454 (7.4L) swap / repair options - 1999 Suburban K2500

[LC2NLS6]

Blueprint engines makes a 598 inch regular deck short block...

 

[Christian Steffen]

Boy this thread really took off lol

My $.02, the factory trim l29 leaves a lot to be desired. Factory tuning, cam, etc suck.

A mild rebuild with a good cam, injectors ( look at takeout LS6 injectors), good tune on an 0411, and some sort of exhaust upgrade would probably make you happy. Strokers make a pretty big improvement, boost is the best. A stock rebuild with some big injectors and a whipple would really make a big difference, just have to make sure you have a good tuner.

I've owned the gen V 5.3, towed with a gen 3 6.0, and driven a gen 4 6.0, none of them handle low rpm pulling well. They make great power when you get them above 3k but down at OD cruising speed they don't have enough torque IMO.

 

[oifla]

ok, got into the valve covers (driver side is where the loudest ticking is happening).

not being an expert, i'm not exactly sure i'm looking at this right but here are some observations:

- there's a broken exhaust stud that may be contributing to the noise from that side of the engine

- no obviously broken valve springs or anything else that stands out under the valve cover. i went through and torqued everything to factory spec

- there are two rockers that had no oil on them (even as I was running the engine without the valve cover for a min)

- no check engine light came on but the engine was running a bit rough (EGR tube was disconnected, plugged at the manifold, plugged at the hose leading to the smog pump).

the no oil on the rocker is concerning because oil pressure on this engine is not great. at idle, it can be less than 20 psi. the oil pressure sender is good, i just replaced it (not sure about the oil pressure gauge).

O.

 

[Gibson]

there are two rockers that had no oil on them (even as I was running the engine without the valve cover for a min)

Do you mean the stud/ball that the rocker arm pivots on?
The oil path is from the lifters, up thru the hollow push rod to the rocker arm.
Chevys normally have an excess of "top end" oil flying around under the valve covers.

oil pressure on this engine is not great. at idle, it can be less than 20 psi.

The official line from Chevy is "5 psi, plus 10 psi for every 1,000 rpm", that's min. with hot oil.
So, a warmed-up engine that's idling at, say 1,000rpm, should have a minimum of ~15psi.
Not uncommon for a higher mileage Chevy, (small or big block,) to idle at ~20 psi.
Note; yes, the newer gen engines like the LS run more pressure, they run "tighter" and they have a "priority main" oil system.

 

[oifla]

Do you mean the stud/ball that the rocker arm pivots on?
The oil path is from the lifters, up thru the hollow push rod to the rocker arm.
Chevys normally have an excess of "top end" oil flying around under the valve covers.

yes, exactly. two were pretty dry. the small hole where the oil seeps up is there but no oil to be found.

The official line from Chevy is "5 psi, plus 10 psi for every 1,000 rpm", that's min. with hot oil.
So, a warmed-up engine that's idling at, say 1,000rpm, should have a minimum of ~15psi.
Not uncommon for a higher mileage Chevy, (small or big block,) to idle at ~20 psi.
Note; yes, the newer gen engines like the LS run more pressure, they run "tighter" and they have a "priority main" oil system.

so my idle oil pressure is off. i meant to clarify that it was 20 when it first starts and sometimes, especially while idling in traffic on a hot day, it dips low enough to engage the 'Check your gauges' light.

to be sure and in order to cut out the potential issue of a bad oil pressure gauge in my instrument panel, i have a mechanical gauge i can throw on to confirm (will get to that).

If loose rockers were to blame for the noise, it should be good now. putting everything back together tomorrow and trying again.

if the oil pressure stays low, i'm not sure what to tackle next.

i'm wondering about the oil pump. i may replace it just to be sure the issue isn't there.

 

[Christian Steffen]

yes, exactly. two were pretty dry. the small hole where the oil seeps up is there but no oil to be found.




so my idle oil pressure is off. i meant to clarify that it was 20 when it first starts and sometimes, especially while idling in traffic on a hot day, it dips low enough to engage the 'Check your gauges' light.

to be sure and in order to cut out the potential issue of a bad oil pressure gauge in my instrument panel, i have a mechanical gauge i can throw on to confirm (will get to that).

If loose rockers were to blame for the noise, it should be good now. putting everything back together tomorrow and trying again.

if the oil pressure stays low, i'm not sure what to tackle next.

i'm wondering about the oil pump. i may replace it just to be sure the issue isn't there.

Odds are, the pump isn't the issue unfortunately. Hopefully the mech gauge says otherwise. Speaking from personal experience my bet is on the main crank bearings. You could also try some heavier oil to see if that'll buy you some time.

 

[oifla]

Odds are, the pump isn't the issue unfortunately. Hopefully the mech gauge says otherwise. Speaking from personal experience my bet is on the main crank bearings. You could also try some heavier oil to see if that'll buy you some time.

the only thing that gives me a little hope is that i ran 10-30w briefly prior to the last oil change and it didn't seem to make too much of a difference as far as PSI. i'm hoping!

 

[oifla]

Odds are, the pump isn't the issue unfortunately. Hopefully the mech gauge says otherwise. Speaking from personal experience my bet is on the main crank bearings. You could also try some heavier oil to see if that'll buy you some time.

sorry, should have asked above. if it's not the oil pump, what do you think is going on?

 

[stutaeng]

the only thing that gives me a little hope is that i ran 10-30 briefly prior to the last oil change and it didn't seem to make too much of a difference as far as PSI. i'm hoping!

10-30? Isn't that pretty close to spec? I've got a 4.3 Vortec with low oil pressure. First of all, get yourself a mechanical guage. Mine was giving me the "check guages" on the dash and mechanical guage was about 5 psi. Dash was below zero, LOL.

I think I switched to something-50 weight. Whatever is the heaviest oil that walmart sells. That was last summer. Pressure increased about 3-4 psi.

She still runs top notch, although I never had any weird noises. As long as it's not raining! That's another story. I figured I needed a rebuild, so what's to lose? It's not like you could barely cause any more damage, so I would try that.

Good luck!

 

[stutaeng]

Bearing clearances, as was already stated above.

Basically, the clearances between bearings and journals have too much slop( wear) such that oil pressure can't be built up to "spec."

But again, without mechanical guage, you can't really know what it is. The dash guage is not as accurate as you'd think.