What should compression be on a 2QM15?

F

Ferency

.
Jun 26, 2020
2
O'Day 30 Chelsea-on-Hudson
Hi there,
I'm going to be doing some TLC to my engine over the winter. Wanted to check the compression and see what I'm getting. Does anyone know what the pressure should read for a baseline? I cannot seem to locate it anywhere in the service manual. Thanks.
 
Charles Erwin

Charles Erwin

.
Jan 30, 2012
1,144
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
In order to do this you need an adapter to replace the injector. Here is an example.

COMPRESSION TESTER KIT: Yanmar Tractor Parts (hoyetractor.com)

You can make the adapter yourself if you already have a compression gauge. I think Hoye sells the adapter only for about $25.

Tip: Don't take anything out of the bore except the fibre washer. You should replace the washer with new when you put the injector back in place.

Charles
 
Charles Erwin

Charles Erwin

.
Jan 30, 2012
1,144
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
Oh forgot. Your motor has a compression ratio of 23:1. So (standard day pressure) 14.7 psi x 23 = 338. On a newly honed GM motor (same compression ratio) after 20 minute break- in I get about 325.
 
  • Like
Likes: Whatfiero1 and Richard19068
F

Ferency

.
Jun 26, 2020
2
O'Day 30 Chelsea-on-Hudson
Thank you both. I actually ordered that exact compression tester and adapter kit from Hoye yesterday! Good tips, thank you!
 
  • Like
Likes: Whatfiero1
RoyS

RoyS

.
Jun 3, 2012
1,742
Hunter 33 Steamboat Wharf, Hull, MA
That adaptor might need some machine work before you can use it but I forget what I had to have done. I think it will have to be turned down in diameter. Length of hose (if used) connecting the gauge will affect readings. Read somewhere that QM engine compression should be 355 to 454 psi. After I rebuilt my engine I was at the low end of those values.
 
You must log in or register to reply here.

Top Bottom