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471k miles, low compression on 3 cylinders, low oil psi about 6 months ago

Robs05hd
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Robs05hd New Member

Robs05hd

Posted
Posted (edited)

Ok, so here we go.

 

2005 Sierra 2500 HD 6.0 4L60E 

471k miles

 

I know for a fact that I have less than 60 psi compression on 1, 3 & 8.  Is there anything I need to specifically look at other than valve train and or possibly rings?

 

So, roughly 6-8 months ago I noticed the oil pressure was low, like low enough for the DIC to display low oil pressure at idle. I've went from 5-30 to 10-30 only to have the oil pressure to sightly increase.  I want to say that I'm about to be replacing the oil pump, but is there anyone that thinks the filter screen under the oil pressure sensor would cause this?

 

I love the truck.  It was a retired company truck when I bought it.  Yeah, I know, it was road hard and put up wet pretty much.  Just looking for advice on where to go from here, and looking for good used 6.0's are rather expensive.  Thanks in advance

 

 

 

Edited by Robs05hd
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richard wysong Senior Enthusiast

richard wysong

Posted
Posted (edited)

Welcome to the forum! With that amount of miles on it it is due for a complete rebuild. Could be excess bearing clearances causing the low OP. Might be more economical to look for a parts truck than an engine or try LKQ yard if there is 1 in your area

Edited by richard wysong
CamGTP Senior Enthusiast

CamGTP

Posted
Posted (edited)

A worn out pump or loose fitting pick up tube o-ring could be the cause for low pressure if the main/rod bearings and cam bearings aren't worn out. But honestly the cam bearings always look worn on high mileage engines. You can also dump an extra 2-3 quarts in the oil pan as a test, the extra oil will bring the level up to the pickup tube o-ring and if the pressure is higher, that is likely the cause. Only let it idle doing that, the oil will be pretty high and you don't want the crank slapping the oil as it flows to the back.

 

Low compression can be from rings and or worn out valves. If you are going to do a in frame service I'd pull both heads and have them cleaned up at a machine shop. Dingle ball hone each cylinder and buy a new set of rings. Slap it back together and see what happens.

Edited by CamGTP
davester Senior Enthusiast

davester

Posted
Posted

OMG.  You ran it for 6 months with low oil pressure, and you are just now going "Should I do something about it?"...

 

And thinking it's just the oil pump. Jebus.

 

The motor needs a rebuild, and I'd at least pull it to do all the cam bearings, and measure the cylinder bores to see if they need to be bored over.

newdude Senior Enthusiast

newdude

Posted
Posted
11 hours ago, Robs05hd said:

Ok, so here we go.

 

2005 Sierra 2500 HD 6.0 4L60E 

471k miles

 

I know for a fact that I have less than 60 psi compression on 1, 3 & 8.  Is there anything I need to specifically look at other than valve train and or possibly rings?

 

So, roughly 6-8 months ago I noticed the oil pressure was low, like low enough for the DIC to display low oil pressure at idle. I've went from 5-30 to 10-30 only to have the oil pressure to sightly increase.  I want to say that I'm about to be replacing the oil pump, but is there anyone that thinks the filter screen under the oil pressure sensor would cause this?

 

I love the truck.  It was a retired company truck when I bought it.  Yeah, I know, it was road hard and put up wet pretty much.  Just looking for advice on where to go from here, and looking for good used 6.0's are rather expensive.  Thanks in advance

 

 

 

 

 

An entire rebuild.  That's what you need here, nothing short of.  

 

An oil pump isn't going to fix 60psi of compression. 

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