You got it, these guys scared the $hit out of me too when I thought it was just a misfire or spark plug fouled.

 

I don't even have a pcv valve and it still pushes oil out from under the oil fill cap. I also have my cap attached directly to the valve cover instead of using the long fill tube. I don't think I can vent the crank pressure fast enough to keep pressure from building in the first place. I still don't have the evac system welded up so may be that will help once it's done. Someday it will be fixed or I'll haver to get the motor done I guess.

The thing I don't understand is no-one makes off the shelf replacement pistons for the 5.3l??? I think more engines this size have been produced for trucks than the others correct?
I really don't want or need any more displacement or power than a correctly running and strong 5.3l could put out. Any more power and then its 4l80 and new 14 bolt HD rear end time. I really don't want to spend any more on this money pit to begin with, just want it to be reliable at current displacement and psi.

 

ya i've read through a lot of your threads TG02z71, thanks for all the hw. But, I have a 6.0 so i don't have to worry as much about finding pistons. Have you done a compression test yet to see if the piston is your problem?

 

I just talked with my neighbor, he has a compression tester (don't know if its a leak down, I've never used either) so we may do it this weekend.
I'm just glad I have a company car to get me around so I don't have to drive the truck all the time. If I had access to a welder, chop saw(exhaust evac), engine hoist etc... this would have been gone through and fixed a long time ago.
If my #7 cyl. is f-ed up I will have no option but to get another engine or rebuild this one I guess. I just don't have any money for this crap right now.
I did drive the truck this afternoon and it runs fine out of the boost, it seems like it misses a little when idling though.
A while back I seemed to ,lose about 4 inches of vacuum on my gauge at idle. I wonder if that was the first sign of trouble??

 

That's another thing, I'm losing no vaccuum at idle. Can that happen with an f'ed up piston?

 

could have been.

If anyone is looking for a nice new LQ4 i have a long block for sale.

 

Always trying to sell something. JK.

Seriously though, for you guys on a budget, this is a good option for you. LQ4's are more resilliant than 5.3's and they don't break the bank. Put the new LQ4 in, run it a little rich, keep the timing under control and still have money to go to the strip club.

 

This is exactly what I'm going through right now....BUT my engine has not had one missfire.


The fact that you are having missfires would be my biggest worry... have you pulled the plugs? How long have you drove it after the missfires started?

A posability of a blown head gasket is up there as well...
Once I do some test on mine, I should beable to guess a bit better on yours...

BTW, That isn't Weedo's old ride is?

 

Just trying to help homie out.

 

Wilde,

I changed the plugs to TR6's once and not one plug looked different then any others and I still have the mis.

And no, I'm the sole owner of the denali.

Let me know how you make out with the test also.

Brian, I'm not familiar with the different engine names, I've got the 6.0, not a 5.3. What's the difference between that and the LQ4?