When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hey everyone, I just finished putting everything back together. I fired it up and everything went wrong. I immediately shut it down and this is what happened.
I pulled the valve out of the cylinder.
The car will easily turn over by hand, but is this cylinder salvageable since the valve didn't go through the cylinder? I was told my timing was off. Just looking for advice on remains.
Since photos make things look worse than they are, that dent may not be as deep as some actually cut valve reliefs. The main question is do you know why this happened so history doesn't repeat itself?
I think I would inspect the cylinder wall for damage first. Then bring that piston to the top and measure not only the depth of that dent to the height the metal raised (sort of looks like a meteor crater). There are some who know the thickness of the piston so the amount of material left can be figured out. Then you can put some grease around the circumference of the piston while it is at the top to prevent filings from getting down to the rings and carefully file it down flat to see how it looks. You may find it is not that bad once it is leveled back out again. Nothing lost here because if bad then you would still need to replace it.
Running it is likely more risk than replacement, so that will depend on whether you want to take the risk.
Last edited by vettenuts; Jan 4, 2017 at 07:48 AM.
Hey everyone, I just finished putting everything back together. I fired it up and everything went wrong. I immediately shut it down and this is what happened.
The car will easily turn over by hand, but is this cylinder salvageable since the valve didn't go through the cylinder? I was told my timing was off. Just looking for advice on remains.
Lots of questions....
Did you replace the lifters? Did you use new pushrods and new valvesprings? Did you use new lifter cups? Did you check the clearance on the rockers? Did you turn over the motor a few times by hand and then rechecked clearance? With a valve dropping into the cylinder a number of things could have happened, is the valvespring cracked on that cylinder? Were the stem locks for the top of the valve both on? Did you find the 2 stem locks or if any others dropped did you find all of them? You may also have to check the rods and bearings on that cylinder because they could have been stressed and the last thing you want to do is put it all back together and then have to do it all over again because of a bad bearing/rod. You will replace it anyways because reusing that piston is a bad idea because it is already stressed and you will get a pretty big hotspot as well as the chance there is a stress crack you cant see. Clean up the top of the piston and look for any signs of cracks.
If no collateral damage is present, get out the dremel tool and smooth it out. Try not to remove too much material but get rid of all the sharp edges.
My buddies Ferrari (tuliped, hollow valves) snapped / swallowed a valve. Damage was similar to yours but maybe a little worse. I smoothed it out and put it back together. That was probably 10 years ago and the motor is still screaming along w/o issue!
I would think that a forged piston would be more stress resistant than a cast one. It's a gamble (risk vs reward). How able are you to replace the pistons -vs- Can you deal with the consequences of a broken piston if it fails?
Is your timing chain off, or did a thin head gasket?
I've seen several engines with similar damages and it not harm the piston to the point that it needed replacement. Smooth it out and see what you got. Sounds like you didn't get the timing gears DOT TO DOT.
Check the piston to deck height on each cylinder at TDC to make sure that nothing else is damaged.
Were they hollow sodium filled valves???
I would:
- Check EACH cylinder head "valve seal" by filling the head chamber with solvent and see if the solvent leaks out. If it does, there's a good chance that valve is bent. If your timing was that far off to make piston to valve contact, you are most likely looking at replacing ALL the valves. Especially if you see ANY marks on the piston!
- Replace EACH push rod.
- Remove and check each lifter roller. If you have not already, replace the lifter trays with new ones.
Last edited by Bill Curlee; Jan 4, 2017 at 12:40 PM.
I always turn the motor over manually a few times after any kind of timing work just as a sanity check to make sure this kind of thing doesn't happen.
As for the piston damage, I wouldn't worry about it. smooth it out and call it a day. Your major concern is if there is any damage to the cylinder wall.
LG5X3 was the cam installed. I replaced the gears, new LS2 timing chain, new dampener installed, new Power Bond UD pulley installed and pinned crank, new lifters, new valve trays, new 7.4 push rods, new double springs, already had 1.7 yella-terra rockers, stock 243 heads and valves, and of course all new gaskets. The car has 74K miles on it.
Thanks for all the advice. I plan on replacing all valves due to a number are bent and not taking the chance with them. I going to find out what caused the problem and continue to inspect. Local guys said they believe my timing was off and that I started on number eight when I thought I was on number one. I'll see when I take the cover off again.
timing marks most likely were not lined up. that would be one reason why all valves would hit. other things would be too much milled off heads. the cam itself has too much duration and valve timing events causing valves to hit. the latter is unlikely as many have installed this cam.
you stated you were on #8 when installing instead of #1. this would cause major issues. don't know how you would have gotten the timing dots lined up doing that though.
didnt see any mention of checking the ptv clearance, i think that cam requires fly cutting the pistons. the timing gears are indexed, as long as you lined it up dot to dot you did that part correct.
Was that a new timing chain? You may have found the problem. The timing sprocket broke. You need to take out the lifters, the pushrods as well. you will also need to have the heads examined because when valves drop they also damage the seats and the quench area. What a nightmare. It looks like there was something that stopped the cam from rotating so it twisted the sprocket and then all hell broke loose. Count your stars the crank key didnt snap as well. Take the whole top of the motor off and I would also say do not re use any of the parts even if they look good. New lifters, new cups, new cam, new pushrods, and have the heads examined for any damage.
I'm also wondering if the sprocket mounting surface was not perfectly flat. Something is out of spec.
It is hard to tell which was the cause and which was the effect without doing a lot of tedious measuring. Unless you have the ability to take measurements, you are just guessing at the root of the problem.
Are you able to tell by somehow lining up the dots, if the sprocket was off a tooth during the install.
97 Cam swap gone wrong
