8.1 Questions

[rieker69]

I have an 8.1 truck. It has the small knock/ping when I start it for maybe 30-60 seconds. I know the 6.0L have this as well. Is it normal on the 8.1's? Anything to stop it, maybe add some lucas oil to it?

[REV353]

Any chance its an exhaust manifold leak?, mine had one on the right manifold that lasted about that long, it wasn't a knocking or pining noise. Other than that it's quiet.

[shermbb]

I have an 8.1 truck. It has the small knock/ping when I start it for maybe 30-60 seconds. I know the 6.0L have this as well. Is it normal on the 8.1's? Anything to stop it, maybe add some lucas oil to it?

 

 

I used to have an 8.1L with the piston slap that you describe. It drank 1 quart of oil every 1000miles, and gm called this "normal". I sold it within a year. The piston slap itself is not a big deal, but the oil consumption was an issue for me.

[vester]

maybe add some lucas oil to it?

 

The only thing adding Lucas oil will do is lighten your wallet. You could try a heavier weight oil (10w40) to see if there is a difference.

[doverarjim]

I don't own a 8.1 but years ago in BB's we would run it one quart over full, and for some reason it would not burn any. Don't flame me for putting more oil in that is called for but that was one trick that for some reason would stop a bb from using oil. Don't know how or why just know in my past that it has done the trick. As far as the knock I'm no help there.

[rieker69]

Any chance its an exhaust manifold leak?, mine had one on the right manifold that lasted about that long, it wasn't a knocking or pining noise. Other than that it's quiet.

 

 

I'll have to check the manifolds. Seems really light knock/ping just upon cold start for 30 seconds or so. I know a couple people with the 6.0's that have the same issue.

[rieker69]

I don't own a 8.1 but years ago in BB's we would run it one quart over full, and for some reason it would not burn any. Don't flame me for putting more oil in that is called for but that was one trick that for some reason would stop a bb from using oil. Don't know how or why just know in my past that it has done the trick. As far as the knock I'm no help there.

 

 

I have been told that putting a 180* thermostat in would fix the oil problem.

[rieker69]

maybe add some lucas oil to it?

 

The only thing adding Lucas oil will do is lighten your wallet. You could try a heavier weight oil (10w40) to see if there is a difference.

 

 

 

May have to try that. The truck used 15w50 from the previous owner, but he was in Arizona. I switched to 5w40 because of cold starts in Montana. Maybe should use 10w40.

[vester]

maybe add some lucas oil to it?

 

The only thing adding Lucas oil will do is lighten your wallet. You could try a heavier weight oil (10w40) to see if there is a difference.

 

 

 

May have to try that. The truck used 15w50 from the previous owner, but he was in Arizona. I switched to 5w40 because of cold starts in Montana. Maybe should use 10w40.

 

 

5w40 and 10w40 are both 40 weight oils, the 5w will just flow easier when it is cold. I had assumed (incorrectly) that you were using 5w30. During the summer you might try a fill of 20w50, if that makes no difference then just leave in the 5w40. If it does help the noise, you may just have to live with it in the winter. I think 20w50 would not be suitable for Montana winters without a block heater. If the oil weight does make a difference, I would recommend asking this same question over at www.bobistheoilguy.com forums. Those people know every oil out there and could probably find you one to do what you need.

[ChrisNJ]

I had three 8.1's, two ate a quart in 4K miles, one didn't. They all had start 'ticks-knocks'. I abused these engines running at full loads a quarter of their lives. They all worked fine, just added a quart here and there. I try not to sweat the small stuff anymore.

[jro909]

the 8.1 is a goliath of a motor, its bounds to eat some oil for that much displacement...the sound is probably the exhaust, mine does it and its from a broken bolt in the manifold...