Cylinder Compression m13a

Hi everyone!

I had Jimmy 2017 with 60,000 kilometers, in the last few months engine warm up(not to the end) only in warm weather and only when up hill(normal road) and then I feels power is missing, also noticed that condensing tank was almost full(coolant return to radiator after cooling), before engine warm up i remember in warm days he goes up 2-3 centimeters.
last month I changed thermostat, radiator cup, coolant replaced(no signs for mod or rust), checked fan clutch all sims to work fine only one noise from engine, it sounds like air leaking.
I checked everything connected and then was thinking maybe the Head gasket is leaking so i made cylinder pressure check and i got about 100 psi all cylinders, that ok?

Test was made with warm engine and all plugs out, also full open throttle.

I understand by engine details compression ratio 9.5:1 is about 140 psi, in workshop manual 199psi not making any sense

Thanks in advance!

Hi
A marked difference in each cylinder pressure reading is usually the indication you have an issue rather than the actual pressure recorded. So it's good that they are all the same, but 100psi is very low. My worn out 1960 land Rover engine manages 120 (just!), I would have expected higher on a low milage Jimny, although I don't know what the real "good" figure should be.
Can you do a pressure test on the cooling system or a cylinder head leak test that looks for exhaust gas in the cooling system? This may be a better indication of head gasket failure as I don't understand why they are all 100psi, unless it's just gauge tolerance. You can get tester kits on eBay etc.

Just out of interest why did you change the thermostat, did you have overheating issues?
Mike

Hi Mke

Thank for your answer, No missing coolant so i cant see reason to check cooling system pressure, my thought was leaking From gasket push coolant to condensing tank although no bubbles come out from radiator.
Anyway its good idea to check gas leaks from radiator, I’ll do that.

Yes engine got overheating same time the air leaking Noise appeared, only overheating in extreme conditions like deep sends or up hill in regular road and only in hot weather so I thought maybe the thermostat doesn’t open till end.

Thank you for reply
Head gasket was my first concern, you said “light machine to clean it up” you meant to milling the head so he is straight?

Many videos on YouTube with people using a sander or a flat surface to sand down imperfections. If it is warped i would send it to a shop that know how too though.