adsm08
Senior Master Grease Monkey
Supporting Member
Article Contributor
Ford Technician
TRS 20th Anniversary
- Joined
- Sep 20, 2009
- Messages
- 34,623
- City
- Dillsburg PA
- Vehicle Year
- 1987
- Engine
- 4.0 V6
- Transmission
- Manual
- Tire Size
- 31X10.50X15
What you really want to do before tear down is a wet/dry test.
You test each cylinder and write down the reading. Then put a teaspoon of oil in each cylinder and do it again. If the number comes up significantly then you know there is a ring issue. If it stays about the same your issue is mostly in the valves and you know that putting on a new head, or getting a valve job is not wasted effort/money because the bottom end is still sealing.
130 is good, 90 is minimum, any cylinder showing more than a 10% drop from the others is a problem because it will cause a noticeable miss.
You test each cylinder and write down the reading. Then put a teaspoon of oil in each cylinder and do it again. If the number comes up significantly then you know there is a ring issue. If it stays about the same your issue is mostly in the valves and you know that putting on a new head, or getting a valve job is not wasted effort/money because the bottom end is still sealing.
130 is good, 90 is minimum, any cylinder showing more than a 10% drop from the others is a problem because it will cause a noticeable miss.