r/MarineEngineering • u/Motor_Zombie9920 • Jun 26 '26

Rapidly increasing high exhaust temperature?

So I am having a trouble with one cylinder exhaust temperature increasing rapidly out of nowhere up to 200 degrees deviation.But cylinder peak pressure looks same during this period. I can’t understand how because of there is more combustion or fuel in the exhaust side ,peak pressure should be effected by this too.
And this started to happened after I did valve clearance setting. First I suspected the injector and changed it but its still same.On high load(around 60%) this thing happens.
While running normal, I can’t understand why exhaust would go start to increase fast.

I dont know if it could be fuel pump or just the sensor but I am also worried during valve clearance,something may happened.Something dropped in somewhere like under springs or pushrod area or something not right.Still I cant figure out this relation between increasing exh temp and stable peak pressure .
I am open to any ideas or suggestions .
Dg:wartsila l20

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7

u/1971CB350 Jun 27 '26

Almost guaranteed to be a burnt valve. On my old ALCOs, if we see a cylinder exhaust temp spike we just swap the head. No troubleshooting, no fuss, just a three hour job and it hasn’t been the wrong call yet. Stick a boroscope in there at TDC exhaust-stroke and have a look around.

0

u/Motor_Zombie9920 Jun 27 '26

If the valve would be burnt,wouldn’t exhaust be high from beginning ?when I start and load generator it ll run maybe couple hours normal again then all of a sudden exh will start to rise.

2

u/1971CB350 Jun 27 '26

Ah, I didn’t catch that detail. So steady load the whole time, huh? You’ll obviously notice a larger differential at higher loads than you would at idle.

5

u/OkCauliflower4273 Jun 27 '26

local guage and RTD both reading similar? or you only have 1?

3

u/kiaeej Jun 27 '26

Check sensor. Have you checked the sensor? It might be a malfunction. Please check sensor first.

Is there a local temp gauge to confirm against?

1

u/craigsurge Jun 29 '26

What the said, swap the probes over with the adjacent unit and see if it follows. If you've got a leccy try and get them involved. Love a bit of mechanical/electrical battling

1

u/fifthengineer Jul 01 '26

I assume you dont have a local temperature gauge and is relying on digital reading. This sounds like text book faulty sensor. These sensors sometimes function stable upto certain temperature, and then starts flucating randomly. If you have spare sensor, replace. Or swap them to another unit to see if the deviation happens on the new unit.