rb26 rebuild, help?

[Billy_Jack]

the engine was in the following condition prior to being pulled:

comp: dry: #1: 145 #2: 147 #3: 150 #4: 90 #5 155 #6: 152
wet: #1: 157 #2: 155 #3: 160 #4: 90 #5 175 #6: 165

leakdown: #1: 7% #2: 8% #3: 15% #4: 70% #5: 16% #6: 8%


-the coolant was murky brown/green but it was not very strong/was not able to measure (ie very little antifreeze)
-there were traces of coolant in the crankcase breather hose.
-during the leakdown test no bubbles came up to the radiator cap

one thing that strikes me as odd is the lack of change between the wet/dry compression test in cylinder 4, if it were the rings that were causing the low compression, wouldn't the wet test be higher? and if the rings were that bad that there would be no change to the compression test, would they actually be able to make 90psi?


so to be sure, would there be a way to do a leakdown test on the open cylinder? if it passed then surely i could rule out rings to be the cause of all this.

thanks, Cory

[GTRADDICT]

Bad valve? or if the rIngs are really done

[Billy_Jack]

yeah i was considering that possibility, but during the leakdown test the air was coming out from the crankcase breather. i'm just curious if rings that bad would be able to make 90psi and i'm wondering if i should continue if theres a way i can rule out pistons as the problem.

[actionbstard]

did you warm the engine to normal driving conditions before doing the compression test?

[mcase]

Could be a melted piston

[Billy_Jack]

Could be a melted piston

yeah somewhat, #4 fell apart in my hand