• Steel Soldiers now has a few new forums, read more about it at: New Munitions Forums!

  • Microsoft MSN, Live, Hotmail, Outlook email users may not be receiving emails. We are working to resolve this issue. Please add support@steelsoldiers.com to your trusted contacts.

8.3 compression test

MAdams

Active member
380
132
43
Location
San Dimas, CA
I searched and didn't see a lot of info about this so I will share what I know. While I had my injectors out I adjusted the valves and checked compression. I was going to use a old hollowed out injector but I bought the proper gauge set.

Cold engine, batteries fully charged, all the injectors removed I was getting between 385-395 psi

Anyhow, leaving this here for someone to find in their future search.
 

WillWagner

The Person You Were Warned About As A Child
Super Moderator
Steel Soldiers Supporter
8,539
2,758
113
Location
Monrovia, Ca.
There is a procedure for that but if there were a loss of compression issue in a compression fired engine, you would have other visible signs of an in cylinder failure, like, lots of smoke out the bottom/blow by tube, popping in the intake, chuffing in the exhaust. In 30 years, never a need to take a comp test, but for midrange engines, there is a spec and procedure to do it.

In short, it is kinda a waste of time to do.
 

MAdams

Active member
380
132
43
Location
San Dimas, CA
Well that explains why I couldn't find any data lol. I bought the compression test kit because I have a Deutz engine in my bobcat that's smoking and I need to diagnose it. So far I have ruled out any faulty spark plugs :lol:
 

74M35A2

Well-known member
4,145
330
83
Location
Livonia, MI
Cummins list advisable compression figures for some engines but not all. They prefer to do it by blow-by volume measurement. But, fortunately, for our 8.3's, they do give some #'s as guidance. Looks like you have some carbon build up working in your favor. Here is what the free online Quickserve program lists for the serial number of my M925a2 8.3L engine:

Note : Due to variables such as starter and battery conditions that affect engine cranking speed, it is difficult to establish an absolute value for compression pressure; however, the following values can be used as guidelines:
  • New engine (cranking speed at 250 rpm) 2413 kPa [350 psi]
  • Used engine (cranking speed at 250 rpm) 2068 kPa [300 psi]


It is recommended that the compression pressure be checked on all cylinders and then compared. All cylinders should be within 690 kPa [100 psi] of each other.

 

Jbulach

Well-known member
Steel Soldiers Supporter
2,661
2,194
113
Location
Sunman Indiana
Interesting, I just checked and my 8.3 with 7 year old batteries cranks exactly 250rpm according to the tach.
 
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website like our supporting vendors. Their ads help keep Steel Soldiers going. Please consider disabling your ad blockers for the site. Thanks!

I've Disabled AdBlock
No Thanks