Compression on Yanmar 3GM30 diesels

[davecalvert]

Does anyone know what the numbers for Yanmar 3GM30 cylinder compression checks should be?


Sent from my iPad using Cruisers Sailing Forum

[a64pilot]

I'll take a shot from memory of other Diesels and assuming a DI Diesel is a DI Diesel compression wise, but I remember around 300 PSI,
If nothing else I bumped your question up the list to where it will be seen.

What number are you getting and are they all about the same?

[damir s]

It is a relative thing to measure the pressure in the cylinders. It is best to dismount all 3 injectors and connect a pressure gauge in place pulverizers operate the engine with the starter for each cylinder, if all three are the same, then test for blowbuy in cylinders for each cylinder by hand crank to bring the top dead point and measured during the pressure drop if all three of the same probably have no problems or engine is for complete overhaul.

[davecalvert]

Thanks A64Pilot for helping.
I recently had a compression test from a mechanic, the three cylinders were close to the same from 320 to 330. The mechanic thought this was low. Mastery Marine, the Yanmar distributor, said it is not so much the numbers but that all cylinders are close to the same. Just wanted more info and other opinions.

[StuM]

Originally Posted by davecalvert

Thanks A64Pilot for helping.
I recently had a compression test from a mechanic, the three cylinders were close to the same from 320 to 330. The mechanic thought this was low. Mastery Marine, the Yanmar distributor, said it is not so much the numbers but that all cylinders are close to the same. Just wanted more info and other opinions.

That's pretty close to the compression tests on my Belize early this year. From memory, they may have been slightly lower than yours but were definitely well over 300. (I tried to find the report earlier for you but seem to have filed in too securely ) My mechanic said they were fine and said the same thing about "close to the same".

[davecalvert]

Thanks StuM,
They both start right up and run fine. Both reach 3,500 RPM full throttle in gear.
Don't know why the mechanic said they tested low.

[HappyMdRSailor]

A quick googlydoo got me this....
About 5,040 results (0.38 seconds)

Manual reported to be 340... Sailorchick has extensive knowledge of 3gms'

320-330 would seem to be perfecto...

[Sailmonkey]

Originally Posted by HappyMdRSailor

A quick googlydoo .

Is that googling while otherwise indisposed?



Sent from my iPhone using Cruisers Sailing Forum

[davecalvert]

I tried a Google search for this and got nothing. I used Yanmar 3GM30 compression etc. What did you use for a search?


Sent from my iPad using Cruisers Sailing Forum

[HappyMdRSailor]

Originally Posted by Sailmonkey

Is that googling while otherwise indisposed?

Sent from my iPhone using Cruisers Sailing Forum

HA HA!

You're getting as bad as the other monkey...

Maybe we should start a forum jackassery group???
The leader is going to be difficult to pick though...

[HappyMdRSailor]

Originally Posted by davecalvert

I tried a Google search for this and got nothing. I used Yanmar 3GM30 compression etc. What did you use for a search?
Sent from my iPad using Cruisers Sailing Forum

just used your thread title, right click search?
https://www.google.com/search?q=Comp...sm=93&ie=UTF-8

I know the chickee has a manual, also gordo might have a link...

[Roy M]

Chapter 3,Table 6 of the pdf that I got from Alan Wheeler's Sticky notes: Pressure for all models of Yanmar: 390-470 p.s.i. (2700-3800 kPa)

[HappyMdRSailor]

Originally Posted by Roy M

Chapter 3,Table 6 of the pdf that I got from Alan Wheeler's Sticky notes: Pressure for all models of Yanmar: 390-470 p.s.i. (2700-3800 kPa)

Discrepancy alert!

Good catch Roy...

Dave... Further research required!
buuuuump....

[Sailmonkey]

Originally Posted by Roy M

Chapter 3,Table 6 of the pdf that I got from Alan Wheeler's Sticky notes: Pressure for all models of Yanmar: 390-470 p.s.i. (2700-3800 kPa)

But at what crank speed?


Sent from my iPhone using Cruisers Sailing Forum

[HappyMdRSailor]

Originally Posted by Sailmonkey

But at what crank speed?


Sent from my iPhone using Cruisers Sailing Forum

How long can you go without bringing up illegal drugs...