1992 3FE Compression Test at 236k

[jonbobshinigin]

Just acquired a 1992 LC80 with 236k. After chasing down an O2 Sensor issue via CEL, I found connector with loose wire and corrected it. This solved the CEL. I cleaned the AIC which also seems to steady idle. While this is my first LC, I do not have experience to reference, but the engine seems to have appropriate power. I do not have full records from previous owner yet, but it allegedly got a head gasket not long ago. I would assume it had valves adjusted then, but I will check that later once I dive into do some other work. For now, I am base-lining it and decided to do a compression test. I let it idle for 15 min or so and then shut off, removed EFI fuse, removed all Spark Plugs, and tested.

Results show as:
123
456

1 - 135 psi
2 - 125 psi
3 - 135 psi
4 - 135 psi
5 - 120 psi
6 - 135 psi

 

[baldilocks]

Looks acceptable for a 3FE with 236k miles. You will be needing a factory service manual.

 

[jonheld]

From the FSM:
Compression pressure:
10.5 kg /cm2 (149 psi, 1,030 kPa) or more
Minimum pressure:
8.0 kg/cm2 (114 psi, 785 kPa)
Difference between each cylinder:
0.5 kg /cm2 (7 psi, 49 kPa) or less

 

[jonbobshinigin]

From the FSM:
Compression pressure:
10.5 kg /cm2 (149 psi, 1,030 kPa) or more
Minimum pressure:
8.0 kg/cm2 (114 psi, 785 kPa)
Difference between each cylinder:
0.5 kg /cm2 (7 psi, 49 kPa) or less

I saw this. I will adjust valves and do the test again at full temperature later and see where it lands!

 

[jonheld]

I saw this. I will adjust valves and do the test again at full temperature later and see where it lands!

Honestly, other than #5 it doesn't look all that bad to me.
When was the last time valves were adjusted? The FSM wants it far more often than most folks are willing to do (every 15K miles).

 

[jonbobshinigin]

Honestly, other than #5 it doesn't look all that bad to me.
When was the last time valves were adjusted? The FSM wants it far more often than most folks are willing to do (every 15K miles).

I explained the status on valve adjustment in OP.