LQ9 Piston Gouge - Advice needed
LQ9 Piston Gouge - Advice needed I recently bought an LQ9 sight-unseen, for what I thought was a good price. So, I get it, and start to tear into the top end to do a cam & valve spring swap.
Now I see why it was such a good price - what I first found (and what wasn't disclosed to me) was a broken intake valve spring. Luckily the valve didn't completely drop & ruin the cylinder. But, it did scrape the piston head in one location.
I'm attaching a few photos of the damage. It looks like it's not too bad. My measurements are approx 0.75" long by 0.125 tall (max dimensions). Based on my feeler gauge measurements, the max depth of the gouge is somewhere between 0.020 and 0.030 (my smallest feeler gauge is 0.032, which is larger than the max depth of the gouge).
I'm replacing all the valve springs, seats, retainers, and seals. Also, I'll replace the culprit valve.
I really don't want to tear the bottom end apart & change out pistons. So, if it's safe to use, I'd prefer to use it. What do the experts here think - Is the piston (safely) usable as-is? Could I just file down the high spots, clean it out & go? Is there something else I can do to the piston while still in the block to make it OK?
Now I see why it was such a good price - what I first found (and what wasn't disclosed to me) was a broken intake valve spring. Luckily the valve didn't completely drop & ruin the cylinder. But, it did scrape the piston head in one location.
I'm attaching a few photos of the damage. It looks like it's not too bad. My measurements are approx 0.75" long by 0.125 tall (max dimensions). Based on my feeler gauge measurements, the max depth of the gouge is somewhere between 0.020 and 0.030 (my smallest feeler gauge is 0.032, which is larger than the max depth of the gouge).
I'm replacing all the valve springs, seats, retainers, and seals. Also, I'll replace the culprit valve.
I really don't want to tear the bottom end apart & change out pistons. So, if it's safe to use, I'd prefer to use it. What do the experts here think - Is the piston (safely) usable as-is? Could I just file down the high spots, clean it out & go? Is there something else I can do to the piston while still in the block to make it OK?
The damage to the piston that you can see in the picture is nothing at all to worry about. Replace that valve, have a valve job done and have the machine shop carefully inspect that valve guide. It could have hurt the guide.
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Joined: Sep 2009
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From: PA/MD
I over reved my ls1 a few times and when I tore the heads off to port them all 8 pistons had marks like this in them from the valves kissing them.....if I hadn't pulled the heads I never would have known.....I got lucky and didn't even bend a valve.
