F23A1AT
Well-Known Member
Hmm good to know stuff here. I didn't think about the fact that these parts are mass produced so matching each set is impossible.
Bad piston!
- Thread starter kacevedo3217
- Start date
I did something similar after I melted through the top of a piston in a Mazda B motor. (touch too much timing, oops)
pulled the piston and rod out, had new piston and rings installed on rod, stuck it back in.
Never even pulled the motor from the car.
It was still running fine 2 years later when it was sold to someone else, and they were still driving it a year after that to my knowledge.
as long as you've not scarred up the cylinder wall it can be done.
Chances are though, if it's not got compression it's probably already killed the cylinder wall.
pulled the piston and rod out, had new piston and rings installed on rod, stuck it back in.
Never even pulled the motor from the car.
It was still running fine 2 years later when it was sold to someone else, and they were still driving it a year after that to my knowledge.
as long as you've not scarred up the cylinder wall it can be done.
Chances are though, if it's not got compression it's probably already killed the cylinder wall.
x5carl3tMurd3rx
Well-Known Member
ya pretty much. we were both detailed in different areas. so with both posts he should know what he's in for haha.
not necessarily but theres no way of telling before getting the head off. unless you borescope it I guess but even then you can't really tell too much.
kacevedo3217
Member
Okay so I pulled the piston and the piston and rings look completely fine and the cylinder walls are fine. So what else can cause that cylinder to have low compression? Bent valves?
kacevedo3217
Member
And it's just that one cylinder all the rest of the cylinders have great compression
98ExAccordwv
I'm Old
Could possibly be a valve issue, but could also be a blown head gasket around the cylinder (there'd be other signs of this). How'd your oil and coolant look when you drained them?
Did you take the rings off the piston and place them in the cylinder and verify that the ring gap is within spec?
Did you take the rings off the piston and place them in the cylinder and verify that the ring gap is within spec?
kacevedo3217
Member
There was no oil in coolant or vice versa so i dont believe its the head gasket and when i did compression wet it was the same as dry so that indicates its not the rings right? correct me if im wrong.
98ExAccordwv
I'm Old
There are varying opinions on the wet vs dry. If the rings are bad, the wet compression should be higher than the dry. Did you try a leak down test, that's probably better in determining the cause. Could just be that the valves are not seating properly. Since you have the head off you may just go ahead and take it to a machine shop and have them re-seat/seal the valves and plane the head.
How's the wear in the cylinder? How egg shaped is it, or is it at all? You'll more than likely not be able to tell this with the naked eye, best to use a cylinder bore gauge to see how uneven the wear is.
How's the wear in the cylinder? How egg shaped is it, or is it at all? You'll more than likely not be able to tell this with the naked eye, best to use a cylinder bore gauge to see how uneven the wear is.
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kacevedo3217
Member
So we pulled out the valves on the cylinder with low compression and the exhaust valves they dont look to good. They are very uneven all around. So im guessing this was my problem the entire time. How much will it cost to get a valve job on those valves? How much more would it be to get them all redone?
98ExAccordwv
I'm Old
It varies from shop to shop. Just call around to a few machine shops and find out. I think my last head job, in which I needed 3 valves replaced, all new seals, and had them re-seated, and had the head milled, cost me around $200.
