My sons and I are considering the possibility of repairing our 1994 GMC Sierra Truck ourselves. The timing chain needs to be changed, but when I took it to the mechanic they suggested another new engine. It received a new engine in 2004. I think it also has a valve issue. I am wondering how difficult this project may be? Do you have to remove the engine entirely to change it, or can it be done while still in tact? I am really interested keeping the truck for my sons to use, but not sure it's worth installing a new engine. I thought the added benefit would be the experience of fixing it themselves and doing a project together with mom. Any advice?
-
Welcome to The Truck Stop! We see you haven't REGISTERED yet.
Your truck knowledge is missing!
- Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
- We have tons of knowledge here for your diesel truck!
- Post your own topics and reply to existing threads to help others out!
- NO ADS! The site is fully functional and ad free!
Problems registering? Click here to contact us!
Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!
1994 GMC Sierra Truck
- Thread starter namaari
- Start date
Let's start from the beginning.
Why, as in what symptoms is it giving you, does the chain need to be replaced? If the chain broke you have bent some valves and pushrods and maybe even a rod. The job is easy, but, you need to be sure it is needed.
New engine in 2004 is nearly 10 years old and how many miles on it?
What condition is the truck in and how many miles? Extended cab? 4x4?
The McDonald's 350, like a billion made, is near bulletproof. The Bic Mac 454 is also really rugged. They are cheap in junkyards and a CL search will give you many options for one.
Why, as in what symptoms is it giving you, does the chain need to be replaced? If the chain broke you have bent some valves and pushrods and maybe even a rod. The job is easy, but, you need to be sure it is needed.
New engine in 2004 is nearly 10 years old and how many miles on it?
What condition is the truck in and how many miles? Extended cab? 4x4?
The McDonald's 350, like a billion made, is near bulletproof. The Bic Mac 454 is also really rugged. They are cheap in junkyards and a CL search will give you many options for one.
I first noticed a problem that seemed like the truck was sort of needing a tune-up. I thought maybe one of the spark plugs needed replacing, or a that I needed a new wire or something. Then, while driving with that problem, I noticed something suddenly happen while we were out one day...like a slight knocking noise and it also started running even rougher. I took it to our regular mechanic, and he told me that he thought there was a valve issue, but that the timing chain was also bad. He didn't want to fix it (the timing chain) though, because of the age of the truck and also because he was concerned about more issues once he got into it...he suggested replacing the engine entirely, if I could, but then he didn't strongly recommend even that. I don't think he felt like it was worth it overall. The body is in good condition and the interior. It's an extended cab 4X4 with a 4.3 liter 6cyl engine. It has a nice camper shell as well. The new engine probably has about 125,000 miles on it. It was running when I parked it, but then when I went to take it in it didn't want to start. The mechanic was able to get it running, but he had to tow it back to me...so running, but not really drivable?
btfarm
America First!
Looks to be in pretty fair shape body-wise. Heck, you can pick up a Goodwrench replacement motor for about the same as building one yourself and it'll have a warranty.
Welcome to The Truck Stop! :welcome2: You should fill out your signature with all the info about your truck so everyone doesn't have to guess.
Go to forum actions above and edit profile and the edit sig function will be on the left.
Welcome to The Truck Stop! :welcome2: You should fill out your signature with all the info about your truck so everyone doesn't have to guess.
Go to forum actions above and edit profile and the edit sig function will be on the left.
The 1994 V-6 engines weren't bad, but, I would drop in a V-8 and get rid of the miss on #7 and #8. :hihi: only if it needs an engine.
The 1994's have an electronic EGR and they like to randomly stick open.
I had a GM reman engine that had a loose rocker bolt under warranty. I fixed the tic-tic-tic myself.
Timing chain slop will show up on a scope by the spark lines jumping around if you snap the throttle open/closed.
I would start with a compression test. This will verify valves and check spark plug condition for a dead hole. Check the distributor for slinging oil, bad cap/rotor, etc.
Any codes in the computer?
I forget the exact injection system 1994 had on the v-6. Some of that era were known to pop the regulator and leak fuel into the intake resulting is rough running.
The 1994's have an electronic EGR and they like to randomly stick open.
I had a GM reman engine that had a loose rocker bolt under warranty. I fixed the tic-tic-tic myself.
Timing chain slop will show up on a scope by the spark lines jumping around if you snap the throttle open/closed.
I would start with a compression test. This will verify valves and check spark plug condition for a dead hole. Check the distributor for slinging oil, bad cap/rotor, etc.
Any codes in the computer?
I forget the exact injection system 1994 had on the v-6. Some of that era were known to pop the regulator and leak fuel into the intake resulting is rough running.
Thanks for the kind welcome, btfarm. WarWagon, thanks for your response. I'd like to ask another question. The electronic EGR, if it sticks open sometimes, would it cause it to idle slow, or even want to seem like it may die? I remember thinking that the fuel pump was a going out at one time, because it seemed to want to die when I would slow down at times. Unfortunately, this truck has been sitting a while now, and I am remembering more as I go along, but in all honesty it has always had more of a rough sounding run to me, and with the V6 I never felt we had quite enough pull, though it does better on gas...I bought the truck new. I didn't have any lights on that I can remember...I wish I had paid more attention at the time. You've given me some things to check into, though. I am going to try to see what I can look into over the weekend. Thanks to you both for your input! AND, if I do go with a new engine, I'll check into that GoodWrench, Mike...oh, and a V8 to cut down on those misfires! :thankyou2:
A pic of the top of your engine will help us know what we are dealing with. Again the advice here is looking at all things without weight to what the mechanic said.
EGR is gas that won't burn and will 'lean' out the engine to the point of misfire or stalling. Just like a big vacuum leak. You should check your hoses as well including pinching off the brake booster line only while parked to check for vacuum leaks.
The EGR will open off idle in gear. If it sticks open the engine can stall returning to idle. It can even run rough in gear with the throttle on if it opens too much.
Check and see if you have the vacuum operated EGR or the electronic one. The electronic one will have a coil the size of your hand. You can move the electronic pintle by hand pushing it open with a screwdriver. Any roughness or binding and it is toast. Vacuum EGR failure can flop open with vacuum applied rather than moving biased on exhaust pressure.
Any coolant or oil use?
A compression test with the injectors unplugged is a fun activity with your son(s). This will verify good valves and give you a direction as to if the mechanic was going in the proper direction. If you don't want to work on something and he didn't say it needs lots of $$ work... (Stupid IMO as this is the simplest and easiest vehicle in the world to work on with lots of room to get to nuts and bolts.)
EGR is gas that won't burn and will 'lean' out the engine to the point of misfire or stalling. Just like a big vacuum leak. You should check your hoses as well including pinching off the brake booster line only while parked to check for vacuum leaks.
The EGR will open off idle in gear. If it sticks open the engine can stall returning to idle. It can even run rough in gear with the throttle on if it opens too much.
Check and see if you have the vacuum operated EGR or the electronic one. The electronic one will have a coil the size of your hand. You can move the electronic pintle by hand pushing it open with a screwdriver. Any roughness or binding and it is toast. Vacuum EGR failure can flop open with vacuum applied rather than moving biased on exhaust pressure.
Any coolant or oil use?
A compression test with the injectors unplugged is a fun activity with your son(s). This will verify good valves and give you a direction as to if the mechanic was going in the proper direction. If you don't want to work on something and he didn't say it needs lots of $$ work... (Stupid IMO as this is the simplest and easiest vehicle in the world to work on with lots of room to get to nuts and bolts.)
DieselSlug
Well-Known Member
Wow, i cant believe a mechanic told you just to replace the whole engine! That's crazy, whats the point of troubleshooting!? An addition to the fuel regulator i had a 95' with the 6 cylinder that came in running rough and oil smelling like gas. Ended up being the regulator sending fuel into the intake.
That compression test will show you that the engine has the ability to run right and make power.
That compression test will show you that the engine has the ability to run right and make power.
Looks like a nice truck, I'd fix it. Like WW said keep an eye on Craigslist or ebay....ect you might find a great deal on another engine for less time/money than tring to fix original.
Welcome.
Welcome.