Changing GM 2.9L Timing Chain and Guides
I took on the task of changing the timing chain, guides, tensioner, and sprockets on a 4 cylinder 2.9L GM engine that comes equipped in GMC Canyon, Chevrolet Colorado, Hummer, Isuzu Ascender, andChevrolet Envoy. It was no easy feat, but there wasn't really anything difficult about changing the timing chain. Really, the only problem was how the engine was engineered - it took an excessive amount of time to remove all the components in the way of accessing the timing chain.
Since Chevy or GMC products are not my bread and butter, I took to the internet to find a detailed guide on replacing the timing components. I didn't find much in my search except basic instructions, so I decided to write a detailed how to guide on changing the timing chain on your Chevy Colorado or GMC Canyon specifically, although the guide will work for other makes and models.
Repairing this stuff can get really expensive, but I can help. Get an easy $100 bonus if you apply for a Discover Credit Card. Even bad credit can get easy approval, but you could also try Capital One if your credit is a bit shakey.
Normally here at Expertswrite, I write articles focused primarily on Ford products because of my job at a Ford dealership. I rarely get the opportunity to work on any other brands of vehicles as I do not generally work on the trade in cars. I came across working on this GMC Canyon because my brother owns it. The local shop wanted, what I thought, was an excessive amount of money so I set out to to replace timing chain, guides, and tensioner on his 2.9L engine in my personal garage to save him a lot of cash. If you want to hear more about the story on my brothers truck or see a video of my thoughts on this project, you can read about it in TechTales :GM 2.9L Engine Crazyness.
There is mentions of specialty tools to time this 2.9L engine in the shop manual, but these tools are not required. The way this timing is done on this engine you actually can do it without any specialty timing tools by following this article. This guide was written by memory of working on a 2010 GMC Canyon 4wd, so likely pictures won't be added in later unless I find appropriate pictures I'm allowed to load elsewhere. The Chevrolet Colorado model may be slightly different, also other years may be different. The 5 cylinder 3.7L and older 2.8L are very similar
A few things you are going to need. Most of the required hand tools are listed in that step of the directions. Here is a small parts list below:
Lets get your truck back on the road...
##Disassemble Timing Chain on 2.9L GM" class="system-pagebreak" alt="Disassembly" />
- Drain the coolant by removing the bottom radiator hose. Drain the oil.
- Remove the air filter housing and duct.
- Loosen 2 bolts, then remove intake sound canceling chamber and duct on throttle body by loosening clamp.
- Unplug, loosen 4 bolts and remove throttle body.
- Loosen bolt and remove map sensor from top of intake manifold, or unplug.
- Unplug all coil packs, unplug other sensors on top near valve cover while following the harness.
- Loosen and unscrew the fan using the fan clutch removal kit with an air hammer. Left is loosen.
- Remove clamp and pull off top radiator hose.
- Pop open the plastic line attachment on the drivers side holding the ac line.
- Remove the fan shround and fan together.
- Remove the belt, then remove the tensioner.
- Remove the waterpump pulley, then remove the waterpump itself.
- Remove the crankshaft pullery with the harmonic balancer removal tool.
- Jack up the vehicle, support on jack stands located on the frame, and remove both front wheels.
- Remove drivers side inner wheel well – a bunch of plastic push pins. Pull out center of pin to release. Fight and wiggle it out of there.
- Loosen bolts to alternator. 2 are accessible at the top, one is accessible through wheel well. You can disconnect and remove the alternator, or pull it out of the way.
- With a long extension, impact, and swivel sockets, by going through the wheel well remove a metal cover on the intake manifold. A few wires are attached to it.
- Up top, remove the bracket that attaches the dipstick tube to the intake manifold.
- Then with the same extension, impact, and swivel sockets, remove all the bolts to the intake manifold. The bolts are in the following pattern from front to back.. 1, 2, 1, 2, 1. Be sure to get them all.
- Pull the intake manifold back far enough to get to the valve cover bolt taht it was hiding. Loosen all bolts and remove valve cover.
- 4WD ONLY STEP!! Quick overview only, do on both front wheels – Remove brake caliper bracket bolts, set caliper aside. Loosen tie rod bolt, remove tie rod. Remove the axle nut. Remove the wheel speed sensor. Loosen upper ball joint nut, loosen lower ball joint nut, then smack knuckle downwards to free of joints, then set knuckle aside.
- 4WD ONLY STEP!! Remove both front axles by prying the axle away from the differential. Remove front driveshat caps, set driveshaft to the side. Unplug the axle lockout. Slide a jack under the differential. Remove the 4 bolts holding the differential to the frame. Set aside the differential.
- Locate steering rack attachment bolts. Two large ones on the left, two bolts and a strap on the right. Loosen and remove bolts. Let rack hang.
- Remove the oil pan. 3 bolts in the front. Several bolts going down the sides. 4 bolts that hold the pan to the transmission. 2 bolts revealed by removing the rubber torque converter housing access plug. Using two oil pan bolts, insert bolts into the provided threaded parts of the pan to "push" it away from the block. These threaded holes are located near the rear of the pan.
- Remove the oil pickup tube. Save the gasket.
- Loosen the bolts to the AC compressor through wheel well. It is important to note that the bottom right bolt can not be accessed with the steering rack installed. You can completely remove the bolts, or loosen until almost out. Slide the compressor away from the block.
- Remove the front cover. Several bolts around the outside of the cover, a few bolts near the center above the crankshaft. Will be hard to pry off.
- Now turn the engine until the timing marks on the camshafts are as follows... the exhaust cam (passenger side) will be on at the 11 o'clock position, the intake camshaft will be at the 1 o'clock postion.
- Loosen the intake camshaft sprocket bolt.
- Remove the two bolts and tensioner assembly.
- Remove the driverside guide bottom bolt.
- Remove the two plugs on the front of the cylinder head, which exposes the single bolt on each side holding the top of the guide. Remove both guides.
- Remove the intake camshaft sprocket.
- On my project, I could not remove the exhaust cam sprocket. We took the camshaft out entirely by loosening the cam cap bolts slowly, starting in the middle and working toward the outside. The cam caps are marked, but note exact location and direcetion. It MUST be reassembled in the same fashion.
- Lift the camshaft up, then remove the chain.
Reassemble Timing Chain on 2.9L GM
Before reassembly, you must clean all parts to be reused thoroughly. All gasket areas need to be properly cleaned. Do not use a die grinder and a abrasive disc. We call them cookies. Instead, use plastic scrappers and utility knife blades. The gasket surfaces on the block are easily cleaned with the blade. Remember to clean underneath where the oil pan mounts to.
The front cover and oil pan is not so easily cleaned. These should really be put into a parts washing system after gasket material is removed. To remove gasket material, start with the razer blade working your way around. There is a little channel, or groove, that gets filled in with gasket maker that needs to be cleaned out. Take the plastic scrapper and remove all residue.
Retiming the engine is rather easy. The chain is marked with multiple black links. Start your reassembly by putting reassembly lube on the camshaft bearing surfaces and roller rockers. Set your chain onto the removed cam, lining up a black link with the timing mark. Allow the chain slack to flow down toward the crankshaft as you align the camshaft back into it's place. Be sure the chain is wrapped around the cam gear – as once the cam is in place, the chain doesn't have enough room to be put on the gear. Find manufacture specs and sequence and tighten the camshaft caps. Rotate the camshaft so that the timing mark is again in the 11 o'clock positon.
Install the driver's side timing guide. Tighten both bolts at this time. It's imperative that this guide be put in first since it curves over the water pump housing.
Lay the new camshaft sprocket for the intake camshaft into place, while working the chain around it. Keep the chain tight in it's span between camshaft gears, then set the black link aligned on the timing mark located on the sprocket. Hand tighten the camshaft bolt at this time.
Pull the chain tight against the drivers side timing guide. Orientate the crankshaft sprocket to align with the keyway. Keeping the drivers side of the chain pulled tight, align the mark on the crankshaft sprocket with the black link closest to the mark and slide it into place. It should be right on - leaving little to no slack between the drivers side guide and the crankshaft sprocket.
While holding the chain from moving, install the tensioner side timing guide and insert the top bolt to hold it into place, tighten at this time. Install the tensioner. A new tensioner is collapsed shut and held that way. It should install easily without much of a fight. Once the tensioner is in place, there should be NO slack between the cam gears, both cam marks should still be at 11 o'clock and 1 o'clock, and there should be LITTLE TO NO slack between the crankshaft sprocket and the drivers side timing guide. All marks should be aligned with a black link. If everything is as that, you are good to pull the grenade pin (timing lock) on the tensioner by going below and using a pair of pliers to remove the plastic wedge. Finally, tighten the intake camshaft sprocket to manufacture specs.
You can now turn the engine over by hand. Do at least 360 degrees. Notice the timing marks no longer line up, should be one tooth off. This is normal.
After all parts are cleaned like mentioned above, lay yourself a good bead of quality RTV gasket maker around the front cover gasket. The bead doesn't need to be too thick – usually a 1/4 to 3/8 bead is plenty. To much RTV will get smooshed inwards into the engine and will eventually break away and get into the oil system, usually causing engine failure.
You should be following the groove with the RTV. Be sure to do around the water pump housing as well. Remember to replace the oil pump pressure outlet O-ring seal. The bead of RTV goes on the inside edge of any bolt holes. It would be wise to also do a small amount around the holes in the center of the cover to prevent oil bleed out of those bolt holes. Alternatively, you can place a small amount of RTV on those bolt threads near the head of the bolt while installing those.
Once the front cover is installed and tightened down, you can now install your pickup tube and gasket. Lay a similar bead of RTV as noted above for the oil pan, and then install the oil pan into place. Tighten everything down.
The rest of the install process is reverse of removal. Pay attention to the order in which these steps are performed – it is essential they are performed in the same order as was originally described for ease of access. A few extra steps must be performed... remember to add new engine oil, change the oil filter, and fill the cooling system with a vacuum filing device.