height: 0.998

gear lug height: 0.585

gear lug length: 0.775


the OEM replacement from sealed power

gear width: 1.105

Gear height: 0.999

gear lug height: 0.593

gear lug length: 0.850


im not a master machinist by any means, so if someone with more experience in helical gears could go over these numbers, we might be able to find out our issue.

[rx2mazda]

Are you measuring two BRAND NEW pumps? I think you would need to measure multiple stock and replacement pumps to get a range in both. I'm no expert but, to me those numbers seem fine.

[[X]treme R/T]

Quote:

Originally Posted by rx2mazda Are you measuring two BRAND NEW pumps? I think you would need to measure multiple stock and replacement pumps to get a range in both. I'm no expert but, to me those numbers seem fine.

both used, factory pump was the original that failed in my car after 145,000, the oem is the sealed power that failed after 35 miles.

i wasnt making any measurments on parts that would take any wear.

i was checking the differneces in the gear its self.

if you notice, the factory gear lug length is substantialy shorter which could throw the angle off on the helical just enuf to cause these failures.

they both are 18 spline, but if the angle is off, it causes a large amount of friction. the only way to see if the angle is was to measure the gear lug legth. the longer the lug, the greater of an angle its going to be.

[xtrempickup]

i think its just poor belt tensioning or mistensioning if you have to ask me

[puppet]

Quote:

Originally Posted by [X]treme R/T both used, factory pump was the original that failed in my car after 145,000, the oem is the sealed power that failed after 35 miles. i wasnt making any measurments on parts that would take any wear. i was checking the differneces in the gear its self. if you notice, the factory gear lug length is substantialy shorter which could throw the angle off on the helical just enuf to cause these failures. they both are 18 spline, but if the angle is off, it causes a large amount of friction. the only way to see if the angle is was to measure the gear lug legth. the longer the lug, the greater of an angle its going to be.

The difference between the two angles using the lug length would only be fractions of a degree. You didn't include any of the I-shaft's gear dimensions.

[[X]treme R/T]

Quote:

Originally Posted by xtrempickup i think its just poor belt tensioning or mistensioning if you have to ask me

its not that for sure cuz the first thing i did when i bought r/t is buy a new belt and time/tension it myslef, that lasted for 22,000 miles till i snapped a rod.

so if i tensioned it right, with my gauge, right the first time, how could i possibly do it wrong the second time?

no chance of that so that rules out that theory.

the only thing that changed in the oiling system is the oem replacement pump vs the factory chrysler stamped pump.

so its the pump

[Millerman340]

I'm going to knock on wood while typing this but, I have run the snot out of my R/T with the holset on it . Been through two clutches & one belt That I have never put a gauge on with at least 30,000 miles on this one. So I don't buy that crap about a loose belt eating a rebuilt engine in 35 miles... I would much rather believe that a over tight belt would cause more damage to the I shaft Bering.

[turbospirit]

Quote:

Originally Posted by [X]treme R/T that lasted for 22,000 miles till i snapped a rod.

How did you "snap" a TII/TIII rod on a basicly stock motor? What was the cause of the failure.

Quote:

Originally Posted by [X]treme R/T the only thing that changed in the oiling system is the oem replacement pump vs the factory chrysler stamped pump. so its the pump

You, like the others, did a FULL rebuild. Thats a LOT more variables then just a pump.


Plenty of us have used the Melling pumps with no issue. And they have been stressed WAY beyond what yours went through in 25 miles.


Facts:
*Its only happening on a few select TIII cars.(3)
*Only to people who are new to the cars.
*All of those did a full rebuild
*One of those 3 used there STOCK pump. And it failed.
*A sealed power pump has failed, a factory installed pump reused after a rebuild failed, and a Melling failed.
*TONS of TI,TII,TIV cars are using the same pumps with absolutely no issue.
*Jackson has more TIII's sitting in his garage running fine with these pumps, then the total number that have failed.(Im a little jealous of that.)


Leads me to believe that it isn't an issue with the pump itself.

But one question. Are the pumps seating right on the boss in the block?
There is a radius in the block that is VERY close to the pump. I always clearance mine when I port the oil pump hole. I think Melling actually warns of this on the literature that comes with the pump.

[turbospirit]

Quote:

Originally Posted by Millerman340 I'm going to knock on wood while typing this but, I have run the snot out of my R/T with the holset on it . Been through two clutches & one belt That I have never put a gauge on with at least 30,000 miles on this one. So I don't buy that crap about a loose belt eating a rebuilt engine in 35 miles... I would much rather believe that a over tight belt would cause more damage to the I shaft Bering.

Its a combination of the harmonics in the belt due to the idler placement and tension, the fact that the valves springs are SO stiff, and that there is no distributor to dampen the oil pump gear on the TIII's like there is on a TII.
Instead of constantly meshing, the gears have the chance to vibrate and beat the hell out of each other. There isn't a large margin of error on the tension. And even doing it with the gauge, the user is still a variable.

[Millerman340]

I get tired of hearing all the smack about R/T's. Yea , I know it's weak points . I hear mine flopping & I tension it by feel , There has to be other issues involved.

[[X]treme R/T]

Quote:

Originally Posted by Millerman340 I'm going to knock on wood while typing this but, I have run the snot out of my R/T with the holset on it . Been through two clutches & one belt That I have never put a gauge on with at least 30,000 miles on this one. So I don't buy that crap about a loose belt eating a rebuilt engine in 35 miles... I would much rather believe that a over tight belt would cause more damage to the I shaft Bering.

my bearig were brand new