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Discussion Starter #1
Hello everyone! So I am new here and I have a problem that's been challenging me for awhile. Purchased a trailblazer LT 5.3 Vortec V8 after it sat for almost a year at a relatives because of a transmission issue. The vechile was a fleet car with high miles (245000). I took the car in and had it looked over before I put a new transmission in. The car is clean and ran very well and quiet. There was no issues or concerning noises. The mechanic that did the transmission said it was clean and thought there was a lot of mechanical life left. So heres the issue-
After about a month of driving with no issues, I got a misfire code for cylinder 6 and excessive white smoke from exhaust. I checked fluids, replaced oil, coil and plugs initially after eliminating other possible issues. Still got the code and oil from exhaust. Pulled valve covers noticed that the push rod did not make contact with rocker arm for cylinder 6. I was able to free the lifter without pulling the head thru a hole o
Under the valley plate. Replaces valve cover seal and Put everything back together. Idled great and ran well with no smoke or misfire for about 2 miles. I came back and pulled the valve cover again thinking the lifter would be stuck again but it was not or at least the push rod was on the rocker arm. I replaced the valve stem seals. Same result pulled everything again and it was stuck. I bought a head gasket and new lifter. A buddy came by to assist but was adamant that if I was able to free the lifter again spraying carb cleaner thru the push rod hole onto the lifter would prevent it from sticking again. I was hesitant because I did not go thru another year down for nothing. Very long story short, I freed it cleaned and lubricated it with the same result. So now I have it back to where I was. The exhaust manifold bolts fought me like heck and I am about to pull the head. Is there something else I should do or any other possible problems incan overlooking? I just do not want to pull the head and put a new lifter in and head gasket if there is an underlying issue that may be collapsing or sticking the lifter like the cam. Would hate to have it taken down and put back with the same result for a 4th time. I appreciate anyone's opinion AMD tine with this- thanks in advance!
 

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Your V8 has Displacement On Demand, later renamed Active Fuel Management.
Under light load conditions, the engine manager computer will deactivate 4 of the 8 cylinders.
Number 6 is one of those cylinders.

You need an DOD/AFM lifter (I believe they must be changed in pairs).

There is an oil filter in the passageway that supplies oil to those of lifter, I'd suggest changing that.

You also need to check the cam lobe, when these lifters fail they are known to take the cam with them.

I'll see if I can find info on the filter.

Sorry, I don't seem to be able to copy a link. But you can find it with an easy search
Use the following in the search field
"AFM oil filter"
Check thread titles only
And use RayVoy in the member field
 

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Discussion Starter #4
Thanks RayVoy,
I did change the filter you're referring too. I did not think that the 2006 trailblazer had the V8 displacement I thought it started with the 07. I was Informed that I did not have this on mine as it was one of the first solutions I had. I'll have to look into that in more detail because I am not aware of it having the displacement. Thanks for the support !
 

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Hey Mike, you may be right, I just assumed all Trailblazer V8s had DOD, let me check.

Is yours the extended Trailblazer, or the SS?
 

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Ok, the internet tells me the extended (longer wheelbase) trucks got the V8 in 2005 and all V8s had DOD.
 

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not extended is a LT 2006 5.3 V8
Mike, Chev never made one.
Chev put the 5.3 only in the extended trucks (3 rows of seats).
Chev only provided the inline 6 cylinder 4.2 in the short wheelbase trucks.
The short wheel based Chev SS trucks got a 6 ltr V8
 
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