Need thoughts on a 'problem'

[GWguy]

GMC Sierra 1500 4.8L extend cab.

Started getting a 'tick', pretty loud, maybe 8 months ago, when I start it up after sitting for a day or two. Sounds like a lifter, but when you accel a bit, it sounds more like a small diesel, or very advanced timing. A low growl. Goes away after 15 seconds or so.

Seems to be better if I run Marvel Mystery Oil in the fuel.

It got a little worse, thought maybe it was from using a synthetic oil all these years. Switched back to standard 5W-30, which is what is called for in the book. It got worse. Now it happens every cold startup, lasts for 15-20 seconds under load. Once the tick disappears, everything is absolutely normal, no noise, no degraded performance, no OBD warnings.

So engine experts, does it sound like a simple lifter issue? Adjustment/replacement? Or could this be a bigger issue, like a rod/bearing? And how would I figure that out without dropping the pan?

Noise only lasts a few seconds, but if I have a rod/bearing issue, I'd hate to be stranded somewhere when it lets go. I've done that once already.... New Jersey Turnpike, Exit 9, middle of winter at 5 am. Not fun.

 

[RoseRed]

Sounds like it's time to buy a new truck!

 

[GWguy]

Sounds like it's time to buy a new truck!

Yeah... wish I could... this one is going to have to last a little longer.

OBTW, it's a 2000 year.

 

[Ken King]

How is the oil pressure?

 

[Gilligan]

A rod or main bearing knock will almost always change sound pretty noticeably as the loading changes, often completely disappearing when the engine is under load and most noticeable when the engine is very lightly loaded or "coasting...like the moment immediately after your release the gas pedal after revving the engine. The only exception to that rule is a spun bearing condition, which can create a fairly constant "thud" ..but that condition usually deteriorates fairly rapidly in to complete failure and an intolerable rod knock (or a ventilated block) so that does not sound like your problem right off.

Valve train noises tend to be fairly constant in volume and characteristic noise regardless of engine loading

Borrow (or make) a mechanics stethoscope and try to pin point the source a little better. My money is on a weak lifter and, frankly, that can be left alone as long as you don't mind waiting for it to pump up every time you cold start the truck.

 

[Chris0nllyn]

The lifters may be draining down and not holding oil anymore.

 

[Ken King]

It might also be an exhaust leak that corrects itself once the engine warms up. Do like Gilligan recommended and trace it down as best as you can to isolate the location of the "tick".

 

[Chris0nllyn]

It might also be an exhaust leak that corrects itself once the engine warms up. Do like Gilligan recommended and trace it down as best as you can to isolate the location of the "tick".

Seafoam is a great way to find out if you have exhaust leaks.

 

[GWguy]

It might also be an exhaust leak that corrects itself once the engine warms up. Do like Gilligan recommended and trace it down as best as you can to isolate the location of the "tick".

Oil pressure is fine, over 50 at idle, close to 90 at 2500rpm (if I remember right).

I would recognize an exhaust leak, so I'm ruling that one out. Good thought tho.

I did try the stethoscope, Gilligan, but the sound disappears so quickly I can't locate it.

I'm leaning towards a lifter, but wanted other opinions on possible bearing failures. The way it acts, and changes with the oil type and warm up lead me to think it's a lifter too.

I do worry a bit that it could be more. I haven't been very easy on this motor. Towing a 16' box trailer with the 'Wing it it to NY and back a few times was an obvious drain on it.

 

[GWguy]

Seafoam is a great way to find out if you have exhaust leaks.

How so? I was using Seafoam for a while just to help clear the injectors once in a while, but how do you relate that to an exhaust leak?

 

[Gilligan]

It might also be an exhaust leak that corrects itself once the engine warms up.

Exhaust leaks are the debil. They can produce some of the most mechanically-sounding and worrisome noises you ever heard. I had one once that I was dead certain was a rocker arm coming loose...

Turned out to be a factured exhaust manifold.

 

[GWguy]

Exhaust leaks are the debil. They can produce some of the most mechanically-sounding and worrisome noises you ever heard. I had one once that I was dead certain was a rocker arm coming loose...

Turned out to be a factured exhaust manifold.

Ok, I'll double-check that one.....

 

[Gilligan]

Ok, I'll double-check that one.....

My money is still on it being a "weak" lifter draining down.

 

[DEEKAYPEE8569]

A rod or main bearing knock will almost always change sound pretty noticeably as the loading changes, often completely disappearing when the engine is under load and most noticeable when the engine is very lightly loaded or "coasting...like the moment immediately after your release the gas pedal after revving the engine. The only exception to that rule is a spun bearing condition, which can create a fairly constant "thud" ..but that condition usually deteriorates fairly rapidly in to complete failure and an intolerable rod knock (or a ventilated block) so that does not sound like your problem right off.

Valve train noises tend to be fairly constant in volume and characteristic noise regardless of engine loading

Borrow (or make) a mechanics stethoscope and try to pin point the source a little better. My money is on a weak lifter and, frankly, that can be left alone as long as you don't mind waiting for it to pump up every time you cold start the truck.

A quick "stethoscope" can be a long screwdriver. To listen for a ticking valve, with the engine running at idle, firmly press aforementioned screwdriver against a valve cover; pointy end down; then firmly but gently press your ear to the screwdriver handle. If a tick exists, you'll hear it. YW

 

[desertrat]

Oil pressure is fine, over 50 at idle, close to 90 at 2500rpm (if I remember right).

I would recognize an exhaust leak, so I'm ruling that one out. Good thought tho.

I did try the stethoscope, Gilligan, but the sound disappears so quickly I can't locate it.

I'm leaning towards a lifter, but wanted other opinions on possible bearing failures. The way it acts, and changes with the oil type and warm up lead me to think it's a lifter too.

I do worry a bit that it could be more. I haven't been very easy on this motor. Towing a 16' box trailer with the 'Wing it it to NY and back a few times was an obvious drain on it.

Exhaust leaks are the debil. They can produce some of the most mechanically-sounding and worrisome noises you ever heard. I had one once that I was dead certain was a rocker arm coming loose...

Turned out to be a factured exhaust manifold.

I had a noise I swore was a pulley or something that rotated anyway. Came and went. No relation to running time RPM, nothing. Turned out to be the top of the muffler had made itself a neat little flap. Thanks Cheseldine.

 

[Ken King]

A quick "stethoscope" can be a long screwdriver. To listen for a ticking valve, with the engine running at idle, firmly press aforementioned screwdriver against a valve cover; pointy end down; then firmly but gently press your ear to the screwdriver handle. If a tick exists, you'll hear it. YW

You learned that the hard way, didn't ya.

 

[GURPS]

try a heavier oil ......

I used to run 20/50 in ALL my Air Cooled VW's ....

The wife's Bronco gets 10/30 - or 40 depending on the season ....

The Saturn gets whatever the Stealerships puts in for the free oil changes, but I top it off with 20/50 over time as it burns off, going to the next change @ 5000 miles .....

My Jeep gets 20/50 ......


I had an old VW Bus that was so sloppy I ran 90Wt with the 20/50 ...

 

[bcp]

Im betting on a lifter leaking down when it sits, and maybe not holding pressure under load.
If the oil pressure is good, chances are that the main and cam bearings are good.
Its not that hard to replace lifters if the noise bugs you, if the noise does not bug you, turn up the radio and run it for another 100k.

but honestly, mine sounds like that every morning when I start it, and anytime Im pulling and put a load on it.
you get used to it.

 

[GURPS]

can you put new lifters on an OLD CAM ?

I thought that was a NO NO

 

[Gilligan]

can you put new lifters on an OLD CAM ?

I thought that was a NO NO

Rollers?..yes, you can. Flat tappets...never a good idea..