I have my younger brothers 97 SS, 40k original mile, M-6. All stock except for headers and ignition. So a couple years ago he overheated the car, due to failed water pump and driving it longer than he should have it also required head gaskets. Along with water pump I did the optics park. I had the heads checked at local machine shop and they checked out ok. I put it all back together, fired it up and all seemed to be fine, except I could hear what my be a faint rod knock. Discussed at this point and it being my younger brothers car and all the repairs were on my dime I let it sit and it has been sitting the last two years.

So here I am present day, I decid to look into the knock. I cranked the engine without the fuel pump for a bit to get some lubrication. I install fuse and crank over, it fires right up but the valve train was noisy as hell. I hoped the lifters would pump up but after 10 minutes no change. I pull the valve covers and find a couple loose rockers, I start the engine and start adjusting valves, here's the weird part. Number #1 and #2 exhaust valves have a jet stream of oil flying out like I've never seen and the rest of the valve have nearly nothing. What could be causing this? Blockage?
When the oil gets warm it shoots out so bad you can't even adjust the valves running even with a homemade acrylic diverter.

I can't diagnose the previous noise of a possible rod knock until I get the valve train quiet. Could these llifter have gone bad just sitting for 2yrs? Not sure what to do at this point any help would be much appreciated..

 

couple lifters could've collapsed causing excess pressure to go functioning lifters. loose rockers, assuming valve lash was properly done before, would likely signal something happened to them.

Personally I'd pull the intake and remove all the lifters and inspect them.

 

for now, just lash them with engine off.

perhaps the previous repair for head gasket may not have been "everything" given the "overheat...brother drove it to far.." thing.

engine off lash will certainly suffice for purposes of running motor, checking oil pressure and leak down.

if you feel you "heard" a knock, given the back story, your call on just diving into the motor now.

 

Thanks for the relies guys.

I readjusted all the valves, engine off. Fired it up and the valve train noise was normal, shut it down to install valve covers. Fired it up again, normal valve train noise.....then started getting loud again. Pulled valve covers and several loose rockers. It seems the lifters are bleeding down. Now is it because lifters are bad or lack of oil pressure getting to them?

I'll pull the intake tomorrow after work and see if I can find anything revealing.

 

How is the oil pressure at idle?

Getting pressure to the #1 and #2 rockers without pressure to the rest does make me raise an eyebrow to some kind of blockage issue.

Scroll down to the bottom of this thread for links to several other threads. Seems to be a pretty decent thread series on how to track down oil flow problems. It's not LT1 specific, but most of what applies to 350 Chevy applies to the LT1.

http://garage.grumpysperformance.com...-rockers.4537/

 

Oil pressure is normal, 28-30psi at idle when it's operating temp.


Thanks for the link. Some very informative info. I have more reading!!!!!

 

No problem. Just bothers me that the rockers at the end of the galleys are seeing oil but not the ones before.....as if all the lifters and/or pushrods are clogged(or blocked) but those two....

Any chance the lifters are spinning in the bores?

 

Just food for thought on the recently loosened rockers, myself and many other have problems setting valve lash properly with the engine off. The engine off method is good for establishing a base line to readjust later while running in my experience.

 

Not unless the dog bones and retainer are no longer on the car. Do you see oil coming out of any of the other rockers or are they dry?

 

Yeah, I was wondering if they were missed on the engine work. Hopefully not.

 

....you really won't know until you open up the motor. Pulling the intake at least.

If the previous builder didn't tighten the spider holding the dog bones than you would see that when you pull the intake

if your knock source is bearing...you will need to go further than the intake removal..

 

This evening I started the engine, with the oil cold the valve train sounds normal once oil starts warming up it sounds like a sewing machine. Very little oil to rockers, except #1 & #2 exhaust rockers, which shoot a stream of oil 8 inches high. WTF? So I pulled the intake real quick and the spider and dog bones are all in place. Ran out of time tonight to do anything, I'll inspect the lifters tomorrow but dont think I'll find anything.

 

has to be either the lifters or the lifter bores being screwy. the lifter should act like a bit of an oil controller to the pushrod, an 8 inch stream of oil screams 'bizarre fukkered lifter issue' to me.

you can pull one apart to inspect the internals, not that there are really any specs, but you can check for visual damage, which i'd expect if you're blasting streams of oil.

i'd get a new set of lifters and throw them in pretty quick. lifters can be a bit expensive, but i've found melling lifters are alright for cheap.

doubt it's rod knock, oil pressure would go to hell.

 

Finally made time to pull the engine and it proved to be the right move. Found number 8 rod bearing spun. So the rebuild will begin.