Offroad Trailblazers and Envoys

2016/17 Winter Engine Rebuild (and more)

Trailblazer and Envoy related, but not off-road related...

by HawkeyeC25 » Mon Jan 02, 2017 2:39 am

Hey all,
I wanted a place to document my projects over this winter, so I'm starting up this thread. Let me know if it belongs somewhere else in the forum. I'm rebuilding my engine myself and wanted to both share my findings for others, as well as take on any suggestions of those who have experience! I'll include the highlights in my Build Thread when I'm done, but until then I wouldn't mind getting this somewhere I can get feedback.

My '05 TB EXT ran great all summer, but a few things were troubling me:

1) There's been a constant slow oil leak. The pan and underside of the block are a mess from blow-back and never found the time to clean everything up and find it's source.
2) The last trip out for the year, the front disco has had a hard time keeping 4WD engaged.
3) Every now and then, I've had what sounded like a lifter knock, and sometimes a mild chirp from deep in the engine. It finally started throwing intermittent misfire codes on the #8 cylinder if left at idle for too long.

All of this lead to the decision to start pulling things out of the truck. I'm down to everything being completely torn out, but it will take me some time to get all the pics and info up here.

Welcome to my journey!!
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HawkeyeC25
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by HawkeyeC25 » Mon Jan 02, 2017 3:16 am

First things first, get that front disconnect out and see what's going on...
Found a peanut buttery mess, along with a pile of metal that used to be the outer bearing on the CV side. The CV shaft also had grooving. Bought a new Detroit Axle CV as well as an OEM AWD disconnect. No more worrying about the front axle engaging!!

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by HawkeyeC25 » Mon Jan 02, 2017 3:32 am

I started cleaning around the oil pan and realized a lot of the perimeter was wet. I was thinking the pan gasket was bad, and I wanted to see inside the engine to see if the phantom noises had an obvious culprit. So I pulled the cross members, dropped down the steering rack, pulled all the wiring harnesses off the oil pan, pulled my AC compressor bolts, unbolted the front diff and pulled it to the side, then dropped the pan.
I found many of the pan bolts loose (one cause of oil leaking), the inner diff seal had been slowly leaking and blowing axle fluid on the one side, and that the previous owner didn't take very good care of this engine. There is a lot of burnt oil on the inside of the pan and other parts. I can only assume they either never changed the oil (just filled it due to the leak) or it got a bit hot at some point and baked some old oil. Either way, the crud can be scraped off, but not easily. Not really excited to think of this stuff breaking off and getting into my engine.

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by HawkeyeC25 » Mon Jan 02, 2017 3:40 am

Next, I pulled the windage tray to get a look at the rotating assembly. I found what I suspected... a lifter had been failing and grinding itself into the cam on the #8 cylinder. The ticking was random (like a collapsing lifter), but when the chirping was there it was at 1/2 the rpm of the engine (cam speed). The lifter roller was cutting right into the cam. It's hard to see in the pic, but the intake cam lobe on the right of the first pick is worn down and grooved/etched into the camshaft. The second picture is of a good lobe.

Looks like I'm tearing into the motor!! :wallbash:

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by HawkeyeC25 » Mon Jan 02, 2017 3:58 am

This is where a V8 becomes a PITA... little space to work! After pulling the intake, washer fluid tank, and ignition coils, I started pulling the coolant and A/C lines that were also in the way. Couldn't even think about getting the exhaust manifolds off with them in the way.
Note the crafty work of the previous owner when a coolant tee broke... copper pipe with hose clamps :facepalm: Time to get rid of the rear heat and A/C, but we'll get to that later.

Valve covers also had the burn oil... uugh.
Valvetrain looked fine.
Pulled the rocker arms and push rods. Some of the pushrods had a layer of burnt oil as well. Not cool.

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by HawkeyeC25 » Mon Jan 02, 2017 4:05 am

Next up, pull the heads! Lifters cannot be removed on an LS motor without pulling the heads.
I removed the intake, removed the exhaust manifolds, unbolt the crap clipped and bolted to the firewall side of the heads, then pulled the LOMA (Lifter Oil Manifold Assembly - solenoids that turn off 4 cylinders for AFM/DOD).
LOMA looked fine, but underneath in the valley, yet another clear picture of the damage to the #8 intake cam lobe.

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HawkeyeC25
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by HawkeyeC25 » Mon Jan 02, 2017 4:13 am

Heads looked good, but in need of an overhaul. Carbon buildup is not horrible for 165,000 miles. I completely disassemble the heads and already have a shop lined up to do clean up and 5 angle grind. Should be like new when I get them back!
Pistons look decent, but more interested in the valvetrain at this point.
Next, time to finally see how those lifters look!!

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by HawkeyeC25 » Thu Jan 05, 2017 10:17 pm

Here you can clearly see the failed intake lifter. This is the one that was grinding into the cam. The rest looked ok. But this forced me to pull the other head off and pull the cam shaft.

I decided since I'm going this far, it's time to upgrade :woot: I went with a complete AFM/DOD delete kit with Stage 2 Truck Cam: Low Lift 212/218, .550"/.550". Should give me a decent boost of torque across the speed range!

Time to rip the engine apart!
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by HawkeyeC25 » Thu Jan 05, 2017 10:27 pm

Well CRAP! The last pic above shows some grooving on the front cam journal. That in itself didn't worry me since I'm replacing the cam anyway, but there is heavy grooving in the cam bearing in the block. And these need to be pressed in.... soooooo.... guess I'm pulling the block!!! This repair has turned into a complete engine rebuild now!! Well, down the rabbit hole I go!!

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by HawkeyeC25 » Thu Jan 05, 2017 10:40 pm

Well, got the engine on the engine stand and time to tear out the rotating assembly. I'm tearing apart the block and heads to prep for machine work. Very light grooves in the cylinders means a slight over bore is in this block's future! I'll let the shop tell me how much I need to go. Fortunately, the rotating assembly looks pretty good.

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HawkeyeC25
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by rScherzer » Fri Jan 06, 2017 11:24 am

Not sure if I am allowed to comment here but, were you going to reuse the stock pistons? Maybe a set of forged ones with a little bump in compression to go with that cam :D
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by HawkeyeC25 » Fri Jan 06, 2017 10:23 pm

Comments are welcome!! New pistons for sure since the couple grooves I found in the cylinders will require boring. I thought about forged, but not sure I can justify the extra cost. I don't plan on putting a blower, but I should check how much more it really is... who knows what future Craig will do :)

As far as compression, the GenIV's already have the flat top pistons, so my stock compression is already up around 9.9. We'll see what the heads look like... could always shave them down a hair :)
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HawkeyeC25
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by rScherzer » Fri Jan 06, 2017 11:51 pm

Forged are nice just in case you decide to add a little laughing gas to it or some other type of power adder. The stock pistons are good, but a little bit more compression is also nice. Then again to match power and you start breaking everything.
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by HawkeyeC25 » Sat Jan 07, 2017 12:58 pm

Yeah - I can get a new set of over bore pistons for about $225. Forged are $665. I can't justify the added cost. A 5.3L with better cam and 4.56 gears will be plenty for me :) Probably gonna start snapping axle shafts next :roll:
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HawkeyeC25
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by HawkeyeC25 » Sat Jan 07, 2017 1:14 pm

Back in the spring I replaced the compressor and blocked off the rear A/C lines. Now that the motor is out, I figured it's time to tear out all the rear lines for BOTH the rear evaporator and rear heater core! They run behind the motor which is why I left the A/C lines there in the first place. Here's a pile of about HALF of the lines!! I feel better now knowing I will not have coolant lines running up and down both frame rails when I'm offroading!

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2005 Trailblazer EXT LT V8 Lifted
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There are 10 types of people in this world, those who understand binary and those who don't.
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HawkeyeC25
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by bartonmd » Tue Jan 10, 2017 9:32 am

Nice! So... aside from the cam and lifter roller that had been a problem for a while, somebody was correct when they said you had likely just hydrolocked the engine and nothing was bent or broken from it, and you didn't need a whole new engine?

Mike
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by HawkeyeC25 » Tue Jan 10, 2017 11:03 pm

bartonmd wrote:Nice! So... aside from the cam and lifter roller that had been a problem for a while, somebody was correct when they said you had likely just hydrolocked the engine and nothing was bent or broken from it, and you didn't need a whole new engine?

Mike

Not sure what this comment means... I never hydrolocked the engine (maybe you know something I don't? :hmm: )... it was running great, except for intermittent lifter knock and chirp of grinding the cam :P

I only decided to tear it all out when I found the bad cam bearing... at that point, I decided to not go with repair, and do a complete rebuild. And so, here we are :)
2005 Trailblazer EXT LT V8 Lifted
Build Thread
There are 10 types of people in this world, those who understand binary and those who don't.
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HawkeyeC25
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Rank: Offroad Rated

by bartonmd » Wed Jan 11, 2017 10:19 am

HawkeyeC25 wrote:
bartonmd wrote:Nice! So... aside from the cam and lifter roller that had been a problem for a while, somebody was correct when they said you had likely just hydrolocked the engine and nothing was bent or broken from it, and you didn't need a whole new engine?

Mike

Not sure what this comment means... I never hydrolocked the engine (maybe you know something I don't? :hmm: )... it was running great, except for intermittent lifter knock and chirp of grinding the cam :P

I only decided to tear it all out when I found the bad cam bearing... at that point, I decided to not go with repair, and do a complete rebuild. And so, here we are :)


Oh, crap. I thought you were somebody else. Another guy from Michigan. He hadn't painted his bumper/kit, though, and he did hyrdolock it last year, and is just now debating on rebuilding it. I was looking at your pics in awe that the steel parts weren't rusted or anything. Whoops. Carry on!

Mike
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by bartonmd » Fri Jan 13, 2017 2:59 pm

Also, just out of curiosity, what oil do you run?

Mike
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by HawkeyeC25 » Sat Jan 14, 2017 9:58 pm

bartonmd wrote:
HawkeyeC25 wrote:
bartonmd wrote:Nice! So... aside from the cam and lifter roller that had been a problem for a while, somebody was correct when they said you had likely just hydrolocked the engine and nothing was bent or broken from it, and you didn't need a whole new engine?

Mike

Not sure what this comment means... I never hydrolocked the engine (maybe you know something I don't? :hmm: )... it was running great, except for intermittent lifter knock and chirp of grinding the cam :P

I only decided to tear it all out when I found the bad cam bearing... at that point, I decided to not go with repair, and do a complete rebuild. And so, here we are :)


Oh, crap. I thought you were somebody else. Another guy from Michigan. He hadn't painted his bumper/kit, though, and he did hyrdolock it last year, and is just now debating on rebuilding it. I was looking at your pics in awe that the steel parts weren't rusted or anything. Whoops. Carry on!

Mike


Haha no worries Mike! Yeah mine has stayed water free, but the bad lifter sure took it's toll.

As for oil, I was running Valvoline High Milage (synth blend), but after the rebuild I'll be back to my go-to for new engines of Mobil 1 Full Synthetic.
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HawkeyeC25
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