Hello, first post here. I'm big into Hondas, but the Corolla is my mom's car. It has 270k miles on it with the original 1.8L (1zz-FE?) engine. Recently cylinders 1 and 2 have been getting misfire codes. New sparkplugs didn't solve it, so I did a compression test:
1 - 85 psi
2 - 60 psi
3 - 100 psi
4 - 105 psi
This led me to believe the cylinder 1 and 2 rings were on their way out or the valves and seals were bent, since the car burns a little oil too. I pulled the valve cover off, head and cams don't show the wear I was expecting in a 270k engine. Borescope'd the piston walls for signs of failed rings, they look amazingly in perfect condition. The piston tops look a little weird, but it's a high mileage engine and all I know are the symetrical honda pistons, so who am I to judge. I know I can't truly test valves with the head on the block, but shining a light into the spark plug hole and borescope through the intake I could see no light. Since it's VVT, I'd assuming the intake would be damaged valve-wise before the exhaust. That lead me to the timing chain. The cams are still in time and line up at #1 TDC, but with excessive slop.
Again, coming from the Honda D, B, and K series engines: The K20 has a recommended chain, tensioner, and guide life of 100-120k miles. D and B series engines use belts, but they recommend similar replacement schedules.
This timing chain (1ZZ-FE? Please correct me if I'm wrong on that engine code) has about 1/8-3/16" of play up and down at #1 TDC. In a K20, that would probably ruin the engine. So, is my bad compression likely due to a failed timing chain and tensioner/guides, or are there other issues present? Car has never had a timing chain service done to it as far as the family know. I've been snooping here on the forums, some users say that the chain is indestructible. The K20 chain is 3 ply (4 links wide) and it definitely is NOT good for the life of the car.
Videos and pictures from the borescope to follow when I can upload them at home.
Please advise.
1 - 85 psi
2 - 60 psi
3 - 100 psi
4 - 105 psi
This led me to believe the cylinder 1 and 2 rings were on their way out or the valves and seals were bent, since the car burns a little oil too. I pulled the valve cover off, head and cams don't show the wear I was expecting in a 270k engine. Borescope'd the piston walls for signs of failed rings, they look amazingly in perfect condition. The piston tops look a little weird, but it's a high mileage engine and all I know are the symetrical honda pistons, so who am I to judge. I know I can't truly test valves with the head on the block, but shining a light into the spark plug hole and borescope through the intake I could see no light. Since it's VVT, I'd assuming the intake would be damaged valve-wise before the exhaust. That lead me to the timing chain. The cams are still in time and line up at #1 TDC, but with excessive slop.
Again, coming from the Honda D, B, and K series engines: The K20 has a recommended chain, tensioner, and guide life of 100-120k miles. D and B series engines use belts, but they recommend similar replacement schedules.
This timing chain (1ZZ-FE? Please correct me if I'm wrong on that engine code) has about 1/8-3/16" of play up and down at #1 TDC. In a K20, that would probably ruin the engine. So, is my bad compression likely due to a failed timing chain and tensioner/guides, or are there other issues present? Car has never had a timing chain service done to it as far as the family know. I've been snooping here on the forums, some users say that the chain is indestructible. The K20 chain is 3 ply (4 links wide) and it definitely is NOT good for the life of the car.
Videos and pictures from the borescope to follow when I can upload them at home.
Please advise.