Knocking in tb42

[King_ady1]

Hey guys. Just after a little bit of advice. Here's the situation.

I have a tb42 with a turbo on it. It has been running fine unroll a week ago when I notices a slight flutter from the exhaust that I noticed the gasket was blown. Went bought a new gasket and manifold bolts because the old ones were getting to there last days.

After replacing gasket started the engine and started making a large knocking sound. Sounds from about the 5-6 cylinder I believe. Removed exhaust manifold and to see if it was the exhaust side. But noise was still there. Removed rocket cover to check valves are operating properly and they are.

Not too sure what could be causing it. My next step will be pulling the head off to check everything under there. So if any1 has an idea what could be causing it before I remove the head would be great. Thx.


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[Ben-e-boy]

get yourself a mechanics vacuum gauge before stripping it down it should steer you in the right direction here is a pic of the readings and what they mean.

http://www.nissanpatrol.com.au/forums/images/imported/2013/01/85.jpg

[Brisat]

where did you get the page from, it looks very much like early 60's to me. Used to have one very similar back then but that was 50 years ago

[threedogs]

We used to tune Early 4 cylinder jap motor bikes with vacuum guages , great workshop tool in the right hands.
My other 4x4 had a knocking noise was a small piece of aluminium sitting on top of piston, eventually it went out the exhaust

[Robo]

Its a long shot but can happen.
When you lift the right boot a sudden back pressure can accure at turbo exducer and blow something back in through the exh valve.
My guess bit of your exh gasket sitting on piston and hammering against head.

This is a common thing believe it or not with ceramic exducer turbos, ceramic exducer wheel can break and a bit sucked back into a cylinder, I've got a pic some where of the damage that can happen not pretty.

Remove spark plugs and look into each cyl best you can for damage.
Or remove turbo dump pipe and inspect exducer wheel for damage.
Or remove turbo completely for even a better look see.
I'd be doing this before removing the head.
cheers

[King_ady1]

Thanks for the idea mate. Checked out the turbo. Seems fine. Removed spark plugs, can't see any damage. I was thinking something might have been sucked back into the chamber. Atm best bet would be to remove head and investigate better.

Yet to get a vacc gauge so might wait till tomorrow when I get one before I go removing head.

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[Ben-e-boy]

where did you get the page from, it looks very much like early 60's to me. Used to have one very similar back then but that was 50 years ago


google images there is quite a few around this was just the first one

[King_ady1]

Ok. An update guys. Pulled the head off and discovered some damage to the 6th piston and head (missing the valves). Looks like marks from some sort of pin or shard of metal. Hope a bit of a file down and it should be sweet to put back on and get going. Or I have a spare head if there's any1 that objects to re-using it.

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[Ben-e-boy]

hey mate do you know where the swarf is coming from?

[King_ady1]

Dunno mate. Spent about 2 hours checking for cracks, chips, scrapes anywhere. Have not found a thing it could be.

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[Robo]

Sorry to be the bearer of bad news but .
You will now probably find the piston has been deformed and crown is now crimping down on the piston rings.
the bore may also be scored
sorry, sorry , sorry sorry.