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Alan Cottrill's Avatar
 
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dropped a screw into intake port

I dropped a screw down the intake port when I took the intake off to replace the rubber boots between the airbox and intake runners on my 2.7.

I have a seriously bent intake valve. I'm sure the piston hit the valve while the screw was holding the valve open.

on the bright side, the screw never made it past the valve.

The motor is freshly rebuilt and just finished breaking in. it ran very well and pulled hard for a 2.7.

I'm thinking I'm just going to get another head and rebuild it, pull the motor and swap the head out.

assuming the heads on my engine now have never been machined, and that the head I get has never been machined, should I worry about a height difference between the new head and the heads still on the motor?

also...I'm hoping the piston only hit the valve once, the first time, and that it had enough clearance after it bent the valve and didn't smack it repeatedly. should I worry about the piston or rod. I'm sure there will be a small scar on the top of the piston but will that really hurt anything?
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Old 08-31-2004, 10:08 AM
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I would check the piston, rod and the rod bearing. Sorry to hear about your misfortune.
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Old 08-31-2004, 10:18 AM
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Sorry to hear about this. I did this on a 78 SC and piston didn't hit the valve. The valve seat was good too. Unfortunately with a small screw the valve seat probably has a nick.
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Old 08-31-2004, 11:56 AM
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thanks guys.

it was a 6mm screw it looks like only the threaded end of the screw got stuck between the valve and seat. Any chance the piston didn't hit the valve? stock 2.7 cis cam.

The reason I ask, is that I have a lot of sympathy with the wife right now...so now might be the time to buy a 3.2, but If I can fix it with a quick engine drop and replace the head, I'd rather do that and spend the extra money other places on the car. but if it's likely I'm looking at piston/rod damage I might just step up with a 3.2 and put the 2.7 on the shelf for a while.
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Old 08-31-2004, 03:20 PM
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Do you know anyone with a bore scope camera? I borrowed one from work, turned the engine to where the valve was all the way open and looked around. I could tell that the piston and cylinder walls were unharmed.

Did the engine run very long with the screw in there?
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Old 08-31-2004, 03:46 PM
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Was the motor running?
If you've fished out the screw (magic magnetic wand) I would run a compression and/or leakdown test on it. No point in doing all that work if it didn't do anything.
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Old 08-31-2004, 04:05 PM
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Like everyone else said, make sure you need to pull it down. If you do, pull the buggered head and a good one. A good machinist will then be able to either fix the broken on to the correct spec or set up a replacement one to exactly match the other 5, that way deck heights etc... should be fine.
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Old 08-31-2004, 04:18 PM
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I ran the engine for about 10 min. when It started to make some noise. no real bad noise just like a loose valve. which after the valve bent it got pretty loose. the compression is only 45 on that cyl now. I've fished out the screw and it runs with no bad noises it just runs real bad because of the dead cylinder.
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Old 08-31-2004, 05:20 PM
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Well you might have lucked out. If you don't have arod knock, then your bearing is o.k. Show some pics of what you got when you pull it apart.
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Old 08-31-2004, 05:30 PM
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Hi

Tough luck, Before you pull the whole engine down it find someone with bore scope to video it for you, They can put a video camera in and look at the piston, then turn it round and video the valve! A guy here had it done to evaluate the extent of a head gasket leak in a 928. Look for a engineering inspection company, not necessarily anything to do with cars/engines

Good luck

Neven
Old 08-31-2004, 07:13 PM
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If you got the screw out and you have 45psi compression, I doubt the piston was hit. When I bent a valve this way I had zero compression and the valve was only slightly bent.
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Old 09-01-2004, 04:31 AM
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If its a fresh rebuild, then I woudl hope that the heads were machined, I doubt an old 2.7 went back together without being clipped. Also, if the screw jammed between the valve and seat, the seat may need to be replaced, since you will either have to grind or cut it to clean up the seat face, and by that time, the valve will be buried down in the head. Also, the guides are shot, and you need a new valve at the least. The contact with the piton may have dmaged the dome, twisted the rod, and pounded the rod bearing. So just keep that in mind.
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Old 09-01-2004, 06:41 AM
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Since you have to remove the head anyway, just take it off and take a look. The screw might have rattled inside the cylinder and done a job there too.

Since the head is clamped between the cam housing and cylinder, and the whole assy. is bolted onto the crankcase, it's important to maintain the same stacked height dimension on each bank.

Sherwood
Old 09-01-2004, 10:23 AM
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