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Hello, I'm new here and I have found this forum to be so helpful already. I need advice badly so I signed up for an account. My wife and I feel like we have had 9 months of TrailblazerTorture and now we face another dilemma.

Background: Our 16 year old needed a solid framed, reliable, 4 wheel drive, sturdy, but yet affordable first vehicle. Was hoping the solid frame, good handling, good towing capacity, and thousands of available TB on the road would provide a good solution. Felt that we could find plenty in his price range and tons of available parts. Normal wear parts like brakes, suspension parts, fenders, bumpers, interior items all easy to get in a junkyard or from aftermarket suppliers. We found one in his price range that looked like it may have had some side door damage which was recently repainted, but was 2008, 125,000 miles, solid body, frame, smooth transmission, smooth 4x4, etc. Tried to teach him to wrench on his own, take care of his truck, be responsible.

air bag light was on and A/c system not working. Used car dealer fixed A/C (plugged canister) and we drove it home. After lots of study/trial error got the air bad light off by figuring out the repainted door was actually from a 2006 and the sensor didn't match what the computer in the 2008 was expecting. Fairly simple fix once we could figure that out.

Since then it has been one thing after another. We doggedly fixed them all:
-winter time slide outs by inexperienced 16 year old driver took out front bumper, fog light, headlight and front fender. Found local place that ordered aftermarket parts and painted for us and we did remove/replace. Replaced headlight from junkyard.
-noise at the front end (oh no, not the dreaded water pump!! but water pump/fan tight) Lucky, it was only the idler pulley and an easy first mechanic job for my teen-age aspiring mechanic.
-manifold developed exhaust leak, my son learned how to change this (even how to extract snapped off manifold bolts)
-soon after engine coolant temp light came on. Can't get to the sensor as it is buried under manifold shields, evap system. Son got to take this all back off and then couldn't get wrench on the sensor. He hacked a open ended wrench in half with grinder and got through that one. Put new EGR valve/body on
-Cold start exhaust fan on bottom side failed. Lines full of water (from bad valve on EGR). Installed used fan, replaced relay, checked wires, replaced EGR valve. Engine light fixed
-Needed brakes and rotors all the way around (expected)
-inner tie rod, upper ball joints (had shop do this). Dust boots are missing on lower ball joint, future project. Alignment done (of course my son had to take out the front wheel well protection so his bigger tires will fit...) Did I mention wheel spacers?
-fix loose exterior door handle (bracket rusted). Trim around inside door handles needed replacing (they keep popping off as fast as we replace them) Inside door handle from replacement driver door was chrome, rest are not so put a matching chrome inside handle on passenger side. Son learned how to get doors apart and back together several times...
-This winter, in a blizzard, driving in heavy snow, in 4HI front wheels locked (yep, forgot to check fluid in front differential and gears went dry/welded to intermediate shaft) Shop could not get CV axle out despite cutting it in half. Second shop struggled but got did get carrier/activator out. Activator cracked, was able to put junkyard carrier/activator in, plus while they were there put in new CV axles both sides up front.

This forum has been so great in helping research all of this. I had a huge problem finding correct seals for the carrier. The names for 'inner/outer' are confusing and the parts stores online do not always specify. When I get time I'm going to start a thread with pictures and proper part numbers. NAPA just got a new line of seals (FAG brand) and they now should be able to get the seals you need if you know what you are asking for. stay tuned...

-Engine started running funny and stalling as if not getting enough juice or battery dead. Alternator tests showed overcharging. Battery tested good. Was able to put in a new alternator and that problem solved.

by this time hoping we have all the bugs out and we can get some reliable driving. Keep remembering all the people who said these engines are bullet proof and go 200,000+. Used trailblazers commonly selling with 180K miles or higher... Come on, come on!!

-Son decided to do a little off roading and hit a puddle. Engine died. He was a ways from home, didn't want to admit he may have wrecked his car. Him and buddies opened air system, dried things out. Got it to turn over slightly and then got it to run. Pretty loud knocking at first. Oh no... Engine light on. Knocking fades a bit, no loss of oil pressure or power. Was able to drive home.

changed oil, no water or shavings. Engine code was misfire cylinder 4 and multiple random misfire. Cleared codes, they did not come back. Knock is more of a metallic clatter, follows rpm exactly (slow at idle going up and down exactly with rpms) No change in character of sound with engine load or not. Present equally with cold or hot engine. Does not get louder or softer with different rpms, just slower and faster matching slow/fast rpms.

Listened to lots of similar clatter on youtube and can rule out water pump/loose fan, anything attached to the front belt. Sound is louder behind passenger wheel, but heard also in front and behind driver wheel. Clearer from bottom of engine not top. Closest sound on youtube is a spun bearing. I can't find a recording of a trailblazer with wrist pin clatter on youtube.

This youtube is the closest sound (sharp metallic click click) I'll try to embed this youtube link next:

oops, first time posters can't share links. I'll do it in my next post :)

I'm new and can't figure out how to attach a mp3 file of the sound recorded through my cell phone.

Question Time:
If this is spun bearing does a puddle with water intake through wheel well into air intake set up for wrecking the bearing? Does wrist pin or bent connecting rod or piston slap sound similar to spun bearing?
My son can't afford to pay a shop to tear it all down to prove which item is making the noise and it sounds like all the bad piston/rod/connector/bearing related clatters are going to lead to a engine overhaul or a donor engine going in. I think either of these are off the table as it will be a big bill, more than car is worth. I'd love to see him learn how to do a motor transplant but he doesn't have tools or experience yet.

Yet, he has put so much into it, new rims and tires, etc etc. Do we sell as is for a big loss, try to part it out (to give more experience in disassembly and teach him not to abuse his car if he can't afford to fix it?)

My only hope is rarely someone has found a clatter is flywheel noise or bent or broken flexplate which isn't as disastrous or expensive to fix. Can I diagnose that myself or tranny has to be loosened?

Sorry for the lengthy post, it has been 9 months of constant learning and battling to try to keep this rig going.

He says, I should have got an old rusty truck, at least all of this would not have gone wrong and the repairs would not be so unsual (who ever heard of the intermediate shaft going THROUGH the oil pan???) He has a point...

:(
 

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Discussion Starter #3
Yikes, I forgot one dilemma. After shop did the front differential job, they sent it back to me with 'service stabilitrack' light on and check engine code for ABS and pointed to passenger wheel sensor. They offered to put new passenger wheel sensor in for us but no fix. Did my own testing and hub noise/grinding on one side. Son and I tackled new hubs in our garage. Lots of interesting lessons there. One is that the mechanic shop in putting in the new CV axles decided to use one of the factory CV axle nuts and one of the aftermarket CV axle nuts. One is a 35mm and one is a 36mm!! My late night parts run for the 35mm socket still was stymied when it only fit on one side! live and learn... But joy!! new hubs solved the ABS light and service stabilitrack issue gone. (hubs grinding pretty good on one side so clearly it was time)

Tonight after that project one caliper is sticking so he is out there taking that back off and reassembly, relubing, getting that problem fixed. Will it never end???
 

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2008 gmc envoy_sle
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sorry to hear about the trouble your having.

I have a 2008 as well. been a bit better than your experience, knock on wood. should remind you to check and replace, transfer case fluid and rear diff fluid as well. not to mention the trans fluid check.

does it get better? good question. no real answer,.as they age these vehicles are and can be money pits.
 

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Discussion Starter #5
Thanks princej! I did check and top off rear diff fluid. Trans fluid checked and fine. Need to check transfer case fluid, but for now, not sure if any preventive maintenance makes sense if I can't drive it.
Anyone know what would be typical for lifespan of car if driving with a spun bearing on one cylinder?
 

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you need to know for sure where the noise is coming from. not sure how easy it would be to spin a bearing on these trucks, there relatively tough and have a good solid reputation.

maybe, listen under truck with mechanic stethoscope. dont run it very long.

fixing the bearing can be a diy job, just removing the oil pan is a nightmare ive been told.

what exactly was your son doing when this happened.
 

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Discussion Starter #7
Son was driving into a puddle that didn't look very deep. Water splashed into grill and into air intake and engine died. We can presume water got in a cylinder or that a cylinder tried to compress water. Knocking was significantly louder and associated with clatter/vibration at first when car first began running again. Initially starter acted like it could not turn over (electrical failure? connection? was engine really hydrolocked? I'm told starter isn't strong enough to bend any piston connecting parts). It eventually started turning over and ran but with a terrible clatter.

Over time knock actually got softer and the next day it settled down to where it is now. Oil change didn't change anything, oil looked good.

Is there a link to share an audio file so you can hear it?

It does sound most like spun bearing comparing it to the youtube link above.

My problem is that we won't know till we pay someone to tear off the bottom half of the engine. And, by that time, how do I find a shop that is comfortable rebuilding the cam, cylinder components, bearing etc depending on what they find? I imagine only a few really are good at it. Most are probably more used to swapping engines into it. I'm not sure how to find a 'junk yard' engine and procuring it. Does the junk yard take the engine out for you is that my job?
 

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Have appt with a engine rebuild shop tomorrow. They said if water caused the issue then it would more likely be bent rod not spun bearing. They said rarely you get lucky and after hitting a puddle you get a warped manifold (not sure how that gives knocking?) I'm wondering if it could be flexplate too.
 

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Engine shop was not particularly worried, which I found strange. They did say these 4.2 straight 6 are a beast to work on. Perhaps they had plenty of work and didn't care so much about my particular situation. They expected to hear a loud rod knock but standing outside the engine it was less noticeable. I would say over the last 2 days progressively it is getting a little quieter.. How can that be? Only thing I did was to change oil and added a little oil and gas additive (mystery oil) based on recommendation on this forum.

I do have a consistent misfire code on cylinder 6 (back one). Last night I swapped coils and misfire did not follow. We put new plugs in about 4 weeks ago and I pulled plug #6 and inspected, it was very clean, gap was correct.

Engine shop did not test drive or do any tests. They revved engine to hear that the noise was consistent and followed rpms without changing character with rpms or after letoff of the revs of the engine. They recommended I go home and do a compression test. They suspected it still could be a valve noise or lifter noise or similar damage in cylinder #6 after a presumed slug of water came into cylinder 6. If water comes in the intake does it tend to take out a certain cylinder before the others? I would think all of the cylinders would get wet at once.

What compression should I look for and I assume there is a range that I will find to be 'normal' on cylinders 1-5?

If it ends up being a top end noise we may actually switch gears and try to pay someone to diagnose and fix. Engine is 140,000 miles, tranny seems to shift smoothly, fluid clean/red, I haven't dropped tranny pan to inspect health of transmission but that would be another thing to consider as it is the next big ticket item that could deep-6 this car.

Thanks to all for your help
 

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you need to identify the source of the noise, listen under truck with mechanic stethoscope.

see for sure if its from top or bottom.

did you drive it to the engine shop? compression test would be a good test to do.
 

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Discussion Starter #11
Yes, drives smoothly idles well. When I clear engine code for #6 misfire it right away scans that the same code is there as a pending code even though by the time I got home the engine light stayed off. About 15 miles, some highway.

Low compression on 6 means leak where? Ways to test?
 

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I dont believe if it was a spun bearing, you will be able to drive it especially that distance.
compression test will tell you where prob is. worst case you might need to pull the head. but hopefully not.
 

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Going thru all the same stuff, been driving Chevy's all my life this one cured me of it though as much as I love this truck I hate it and would never ever recommend one to anybody else,problem is I'm so far into it that I got to drive it till the wheels fall off to even come close I could have bought a brand new car and made the payment and pay less and I've paid on this car and parts & labor in The last 5 years. Then when I talk to my friends that work for Chevy in Detroit on the assembly line tell me they would never buy one I should have talked to them first, live and learn I got $14,500 into a truck that's worth about 3 Grand ,seventeen thousand miles on the "second" brand new motor, 160k on truck '07 ls 4.2.
 

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Back to the OP, I'm guessing that you have been likely all over the front end to notice, but just in case. Any apparent damage to the oilpan? If I remember right, the interior of the pan has a baffle or two that may have hit the crank, and now has beat almost enough clearance out of the baffle to not make as much noise. If that is a possibility, then so could be the oil pickup tube. Won't help you with the code on #6, but that could be two separate issues cause by the same off-road "test." ?
 

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Discussion Starter #16
Posting an update. For DDS-029, we can certainly dive under there and see if there is damage to the oil pan. Here is what we have done since my last posting.

We changed oil, added mysteryl oil additive and later a little bit of transmission fluid to oil based on advice of a local engine rebuild shop. Strangely the knocking keeps getting quieter. I would say over the past week it is stable (no better, no worse). My wife can't hear it standing next to the car, but with higher RPMs I can clearly hear the repetitive tick tick tick. The truck continues to run good, idle smooth, smooth acceleration.

We troubleshooted all the packs and spark plugs. I moved spark plug 6 to 2 and inspected #6 for any cracks or carbon tracking. It looked as if the metal bar that goes over the electrode (where the spark jumps to) was bent just slightly over to one side, it wasn't perfectly over the electrode, but when we moved that spark plug to #2 the misfire still happened on #6. Moved plug packs around, no change.

The car will drive around for a day or so after I turn off the engine light and will have a 'pending' misfire code for cylinder #6, but then eventually the actual code will activate and the light will come back on. There are no other codes related to fuel issues.

My son did finally get a compression tester and did compression test. We may have done something wrong as the numbers do not make sense. I was told standard compression is 190. He did cylinder #2 and got 150. He did cylinder #6 and got 120. He could only do so many tests and the battery died so he quit. We bought a good tester that threads into the spark plug hole.

I guess if #6 is low on compression that that tells us the miss may be from ring on outside of piston not sealing (would a spun bearing give low compression or any of the rod connectors or sleeve pin?), or possibly a stuck open fuel or exhaust valve on the top side?

If we tore down and opened the valve cover would we be able to see the stuck open valve and if so can it be replaced from the top side?

Since it is running smoothly we haven't put as much time and energy into it lately. Would love to have that light off someday though in case we decide to sell it.

My son was unloading some pallets and one tipped and fell right into his driver's window and smashed it. He then learned a lot about how to get a replacement window out of a junk yard car (Dad, you can do anything with a prybar...) and then figured out how to get window trim and side mirror off and installed the replacement ($20 plus $2 to get in)

Next project is to give him experience dropping tranny pan, cleaning it, inspecting fluid, replacing filter and not get a bath while doing it. I'm thinking we may try this one out in the woods to save the mess from hitting the garage or driveway.
 

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sounds like your making a bit of progress.

the low compression on #6 suggests possibly a valve problem. taking off the valve cover is quite a task (good writeups on this site) , but it would be the next logical step to take.

too bad about the window, but junkyard $20 is not too bad.

keep us informed.
 

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Discussion Starter #18
The TB gave up and died this week. The engine ran great, idled, great, and provided a few weeks of good transportation. My son started actually taking some pride in ownership and installed an amp and a subwoofer and put new body clips in his loose driver door to replace the broken ones. He even modified his exhaust to give it a more aggressive tone...

One day car was cold, he jumped in and revved a few times to hear the growl of the muffler-less TB and took off. Less than a 1/4 mile down the road he heard a loud mechanical bang from the engine and instant grinding in the engine and low oil pressure light came on. He lost power and heard loud knocking. He turned around and limped it home watching a big trail of oil appear behind him. He hardly made it up the slight grade of our driveway and shut it down with billows of steam coming out from under the engine.

We assume the first knock was a wrist pin or rod or spun bearing. This time he probably had catastrophic failure of the bearing or piston rod and probably has a hole in the oil pan or block wall somewhere? The steam is likely coolant passages that were breached? Oil is all over the lower half of the frame and both wheel wells.. Strangely from mid engine to the top it is clean and dry. I can't seem to spot the breach, maybe hidden between oil pain and engine? Pulled dipstick and it is dry.

For a low dollar TB we can't afford to put in a crate engine. The part that hurts is all his money went into this thing and now he gets to learn that having fun, offroading, going through a puddle, revving, it comes at a price. It makes me sick that we just got all the wear parts fixed (ball joint, tie rods, new rims and tires, new brakes and rotors all the way around, new CV axles and installing a new/used front differential. We got all the engine lights off that related to traction control and ABS and also fixed the codes related to the waterlogged air pump/EGR system. Wiper pumps replaced so that is all working and several body panels painted and replaced, new front lights and new LED bulbs, 140,000 miles and the truck should have had 100,000 miles left in it...

Now what? I guess could sell for a parts truck, or try to part it out? My son thinks he may try to find another trailblazer and can at least reuse his rims and tires and I guess if he had desire he could take brakes and rotors and CV axles off and put them on the new TB?

Thanks to all for their help. I guess we knew with the prior knocking that we were on borrowed time....
 

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So, it is still setting in the driveway... What to do. Can someone tell me the possible pros and cons of finding someone to put a new motor in? I'm aware that you can buy a 'crate motor' but does this mean all the accessories, wiring harnesses, hoses, belts etc are stripped off? If I get a motor from a local junkyard is that worse or better? What year trailblazer or envoy can I get a donor motor from if my truck is a 2008? Finally, there are local back yard mechanics who will offer to take my old one out and put a new one in but I'm worried about their experience and ability to do it correctly. A engine shop is quoting north of $1500 for labor and then it appears that a crate motor with similar miles to what we have now (about 140k-145k) is another $1400 to $1500. Hard pressed to decide if that is worth it or not. Anyone have advice? Do we give up since we don't know for sure conditon of tranny either or do you put a used tranny in at the same time the engine is out because you are that far already?

Hoping someone has been through this already with their 16 y.o. and can advise...
 
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