Distributor Gear Woes

Well here's one I can't figure out. I'm on my third distributor gear. It's a 96 GMC 2500 7.4L with a modest cam. Even prior to changing the cam it started eating the distributor gear. I've tried a new distributor, Melonized gears, basically everything that my favorite mechanic and the local dealer recommended. Anubody out there have this sort of issue before? I need some ideas on where to look next!

Reply to
Daveman
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What weight/grade of engine oil are you using? (distributor gear drives oil pump too)

Reply to
TheSnoMan

I'm using 5-30w Castrol

Reply to
Daveman

Curious. When the gear fails, what is wrong with it?

Reply to
TheSnoMan

It grinds down the teeth. Acts like the gear is running sightly tilted on the cam gear. So far it hasn't damaged the cam gear anyways!

Reply to
Daveman

It is quite possible that your block was not properly bored at the factory or did you change the cam and the problem appeared afterwards?

Reply to
TheSnoMan

Sounds like a high volume oil pump.

Al

Reply to
Big Al

Problem was found when I had a noise coming from the motor that everyone tought was the distributor. Pulled the distributer and found the gear was bad. Replaced the whole unit. (Only $25 more for a complete distributor as apposed to just a gear.) Noise didn't go away. Pulled the covers and found two lifters not going to full height. Pulled the cam and lifters to find two seased roller lifters. Ate the cam lobes for lunch!! Anyhow that's the storey behind this project. Drove it for about two weeks before pulling the cam. Cam gear looked good still but the distributor gear was starting to get chewed up again.

As far as the oil pump. That may be a high volumn. Since it has 80 lbs when cold and 40 lbs when hot. There's 213,000+ miles currently on the truck. But I was told the melonized gear would take care of that. Currently I have a custom made gear in it from CNC Motorsports. Don't know it's fate yet. But I'll be pulling it as soon as the weather breaks again to check it. Been in there about two months so far.

Reply to
Daveman

My guess is that it is a little off from factory and when you installed a difference dist, it ran distributor tighter against the cam gear. I have not had much lot with rebuilt distributors myself. Several years ago my dist in my 89 burb was binding a bit in the bushings so I though I would replace it. Not of the aftermarket one fit right so I repaired the one in there and reused it and I have not had any trouble since.

Reply to
TheSnoMan

found

Don't

Ok if I have this correct, the drive gear was getting chewed BEFORE you replaced the cam. You have since replaced cam and lifters, and a new gear on the distributor, BUT not checked the drive gear since doing this. The reason for changing was cam was messed up by lifters, which could have been causing some thrust movement in the cam, chewing on the drive gear. My 91 still shows max on gauge when cold, and about the same as yours when warmed up, and I haven't had any problems with the drive gear, so I doubt that is the problem, most I have driven are the same way, oil pressure readings that is.

Other things that come to mind, if lifters were on the same bank could cause wear in cam bearings letting cam move laterally, and/or even have bent the cam ever so slightly. Cams will bend on their own improperly stored, like stood on end leaning against a wall, or improperly supported the full length if stored horizontally, same as warping a guitar neck. This would put driving gear on the cam out of proper relationship with distributor gear, and cause wear, just like not setting a ring and pinion up correct. I would ask about lateral play in the distributor shaft but you state it was replaced, so the bushings should be good.

Whitelightning

Reply to
Whitelightning

I remember the old 350 engines .. Chiltons /motors manuals Stated that The distributer must be positioned close to the original way it was set it. otherwise The lubrication of the Shaft and Gear wud be cut off. This never made sense to me at that time 1960 thru 1989 . because there was the dist houseing is made, The lubrication Hole was in the center of a VALLEY ( Between 2 ribs) ( oil hole in the VALLEY ) Maybe this is your case and there is a OIL Hole plugged in the BLOCK. Maybe the oil Comming down the PUSH RODS isnot Enough to Get to The Gears Just a GUESS

Reply to
no one

Very good point!

Reply to
TheSnoMan

To clarify position.. You can just Stick a Distributor in the engine , lineup the oil pump Shaft . with the Rotor pointed in any Direction.

Then to Get it running You rotate the disributor till u get it to Run

This is what to AVOID.

in the older distributor We would look at The VACCUM ADVANCE and make sure it was in the proper place.. On Electronic IGNITION we made sure The 12 Wire hook up Was Directly in the BACK and point the Rotor to the Spot #1 plug is Suppose to use in the CAP. otherwise Lubrication was cut off to the SHAFT and GEAR.. this is why u should look in a Manual to See EXACTLY where #1 plug wire should be positioned

My Guess is That if The Distributor Gear Was Worn off, Then you have PITTED the Teeth on the CAM GEAR or At least made the ENDS SHARP as a RAZOR

its light Rebuilding a Manual Tranny. If you Have a Broken Gear, You Change The other Gear that Came in Contact with it. Because it is also WORN or PITTED

sorry for puncuation and error. I am a ONE handed person.

Reply to
no one

. That was the old first 265 and 283 distributor that cut off the oiling.

Al, old enough to remember....

Reply to
Big Al

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