I'm doing a compression check on my 05 right now. Does anyone know what it should be? I has 40,000 miles on it.

CRIS

 

I dont believe Cummins gives a specification for compression values. There method of checking for loss of compression is checking for excessive blowby. With so little miles, can I ask why a compression test is being run?

 

I think that my head gasket is blown between 2 cylinders. I'm getting a poping from the intake and from the exhaust. The engine also has very little power.

Thanks Cris

 

You should see about 350#-375#. It should jump up about 150@/ stroke for the 1st couple, & then slow down. Should get to max after about 5-7 strokes.

 

Heres the compression #s 3 tests were done on each cylinder for 5 seconds each.

#1 480lbs 485lbs 475lbs
#2 475lbs 490lbs 490lbs
#3 520lbs 530lbs 535lbs
#4 520lbs 510lbs 520lbs
#5 530lbs 540lbs 520lbs
#6 515lbs 515lbs 510lbs

I just can't figure what is causing the poping and the loss of power in my engine

CRIS

 

Something valve related maybe? Just a thought.

 

Could it be timing.

 

Could still be a leak only under the higher pressures of combustion.

Have you checked low side fuel pressure, rail pressure? Rail relief valve?

Popping under hard throttle is usually a good sign the rail is draining or pressure dropping?

 

Did you leave all of the injectors out while running the test to make sure its not blown between two cylinders?

 

The truck is poping through the exhaust at idle

We checked the pressures with the injectors out and with them in.

As for timing I don't have a clue A great and trusted friend of mine said that the cam may be bad, so I'll have the check the lift on all the push rods.

We also checked #1 + #2 cylinders with air pressure, but nothing was coming through the valves just past the rings.

This problem is stumping me, the dealer said that they can't find anything wrong I know that there is something wrong because of the poping and the fact that the truck is a SLUG.

I really think that the gasket is blown between 2 of the cylinders, but I have no way to prove it without pulling the head.

Thanks for all your help

CRIS

 

if its blown between two cylinders then if you have the injectors all out you will hear/feel air coming from the cylinder that it is blown across to from the injector hole. you may want to try a leak down tester also.

 

One of out trucks at work has a NTC 400b/c, it was running away, smoking, and no power, I checked the exhaust manifold with my heat gun but reading were chaotic across the board, so I pulled the exhaust mainfold/turbo plugged the oil feed line and started the engine. #2 cyl not fireing at all, fuel return to tank was charging tank with compression, found a broken injector hold down bolt which in turn took the injector, injector cup, and head with it. Moral to the story, the engine ran horrible without a defined skip, it was popping and sputtering, with no power all because of the compression gasses interference with the fuel supply.


Good luck,


Tim