knocking after head gasket leak

[kipawaoutpost]

hi - I changed my head gasket due to white smoke out the muffler
took head to engine place to get cleaned up and the installed 3 new exhaust valves as well
put back together and get an engine knocking sound .

funny thing when I start it it sounds normal but smoke from muffler - looks like one cylinder not firing the when it does smoke is gone but knocking starts?

can anyone help ? thanks

Paul

 

[85Hokie]

So, as it gets warm, the knocking starts? And I hope that all the valves were set at the correct specs? Sounds like one is too tight? They shave the head at all?
Does the one cylinder start to fire after a bit? Sounds like you got one glow plug not doing its job?

 

[torch]

When you first fire it up, before the noise starts, is one part of the exhaust manifold colder than the others? That might identify which cylinder is not firing. A compression test might be another way to locate the culprit.

I assume the noise was not there and all cylinders were firing before the head came off? Have you double-checked the valve clearance adjustments? Any reason to suspect anti-freeze got into the engine oil?

I would have a careful listen with a mechanic's stethoscope to try and track down the source and nature of the noise. Applying the stethoscope rod to the engine casting, the noise will get louder as you get closer to the source.

My experience is primarily with gasoline engines, so some of this may not translate to diesel, but:

Some small engines can sound like they have a mechanical knock if there is a small exhaust leak at the manifold to head joint.

A main bearing knock will sound very deep and be most noticeable down low, often through the oil pan. It usually gets worse under load and often gets louder as the oil warms and thins.

A rod knock is similar, but higher in pitch and is usually worst when decelerating.

A piston pin slap is usually a double tap, worst at idle. It will be heard best on the side of the block, towards the top of the affected cylinder.

Valve noise is up at the top of the engine and is usually more of a tapping sound than a deep knocking sound.

 

[hodge]

A bad injector can create a knocking noise, too. Did you find a blown gasket when you pulled the head, or could your white smoke been due to a misbehaving injector?

 

[L.C. Gray]

A bad injector can create a knocking noise, too. Did you find a blown gasket when you pulled the head, or could your white smoke been due to a misbehaving injector?

I almost changed out a perfectly good engine for an injector knock.

I had heard of the phenomenon, but not experienced it. I had a 6.9 Navistar that started knocking bad on me. While deciding how to go about changing out the long block I accidently ran it out of fuel. After bleeding the system and restarting the engine the knock was gone never to return.

 

[kipawaoutpost]

the knock started after a bit
as it was running I loosened the 2nd injector and the noise went away.
so I assume I screwed up the injector?
I know I had to take them appart to get out of the head .

is there a way to fix the injector or should I just buy a new one?

that for all the posts as \I think you were al right.
Paul

 

[hodge]

There are diesels everywhere, so I bet that there is a diesel shop in your area. They should be able to test, and rebuild, your injectors. Or, you can buy new.

 

[BAP]

If you pull your injector to take to a diesel shop, pull all of them and have them checked. Your engine will run better if all the injectors open up at the same pressure. It shouldn't cost too much to have them checked and cleaned up.

 

[L.C. Gray]

I loosened the 2nd injector and the noise went away.

Sounds like you fixed it to me....

That's basically what happened with mine. When I bled out the lines trying to get it fired back up whatever was going on was cleared. Saved me from changing out what I thought was a bad engine. No other issues with the engine after that.

I'd run it and never look back.

 

[65specialk]

Sounds like you fixed it to me....



That's basically what happened with mine. When I bled out the lines trying to get it fired back up whatever was going on was cleared. Saved me from changing out what I thought was a bad engine. No other issues with the engine after that.



I'd run it and never look back.

While wearing rubber gloves, Crack open the injector line till you get full fuel and no air. Be VERY careful to stay clear of the spray. Did you have the head checked for cracks? White smoke is antifreeze leak.


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