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Engine noise after head off and new rings


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Without an audio recording I think we're shooting in the dark here.

Pete, Yes only Phil will know if that's the noise. I once had that fault but not on the TR - Morris 1000 I think. Dreadful clatter, not at all muffled. Peter

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The sump is off and it all looks ok, my plan now is to pull off the top and start checking for the obvious, ie new rings all fitted ok, no rung bearings and valves all moving freely.Not sure its a starter motor issue as it was on the flat when i fired it up.

Pete is right, so once its all back together IF the noise is still there i will try to do an audio recording and post it,

Thanks again for everyone's input, much appreciated.

Regards

Phil.

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When you fit the rings, the one marked TOP is NOT the top ring, this ring is usually the second one down, as it usually has a tapered face that runs against the bore to act as an additional oil scraper. Fit this ring with top in the second position. The top ring is usually a chrome finish, and can be fitted either way up.

You can check this by standing the ring up on a flat surface, with you finger on the inside of the circle holding it onto the surface, you will see the ring doesn't stand vertical. You will also see on the outside of the ring that there will only be a minimum of contact on the ring face.

Make really sure the bores are spotlessly clean if you have used a honing tool, you would be amazed how much carborundum is left on the bores, to be really sure its clean wipe with white paper, if it comes grey clean again, and again!

John

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Hi Phil, did you check all the ring end gaps before you fitted them to the pistons, you are looking for a gap of around 12thou, if smaller than this, especially with a freshly de-glazed bore, what can happen is this, on start up there is much friction on the rings and they heat up and expand, the gaps close up completely and the rings lock in the bores and create that horrible sound. In this situation what you can do is stop the engine and wait for the whole block to heat up and expand a little, turn the engine over by hand, if free then cautiously run the engine again until the noise no longer happens, another trick is to bung some 2 stroke oil in the tank for a couple of fills, no more than this 'cause you want to bed the new rings in as quickly as possible.

If you do take the rings off again to check the gaps it is also worth stone-ing a 5 to10thou radius on the ends, this stops the sharp ends from digging in to the the bores.

Cheers Rob

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John, Rob,

The rings came in nice little packets marked "top ring" and "second ring" , both types were marked up with "top", I was careful to make sure they were in the right place, the oil control rings also had red end and green ends so making sure they were visible ensured they were correctly fitted. I even pics of every piston to satisfy myself I did them all correctly.

Bores were cleaned, hmmm maybe not enough so will use the white paper tip this weekend.

The gaps were all above the minimum advised in the brown book, again tip on stoning the ends appreciated.

If nothing else I have learnt a lot this week,........... mainly don't do this again !!!!! :lol: .

Regards

Phil.

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Hi All,

An update on the engine noise, managed to get tie in the garage and decided to pull the head off.

What I found was interesting, in cylinder 6 there was a lump of metal, see picture , around 12mm in length, origin unknown..

The piston was pebble dashed but has actually cleaned up quite well, so am in the process of putting all back together again..

The origins of the rogue metal remains a mystery, my best guess is that when the head was washed off afer the valve seats were re-cut in the machine shop , the pesky thing was hiding in the head. I thought I had looked and it was all clean, obviously not, so will take that as a lesson learnt.

I am 99.9 % convinced this is the cause of the noises I experienced, with luck will get it all back together later this week, time permitting.

Thanks again to all who contributed, will keep you advised as soon as it is running.

Hopefully the pics will show all.

 

Regards

Phil.

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Phil,

Maybe its a dowel, part #2: http://www.rimmerbros.co.uk/Item--i-GRID600063

The piston will have been twisted when that was trapped under the squish platform - when it got squashed.

Is the skirt OK ?

Peter

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Hi Peter, Other than the top face the piston is untouched, no damage to the skirt , bores look untouched, rings had started to bed in and were untouched, so I count myself lucky at this stage.

it looks like it was in the head and fell into the bores and bounced about for a few thousand revs, cant imagine how else it got in there.

The valves and head are unscathed, I took out the valves to see if there was anything else lurking inside, and the valves look fine, so decided to start the reassembly yesterday afternoon, and hopefully without anymore issues.

BR

Phil.

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Phil, It will have bounced around except under the squish segment where the head/piston gap is about the same as the compressed gasket thickness. We can see the square-ended depressions it made in the crown under the squish at the bottom of the photo. It could have been displaced when fitting the manifolds. Three manifolds and two hands are never easy.

I would check the top ring slot has not been compressed under those square dimples - by looking along the groove. Peter.

Edited by Peter Cobbold
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Hi

I had the same self inflicked problem a couple of years ago I had driven the car for about twenty odd miles when there was a banging sound which sounded like something banging on the exhaust, looking through the plug holes I could see bits of metal in the bores, on stripping of the head found pieces of a spring washer, had got into combustion chamber, the bits looked identical to what you have found and as Pete has mentioned it had compressed the piston ring gaps jamming the rings, lucky no bore damage but had to replace the piston, mine runs on SUs,the washer was from the filters, I had heard the washer drop but thought onto the road!!!

I would recommend checking the piston.

Regards Richard

Ps I try and put some photos up

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Phil-About 3 years ago I installed new rings and on startup, there was a very bad noise. When I removed the head, I found damage to #4 piston as shown in the photo. It looks like debris of some sort was trapped between the piston and the squish area of the head. There was slight pitting on the head, but no damage to the valves or seat. The top ring groove was crushed in the area of the piston, but the ring wasn't broken. The rings were Grant, with the 3 piece oil ring, same as you describe.

I am speculating that the damage was caused by a piece of scale in the water passage of the head breaking off when the head was installed and finding its way into the bore. The debris must have broken up on impact so it didn't damage the exhaust valve on the way out.

Berry

 

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