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Discussion Starter · #1 ·
i have a 99 3.0 ohv and it is not a lot of miles on it i have one person telling it could be rings and two people are saying it is valves these are my number
cyl w/o oil in cyl
1. 175
2. 100
3. 175
4. 175
5. 175
6 175
cyl w/ oil in cylinder
1. 225
2. 125
3. 225
4. 225
5. 225

what do you think it could be
 

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It should run and fire, but it'll most likely have a "miss" or the feeling thereof. I would do a leak down test next. From there sounds like a gasket went south or cracked head/block.
 

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How much oil did you put in each cyl? 225 is way high unless you have a 11.5:1 compression ratio engine.

As noted above, a leakdown test wil help isolate why #2 is way low.
 

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Discussion Starter · #4 ·
How much oil did you put in each cyl? 225 is way high unless you have a 11.5:1 compression ratio engine.

As noted above, a leakdown test wil help isolate why #2 is way low.[/QUOT

how do you do a leak down test and what is it
 

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Discussion Starter · #5 ·
How much oil did you put in each cyl? 225 is way high unless you have a 11.5:1 compression ratio engine.

As noted above, a leakdown test wil help isolate why #2 is way low.

i could have put to much oil in it
 

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Obviously your #2 cylinder is your problem child. All readings look normal except number 2 cylinder. Anything below 120psi without oil is suspicious.

Your approach to this problem is correct, test with and then without oil. Is number 2 misfiring? Perhaps a trouble code?

Lets look at events that could have caused a low reading for number 2.

1) Overheating an engine will cause warped heads, warped block, cause the head gasket to leak. If any of this is bad a coolant pressure test will determine this because it will not hold pressure. Overheating will cause burned valves as well, most likely the exhaust valves and may not be diagnosed as a coolant leak. In other words you have a burned valve but the coolant test passes.

2) How to determine if its the bottom end or top end of the engine using oil as a seal. Your reading for number 2 went up slightly with oil, , while the rest of the cylinders went up by 50 psi. If you had bad rings the pressure would have gone up dramatically, say 175 psi. At 175 psi, this would indicate your valves are good.

3) The reading of 125 psi with number 2 using oil would indicate to me the top end has issues, head gasket, leaky valves, ect. See item 1 for root causes. If a valve does not seat all the way down to get cooled by the valve seat it will "burn". Burned valves are no longer circular to hold the pressure from the piston. However, you can burn a valve if head temperatures get abnormally high like in a overheat condition. Overheating an engine is almost sure death given todays close manufacturing tolerances.

The good news is the top end is easier to fix than the bottom end and in my opinion worth investigating. When pulling the head look at the number 2 valves to determine if one is defective or burned.

Just my 2¢.

Monsoon
 

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Discussion Starter · #7 ·
Obviously your #2 cylinder is your problem child. All readings look normal except number 2 cylinder. Anything below 120psi without oil is suspicious.

Your approach to this problem is correct, test with and then without oil. Is number 2 misfiring? Perhaps a trouble code?

Lets look at events that could have caused a low reading for number 2.

1) Overheating an engine will cause warped heads, warped block, cause the head gasket to leak. If any of this is bad a coolant pressure test will determine this because it will not hold pressure. Overheating will cause burned valves as well, most likely the exhaust valves and may not be diagnosed as a coolant leak. In other words you have a burned valve but the coolant test passes.

2) How to determine if its the bottom end or top end of the engine using oil as a seal. Your reading for number 2 went up slightly with oil, , while the rest of the cylinders went up by 50 psi. If you had bad rings the pressure would have gone up dramatically, say 175 psi. At 175 psi, this would indicate your valves are good.

3) The reading of 125 psi with number 2 using oil would indicate to me the top end has issues, head gasket, leaky valves, ect. See item 1 for root causes. If a valve does not seat all the way down to get cooled by the valve seat it will "burn". Burned valves are no longer circular to hold the pressure from the piston. However, you can burn a valve if head temperatures get abnormally high like in a overheat condition. Overheating an engine is almost sure death given todays close manufacturing tolerances.

The good news is the top end is easier to fix than the bottom end and in my opinion worth investigating. When pulling the head look at the number 2 valves to determine if one is defective or burned.

Just my 2¢.

Monsoon
your two cents to me is like 100000.00 THANK YOU VERY MUCH that is a big help
 
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