3B compression...whats a good number? (1 Viewer)

Joined
Dec 16, 2004
Messages
1,115
Location
El Dorado Hills, CA
 
 
 
Guys,

I tried a search on this but the datbase is down. Whats a good DRY compression test reading on a 3B with 200kms on the clock?
 
Joined
Dec 16, 2004
Messages
1,115
Location
El Dorado Hills, CA
 
 
 
nope..not 1 cylindar...all 4 accross. No wonder I make s*** power at 9lbs boost. Anyone else out there who has actually done a compression test? I'm getting worried here...help me feel better
 
Joined
Mar 14, 2003
Messages
4,506
Location
Between Here and There
 
 
 
mine was
405
400
425
400
like 2-3 years ago

but I haven't done it since I rebuilt the head on this. I'm very curious as to what my #'s are today. I just can't spend 100+ on a guage and I dunno anyone with a diesel compression tester..

You have to be burning some oil.. no?
 
Joined
Aug 2, 2005
Messages
4
Make certain you disconnect the EDIC linkage when compression testing so the injectors do not load fuel into the cylinders..
 
Joined
Jun 7, 2003
Messages
1,271
Location
Foam Lake, SK
 
 
 
Aslo make sure your compression tester is OK. I just had mine re-calibrated. It was 20lbs off.

The cheaper testers tend to fail often and they all get contaminated easily..

My 3B is

415
420
420
415
 
Joined
Dec 16, 2004
Messages
1,115
Location
El Dorado Hills, CA
 
 
 
ya...somethings rotten in denmark here. This thing has been babied it's whole life, there has to be something wrong with 340. I just looked in the FSM and waynes pretty much bang on...427 is spec and 284 is min
 

crushers

post ho
Joined
Feb 10, 2004
Messages
22,180
Location
Tara Ontario
 
 
 
that is excellent numbers, seems like you might have a bit of carbon built up on a couple cylinders...
accordign to the manual "425 or more", i tested a 3B a few years back that had 480, 425, 425, 425... i tested it mor ethan once to make sure it wasn't the gauge... not sure why but the customer was happy...
 
Joined
Jan 20, 2003
Messages
11,194
Location
Wherever the truck stops!!
 
 
Is this a cold engine or a hot one? The numbers are different. The real numbers are on a hot engine. I was told that they can be tough to start and run when the pressure is low as well because of insufficient pressure for ignition.

I think my compression gauge fits the injector holes. I haven't done a compression test for a few years.
 
Joined
Jan 31, 2004
Messages
667
Location
Fort Davis, Texas
 
 
 
Just tested my BJ42 and am NOT happy.... 420, 390, 375, 375 Thats dry and at operating temp. Will try a wet test in the next week or so.

Colby
 
Joined
Mar 28, 2002
Messages
4,693
 
 
 
 
colby1979 said:
Just tested my BJ42 and am NOT happy.... 420, 390, 375, 375 Thats dry and at operating temp. Will try a wet test in the next week or so.
Colby
Did you do a valve adjustment 1st?

gb
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top Bottom