jc01sable2x

Hey guys.. need some help. 2001 3.0 vulcan engine.. blew the rod. so replaced the bottom block with a good used block, and now it has a misfire on cyl. 1.I did the compression test,.. and number one shows 60 psi.. or so leak down test,.. left the tester on the cyl., for 10 minutes or so, and holds steady.. no leaks on the cyl. 1.holding 60 psi.. the head gasket seems good,.. no exhaust smell on the coolant,.. or overheating,.. etc... the block I'd put in,.. had been tested with liquid on the cylinders.// before the install. had been good.no leaks.. quite confused.. what to do next,..of course it shows misfire on the cel,.. on cyl 1.. your inputs will be appreciated.. thanks.. jc..

chipset

When the rod let go are you sure the piston didn't come up and bend the valve ?
On your leak down test where is the leak ? Intake, exhaust, rad or block ? Test it again.
Very easy to find. Regaudless the motor will have to come apart.

jc01sable2x

thanks for your input.... I think it may be the valve.. the piston did not hit the valve.. there is no sign of hits on the valve or the piston.. little luck there.. can you tell me how to do those procedures.. I'm not a mechanic.. just a weekend garage guy,.. fixing my cars as hobby.. a head machine shop that I had called today said.. some of the sludge can be on the valve seats.. told me to tap the valve with hammer on the spring side,.. and spray some tb cleaner.. to see if that would make it better..??? well.. any inputs on this..???

jc01sable2x

forgot to put some of the symptoms...It starts and runs allright.. I can feel the miss on the idle only.. in high idle,.. it seems fine.. runs great.. at cold idle,.. the engine rpm goes up and down a little,.. 600-1200 rpm or so.. and as car warms up,.. it gets better.. but when I put the gear to drive,.. engine wants to lurks.. I wonder if this is the right word to describe.. on off on off on off pushing the car..well this could be some kind of a vaccum leak somewhere.. or air leaks on the intake.. I suppose.. but right now I'm concerned about the low compression.. on the cyl. 1.. help is appreciated.. thanks..jc

chipset

How do you know the piston didn't hit the valve ? You need a micrometer to measure it.
a couple of thousands out will cause the valve to not seat. A couple of thousands out
will make the piston take an egg shape if it was hit on the top. You have to take one thing at a time. Do not jump from one thing to another. Your 600 - 1200 rpm difference
has nothing to do with your low compression. You have more than one problem. The leak down test is easy. Fill the cylinder with air and listen for the escaping air. Good luck

jc01sable2x

hey.. chipset.. thanks for your response.. well.. I know it's a hard one,.. the way I did my compression test,..
pulled all spark plugs out.. disabled the gas pump from the trunk. disabled the spark by takingout the coil pack connector.

put my compression tester. gave it a few turns, and the psi goes up.. and I left the tested result for about 10 minutes or so.. and the psi did not drop..
my basic knowledge will be that if the pressure holds up.. which it did,..but low at 65 psi or so.. even after 10 minutes of holding the pressure on the cylinder.

wouldn't that make the theory of rings of the pistons and valves to be o.k....???? just out of my common sense..`

what do you think... thanks.. jc..

chipset

I'm sorry i don't get what your saying. I think you said your compression is 65 lbs
after a few cranks and it held at 65 lbs. ? It does not go higher than 65 lbs. ? Did you leave your compression tester connected to the cylinder for 10 mins ? How do you
know your compession tester didn't leak ? Something is not right here. EXP. If you get a
pressure reading of 140 psi on a cylinder during a test and leave the tester on for 10
mins it will drop, probably 50 lbs. due normal leakage. You do not leave the tester on.
You read the pressure immediatly and record it. Missing a lot of info. It's very hard for me to help you when i'm not there to see what your doing. I need your info. I think i know what your problem is. MAYBE.