Engine lost oil pressure/ problem found

SloGN

I'm a ASSHOLE.....
Joined
Dec 25, 2003
Howdy Guys

I thought i would share this with the board and get some feedback...... This is a friends car that i'm trying help fix .......

This Engine was built a couple of yrs ago . The engine is a 109 block with 2 steel center caps. A steel stock stroke crank. The Rods are Stock rods worked with arp bolts than are full floating pins. The pistons are weisco.. The cam is a cast roller unit.

The Front cover was built up using the Tall gears and the spacer for a stock gm cover.

When the engine was broke in The oil pressure was in the 60 psi range hot with the engine at about 2-2400 rpms.

The engjne was installed in the car and run great (still does) and after a few thousand miles it started losing oil pressure. Hot idle was less than 5 psi.

So i got the car and started doing some investigating on the oil pressure loss. The first place i looked was at the oil pump itself. So i removed it from the engine. The pump gears have about .0015 clearance and doing a flow test on the pump revealed nothing wrong with the pump itself.

I also removed the cam gear to see if the oil galley plugs had maybe came out. Well they were in place and staked in.........

WELL WHAT TO LOOK AT NOW...........

The next logical place to look is the Main bearings ( removing the oil filter and cutting it open showed nothing) . So i removed the oil pan and pulled the 2 steel caps and checked those bearings and they showed hardly any wear at all.......WTF is going on here.........


So after some thinking and smelling smoke......

I decided to take a air gun and pressurize the oil passage ways to see if i can possibly hear where the biggest leak is...... Well this helped me big time.....What i found was the Air was leaking big time around the #2 cam bearing area...So now that i had a place to start looking. I grabbed the small inspection camera and did some proctology work and found that the cam bearing had came loose towards the front of the engine to be stopped by the cam lobe........

So my question is how did this happen.....Is this block repairable ?


Here is a pic of said bearing...........

BK8K0069.JPG
 
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I have seen this happen and it was due to a crack that ran from the main bearing bore up to the cam bearing hole thus relieving any press fit retention on the cam bearing. Look for cracks real good once you get it apart.
 
Howdy Guys

I thought i would share this with the board and get some feedback...... This is a friends car that i'm trying help fix .......

This Engine was built a couple of yrs ago . The engine is a 109 block with 2 steel center caps. A steel stock stroke crank. The Rods are Stock rods worked with arp bolts than are full floating pins. The pistons are weisco.. The cam is a cast roller unit.

The Front cover was built up using the Tall gears and the spacer for a stock gm cover.

When the engine was broke in The oil pressure was in the 60 psi range hot with the engine at about 2-2400 rpms.

The engjne was installed in the car and run great (still does) and after a few thousand miles it started losing oil pressure. Hot idle was less than 5 psi.

So i got the car and started doing some investigating on the oil pressure loss. The first place i looked was at the oil pump itself. So i removed it from the engine. The pump gears have about .0015 clearance and doing a flow test on the pump revealed nothing wrong with the pump itself.

I also removed the cam gear to see if the oil galley plugs had maybe came out. Well they were in place and staked in.........

WELL WHAT TO LOOK AT NOW...........

The next logical place to look is the Main bearings ( removing the oil filter and cutting it open showed nothing) . So i removed the oil pan and pulled the 2 steel caps and checked those bearings and they showed hardly any wear at all.......WTF is going on here.........


So after some thinking and smelling smoke......

I decided to take a air gun and pressurize the oil passage ways to see if i can possibly hear where the biggest leak is...... Well this helped me big time.....What i found was the Air was leaking big time around the #2 cam bearing area...So now that i had a place to start looking. I grabbed the small inspection camera and did some proctology work and found that the cam bearing had came loose towards the front of the engine to be stopped by the cam lobe........

So my question is how did this happen.....Is this block repairable ?


Here is a pic of said bearing...........

View attachment 266030
And great idea on using the compressed air to find the leak
 
Thanks guys..........

Thats what i was afraid of............I'm gonna work on getting the engine out of the car and really start digging..........
 
Had this happen about 20 yrs. ago on one of Dads motors. We figured something bad had happened to let the cam bearing walk out like that. Pulled the motor & tore it down. We couldn't see anything wrong, so took it to our machinist. He hot tanked the block & magnafluxed it. He didn't find anything wrong either? So we decided it had to be something with the cam bearing? Since our machinist had put the cam bearings in the block, he was gracious enough to eat the inspection costs! (He obviously didn't have too) Put new cam bearings in the block, & put all back together. Never had another problem. Hope you have the same luck, SloGN.
 
Good catch Patrick. As mentioned seen it happened with cracks from the cam bore to the mains. Other time was when cam bearing installer screwed up on install knocked bearing through and reinstalled cam bearing again as they were to cheap to get a new cam bearing and the bearing was shrunk and walked out.
 
possibly a wrong bearing???
The 4.1s use a different bearing than the 3.8s. Could there have been a mix up?
 
Ok guys .......

The engine is out of the car and i took the cam out of it and checked the cam bores and it looked perfect no cracks or nothing... The bearing was messed up pretty bad ...

The Front cam bearing had been changed..But the bearing that had came out #2 was the original GM bearing.... It didn't show any signs of spinning in the bore.

So new bearing got installed and they went in tight and the cam spins freely....

So i guess put it back together and see if it lives!

IMAG0269.jpg
 
Ok guys .......

The engine is out of the car and i took the cam out of it and checked the cam bores and it looked perfect no cracks or nothing... The bearing was messed up pretty bad ...

The Front cam bearing had been changed..But the bearing that had came out #2 was the original GM bearing.... It didn't show any signs of spinning in the bore.

So new bearing got installed and they went in tight and the cam spins freely....

So i guess put it back together and see if it lives!

View attachment 266397
Thanks for the update. That bearing was pretty ugly, best of luck brother.
 
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