Recently my 350 began to smoke heavily after it warmed up. I figured it was probably the head gasket since it appeared to be white smoke. I pulled off the heads the other day and #8 has a vertical score that I can feel with my finger, but not really see looking at it. I was wondering therefore how I can tell if the score is the problem, and would it fit the description of the problems I'm having? Also, what is the easiest way to go about fixing it should I need to? Machine shop? Honing kit and some new rings? Please advise.

 

well, you could always get yoru cylinders bored over. if the scratch isn't that deep then that'd fix it.

so you'd have to pay a machine shop to do that, and buy new rings. (there may be more, somebody please feel free to comment if there is)

 

maybe you should of leaked it or ran a compression test before you took it apart. that hole might not be causeing you any problems. depending on how deep it is you might get away with doing nothing, honeing it, boring or as a last resort put a sleeve in it.

 

Yeah I did a compression check on all 8 before I decided to rip the heads off. 6 and 8 were 15 psi lower, which to me pointed to a headgasket. It occured to me later that the battery may have been getting low by the time I did 6 and 8 causing the air not to heat up as much thereby lowering pressure. Is there any way to easily measure how deep a score is and if so what depth calls for what fix?

 

no flame .....just curious..what the heck does the battery have to do with the compression?

 

the battery is what you use to turn the engine over fast enough to get an accurate compression reading, if it was cranking slowly ie dead battery then it would reach it's maximum compression and also it is possilbe that you have a brokan oil scavengeing ring and thus caused the scorring, if it is deep enough that you can feel a ridge then you need to go ahead and tear it down and rebuild/bore out
these are just some ideas and they may not be correct but it is just the first things that I thought of.

 

what were the numbers you got? 15 psi might of been within acceptable range, or just out of range but it sure doesn't indicate any sort of problem other than a little wear. did you check the compression the correct way or just screw a gauge in and crank away? you can measure the score with a i/s mike, snap gauge, bore gauge.

 

of course..guess i was't thinking...

 

I'm guessing its a broken oil ring I just don't want it to be that. Its a new engine (5k miles) from Scoggin Dickey. Under warranty, only thing is they wont work on it since it isnt factory for a 91 TA (its an LO5). Out of curiosity what is the "correct" way to check compression. I pulled fuel and spark pluged the checker in and at open throttle gave it 5 pumps each.

 

Did you remove all the spark plugs? Did you prop the throttle all the way open?

You have to do those in order to get optimum cylinder pressure (not compression). They call it a compression check, but it's really a cylinder pressure check.

Anyway, for those about to do it, start with a cylinder pressure check (aka comp check). If you notice a wide variation (usually more than 10%) then do a leak down test. This will tell you abou 10 times more than a cylinder pressure check will, like where you're losing pressure at.

Helps you figure out REAL fast what the problem is.

AJ

 

if you pulled the plugs and had the throttle open that's good, lot of people don't or forget to the accepted deivation is 10% between readings and 120 is about as low as you'll see and a lot of times it'll go 160 or more, depending o nthe engine and the condition it's in.

 

all cyls were 180 excluding 6 and 8 which were around 168.

 

that's all within the acceptable range, you don't or didn't have a problem

 

I think I'll just hope for the best and slap the engine back together with new gaskets. It only takes a few hours anyway the scored cyl just made me nervous.

 

just for the record....

As for the compression test, you first run all the cylinders in the normal fashion (all plugs out, coil disabled, choke and throttle held full open, crank each cylinder until max pressure reached, record each cylinder's pressure, etc.). That's the dry test. Then, you put a tablespoon or so of oil in the cylinders through the spark plug holes, turn the engine over a few times to spread it around the cylinder, and then repeat the compression test. If the rings are worn, the oil will tend to enhance the seal and raise the compression pressure significantly from the dry test. You have to do both in order for the wet test to have any meaning. If the dry test numbers are close cylinder-to-cylinder and where they should be (say 150 psi), and no significant change to the dry test, then everything's fine. If the dry test is low and the wet test is low, then you have valve sealing problems.

 

Just for the record, I know this was a long time ago, but I want to tie the thread up so others don't get confused.... This was all a leaking fuel injector. My engine was fine.