288sunny

I was having some trouble with the motor, and we found that the reason it was acting up was because a valve spring was broke. So today we put a new valve spring in and keepers and put it back together. the whole time while we were doing this we had air in the cylinder to keep the valve up and sealed and the leak down showed 10%, which is outstanding..

So next we install the rocker arm and start tighting it down and loose the leak down tester, like it just opened the valve, so he backs off a few turns and it seats its self. So then we tighten it back up and we loose it again.. From this point we roll it over a few times, looking at all angels and trying to figure out whats up, it appears the valve is seating and it appears everything is working ok, however my buddy thats helping with me, now thinks its a lifter problem.. are there any tricks to see if the lifter is working properly, easy tricks to free one up, etc... Im not a motor expert however by looking at the lifter it appears its sitting a tiny bit higher than the others, but who knows, im not sure this bad luck is ever gonna run out!!

Thunderstruck

Is the cylinder with the issue at TDC on the firing stroke? If not put it at TDC on the firing stroke for the cylinder with the bad valve spring. Both valves should be closed. Then, roll the push rod with your finger back and forth while tightening the rocker arm nut by hand until the pushrod stops turning. That is zero lash for the pushrod/lifter/rocker arm. Then tighten 1/2 or 5/8 turn past zero lash or whatever the 496 lash specs are and lock it down. Sounds like you are tightening the rocker arm nut too much if you have to back off a "couple of turns" to get the valve to seat or the piston is not at TDC on the firing stroke i.e. the lifter in question is not on the base circle of the cam.

The valve will adjust like it is OK even with a not too bad broken lifter. After you adjust the valve, look down the row of rocker arm nuts or lay a straight edge on the nuts, intake or exhaust. All the nuts for the intake and all the nuts for the exhaust should be at the same height. If your problem valve rocker arm nut is noticeably lower than the rest the lifter is collapsed or you have tightened the nut too much.

BTW did you use the exact same spring as the others??

288sunny

I dont think the 496 works like that of a older motor, according to the book, the nut gets torqued to 19 Ft. lbs and then your done, we can barley even tighten it up and it starts to leak..

Thunderstruck

OK, does the pushrod move up and down with the cam lobe? Once again is the lifter in question on the base circle of the cam when you are tightening the nut? Didn't realize the 496 doesn't have adjustable rocker arms but the principles are the same except for the turn past zero lash part.

GO4BROKE

iTrader: (1)

To fidnd TDC on the firing stroke, turn the motor over (by hand), watch for the intake valve to open and close, then turn it until the piston is at TDC (usually not much past the valve closing). If you are sure you are on the base circle of the cam, you probably do have a bad lifter, may have caused the spring failure in the first place. I would be replacing the pushrod also.
How many hours on the motor?
Make sure you don't have, or make, any marks on the valve stem, if so it will fail later.

bobl

The lifter is pumped up with oil. Go ahead and tighten it down then rotate the engine until the valve opens and let it sit a little while. This will bleed the lifter down. Then bring it back to TDC and recheck leak down. I bet it is OK then.

Bob

288sunny

Any idea how long the motor needs to sit for the oil to drain out of the lifters? I would think it should be good now, its sat all night, but just want to check, next step is a compression test.

288sunny

well i just got done with the compression test, my buddy/helper and bobL were right, the compression came back, tried it a couple of times and every time the compression came up, only thing that seems odd is the gauge is reading about 200-210 compression, Im being told its because of the 30wt oil we put in the cylinder a few days ago, but i would have thought most of that would have been gone by now, most if it is laying in my bilge right now, but i guess it doesnt take much?

Is there any way i can check to see if it is the oil, something i can spray to wash it down and recheck compresssion, i was just want to make sure the oil isnt masking another problem, before i put this motor back together?

bobl

Probably is the oil in the cylinders causing the high reading. If you're still concerned, fire it up and get everything stabilized then rerun your test. I think you are in good shape now.

288sunny

I Sure hope after all this, im headed down the right road, very tired of wrenching and bothering people, just wanna boat..

Its things like this that make me change my mind every time about adding more juice to my motor....