No compression cylinders two and three

JACKSONSGTP

MEMBER
2000 CHEVROLET MALIBU
3.1L
V6
2WD
AUTOMATIC
93,000 MILES

Car listed above 'J' original problem - blown head gasket. Fix: both heads to machine shop for resurface and pressure checks/repair. Heads returned to service. Block to head surface checked for war-page. Visual inspect pistons and cylinder walls for cracks. New Fel-pro gaskets and head bolts and intake gaskets and bolts - all torque per Haynes manual for make and model year. Rocker arm bolts torqued per Haynes spec. Result: starts and idles little rough, threw p300 multiple cylinder misfire code performed compression check and no compression cylinder two left side (fwd) cylinder and cylinder three right side, other four cylinder's check 160-170 psi. Removed valve covers. Observed rocker arms and valves with engine running appeared normal. Loosened all rocker arms and performed rocker arm torque process again per spec. Same result no compression cylinder two and three. My next test will be a cylinder leak down test, mine is broken and the new gauge will not be delivered for a few days. In the meantime, could it be possible for the block to be cracked enough to have 0 psi compression? Leak down test is for sure next step, but anyone have any ideas?

5 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning.

No to the block.

No compression could be one of the following:
1. Leaking valve or valve not seating.
2. Samaged piston.
3. Valve lifter not centering and settling in.

When the 3.1 have lower intake gaskets or head gaskets it is common for the lifters to cause no compression until they settle in. Sometimes they do not. Then they need to be replaced. I always replace them when I have the push rods out due to this issue.

What you could try is loosen the rockers and start the engine and see if the miss goes away. That would confirm it.

Roy

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Saturday, June 30th, 2018 AT 4:50 AM

JACKSONSGTP

MEMBER
3 POSTS

Thank you ASEMASTER6371! The blown head gasket caused the oil/Dexcool messy milk. I pulled the lifters, push rods and rockers in an organized labeled box for location. The lifters and rockers I wiped clean, visual inspect and blow gun well. Then dabbed the roller areas and push rod surfaces of both in Lucas Oil treatment. Push rods I wiped clean and blew solvent through oil passage hole, blow gun well. Visual and roll test/inspect. They all went back into same locations as they came out. I also double checked the shorter push rods were in the intake valve rocker and the longer were in the exhaust. I wonder if I dipped a lifter or two into too much Lucas? That stuff is pretty thick, but still the oil pressure from starting and running engine should have flowed through well. Car was ran for about twenty minutes diagnosing. I would think that would have been time enough for the lifters to hydraulically pump up correctly. Car is out of the shop and waiting for the new leak down gauge next week. That will tell the story. I can go ahead and pull valve covers and loosen rockers before hand, just to try it. Any other ideas?

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Saturday, June 30th, 2018 AT 10:17 AM

ASEMASTER6371

MECHANIC
52,797 POSTS

Could be valves or piston, but my money is on the lifters.

Roy

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Saturday, June 30th, 2018 AT 10:54 AM

JACKSONSGTP

MEMBER
3 POSTS

Thanks, ASEMASTER6371, Let me ask this, assuming it is the lifters. I can order four new lifters (the two cylinders in question) today and will be delivered by Tuesday. I will have the leak down gauge Monday, so depending on results of test, I could use the new lifters if needed, and have this car gone from the shop by the holiday. Is there any harm to just replacing those four lifters and keeping the original "working" eight lifters? I would just hate for the leak down test to reveal something else and I will have to either eat the cost of the lifters or take a return to stock fee. I typically replace all lifters on other jobs but this one I am just trying to complete, break even on the job and move on.

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Saturday, June 30th, 2018 AT 11:58 AM

ASEMASTER6371

MECHANIC
52,797 POSTS

I know you are only doing the four, but I would do them all. I would call the customer and tell them lifters sometimes fail in a repair such as this and they need to be replaced. I would not eat them at all.

When you gave them an estimate, that is what it was, an estimate not an invoice. I had to educate my customers on this many times.

Roy