We had a new oil pump gear failure over the weekend. This is a new engine with less than 500 miles on it. I have a couple questions. Of course I'll be pulling the pan. I think it will come out in the car if I drop the center link? But is it worth it or should I just pull it out? How do I determine if the cam is ruined? Is ther any objective way of determining that or do I just look for scars, chips, ..etc?
We did not have a positive stop in, but I will be making one up. Should I consider the new gear from the Cox brothers? I already have a new oil pump to install but I need to know what kind of contact pattern I am to look for? Centered on the gear ???
This was a new pump from PAW, with 7/8 rotor. Running 10/30 oil. Engine was idleing through town when it lost oil pressure. Immediately was shut off and no engine noises were heard.

Anything else I should be looking for? Doing?

Don't have any immediate suggestions, just lotsa questions. Did you use a double-roller timing set? Did you pack the oil pump gears with vasoline?
When you pull the pump is there anything caught in the gears? If you have the capability, Pics may be useful.

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'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

Rick:
Sorry to hear this, I had the same thing happen to me this spring. I will tell you about mine in hopes it will help you out. My engine was a fresh 30 over stock rebuild with all good parts and work done at a GOOD shop. I used a Mopar cam and a Mopar hi volume pump with stock spring. In less than 500 miles my OP gear was worn off. I think it stopped pumping while the truck was idling in the driveway with the hood open. I didn't catch it right away as I was letting it warm up. I caught on quick when I reved it up and it sounded just like one of those cummins diesels. I had been following the OP gear failure talk on the net but was not worried as I was not racing, so when it happened to me I was shocked. A few years ago I had a new ring and pinion put in a dana 44 in my W200. In very few miles the pinion gear had worn down to just points, it kinda looked like my now worn out OP gear, the ring gear was intact but not pretty. When I made the truck shop warranty their work and parts, they put in a new set n/c and told me it was a hardness issue and that they were sending the old parts to Spicer to look at. Armed with that experience I felt that the OP gear was not hardend right, to prove my theory I changed oil and put on a stock used pump. I pulled it a few times to check the tooth wear. After a few thousand miles I was detecting a pattern of wear but I would guess it would go a long time before it also wore out. Then to prove it was the gear and not the pump I pressed off the worn out hi volumn pump gear and pressed on a used one off a stock pump. I ran that one the rest of the summer, a few thousand miles also with no problem. When I pulled it for inspection I noticed that same wear pattern as on the last pump. Both cam and pump are 13 teeth. so same op tooth runs on same cam tooth--always. Having a patten develop told me I had some damage to the cam gear. I pulled out the motor last week and I do have cam gear damage, it has many chipped teeth, but none worn. The rest of the engine looks like a high mile motor, the kind you would drive anywhere if you didn't know the history, but I do, so we will go thru it again. I think a bad bunch of OP gears got made. I wonder if one supplier could have made and sold that gear to Mopar, Melling, etc, etc. Well there you have it, a low tech, but it worked for me solution. I would guess that you will need a new cam, but maybe you can drive this combo for a while and see if you like it, or want to make some changes.
Jerry T

I agree with Jerry T. that the current replacement OP gears used on replacement pumps are not as good as the OEM ones.

Most of the ones we tested were real soft, when I talk with Melling they did not think that any special iron alloy was being used and the new gears are not heat treated in any way. Looking back to the Mopar specs, a special "M40" (high nickel) iron was called-out for the OEM pump gears.

As for your cam, you need to pull the pump and pan and have a look at the cam gear. You will most likely see some chips on the cam gear. Surface chips can be dealt with as long as the teeth are still in one piece. ("dress" the sharp chip edges with a stone or grinding wheel)

I worked with a local heat treater to case harden a batch of OP gears, those have been working well with no reported failures.

http://www.slantsix.org/articles/oil-pu ... report.htm

DD

Rick:
I just went and looked at my cam gear again. I have 6 broken tooth ends, 6 chipped teeth and 1 ok tooth. Under a glass I do see wear on the cam gear. If I had pulled my pan and saw this mess I would have never tried to run it, but I didn't and I did and it worked, it got me through the summer ok. Has anybody tried to get some compensation for this? We must have 10-20 guys with the same problem.
Jerry T

Doug,
I just don't want another failure in 500 miles. This engine was still being broken in and we didn't even get to put in the synthetic oil in yet!! Can I buy one of the case hardened gears from you? Or are they the same as the ones the cox brothers had made? Thanks. You can contact me off site if you want.

Merry Christmas to all!!

Rick

beautiful day

top down

off work early

no traffic

75 mph- 3.91 gear

dual carbs and pipes

DAMN THE PUMP DRIVE!

DAMN THE PUMP DRIVE!

-james

where are the coffee and bongos?

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I took a little closer look through the oil pump hole with a light and a mirror. I can see some of the teeth look OK. some have some small chips off the tips of the teeth. I will get the pan off on Thursday and really be able to see what I have.
I think I will contact PAW and talk to them. I don't know that it will do any good but at least they will know that the problem exists. I do have another identical cam that I could use, but that was going to go into my race car.
Well its Christmas eve, and off to Grandma's we go!!


Rick

Find-out who made your PAW supplied oil pump, my bet is that it is a Melling unit.
I have some hardened gears boxed-up for you, I will send them out tomorrow.

Please send me your failed gear, I have a collection going.
I want to send them all to Melling.
Melling needs to start hardening these gears themselfs.
DD

Thanks Doug,
I appreciate you getting them out for me. I'll get the gear off my pump and send it to you. I think we have decided to go ahead and pull the engine, replace the cam and do it right, again!
I'll touch bases with Jim Cox tomorrow and let him know that you are sending the gears. I need to get some other items from him anyhow?

Thanks again,
Merry Christmas

Doug...

Are most of the reports of pump gear failure you're getting from racers or does this seem to be occurring alot in stock, street-driven engines as well?
I put a new pump in my daily driver Dart when I had the engine out a few months ago, but can't recall which brand pump I put in as I had 2 or 3 new ones sitting around at the time. So far no problems... but maybe this would be a good time to install a quality, aftermarket OP gauge.

---Red

a nice gauge is a great idea. even better would be one of those "kill switch" senders that but off the motor when pressure drops below 10psi. i was reliant upon the oil light in my dart and when the pump $#!+ it was too late. when i can hear it over the pipes it's trash!

-james

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The gear failures come from racers and street cars, not a super high occurence but steady. I'm sure there are many failures out there which we never hear about. (non internet users)

My advice for anyone who installs a new pump on a SL6 is to pull-out the oil pump after 200-400 miles and inspect the gear for trouble, for "hard to pull the pump" chassis, at least pull the distributor and look at the gears to see if any bad wear is happening.

I just tore-down the the seized motor out of the Dragcar and it's OP gear is wearing fast towards failure. May-be 50 miles of street driving and 20 passes on that gear. It was good to catch it before it damaged the cam.
DD

Doug ,
if the replacement pumps and the high volume pumps are creating a heavier load than the stock pumps; Is it possible to still get the narrow (small width rotor) pumps for a street car application? I just ordered the standard pump from PAW and it has the 7/8" rotor.

Thanks,
Rick

The rebuild kits are still around for the OEM 5/8 rotor thickness pump. (6 bolt pump is how Melling identifies them)
I have been rebuilding these as I need them.
I do not know of any aftermarket pumps offered with the thin rotor, these were all diecast aluminum pump bodies.
DD