Compression Test results - Thoughts??

[Seattle12]

2020 Malibu 22 LSV
Compression - 1-215 2-190 3-215
4-200 5-190 6-200 7-210 8-200. 992 engine
hours. Price - $75,000

I am VERY green to boating - what are the thoughts on the results of the test? Does this signal a strong engine? How many more hours can I get out of it if it’s well maintained. 

[Steve B.]

Looks good especially for 900 hrs. None of the values were zero, ha !

[Seattle12]

Could you explain a bit more - what makes it look good? Thank you! 

[DRB10SEVEN]

GM certified technician here. If you are curious, here is a quick snippet from the service manual for performing a compression test on either a 5.3 or 6.2 direct injected engine. Just using this as an example, most GM engines are the same although some specs may be slightly different for supercharged engines or something like that. Use this as a good rule of thumb. In my personal opinion those numbers look perfectly fine and raise no concerns in my mind.

"Compare the compression readings from the tested cylinders.

- The lowest reading should not be less than 80 percent of the highest reading.
- No cylinder reading should be less than 862 kPa (125 PSI)."

[DRB10SEVEN]

Just checked the supercharged LT4 compression test specs since I was curious. For that engine it is a minimum of 100psi and a 70% difference.

[dizzygti]

14 hours ago, Seattle12 said:

what makes it look good? 

Basically you want consistency across the cylinders, and that everything is above a minimum spec.    Think of it as the health of each cylinder's sealing capability.    If you can't compress the air and fuel, you get less boom.   You don't want to see one or a few cylinders with really low results compared to the others, as obviously those lower numbers mean sealing has been compromised to some degree.   The engine will still run with low numbers, but you have less efficient combustion, lots of blow by, higher oil consumption, oil dilution, etc.   Minumum 125 and this engine's lowest cylinder is 190, you're good to go!   

[oldjeep]

On 4/25/2024 at 5:42 PM, DRB10SEVEN said:

Just checked the supercharged LT4 compression test specs since I was curious. For that engine it is a minimum of 100psi and a 70% difference.

Supercharged and turbo motors are typically lower compression.