Lifters noise

[TNBob]

Hi, I have an 2007 Tahoe with 180,000 miles. As common I had a lifter/cam issue. I perform the AFM Delete (change all 16 normal lifters and regular camshaft and re-program to dissconect the AFM on the computer).

I been having low pressure problems . I already change the oil pump and double checked the O ring on the pump.

When is cold the pressure goes over 40 (normal) and the engine sounds great. But when it warms up the oil drops under 20 and the lifters start to make noise.

Any help will be appreciated.

Hi, I have an 2007 Tahoe with 180,000 miles. As common I had a lifter/cam issue. I perform the AFM Delete (change all 16 normal lifters and regular camshaft and re-program to dissconect the AFM on the computer).

I been having low pressure problems . I already change the oil pump and double checked the O ring on the pump.

When is cold the pressure goes over 40 (normal) and the engine sounds great. But when it warms up the oil drops under 20 and the lifters start to make noise.

Any help will be appreciated.

Others can do better at specific diagnosis, here are a few general thoughts.

Lifter quality is absolutely critical - GM or Delphi, or specific aftermarket brands recommended by others. It's not a place to cut corners, same with trays. I just bought a set of the GM lifters (12499225), and it was about $400 for the set from GM Parts Giant - money well spent.

I agree with others, go with 5W-30 oil (or whatever is specified on the filler cap). An oil change to the correct viscosity is the first thing I'd do.

A common failure point with AFM engines is the oil pressure relief valve. If you didn't have pressure problems before AFM delete, it's probably ok. Some guys replace it with a plug after AFM delete. If you pull the oil pan again, you should replace the valve if you don't plug the port - it's a $10 part (GM 12608835).

You didn't mention replacing the VLOM with a plain valley cover. I don't know if leaving the VLOM in place will definitely cause a problem, but it's SOP to replace it with AFM delete. The part is cheap (about $50-60 if you use the L92 version with PCV valve in the valve cover).
Oil pump may vary with block material. Iron blocks (probably LY5, assuming you have a 5.3) get the Melling M295. Aluminum blocks (LC9) need the higher volume M365 with AFM. Some people go back to M295 after DoD delete, but the Al blocks have looser clearances around the lifters and need more oil. Check here and call Melling to confirm the right choice. GM is now shipping these Melling pumps as OEM replacement parts.

Several different o-rings were used on the oil suction tube. For LY5/LC9, the correct one is probably red/orange (GM 12584922). Aftermarket suppliers may use different colors. Make sure you used the right one. If you drop the oil pan again, add a hold-down bolt (Sac City Corvette) or girdle (Improved Racing, others) to secure the pickup tube to the oil pump.

Good luck, and keep us posted!

 

[Geotrash]

Others can do better at specific diagnosis, here are a few general thoughts.

Lifter quality is absolutely critical - GM or Delphi, or specific aftermarket brands recommended by others. It's not a place to cut corners, same with trays. I just bought a set of the GM lifters (12499225), and it was about $400 for the set from GM Parts Giant - money well spent.

I agree with others, go with 5W-30 oil (or whatever is specified on the filler cap). An oil change to the correct viscosity is the first thing I'd do.

A common failure point with AFM engines is the oil pressure relief valve. If you didn't have pressure problems before AFM delete, it's probably ok. Some guys replace it with a plug after AFM delete. If you pull the oil pan again, you should replace the valve if you don't plug the port - it's a $10 part (GM 12608835).

You didn't mention replacing the VLOM with a plain valley cover. I don't know if leaving the VLOM in place will definitely cause a problem, but it's SOP to replace it with AFM delete. The part is cheap (about $50-60 if you use the L92 version with PCV valve in the valve cover).
Oil pump may vary with block material. Iron blocks (probably LY5, assuming you have a 5.3) get the Melling M295. Aluminum blocks (LC9) need the higher volume M365 with AFM. Some people go back to M295 after DoD delete, but the Al blocks have looser clearances around the lifters and need more oil. Check here and call Melling to confirm the right choice. GM is now shipping these Melling pumps as OEM replacement parts.

Several different o-rings were used on the oil suction tube. For LY5/LC9, the correct one is probably red/orange (GM 12584922). Aftermarket suppliers may use different colors. Make sure you used the right one. If you drop the oil pan again, add a hold-down bolt (Sac City Corvette) or girdle (Improved Racing, others) to secure the pickup tube to the oil pump.

Good luck, and keep us posted!

All excellent advice, in my opinion.

 

[Faustof]

I order the OEM lifters and trays (thiking of keeping the Camshaft (non original). I will let you know the results. Thanks

 

[TNBob]

Since you're going back for surgery - I read on another forum that the VLOM can definitely be the source of oil pressure problems. You have to remove it to get to the lifters anyway, so replacing it with a plain valley cover is worthwhile. The usual valley cover is GM 12598832 - includes gaskets and bolts. You can get one from a GM dealer or any of the reputable merchants who sell quality products online - Summit Racing, Brian Tooley Racing, Scoggin Dickey, Texas Speed, AMS Racing, Michigan Motorsports, JEGS, etc - don't mean to leave or single anyone out.

Replacing the pressure sensor (probably 12673134 for your vehicle) and screen 12585328) is also recommemded.

 

[Faustof]

Since you're going back for surgery - I read on another forum that the VLOM can definitely be the source of oil pressure problems. You have to remove it to get to the lifters anyway, so replacing it with a plain valley cover is worthwhile. The usual valley cover is GM 12598832 - includes gaskets and bolts. You can get one from a GM dealer or any of the reputable merchants who sell quality products online - Summit Racing, Brian Tooley Racing, Scoggin Dickey, Texas Speed, AMS Racing, Michigan Motorsports, JEGS, etc - don't mean to leave or single anyone out.

Replacing the pressure sensor (probably 12673134 for your vehicle) and screen 12585328) is also recommemded.

Thanks a lot. I already change the valley cover with a plain ( with no coils)

Since you're going back for surgery - I read on another forum that the VLOM can definitely be the source of oil pressure problems. You have to remove it to get to the lifters anyway, so replacing it with a plain valley cover is worthwhile. The usual valley cover is GM 12598832 - includes gaskets and bolts. You can get one from a GM dealer or any of the reputable merchants who sell quality products online - Summit Racing, Brian Tooley Racing, Scoggin Dickey, Texas Speed, AMS Racing, Michigan Motorsports, JEGS, etc - don't mean to leave or single anyone out.

Replacing the pressure sensor (probably 12673134 for your vehicle) and screen 12585328) is also recommemded.

Thanks a lot, in fact I already change the valley cover with a plain one, (without the coils), and reprogram the car computer to turn off the AFM for good. Thanks

 

[j91z28d1]

You adjust them initially to complete the long block or when putting heads/valve train, etc back on. Its not like a solid roller or flat tapper cam where lash has to be periodically maintained but hydrauic pushrods / lifters can occassionally come out of adjustment but admittedly its rare.

I suggested it as the noise sounds like out of adjustment valves or lifter noise (failing lifter). If there's no valves out of adjustment then he's taking the heads off to replace the lifters (unless we're hearing rod knock or some other bottom end noise but doesnt sound like that to me)

as far as I know these ls are not like a old small block chevy. there's no adjustment in the rocket arms. they just bolt down. you adjust buy buying new push rods. I've seen guys throw the rockers on and impact them down from needing to replace a head between rounds.

they do have expensive aftermarket rockers with an adjustment end where the push rod hits the rocker. but I'm pretty sure thats not a street setup as much as for solid cams.

unless the heads have been milled or the valve seats sunk to far in the head, or I guess aftermath valves with a different length. it shouldn't change from stock. but if it does, it's a hassle to set up.


Honestly as much as everyone loves these ls engines. compared to a Gen 1, everything is a major hassle just to get good flowing heads form the factory ha.

 

[NickTransmissions]

as far as I know these ls are not like a old small block chevy. there's no adjustment in the rocket arms. they just bolt down. you adjust buy buying new push rods. I've seen guys throw the rockers on and impact them down from needing to replace a head between rounds.

they do have expensive aftermarket rockers with an adjustment end where the push rod hits the rocker. but I'm pretty sure thats not a street setup as much as for solid cams.

unless the heads have been milled or the valve seats sunk to far in the head, or I guess aftermath valves with a different length. it shouldn't change from stock. but if it does, it's a hassle to set up.


Honestly as much as everyone loves these ls engines. compared to a Gen 1, everything is a major hassle just to get good flowing heads form the factory ha.

I'm no engine expert (have built a few of various pushrod types over the years GM, Ford and Dodge) so feel free to dispute me on any of this but IIRC pushrod length is determined by cam lobe profile and, for non-stock applications (or in some cases when the heads have been milled in otherwise stock applications) you determine push rod length using an adjustable push rod and lengthen or shorten the OAL until the rocker arm's roller is centered on the top of the valve throughout the opening/closing cycle of that particular valve as you're turning the engine over. I would check a couple intake and exhaust valves with Dykem until I got consistent results. Then I'd measure the length of the adjustable push rod and then order pushrods for that length or as close as possible (think they're available in either .050 or .025 increments for most pushrod engines from most push rod manufacturers).

If valve train would ever get noisy after rebuild, we would remove the valve covers and with engine running, attempt to adjust until they are quiet again. If we couldn't get the noise to stop then we would figure the lifter to be bad and replace which fixed the problem. Granted, I've never done that (or had to) on a Gen 3 or newer engine so perhaps they are diff. I built a grand total of one (1) LS-based engine and this was almost 10 years ago but from what I recall, the initial "adjustment" procedure was to bring the engine to TDC at #1 then tighten certain intake and exhaust rocker arm fasteners to 20 or 22 ft lbs then rotate the engine 360 then tighten the ones not yet touched to the same torque spec, which is what you're likely referring to.

Can't argue when it comes to factory head flow not being optimal.

ETA: here's the rocker arm procedure from my Tahoe's factory svc manual for anyone that needs the info

 

[j91z28d1]

yeah that's the general way of measuring pushrods. there's a debate about what you're actually looking for as far as contact on the valve. but it doesn't really matter which one you agree with as long as they aren't some touchy valve angle heads that like to kill guides. all ls based engines good, ls7 not so good haha

but what I mean is remember Gen 1 days, the center head bolt on the rocket. you'd put that on the base of the cam lobe, tighten down the rocker nut till zero lash on the pushrod and then go either a half turn or quarter turn depending on thread pitch and lifter specs. you wanted it pre loaded in the middle of the lifter internal bore and then lock down the set screw in the middle to keep the nut from moving.

well these ls engine doing have that center bolt that adjusts rocket height. you just tighten them to your spec and go. there's nothing to adjust but push rod length to center the lifter plunger in its bore.

that book just wants you to tighten them down on the base of the cam, which is probably safer than just hitting with an impact incase one happens to be sitting on the top of the cam lobe. I'm not sure what it would actually hurt, but it would probably press all the oil from the lifter and tap for a while at first start.


if anyone is curious, I lean this way with my pushrod length. this guy's saved my but with a set of heads that had a 13deg valve angle and were known to eat up guides. they actually ended up discontinuing the heads over it, even after comp developed a rocker arm just for it. it still ate guides for people. once I used this method, never had any more issue, and I still have 2 sets of the heads. one on a car, and another on a shelf I just hate to get rid of even thou they probably need 1000$ worth of port work to match what todays aftermarket heads flow.

Basically geometry over wear pattern. get the geometry correct and who cares where the wear pattern falls on the valve, that's up the the engineers designing these things. we can only buy parts and assemble. throwing the whole geometry off trying to center the contact on the valve cause more issues than the solves.

 

[Faustof]

Thanks to every one, your information was very helpful. I changed the lifters to original OEM and the original OEM lifters tray. The result was a very smooth noise free engine. Thanks for caring for people (like me) that does not have experience. Ialso put the Dexo 10W30 syntetic oil , no more 1985 engine oil for my truck. LOL.