01 WS6 155k well taken care of car, Oil changed every 4k. Oring on the pickup tube was leaking air into the oil. Engine would get noisy then quiet back and forth. Oring was changed same time rag was left in oil pan. Engine started quiet but after 15mins started losing oil pressure and was shut off.

Car was rowed to a new shop and pan was removed rag cleaned out, pickup tube and oil pump replaced with Melling M295 with new Melling pickup tube.

Now on to the new problem, cold start engine is quiet no noises at all. Drive 20 miles still quiet oil pressure gauge is very responsive engine quiet 40 psi at idle in gear. After driving 30 miles oil pressure still 40 psi in gear BUT the lifters start to chatter AND the oil pressure is slow to rise on the gauge. As I accelerate from a stop I can hear the lifters chattering then quiet down until the next stop. Then it does the chatter thing all over again. Very frustrating at this point because Its not doing what it did when the old oring was bad. Not sure what to do. I know others reported when the oring leaked the oil pressure was slow to rise. This has the normal 40-65 oil pressure but it acts very slow to move above 42 then at about 3k rpm it jumps up suddenly.

 

UPDATE, noise is terrible between 1000-1500 rpm at light throttle in gear or out. It sounds like all the lifters are full of air rattling. If I give I give it just a tad more throttle instantly its gone. It seems like the noise is there only when the valve train is lightly loaded and only between 1k-1.5k Weirdest dam thing I've ever encountered. I'd say it might be rod noise but everything was checked when the pan was down and it looked good. I tried adding 1/2qt of synthetic Lucas oil stabilizer just to see if thickening the oil would help or change any thing. Didn't help in fact It made it louder???? Gotta be something crazy in the lifters but what? Worn axles? But why after changing the the pickup tube and oil pump? I may add some ATF just to see if it changes anything. I guess soon I will have to take it to someone to tear it down.

Anyone?

 

Did you use the correct color Oring? There are some videos by Melling on Youtube.

 

Shop says they did. I changed the oil yesterday and there was some wear metal on the magnet. More than should be there, I'm guessing there is something worn on the cam-lifters. Its got high miles.

 

^^ As in cam bearings toast?
Rag fibers in oil galleys, lifters, push rods?

 

They cleaned it very well, no rag material made it past the pickup tube screen. Old pump was clean and so was the filter....nothing found. Oil pan and frt cover and windage tray all disassembled and cleaned. They used spray solvent to wash everything out then spray lubed and primed the engine before starting. Now here something I've discovered today, If I run it moderately hard it quiets down but after driving it normally the lifters start ticking and chattering but only at very light throttle. Give it more throttle its gone and it sounds like chattering not lifter tick. Putting in heavier oil didn't help so I doubt its a bearing issue Plus running it harder helps. Also If I shut it off hot on warm restart lets say 15 mins later the lifters will tick and tap then slowly clear up<Never did this before.

I'm really at a loss to figure this one out. I looked carefully for air in the oil by the dip stick, there are a few bubbles but its not aerated. But when I changed the oil there seems to be a bunch of air bubbles on top of the oil and some in the filter. So dam hard to say whats too many. Also going up a long hill it doesn't start ticking at the top like it did when I know the o ring was leaking in the 1st place. I'm starting to question the pump if its maybe cavitating some for reason. I really don't have much choice but to take it to another shop and have them replace it with a GM pump. I didn't want this Melling pump to start with but these guys bullied me into it, I wanted to reuse the stock LS6 pump that was in it. I was just glad to get the rag cleaned out. The shop that did the work is a decent shop but they only drove it 5 miles after the repair. They think some lifter noise ok but Its that bad at times no one would accept it and I'm not going to argue with these guys about it.

I think the fact air bubbles were in the filter points to something at the pump or the pump leaking air. I can see some bubbles on the dip stick but the bubbles I found in the oil filter when I dumped it is wrong.

 

Oil pressure by pass valve leaking-sticking?? causing oil pressure to fluctuate prior going to lifters...

 

What kind of oil did the shop use?

What kind of oil do you use?

 

I'm sure I found the problem, the lifters were a bit noisy before ALL this crap happened. I think cleaning everything with the oil pan off washed the oil out of some of the roller bearings on some of the lifters. Now at light load they chattering badly, it isn't air getting into them because they are not tapping. At idle they are quiet but just raise the rpm to 1000 and they CHATTER LOUD then go up further past 1800 and there is enough load on the valve train and they quiet back down. Also there is one that is especially loud and I'm sure ready to fail. This is why if you drive it hard you don't hear the noise. Well here I go again, I need to find someone honest that can do this work for me. I can't do it any more do to health problems.

At least I know where I stand now. All the LS1 cars I owned had some roller noise at light throttle but dam this is bad enough can't drive it too far from home. Also I noticed small amounts of metal on the magnet that shouldn't be there is just 500 miles AND this noise defenatly got much worse over those 500 miles. Can't miss it now, every time off and on throttle CHATTER.

 

Well its not lifters because after driving it out on the highway for 25 miles @ 70mph the noise is almost gone. Can only hear it for second as the engine rpms rise past 1200 rpms. I'm starting think its the new oil pump, something in the gearing. As much as I hate to change it out again with a GM factory pump I believe that is the solution. Going to drive it some more and see where it goes. Thanks for the replies.

 

Please let us know how this turns out. I am facing a similar problem - except I also have a new cam, lifters, pushrods and M295 oil pump. Have correctly measured required push rod length for proper preload and am getting what sounds like valve train noise (ticking, some would call it the sewing machine noise). However, the ticking noise is somewhat intermittent and is worst at about 1700 rpm. I neglected to properly center the oil pump on the crank when doing the install (just bolted it on) so I am now wondering if the pump is the source of the mystery tick sound.

 

DITTO, they didn't center it either. Another thing I noticed right away is air bubbles in the oil filter. Try running it till its warm then shut it off pull the oil filter and dump the oil filter into a pan and look for bubbles. If you can take a picture, mine has a lot in the filter but the oil pressure is normal. I think all my noise is in the pump. The noise I have was bad between 1000-1500 only at light throttle, now after 1000 miles its gotten much better and is right around 1200. I also have some light ticking at times BUT before all this and the oring was bad on the old pump it ticked all the time. My engine is much quieter overall than before but this chattering sound is completely insane. I'm going to call Melling today to see what they think.

 

Thanks. I have not yet changed the oil or filter. No visible bubbles on the dipstick. Oil pressure is rock solid - 30 psi hot idle, 40+ psi hot when driving. Tick most noticeable at very light or no throttle. My quick search on oil pump alignment says it is not necessary on the M295 - only really required on the high performance pumps. Also, GM Service Manual does not require alignment. GM techs are instructed to just bolt it on.

 

Yeah I agree as long as you pre oil the pump you can bolt it right on. Oiling the pump causes the gears inside to clearance a bit so when you bolt it up the gears are not metal to metal. I tried calling Melling but they only take a message to call you back. I may just have the pump changed out to know for sure if its the pump, I'm that sure its the problem.

I have 65 cold 42 hot idle and 65 hot @ 3500rpm's.