Help me understand this compression test - 1 cylinder is HIGHER than others.

[K4fxd]

https://www.washingtonexaminer.com/...shops-would-be-curtailed-under-hill-proposal/

I'll admit I am not a fan of Lund but I will stand with them to stop this EPA BS.

Why does the EPA need an armed unit?

And people think the person out of power is a threat to democracy.

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[horsepower addiction]

Did a compression test on my 15 GT with a cold engine.

All cylinders read at basically 212 psi except cylinder #5 which reads 240.

I repeated the test multiple times to verify. Wet test still increased readings verifying the increased reading isn't from oil.

All spark plugs looked basically the same. All plugs had a small amount of oil on the threads but also looked to be burning cleanly.

Car has been running fine. No detectable oil loss that I've ever seen.

So, am I possibly dealing with Carbon buildup? Sticky exhaust valve? Valve seals? Bad lash?

Ok the first problem is that you are supposed to do a compression test on a engine at operating temperature

second problem is that there is no problem. Cylinders need to be within 15% of each other. Your fine. You are looking for a problem that doesn’t exist

if you want to know the condition of your engine do a leak down test

 

[horsepower addiction]

Install a water/meth kit and set it to run any time you are over 4000rpm. Run through 2-3 gallons of water/meth or straight water and those combustion chambers/cylinders in that engines will be as clean as new.

 

[CrackedHorn]

Ok the first problem is that you are supposed to do a compression test on a engine at operating temperature

second problem is that there is no problem. Cylinders need to be within 15% of each other. Your fine. You are looking for a problem that doesn’t exist

if you want to know the condition of your engine do a leak down test

Cold engine should still give me a comparative baseline between cylinders, no? I'm not concerned with the actual number inasmuch as the delta.

Cylinder #5 is 15% higher. This just seemed like a red flag.

 

[Skye]

Given the option, I'd select warm-to-hot.

I realize your looking for delta, but that could all be different close to or at operating temperature.

 

[CrackedHorn]

Ok the first problem is that you are supposed to do a compression test on a engine at operating temperature

second problem is that there is no problem. Cylinders need to be within 15% of each other. Your fine. You are looking for a problem that doesn’t exist

if you want to know the condition of your engine do a leak down test

Cylinder #6 pictured below. My concerns and curiosity are now both fully piqued. Lol

 

[Skye]

You mention 91 octane. What is the brand of fuel?

In the most recent photos, it appears to be oil. Is the engine consuming oil?

 

[K4fxd]

Cylinder #6 pictured below. My concerns and curiosity are now both fully piqued. Lol

Is there a piece of the piston gone?

 

[CrackedHorn]

Is there a piece of the piston gone?

Sure looks like it based on this borescope.

Below is cylinder #4 which looks very similar, though.

I'm not sure what I'm looking at through this camera. Lol

 

[SheepDog]

There's nothing missing from the piston, you can clearly see the edge of the piston through the liquid pooled up in the cylinder.

 

[horsepower addiction]

Cold engine should still give me a comparative baseline between cylinders, no? I'm not concerned with the actual number inasmuch as the delta.

Cylinder #5 is 15% higher. This just seemed like a red flag.

The cylinders could read 15% off cold and 2% off at operating temperature leak down test is your best bet

 

[horsepower addiction]

You cylinders are only 11% apart not 15% so you’re still looking for a problem thats not there. I would clean out the engine by driving it and introducing water and seafoam into the engine. You can run a small vacuum line into your passenger key compartment and introduce a little bit at a time

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