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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: thefarmboy21 on September 26, 2014, 08:13:38 am
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Well my Fresh'ish 350 that I just dropped in my 86 has got my blood pressure up. I've been noticing it sounds kind of like an old IDI non turbo diesel.....not loud just kind of rattly. It doesn't sound like a knock, but not like valve chatter either really. And it's really quiet but I know it's there. Also when I changed my oil, the oil out of the pan looked fine from what I could tell. I stuck a rag under it and rubbed my fingers in it as it flowed out and looked normal. Then I dumped the filter and it looked fairly pearly coming out. Not like big glitter or overly silver'ish but definitely had some shiny stuff mixed in coming out. SOOO......now I'm wondering what happened. Main bearing, cam bearing, wiped cam/lifter, OR is it just breaking in more. Idk. I build the bottom end in 2009 I think? Ran it in my derby car for a while with no problems and tons of power. Then heads had to be changed so I threw a set of centerbolts on it and into the K20 it went. I don't know what kind of oil pressure it has because my gauge quit and just stays at 20psi running or not.....but I've got a new one to put on this weekend.
THOUGHTS????
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Pearly oil most likely is from wiping cam lobes/lifters. Did spring changes increase pressure with the new heads? Did you use ZDDP enriched oil? I agree, you need to check and monitor the oil pressure - maybe even drop the pan.
Is the rattle emanating from the valve covers - as in noisy roller rockers? If you're running forged pistons, the noise maybe slap - although that should diminish as the engine warms. Wrist pin is another possibility, as is preignition.
Try to determine whether the noise is from the top or bottom.
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Just has stock valve springs and stock stamped rockers with only .462/.447 lift. Basically an RV cam in a stock motor. Bottom end is a 70-72ish 350 from a truck. I rebuilt it a few years ago. I run RotellaT 15w40 because it has more zinc. I listened with my stethoscope and can't really pinpoint it. Sounds the same if I take the breather/pcv valve out and listen. SO......I'm also kind of leaning towards a cam starting to wipe. This seriously sucks.
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Give each of your rocker arm nuts a 1/4 turn and see if the noise goes away. Had to do that on my '94 K2500. My cam was fine, the lifters just needed to be reset.
My first oil change on my '77 truck's 454 had lots of glitter out of the oil filter. Everything in that engine was new save for the block, and head castings. I chalked the glitter up to the break in wear from the piston rings.
And you really need to get an accurate oil pressure gauge.
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I'm going to install the new gauge sometime in the next few days and adjust the valves again. The reason the glitter worries me is because it should be broke in. That motor has been through about 15 heats of derby since 2009, plus all the test&tune time around the garage in the derby cars. I had to change the heads because we floated the valves a couple times and the bronze valve guides shoved through on the race heads that it previously had. SO, that's another reason I'm worried about the cam.
*IF the cam is wiped, but motor has good oil pressure, would a quick cam swap and a couple oil changes be enough to flush the motor? OR are the bearings likely shot now?
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Accumulated hours on the engine is why I suggested cam/lifters. Even so, you realize this is cracker barrel conversation. The only way to know is to look. That said, a good oil filter should protect rod/main/cam bearings.
Adjust the valves and check for obvious loss of lift at the rockers. Cam failures develop fairly quickly. If looseness recurs in the valve train, you'll know.
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They have been removing zddp from rotella!
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If your cam wiped a lobe the oil filter should have caught the metal.
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Well I smacked my gauge a few good times and it sprang up to 40+ psi at idle. I'm still going to change it out and check but I can watch the oil shoot up the plastic line when I start it, so I'm hoping I'm good. I'll check the lift with my dial indicator as soon as I get a free couple hours. As said, the oil looked normal flowing out of the pan, I didn't find any shimmer until I Dumped the filter, so I'm pretty hopeful the bearings are ok and that worst case scenario is swap the cam with the motor in the truck.
How do you all adjust your valves? Tey way I've always done it was tighten them to zero lash and when I can't rattle the pushrod anymore, but can still spin it freely, then tighten it just barely until there's resistance when I spin the pushrod. I never really thought the extra 1/4-1/2 turn sounded like a good idea. To me it seems like the valves wouldn't close? BUT now I'm wondering if I did something wrong.
My buddy just gets them close and then starts it up and backs them off until they tick, then tightens them back up until the ticking stops.
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Exhaust opening, intake closing--EOIC method. Just google that, as it is probably the most common method. Assuming you have hydraulic lifters, you can also start the engine with a valve cover off, back one off until it ticks, turn it until it just stops ticking, and then give it a 1/4 to 1/2 turn. The extra 1/4 to 1/2 turn is important, otherwise you are right on the edge of being loose and having ticking valves.
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Frankly, the answer to your question on the preferred method of hydraulic valve lifter adjustment depends on who answers. GM recommends a method of valve service adjustment that works well for stock to mildly modified engines. For example, look in the 1987 Service Manual (http://www.73-87chevytrucks.com/techinfo/7387CKMans//Service/ST_330_87_1987_Chevrolet_Light_Duty_Truck_Service_Manual.pdf), pages 525 & 526 (6A4-6/6A4-7). Some techs decry GM's approach as problematic. On the other hand, EOIC is broadly used for all builds with good success, as is the wet method (engine running) described by jaredts. The main drawback of the 'wet method' is the consequent and unavoidable mess.
Regarding lifter preload, the GM spec of one full turn after zero lash approximately centers the plunger in the lifter body - a good choice for a stock to mild build DD that won't see regular high RPM use (above ~4,700 RPM). Adjusting the lifters to less than 3/4 turn, arguably, can benefit high RPM use by decreasing the tendency for the lifters to "pump up" and temporarily hold the valves slightly open once they begin to float. Realistically, if you are floating the valves there is a spring problem or you're abusing the engine by pushing it beyond its build limit.
Comp Cams simply recommends zero lash (no preload) with some of their performance hydraulic lifters. I disagree with this approach for street builds as it virtually defeats the purpose of having hydraulic lifters.
For your type of application I have used the GM method, EOIC, and the wet method with similar good success. For what it's worth, now I use the EOIC method fairly consistently.
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I got my new oil pressure gauge installed and I DO have good oil pressure. It's idling at about 600-650rpm and has 50psi idling from a cold start and remained the 10 minutes or so I let it run. Went past 60psi when I revved it up. After I installed the new gauge and before the startup, I removed the valve covers so that I could watch the rocker arms. All rockers APPEAR to be in full lift, but I know it would be hard to tell if it's in the early stages. HOWEVER I did not have any ticking rockers and I would've thought that a wiped love or worn lifter would've caused a lifter tick from lost lift? Anyway I used the the wet method and adjusted them all after the oil warmed up a bit. They all seemed to be pretty dead on.
*The only thing I wasn't sure about, is that it took a good minute or two for oil to make it up to the rockers....some oddly longer than others but eventually all had a nice flow. Maybe because it was idling at <650rpm?
The strange noise is still there and I have no idea what it is. -_-
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I also want to note that while searching today I kept finding posts in various forums about similar issues.....all saying that it took longer than normal for the rocker arms to get oil to them and once they got oil it just kind of seeped out rather than ran out causing the normal mess. Almost all of these came back claiming it was the aftermarket Hyd. flat tappet lifters (mostly from comp cams and a couple fr lunati) they claim they swapped lifters and all was well. Anyone had such an experience????
While adjusting my valves via the "wet"/running method, as soon as I snugged them down from ticking/clacking to quiet, if I went further the engine bogged. Is that the preferred stopping point or should they have preload? One place I read said adjust from clacking to quiet, then TURN IT OFF and proceed to crank all 16 and additional 1/2 turn?
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...While adjusting my valves via the "wet"/running method, as soon as I snugged them down from ticking/clacking to quiet, if I went further the engine bogged. Is that the preferred stopping point or should they have preload?...
This is normal. Once you remove the initial lash, adjust the additional turn s·l·o·w·l·y over 10+ seconds. The lifters will bleed off, the valves will close and the engine will idle normally.
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So an additional 1/2 turn each or what?
Better to do SLOWLY while running, or just shut it down an do it not running? I mean is one preferred over another?
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Although there maybe some disagreement from the performance crowd, settling on one-half to one full turn after zero lash isn't as important as adjusting all the valves using the same preload. The only thing that preload accomplishes is to allow the hydraulic lifters to function like hydraulic lifters and maintain zero lash under normal operating conditions. If you regularly twist a motor tight, stoplight-to-stoplight, then use less preload. If your after extended service intervals, adjust to one full turn.
Additionally, whether you complete the adjustment running, or just barely remove the lash running then shut the engine off before cranking down the final amount is also arbitrary. What is NOT arbitrary is preloading the lifters slowly, because you don't want a valve kissing a piston, running or not. So, take your time tightening beyond zero lash.
All of that said, I generally adjust three-quarter to one full turn beyond zero lash for all stock to near-stock configurations. It's arbitrary.
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Well I'll adjust to 3/4-1 turn past zero and MAYBE my strange chatter will go away. However, I've done even more research on comp lifters being the culprit and there are lots of people with this issue. The general consensus is that in 2008/2009 Comp had to use a different manufacturer for their lower end lifters, because the place they were using shut down. And that's when I bought my cam kit.....crap. Some said they just run the noisy lifters and some swapped out for a different set or different cam kit all together. I really don't mind the noise as long as it's no real problem. My main concern is that the rockers get adequate oil!
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I adjusted my valves this morning to 3/4 turn and seemed to quiet the diesel sound down, BUT I can still hear it. THEN I noticed that both exhaust pipes were sucking my hand in at idle??? So I backed the passenger side back off to zero lash thinking maybe they were too tight......still sucking my hand. Now the passenger side is back to 1/2turn past zero and drivers side is at 3/4 until I figure out where I stand.
* Here's why I'm still confused:
1. I just worked the heads myself, replaced one burnt valve, re-seated all of them and now they have about only 250miles on them since I put them on.
2. I have true duals and it's sucking equally on both sides.
3. It runs incredibly well. Tons of power, no backfiring and no hesitation.
I know I have some exhaust leaks due to a fresh/cheap exhaust kit, but would and exhaust leak cause both tail pipes to suck that strongly? Also it has about 70miles on a fresh oil change and it already has a black tint to it and smells kinda like burnt fuel?
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You realize that you are talking yourself into deeper confusion by focusing on your uncertainty instead of focusing on what you know from your experience. Stop second guessing yourself!
If you're concerned about fuel in the oil, let a drop of oil from the dipstick land on a clean fingertip to see if the oil holds its circular shape or tracks along your fingerprint. It should hold its circular shape.
"Sucking" at the tailpipe is probably due to reversion of the exhaust pulses as acoustic waves reflect back up toward the cylinder head from the end of the open exhaust. It's the same principle that helps scavenge a combustion chamber and why headers benefit performance. Acoustic waves move through the exhaust pipe in both directions. The 'sucking' is probably related more to valve timing, ignition timing, RPM and the length of the pipe than anything else.
If your worried about combustion chamber sealing, perform a cylinder leak down test or compression check. If you have a lot of engine hours on the timing chain, check it for stretch. Get the idea? Perform standard diagnostic tests and focus on the results.
You maybe right on the lifters being the source of the noise, especially if the manufacturer restricted oil flow through the lifters to enhance anti-pump-up characteristics.
Use a 1.25" x 3' long thick-wall rubber hose as a listening tube to try and pinpoint the engine clatter. Then rely on standard tests, observation and your experience.
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Yea I'm stressing myself out over stuff that doesn't make sense, when it runs fine. I'll just check my oil again and cut the filter open to see of anything is in there and just drive it a while. Thanks for the help....I'll reply after something actually goes wrong.