GM engine guys, I need your help!

[GLOCKMAN23C]

I'll try and make this short, I replaced the intake on my 1996 GMC Truck, now, I have what sounds like a piston rod slap, that was not there before. It is also hard to start, and rough when it finally does.

Here are the specs:
1996 GMC Sierra Extended Cab Long Bed
5.7L V-8
Automatic Trans.
4WD

I set the [STRIKE]timing[/STRIKE] distributor to the timing marks on the crank balancer. I know I had it set incorrectly the first time I put it in, and am pretty sure it is right now.

Did I FUBAR the engine?

 

[darrin5]

Sounds like maybe something has fallen down into a valve port, have you done a compression check? Also carbon on top of a piston will do the same thing.

 

[churchmouse]

Did you hydraulic the engine?
Was the intake leaking fluids?
Miles on the clock?
Are you absolutely sure the distributor went in correctly and you followed the timing procedures?

 

[darrin5]

Oh good one hydraulic lock of a cylinder from antifreeze forgot about that one, I would think if his timing was that far off it would be back firing thru the throttle body.

 

[GLOCKMAN23C]

No, I have not done a compression check. I don't have the tool.

 

[churchmouse]

Oh good one hydraulic lock of a cylinder from antifreeze forgot about that one, I would think if his timing was that far off it would be back firing thru the throttle body.

There is a procedure to get the computer on track with the distributor on some of the older 5.7's and it will run rough as heck if you do not do it. Not sure about the 96.


Mileage....

 

[GLOCKMAN23C]

The intake was not leaking internally. The fitting for the heater hose was leaking, I went to replace it, and broke the intake in the process. It has about 125k on it. I think I'll go pull the plugs on the right side, since that a appears to be where the noise is coming from.

 

[churchmouse]

Check the plugs to see if one or more took a hit. Should be very obvious. Possibility it did swallow something when the manifold was off.

 

[GLOCKMAN23C]

Check the plugs to see if one or more took a hit. Should be very obvious. Possibility it did swallow something when the manifold was off.

Plugs look good, possibly yes, but unlikely.

 

[churchmouse]

Pull all the plugs and spin it over. If something is in a cylinder you will hear it.

 

[SK 1911]

This may sound stupid but the engine didnt overheat did it? I know that on my old 93, it overheat once for about 10 minutes and had a small knock ever since.

 

[GLOCKMAN23C]

Pull all the plugs and spin it over. If something is in a cylinder you will hear it.

Sounds like it is below the cyilnder. I can hear it after about 5-8 seconds of cranking.

This may sound stupid but the engine didnt overheat did it? I know that on my old 93, it overheat once for about 10 minutes and had a small knock ever since.

No it has not over heated.

 

[dhnorris]

****ing democrat liberals have sabotaged your carbon footprint

 

[GLOCKMAN23C]

****ing democrat liberals have sabotaged your carbon footprint

That just means I'll have to go find something with a big block, and remove the cat's. Not that I'll be able to afford to drive it.

 

[dhnorris]

my brother left a rag in one of the holes from gasket scraping.

 

[giovani]

You need some one to get a scanner on it and set the timing per the scanner.
You should have scribbed s line on the dist housing and put the dist back to the mark.
You can't time the 96 through early 2000 5.7 per marks on the balancer.

 

[giovani]

Not saying the others are incorrect that something might have gone down an intake runner.

 

[churchmouse]

We were swapping manifolds and doing a set of headers on my sons short bed 81 and a small nut went down into #3. Have no idea how but it sounded really bad. We lucked out hearing it when we spun it over to get #1 up TDC. Pulled the head and there it was. Some scrapes on the piston that cleaned up easily and lesson learned.

Probably not a rod if you can hear it cranking.

 

[concrete dog]

I'll try and make this short, I replaced the intake on my 1996 GMC Truck, now, I have what sounds like a piston rod slap, that was not there before. It is also hard to start, and rough when it finally does.

Here are the specs:
1996 GMC Sierra Extended Cab Long Bed
5.7L V-8
Automatic Trans.
4WD

I set the [STRIKE]timing[/STRIKE] distributor to the timing marks on the crank balancer. I know I had it set incorrectly the first time I put it in, and am pretty sure it is right now.

Did I FUBAR the engine?

I drove a 97 and it did the same thing when the timing was off

 

[giovani]

The reason you can't set the timing like a normal distributor is it's not really a distributor.

It is only a secondary "high voltage" switch.

The primary" low voltage" sensor and module are not in this unit.

The crank sensor in conjunction with the ignition module and the pcm actually determin timing.
The " distributor" switch was to be in time with the primary circut to be in time with the mechanics of the engine.
Scanning it and adjusting it untill your spark retard parameter = 0 is the only way to get it back in time.