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Old Yesterday, 02:16 AM   #1
Outbkjac
 
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Default Rebuilding my vg30e hardbody engine

Hello
I am new to the forum. My engine has 183k miles. Never a problem. I recently made a bone head mistake and bent my valves. The heads are at the machine shop now. Would you do a whole boom end rebuild or just bolt the heads on and go?
Also I need a head gasket set, head bolts a clutch and seals. What brand do u recommend? Thanks to all
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Old Yesterday, 11:54 AM   #2
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Unfortunately, you can bend the rod(s), destroy piston(s), etc., so yes, the block needs to come out for a total going-through. On one Ford I worked on, there was nothing left of a piston's skirts, and the rod was spaghetti.
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Old Yesterday, 02:59 PM   #3
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If the tops of the pistons look OK and the engine ran good before you bent the valves I'd just have the heads reworked and put back on.

I had to do this job because the timing-belt tensioner stud snapped off in the block. I'd buy my seals from Nissan, they don't cost much more and you know you're getting the right part. I'd do the complete front of the engine service. EG. water pump, front crank seal, belt, tensioner, thermostat, small radiator hoses, etc. while you're in there unless you know they've been done recently. As a minimum, buy your thermostat from Nissan. You can order OE parts from Nissan using your VIN to ensure you're getting the right parts for your truck. Dealer parts departments in your town might match the online prices, just ask them.

Clutch kits, bolts, gasket sets can be bought from www.rockauto.com, good selection/prices.

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Old Yesterday, 03:59 PM   #4
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Quote:
Originally Posted by LugNut1990 View Post
On one Ford I worked on, there was nothing left of a piston's skirts, and the rod was spaghetti.

And, from above with the cylinder head off, the piston(s) all looked fine, and the short-block rotated freely.
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Old Yesterday, 05:25 PM   #5
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Quote:
Originally Posted by LugNut1990 View Post
And, from above with the cylinder head off, the piston(s) all looked fine, and the short-block rotated freely.
Nope, there's no guarantee the lower end didn't suffer some damage as well. We probably need more info about why/how the valves got bent to begin with but if it was the TB that snapped, he's probably good just having the heads done.

Lets see if the OP comes back and gives us more detail.

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Old Today, 04:42 AM   #6
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Over at Quora dot com, the Q and A website with the Secret Squirrel experts galore...I asked this question:

If you bend your valves, does it cause damage to the pistons? I won't quote over the whole answer, but it went like this:

1) You can figure out if your pistons were damaged without taking the engine to pieces, once you get the head off...and this is how he said.

2) Bring each cylinder to the very top and look for damage. If you just see scratches but nothing major, then go on to the next step...

3) Bring cylinders to TDC one at a time. Using a depth micrometer or some other method, measure the depth between the flat face of the head and the top of the pistons.

4) If they are all the same depth, you are good to go with just doing the head.

5) If one or more of the piston tops is deeper than the others, even by a little bit, then the ones that are too deep....rod is slightly bent.

6) He also says that if you bent the valves while the engine was just idling, and then the engine was shut down...chances are that the rods are still fine. Also said that if one rod was slightly bent, truck would probably still run anyway, but the idle would be irregular permanently until it was fixed. He says that the usual times damage happens is if you were cruising down the freeway, or racing the engine when it happened, otherwise probably okay. Basically, low rpms and a quick shutdown...almost never any damage. But higher rpms and an extended time that the pistons are hitting the valves...greater chance of damage. But you should be able to tell by measuring once the head is off.

An excerpt from the answer at Quora, with a note saying that if the valves are really bashed, or bent over at 90 degrees, you DO have rod damage:

Quote:
'Even if the piston(s) are not badly damaged, in which case it has to be replaced, you still MUST make sure that the rod is still good, not bent by the impact;

You do this without dismantling the block: you bring the pistons up to TDC and measure it’s height relative to the block and compare it to the height of the other pistons; ideally you’d use a depth mic, but you can do it with a good caliper or with feeler gauges and a short metal piece acting as a straight edge; you need to be careful and do a few measurements, because the piston moves, it rocks around its pin. If the depth is the same on all cylinders, there is probably no rod damage...'
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