Rough idle 300 I6
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Rough idle 300 I6
My 1995 300 I6 beguins to shake a little at idle. Plugs ok, injectors ok.
Doing a revision, the problem is cilinder nro 1. It has lower compresion.
All cilinders 160-170 psi, nro 1 120 psi. Chek the lifters..ok
Wath could be? A piston ring? a valve? the camshaft lobe?
Doing a revision, the problem is cilinder nro 1. It has lower compresion.
All cilinders 160-170 psi, nro 1 120 psi. Chek the lifters..ok
Wath could be? A piston ring? a valve? the camshaft lobe?
Fleet Mechanic
Joined: Jul 2011
Posts: 1,916
Likes: 4
Low compression can be due to a number of things such as the valves not sealing properly on their seats, the head bolts might not be torqued all the way down, or a bad piston ring.
I doubt the head bolts aren't torqued properly because it's only on one cylinder.
Unless you changed the cam in your truck, the lobe is more than likely fine. Worn cam lobes can happen mainly due to a lack of break in grease on the cam lobes of a new motor, and this flattens them out within the first 20 minutes of running.
You said the lifters were okay. Since yours is a 1995, you should have non-adjustable rocker arms. If you need to adjust your valve lash at any point, get adjustable push rods. That's the only way you can adjust valve lash, as the rocker arms just torque to spec.
Loose valve lash won't cause low compression though.
If it's just the #1 cylinder, it might be a piston ring.
How long has it been since you changed your motor oil and filter?
I recommend trying Seafoam on your motor first. It cures loose/sticky lifters and frees piston rings.
Sea Foam | Home
I doubt the head bolts aren't torqued properly because it's only on one cylinder.
Unless you changed the cam in your truck, the lobe is more than likely fine. Worn cam lobes can happen mainly due to a lack of break in grease on the cam lobes of a new motor, and this flattens them out within the first 20 minutes of running.
You said the lifters were okay. Since yours is a 1995, you should have non-adjustable rocker arms. If you need to adjust your valve lash at any point, get adjustable push rods. That's the only way you can adjust valve lash, as the rocker arms just torque to spec.
Loose valve lash won't cause low compression though.
If it's just the #1 cylinder, it might be a piston ring.
How long has it been since you changed your motor oil and filter?
I recommend trying Seafoam on your motor first. It cures loose/sticky lifters and frees piston rings.
Sea Foam | Home
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