engine rebuild piston rings size?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

ChainsawMonkey

New Member
Joined
Jun 12, 2017
Messages
6
Reaction score
0
Location
Maine
Hello all
I have been rebuilding the engine from our 3.7l 2002 jeep liberty sport.
I just honed the cyls and I assumed I could just put in standard piston rings.
Well I desided to measure first. Not having the correct tool I desided to check the ring gap with the old rings. Well the the upper is out on every cyl. 0.65mm 0.58mm 0.60mm 0.63mm 0.58mm and another 0.58mm.
Spec being 0.23-0.39mm with a wear limit of 0.43mm
So do I assume this is from wear and order new standard rings or go a size up? What size would you recommend?


Cyl walls are coming in at 24.720in 24.675in 24.745in 24.685in 24.705in
Intermediate rings all came back good. 2 at 0.55mm 4 at 0.53mm spec is 0.40-0.66mm with a wear limit of 0.74mm. Which has me completely confused. Why are the uppers so off when the Intermediates are right on?
 

Road_Runna

New Member
Joined
Nov 4, 2011
Messages
20
Reaction score
0
Location
Ogden, Ut
2024 and just seen your post.
I'm doing a rebuild on mine, and measured about .030" thou of an inch on the old rings.
I checked gap on my new rings (standard bore of 3.66" of an inch) I honed it with 230 and finished with 320 grit and I'm sitting at .013 on an inch on my top rings, and .0165 on my secondary rings.
I noticed Jeep used chamfered top rings from the manufacturer, which break off easy.

Did you use a diabore to check diameter of the piston bores? A dial caliper would give you that many inconsistent readings like those you mentioned.
 

KJowner

Full Access Member
Joined
Oct 20, 2022
Messages
1,437
Reaction score
820
Location
Uk
If you have worn bores then a hone isn't going to fix them, as you have discovered they don't wear round and a hone just follows the wear and makes matters worse by increasing the clearance.
How slack are the pistons in the bores?
 
Top