My wife has a 05 trailblazer with the 4.2L in it. truck has been great to us up until lately. It started with running rough and quitting at idle when the a/c was on. Once I found this site and moved from the other one to this one I found some great info on what was causing my issues. I cleaned the throttle valve and replaced the plugs and drained the water from around the plug under the drip edge which I think was number 4 or 5. after that it ran a lot better and the check engine light was off. during the summer when we were pulling our 25 foot camper we noticed that it was running hotter then i thought it should, once we got home i checked it over and found that the fan was not working. After trying to find an aftermarket fan hub (i think that is what it called its what we call it on heavy trucks that i'm a licensed mechanic for) i was told it was a dealer item only and dealer want $500 and a week to get it. i haven`t got one yet i just keep an eye on the temp and don't pull the camper anymore. it worked good all winter and didn't have any issues other then the air pump system throwing a check engine light. that was until last week when it died on my wife when she was coming home from town. she called me and said it was running like crap and the "engine down" light was on. i took my matco reader and went to see if i could get it home. i found that the "engine down" light was the derate light and that there was a code for throttle problems. i wrote down the codes and cleared them and truck fired up and was able to limp it home. once home i started to see if i could get it repaired. I have codes P0128, P0410, P0442, P0068, P0014, P0017, and P0106. I figured a good place to start would be with the cam timing issue. I found on here how to get to the cpas and what to look for.being a mechanic it was no problem for me to get it pulled and that's when things went really bad. it had all the screens but was full of metal filings. i took an oil sample and did a oil flush and change. the engine ran better but the tick that i had can not be heard better and is a rod knock for sure. this is where i really need some help. what do i do from here. i dont want to put a pile of money into it if its just going to throw a rod and leave me on the side of the road (i wont let the wife drive it now as i would rather be stranded then her be stranded with the kids). I have heard that to pull the engine and rebuild it the body needs to come off and the front axle come out with the engine. i have no problem rebuilding the engine but pulling the body is to much for a drive way job and i don't like paying someone to do something i could do myself. is the engine worth rebuilding and does it have to come out that way? oh i almost forgot the truck has 225000km on it and is rust free. also does anyone know what the cost to rebuild one of these engine would cost for parts only, not worried about labor cost as mine is free if the wife is happy.
Death of the 4.2L
- Thread starter towdriver
- Start date
gmcman
Member
- Dec 12, 2011
- 4,681
I surely wouldn't be looking at a rebuild, what you are likely dealing with are common issues and happen to every vehicle. Are these codes fresh or have been stored for quite sometime?
Did you perform a TB relearn after the cleaning?
I would check the TB and perform a relearn which includes removing the battery cable which should clear out the old codes and see which ones come back. Do you have a scan tool?
Have you ever changed the plugs?
The noise could most likely be the water pump. Sound like you have some good DIY symptoms and we will surely help you along. If you are remotely mechanically inclined you will be fine.
Did you perform a TB relearn after the cleaning?
I would check the TB and perform a relearn which includes removing the battery cable which should clear out the old codes and see which ones come back. Do you have a scan tool?
Have you ever changed the plugs?
The noise could most likely be the water pump. Sound like you have some good DIY symptoms and we will surely help you along. If you are remotely mechanically inclined you will be fine.
Yes I did a relearn after cleaning. I also changed the plugs when I did the throttle cleaning and relearn. I believe it was MAY03LT's steps and video that I followed. From what I can tell with my scanner all the codes were active and not stored codes. It's not the best scanner but I mainly bought it to take with me on trips so that I could fix the vehicle on the side of the road or know what was wrong. So far it has worked well for me but I can see and upgrade in the near future. The knock is there even with the belt off and gets worse as engine speed increases. The filings I got out of the class and filter lead me to believe it is a rod bearing gone bad. I should have the oil sample back either today or Monday and will see what it says. The knock sound very much like the knock I have heard in transport engines that had bad rod bearings before I rebuilt them. As for my mechanical ability I'm a licensed truck and coach mechanic for 12 years now and worked in the trade for 15 years. I spent 10 years building the ford 7.3L diesel engines so I have a good idea of what to do but have never built a gas engine before. I found tons of good info on this site and figured it would be the best place for help with a gas job. Thanks
Take a deep breath and dive in. I'm sure you are pretty confident that it's a bearing. The engine is going to have to come out and be rebuilt or replaced. It's not that bad of a job. I just replaced my engine (03 Envoy)and the body does not have to come off the frame. I did remove the grille and upper tie-bar. I also removed the front suspension (shock/springs) in addition to the axle shafts which must come out anyway. With the springs out I was able to remove the motor mount brackets. This allowed me to lower the engine to rest on the crossmember. I was then able to get to the two top bell housing bolts from above.
The front diff comes out with the engine. The splined disconnect can stay on as well, just be careful when removing the engine. I elected to reinstall the disconnect after the engine was back in. There is plenty of room to do so. My original engine suffered catastrophic failure. It dropped a valve and destroyed the head and cylinder. Not sure why because I bought it blown up so I had to buy an engine. I found a used complete engine with 54k for $750. There are a ton of 4.2s out there and depending on what you find internally it may be the way to go. Good Luck!
The front diff comes out with the engine. The splined disconnect can stay on as well, just be careful when removing the engine. I elected to reinstall the disconnect after the engine was back in. There is plenty of room to do so. My original engine suffered catastrophic failure. It dropped a valve and destroyed the head and cylinder. Not sure why because I bought it blown up so I had to buy an engine. I found a used complete engine with 54k for $750. There are a ton of 4.2s out there and depending on what you find internally it may be the way to go. Good Luck!
gmcman said:
I definitely AGREE. It seems we are getting more reports lately of people with bad water pumps. The pump going bad definitely sounds like bad bearings in a sense. Very deceptive sound. It's the type of sound that could make you throw your hands in the air, yell wtf, and want to get rid of the truck. Many here have been there. Don't give up.
gmcman said:
Yep, and a lot of us ARE mechanically inclined. But this vehicle along with other vehicles have their own quirks/noises/smell, etc... Definitely don't make the mistake of rebuilding or replacing the engine unless you absolutely have too. Just don't want to see you wasting your time unnecessarily.
The knock is always there and gets worse when the rpm increases even with the belt off. I have had another mechanic listen to it and he also thinks it's a rod. I'm looking for a used engine or another truck cheap at this point and may end up building this one into a sleeper like my wife has always wanted.
Well I have been told that all the problems I'm having are coming dirty fuel filter and injectors. My father in-law who has sold lumber all his life and doesn't even know what fuel to put in his new truck he just bought (he put gas in his diesel) has told my wife that that's all it needs and is going to get them changed for her. I guess my mechanical ability and scan tool were all wrong. Thanks for the info everyone gave me it helped me to pin point the problem and I know what to do once the rod goes out through the block.
No he bought a brand new 2013 3/4ton diesel Chevy pickup to pull his camper. He drove off the lot and went to fill up the truck and filled it with gas.
No he drove it home and when it was running like crap he had it towed back to the dealer and that' when they found the gas in it
Voymom
Member
- Feb 3, 2012
- 2,523
With the over heating...did you happen to check or change the thermostat? It is a common failure for our vehicles, a long with the water pump as said above. It could also be the fan clutch which is also a common failure, but those would be my 3 guesses, or at least the 3 things I would get at to see if it helps.
Yes that is the overheating problem. I know it needs both a thermostat and fan clutch. With the engine running and hot you can reachin and hold the fan. I now told that that is caused by a dirty fuel filter according to my father in-law.
sorry I didn't explain right. when I was able to grab the fan the engine was hotter then normal with I figured should have the fan engaged. when I was able to hold it I let the truck go into a overheat condition and was still able to stop the fan by hand. that make me figure that clutch was no good. I also figured I would change the thermostat and temp sensor while I was at it. that was till I found out the fan clutch was $500 and no aftermarket available.
As for the father in-law's truck they made him pay for everything as he was the one that ordered it in diesel then filled it with gas.
As for the father in-law's truck they made him pay for everything as he was the one that ordered it in diesel then filled it with gas.
Who said aftermarket parts are not available? Check out rockauto.com, or parts4chevys.com. I recently replaced my fan clutch for $160. If it was the stealership that said "aftermarket parts aren't available" turn and run.
I went to th aftermarket stores around me and they all told me dealer item only. That's when I went to the stealershhip but there is no way I'm paying that much. Thanks for the info
Try elsewhere, besides the dealer, I've seen fan clutches for $231 AcDelco on Amazon.com
Good luck.
Carlos
Good luck.
Carlos
triz
Member
- Apr 22, 2013
- 746
If your looking for a fan clutch here you go. Its the exact OEM replacement for our trucks. Its also made right here in the US. I did mine not too long ago and when I pulled the old one and compared it to the new one it was the exact one. The price has gone up some. I paid $149 for mine but still a bargain at $184.00
Hayden, Inc. 3200 Thermal Fan Clutch : Amazon.com : Automotive
If you plan on doing the thermostat the Dexcool coolant works great and can be had for about 12 dollars a gallon at Walmart or Advance Auto. If you do any type of towing I recommend adding some of the coolant boost.
AMSOIL Dominator® Coolant Boost
I also recommend you check your water pump since the fan clutch threads into that. I ended up replacing mine when I did the fan clutch. It was leaking coolant. I have one available NEW not reman that Napa replaced for me. I can ship that out to you for 35 if your interested in it.
Hayden, Inc. 3200 Thermal Fan Clutch : Amazon.com : Automotive
If you plan on doing the thermostat the Dexcool coolant works great and can be had for about 12 dollars a gallon at Walmart or Advance Auto. If you do any type of towing I recommend adding some of the coolant boost.
AMSOIL Dominator® Coolant Boost
I also recommend you check your water pump since the fan clutch threads into that. I ended up replacing mine when I did the fan clutch. It was leaking coolant. I have one available NEW not reman that Napa replaced for me. I can ship that out to you for 35 if your interested in it.
Voymom
Member
- Feb 3, 2012
- 2,523
towdriver said:
The fan has nothing to do with the fuel filter....
I don't want to insult or be rude, but I wouldn't be taking advice from this person....you may end up in a heap more of sh*t than you're already in.
I would start with the easy/cheapest and go from there...Also Rockauto has some decent prices on fan clutches. I would do the thermostat, temperature sensor. If the fuel filter is original...I'd change it, since it is considered regular maintenance and it's a cheap and easy fix...if it is external from the fuel tank.
Can you get a video or audio clip of the knock??
Oh not to worry I'm not taking his advice, now if I could convince the wife of the same we could get this trailblazer fixed and back on the road.
As for the fuel filter,that's the part that had me laughing the most as gm hasn't used external fuel filters since 03 or 04. They figure they arent needed and the screen in the fuel tank is good enough.
A lot of the reason I say that it's a rod bearing and I can't remember if I said this before or not but when I had the cpas out it was full of metal filings. Once I find out for sure if it is or isn't a rod then the next steps will be either looking for a used engine to build or putting a fan clutch, water pump, thermostat, temp sensor and fixing air pump system. I have considered getting rid of the air pump but understand the ECM needs reprogrammed after doing this and don't have a programmer to do that yet.
As for the fuel filter,that's the part that had me laughing the most as gm hasn't used external fuel filters since 03 or 04. They figure they arent needed and the screen in the fuel tank is good enough.
A lot of the reason I say that it's a rod bearing and I can't remember if I said this before or not but when I had the cpas out it was full of metal filings. Once I find out for sure if it is or isn't a rod then the next steps will be either looking for a used engine to build or putting a fan clutch, water pump, thermostat, temp sensor and fixing air pump system. I have considered getting rid of the air pump but understand the ECM needs reprogrammed after doing this and don't have a programmer to do that yet.
Okay so here is an update. While I was at work my father in-law took the trailblazer into Canadian tire to have it fixed. They replaced the cpas and told the wife it was good to go. She picked it up and told me the check engine light was on. I scanned it and all the same codes were there. Truck still ran like crap and has a knock. I open the hood to see if they really changed the cpas and found they did but also didn't put the air filter cover back on. I called Canadian tire and they said it was never there and not their problem. I have a audio file of the knock but can't upload it. It is recorded with a blackberry phone, any ideas how I would attach it here so everyone can hear it.
Okay I now have the audio clip in both blackberry and mp3 formats but still can't load it.
If I was going to replace the engine what years would be a direct bolt in? I'm looking at buying a salvage trailblazer and shaping the engine and another good parts and also have spare parts if ever needed.
If I was going to replace the engine what years would be a direct bolt in? I'm looking at buying a salvage trailblazer and shaping the engine and another good parts and also have spare parts if ever needed.
Mooseman
Moderator
Going through Car-Part.com--Used Auto Parts Market, seems only 2005 is the same but that can be deceiving as their interchange looks for exact matches even though there might have been only a minor difference. For example, my '02 has an oil level sensor but '03 and up didn't so they didn't give those as a match but that is what I wound up getting and just swapping the oil pan. Maybe someone more knowledgeable can chime in as to what years will fit but there are a few in Ontario according to them ranging in price from $700 in Pembroke to $1100 in North Bay and $1800 in London. At least if you do get a used engine you'll know where to look (CPAS) for any metal or damage without taking it apart.
yeah I wasn't able to find many in Ontario but there are quite a few in the states and a fair number just across the border. I found a site while looking for salvage trailblazers on google that has then all over north American. I don't mine going to the states to get one and have a guy near me that will get me across without any issues as he does it all the time.