4.7 scoring on cylinder walls

jeovanicorro · Apr 4, 2024

i’m rebuilding my 4.7 engine it had a a misfire on cylinder 1 and excessive crankcase pressure so i though it would be a piston ring i took it apart and the piston was missing a really small piece under the oil ring and it scratched the cylinder walls i honed the cylinder walls and cylinder 1 has scoring when i pass my nail on it i can feel it but it won’t get stuck on it i just feel it im wondering if i can run it like that and just throw new rings and new pistons im doing this as a learning experience im not tryna have anything perfect im just tryna drive the truck daily without any misfiring don’t matter if it consumes a small amount of oil

jws123 · Apr 4, 2024

jeovanicorro said:
i’m rebuilding my 4.7 engine it had a a misfire on cylinder 1 and excessive crankcase pressure so i though it would be a piston ring i took it apart and the piston was missing a really small piece under the oil ring and it scratched the cylinder walls i honed the cylinder walls and cylinder 1 has scoring when i pass my nail on it i can feel it but it won’t get stuck on it i just feel it im wondering if i can run it like that and just throw new rings and new pistons im doing this as a learning experience im not tryna have anything perfect im just tryna drive the truck daily without any misfiring don’t matter if it consumes a small amount of oil

make sure you check the valve seats on the cylinder heads make sure none of them look like they are coming out are you able to get a picture of the scoring?

Mister Luck · Apr 4, 2024

Sometimes you can get just by using a fine flex ball hone on a drill with a little oil and a coffee can splash guard

Most posted videos use a drill speed that is too high rpm you just make two of three passes otherwise you risk removing too much and changing the tolerance of the ring gap and going oversize which leads to other complications .

Do you have a machine shop to go to
so you can source out just one set of rings and one piston ?

Ring Gap Tips

4.7 rebuild ring gaps

jeovanicorro · Apr 4, 2024

jeovanicorro · Apr 4, 2024

valve seats are good i took my heads apart changing stem seals im just concerned about the scoring from what i saw the truck suffered from oil starvation only had the truck for like 2 or 3 months

Mister Luck · Apr 5, 2024

Is that a liner ?

jeovanicorro · Apr 5, 2024

i don’t know what you mean by liner

rzr6-4 · Apr 5, 2024

jeovanicorro said:
i don’t know what you mean by liner

Instead of the piston riding directly against the block, when you use a liner your bore out the block to make the hole bigger and you insert a liner or sleeve to get the right inside dimension. If the bores are all jacked up that is a common technique to be able to reuse the block.

This sleeve is fairly thick. You should be able to see if it looks like your piston bore is a separate sleeve or part of the block itself.

jeovanicorro · Apr 5, 2024

so its re sleeving a block with the stock bore

rzr6-4 · Apr 5, 2024

jeovanicorro said:
so its re sleeving a block with the stock bore

yes.

Mister Luck · Apr 5, 2024

jeovanicorro said:
i don’t know what you mean by liner

The cylinder is a different color and I thought you might have had work done to it already because in looks very clean.
Maybe I should have said “why is it so clean?”

When an engine is serviced with factory replacement parts it is my experience that factory parts are not offered in oversized dimensions ..crankshaft bearings etc.

Ok my fault for not understanding that you honed the cylinder yourself without creating a crosshatched pattern

jeovanicorro · Apr 5, 2024

i rehoned it and was working on doing the other ones i took the picture before i did the rest of the cylinders i used the 3 leg honer not ball honer

jeovanicorro · Apr 5, 2024

also noticed towards the bottom of the bore is where the piston scoring is deep and you can feel it as it goes towards the top you can’t feel it with your nail at all

jws123 · Apr 6, 2024

jeovanicorro said:
also noticed towards the bottom of the bore is where the piston scoring is deep and you can feel it as it goes towards the top you can’t feel it with your nail at all

how many miles on the truck fron the pics that cylinder looks prty worn.

Wild one · Apr 6, 2024

It'll run,but it'll use oil and probably foul those 2 plugs faster then the rest. Have you measured bore taper from top to bottom,as it might not even be worth throwing pistons in it,if it has excessive cylinder taper. Have you looked around for another low milege used 4.7,that might be a better option

Mister Luck · Apr 7, 2024

jeovanicorro said:
also noticed towards the bottom of the bore is where the piston scoring is deep and you can feel it as it goes towards the top you can’t feel it with your nail at all

I’m not sure what your options are for piston ring sets.
Your cylinder walls should be as uniform as possible
Crosshatching on the cylinder walls is to retain an oil film so the rings don’t bind when expanded from the heat and compression of fuel ignition.
Are you going to check the crankshaft bearings for contamination ?
You’ve heard all the sayings regarding engine rebuilding
“Anything worth doing is worth doing right or at least doing twice”
“The devil’s in the details”
Check prices on rings sets and the piston you need to replace
If you don’t have a cylinder bore gage you could invest in a used one or you might have a set of feeler gauges and use a ring and measure the gap through out the cylinder bore.
A good machine shop will probably be willing to help you out with pressing on the pin for the piston rod depends on the shop and how obliging they are.

Dusty · Apr 8, 2024

All this depends on your ultimate goal. If you're contemplating putting new rings and pistons in it, the work and cost involved indicates you think the investment into the vehicle is worth it.

However, the vertical scoring looks bad enough that you'll likely have an oil usage issue once you're done. I would advocate for a fresh block or pull the block out and have a machine shop clean and dress the motor. You'll need new pistons which you already seem committed to.

Of course, that's assuming the crank and heads are still serviceable.

These done half right usually often turn out to be half wrong.

Good luck.

Regards,
Dusty
P.S. I would have the heads checked for any warping, which is easy to do on that motor if it's been overheated.
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 108704 miles.

Hardracer · Apr 11, 2024

It'll run like Wildone said.That hone you have can get you in trouble quick if you dont have a measuring device of some sort....
If money is a concern and that hole is bugging you,instead of doing(boring)all the holes and buying a full set of pistons, take it to a shop and have them bore/hone that 1 hole,they can measure the others while it's there and have them just touch hone the others(is what it is kinda thing,it will run)...I can't tell about the scratches but I would think +.005 would clean that up(unless you've already taken alot out)buy the 1 piston and re-ring all pistons,you could be .002-.003 over and be fine with a re-ring,Also,have them mount the rod on the new piston.I dunno if thats a floating rod or not.
i also wouldnt think that it would be a balance issue at +.005..ive seen stock 305/350 GM crate motors be out more than 28grams on the balancing machine we have here.
it is a 4.7...doesnt sound like you want it to be a racer ..I think ull be fine with this type of scenerio.

Dusty · Apr 11, 2024

4.7 rods are pressed fit.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 108953 miles.

4.7 scoring on cylinder walls

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