LB7: Ticking and running strange

[CancerPipe]

So I just did headgaskets and studs on the truck. It's been back together for a week now but with work being so busy I just got out in the garage to start it yesterday. I left the ficm unhooked and turned it over a while to prime the oil. I started it and it's got a tick and strange exhaust note. Not as loud as any stuck injector I've seen and there's no smoke once I let it warm up and cook off anything that may have been in the cylinders. I've got no codes and can't find any loose wiring. Balance rates look fine to me. Also replaced the FPR and added a downpipe. Not sure which way to look. I used dvt to shut down the injectors and when I shut off number 3 the idle smooths out but the noise is still there. Valve lash is dead nuts on .011 and was checked many times. I also used assembly lube on all the valve train parts after I cleaned them thoroughly and soaked them in oil. Also cleaned the injectors and installed new lines. https://vimeo.com/162210880https://vimeo.com/162210927


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[CancerPipe]

No one has any ideas?


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[PureHybrid]

Sounds valve train related. In the video it sounds more pronounced in the engine compartment, so most likely intake side. I'd say reset lash per the recommended procedure. I know you said it checks fine, but make sure you set it in the correct order/sequence.

Take the cold side intercooler pipe off and idle the engine, if you can feel air puff back through you have an intake valve hanging open.

Were the heads checked when you had them off? How many miles?

 

[catman3126]

Is there any way something got dropped in there and is hammering on a piston?

 

[CancerPipe]

Heads were rebuilt and surfaced. It doesn't make any noise when turned over by hand.


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[custom8726]

Did you Rotate the engine over at least 10 revolutions after you set the lash? Then Re-check? I know I just went through this on my LB7, I set everything to spec but didn't rotate the engine over after i set all of them. Started the truck and it was tapping, After pulling it all back apart at least 1/2 of the valve train was out of spec.

 

[CancerPipe]

I did the whole thing twice. Set the lash. Rotated 10 revolutions. Went back around and checked. 10 more revolutions and checked again. Not saying it's impossible, but I tried to be thorough. The tapping is bad, but the exhaust note and slight miss is what's got me baffled. Going to scope it and listen around and take some notes before I pull the valve covers off.


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[kenp313]

I had a similar problem and found that one of the valve bridges was not installed correctly (sitting crooked) giving me a false 12thou. Just my .02 good luck with issue

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[IOWA LLY]

I think I would pull the valve covers and check everything over.

 

[dirtydmax]

Pull the oil fill cap and check for pressure.cap upside down on fill tube.just curious...you set #1 on compression?!

 

[CancerPipe]

Can't work on it until Thursday but plan on taking the valve covers off for a start. Cylinder number one tdc compression stroke. Set lash. One revolution set lash. Rotate 10 times. Repeat.


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[dirtydmax]

Smell your oil.if it smells burnt youll know.

 

[custom8726]

I had a similar problem and found that one of the valve bridges was not installed correctly (sitting crooked) giving me a false 12thou. Just my .02 good luck with issue

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You mean it was 180deg off? Trying to figure out what you mean by "Not installed correctly" I know if there in backwards the injectors won't fit between them but not sure how that would give you a false 12thousands even if they were backwards (Up side down) ?

 

[kenp313]

When i installed it i must not have pushed down on it from the middle which made it sit uneven. When I looked at it I noticed it was sitting at an obvious angle. When I pushed on it in moved down into position with a slight click noise. I then reset lash and all was good

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[CancerPipe]

Well it's up and running and all is good. Replaced the injector and re-set the lash. Cyl #3 had fuel sitting in it. It's all good now. Except that I forgot to hook the line back on the bottom of the pcv box.


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