So I had a bit of blowby...

[XfireZ51]

I thought I would do a little documentation of a light refurb I am having Pete do on the LT5. This is another case of the "while u are there" but there were several issues I thought may need addressing.
When the motoring season started, I got things going on Roza Nero. The winter project was taken up w mostly getting ready to do the MR run for the first time.
That involved installation of a Pioneer AppRadio4 with Car Play. Came in VERY handy. During some of the shakedown runs, I noticed some blackish gray smoke going on when I would "get on it" At first I chalked it up to blowing out the carbon after a long winter sleep. Car was running pretty well, altho it was using oil w a quart every 7-800miles. It had always "used" some oil, but that it seemed to be a bit more now. And that seemed to coincide with the addition of my Air/Oil Separator. Some mentioned a bluish smoke during decel.
We headed down to Blowing Rock, NC for MR5, and the ZR ran fine. Met up w Robert DeMarco and PauL Workman in Knoxville. When we arrived in BR, Paul mentioned that something had flipped past his windscreen from the rear of my car. Left side exhaust was hanging with a hole in rear of muffler where the mounting stud used to be. We had driven roughly 1000miles in 2 days and I was down nearly 4 quarts. However, no other signs of problems w how car was running. Idled fine, cruising was good, response good. Got the muffler repaired at a local place near Blowing Rock. Pretty good guys. They liked Vettes. Hadn't really seen ZR-1s before. Bob DeMarco was a big help here staying back with us and leading us ack to the rest of the pack.
Spoke to Marc at BG about the oil consumption which he suspected was attributed to a mismatch of the Injector Housing/Cylinder Head crankcase venting restrictors. He suspected both were wide open.
Drove back thru Nashville, and aside from adding additional oil (didn't need an oil change) motor ran well and tallied 23mpg at a steady 75-80mph.
Once back in Chicago, I basically put the car out to pasture until Pete could get to it. Meantime I pulled the plugs for running a compression check and noticed #7 was sooty and black. However, compression checked to 220psi.

http://www.zr1.net/forum/showpost.ph...11&postcount=1

Finally, Pete has been able to get his hands on the car. Basically we started with a checklist of things to look for.

Sooty #7. Leaky Injector/Valve Guides or Seals? Or not.

Check Clutch Disk. Suspect lack of trap speed to be slipping disk

Trans Leak . Its not the rear seal

Busted Muffler Stud. Busted Motor Mount allowing over-flex of exhaust

Rod Bearings. Just in time to change. An unknown "while ur
there.."


So I hope to document our progress on this and see what results. Pete has the lower end about done.

[mike100]

As far as the trans leak goes- Mine leaked out the tail-housing, but it wasn't the lip seal...it was the metal plug in the end of the driveshaft yoke that was leaking.

[XfireZ51]

Originally Posted by mike100

As far as the trans leak goes- Mine leaked out the tail-housing, but it wasn't the lip seal...it was the metal plug in the end of the driveshaft yoke that was leaking.

Mike,

This appears to be the middle seal in the case. There's seepage there.

[Paul Workman]

Originally Posted by XfireZ51

Mike,

This appears to be the middle seal in the case. There's seepage there.

Broken top ring on #7 too...was mentioned @ the FBI pizza nite two weeks ago.

Anywayz...aounds like the "Rose" is getting a new lease on life!

[Ccmano]

Originally Posted by Paul Workman

Broken top ring on #7 too...was mentioned @ the FBI pizza nite two weeks ago.

Anywayz...aounds like the "Rose" is getting a new lease on life!

That would explain the blow by. Were those the original rings?
H

[XfireZ51]

Originally Posted by Ccmano

That would explain the blow by. Were those the original rings?
H

As far as I know, yes. The motor has been w me for the last 10 years.

[tnova]

The right muffler bracket broke twice on my '91. Now I'm rebuilding the engine (160k miles-oil consumption and the need for more power) and found one of the motor mounts was broken. But for your post I would not have correlated the two. Thanks.
Tnova-'91 ZR1

[XfireZ51]

Originally Posted by tnova

The right muffler bracket broke twice on my '91. Now I'm rebuilding the engine (160k miles-oil consumption and the need for more power) and found one of the motor mounts was broken. But for your post I would not have correlated the two. Thanks.
Tnova-'91 ZR1

Yes I suspected that excessive movement of the motor was causing a flexing of the muffler sheetmetal where the muffler's rear mounting stud is attached. Ultimately, it rips the sheetmetal. The motor mount on the driver's side was cracked, and it was the corresponding muffler mount that failed.

[Ccmano]

My last Z had bad motormounts at 50k miles. I'm doing new mounts on the new one when I do the headers in the next few weeks. I noticed one of the exhaust system hangers was broken last I was under the car. I suspect I will find a broken mount as well.

What are you doing with the ring issue? Might be a good time to go larger displacement if its all apart anyway. It just a matter of money....

Move here to Reno and you'll save many thousands in taxes.
H

[LGAFF]

Engine ring failures(breaks) are usually caused by detonation....any thought what might be the cause? Low fuel pressure, too much timing, bad injector?