IS your pump a high volume pump ? That`s what striped mine For some reason lt1`s have the same problem big blocks have on there dist. with the gear . look at the teeth if you take it out and see how seating. or maybe broke the tab on the half shaft and push it up? Good luck!

 

My pump is a melling 155 or something like that. The one with the thicker casting. I thought it was a normal volume pump but it does have a high press spring. I will check this stuff out tomorrow. Will let you know.

 

Well, i found the problem.





The gear is completley stripped on one half, and mostly stripped on the other. I ordered a new one and i wont get it for 2-3 days. Im hoping that it still managed to keep enough pressure to keep me from blowing my bearings. We will see, i will install it and verify the oil is flowing, and start up the car. Hopefully no bad noises follow.

I tried to take a peek at the gear on the cam, and from what i could see it still looked ok.

What would cause this problem?

 

Hard to tell from the photo, but I would venture a guess and say it is a bad gear. Doesn't appear to be worn, just broken teeth, and since you can't install it wrong, I'm going with bad gear.

However, I wonder if excessive cam play would bind up the gear and cause this?

 

I would go with bad gear, but this gear previously had 100k on the clock before the rebuild. Could the higher pressure being delivered somehow over torque the driveshaft causing this?

 

Bingo! That`s what I was talking about mine striped completely with no teeth when I took mine apart the crank and rod bearing were ok but I replace them to be safe. this is cause by the use of hv pump I replace with standard pump and have no issue`s. Look at the teeth if any are left to see if you can see ware pattern. Before this happen I look at some of my old one`s because the plastic arm would crack so I would replace it not looking that close at the gear but when I broke the gear I notice all my half shaft`s had a lot of teeth thin down. Did the arm show any crack`s where you bolt it down to the block? If so there are thread`s that talk about this problem. Well glad you have the answer. Good Luck!

 

Common thing running the HV pump. It is not needed, though there will be some debate on this. I have been running the HP pump with no ill effects. Many a time is spent at the redline of 6800rpm. Pressure at idle is around 40psi and 80psi at redline.

 

Yes thanks guys for saving me the pita of pulling my oil pan.

As far as i know my pump isnt a HV. I bought it with the idea that it was normal volume, and i just put the white spring in. It does have a 3/4" pickup though. I really dont want to replace the pump.

Why does a HV pump cause this?

 

It's not the pressure, it's usually incompatibility in material the 2 gears are made of.

 

If you are not doing to pull the pan I would at lease take low oil sen. out and get one of little magnet pins and try to fish out those`s piece`s of the broken teeth that might be in your pickup tube or get a large magnet and move them over to drain hole but If I were you I would pull the pan to safe. hv pumps take more tq to turn because of diff. gears inside these pumps but if you have standard pump you should be ok! Just remember if you tear down for cam change always` check that shaft for wear. Good Luck!

 

Okay, now that you've found the damage, next thing is to find the cause.

High Pressure oil pumps are known to kill those gears, both in LT1s and L98s. I've had it happen to me on THREE different engines - two L98s and one LT1 - the common part in all three engines was the high pressure oil pump.

As far as metal incompatibility, what/whose camshaft are you running?

Jake

West Point ROCKS!

 

GM hotcam. So i doubt its metal incompatability. It wierd that it would be my pump also, from what i understand the one i use is a common pump to use on rebuilt LT1's.

Edit: Im 99% sure im running the Melling select 10554 with the gm white spring, and a 3/4" pickup tube.

 

The stock pump IS a high volume unit so adding a HV pump, which is usually harder to turn than the stock unit, is both unnecessary for volume and potentially damaging as you found here. The high pressure spring didn't cause this as it just opens at a higher pressure than the stock one, it doesn't increase gear loading at all.I recommend people use a stock pump with a high pressure spring because it's the pressure that floats the journals, not the volume.
I'm not sure whatyou can do at this point short of pulling the pump and reinstalling the stock unit if you're looking to not ever have this problem recur...

Good luck,

 

My pump is advertised as a normal volume unit.

Im going to install the new gear, and start the motor, if there is knocking, then obviously i will pull the motor and have new bearings installed, and while its out i willl get a stock pump.

 

Well i put the new gear it and reinstalled the manifold and sealed everything down. Fired it up, ran right up to 55-60 psi. Got oil all the way up to the rockers. No knocks or odd noise. Went for a drive and ran it through the rpms, still no noises. Ran at about 20 psi hot idle.

Is it possible my gear was bad before from the start? I dont ever remember my psi being that high on a cold idle.