Duramax Diesel Engine Removal

By Brandon Meyers / BMDMAX

With the diesel drag racing and sled pulling sports experiencing rapid growth, more and more diesel owners are pushing their rigs to the limit.The Duramax certainly is a tough platform but with new tuning and parts like dual CP3 pumps coupled with big turbos creating horsepower figures north of 700, engine failures are becoming commonplace.

Having recently experienced an engine failure of my own, I decided to pull the engine myself and begin the rebuild process to create a race capable engine.This guide, the first in a three part series details the necessary steps to remove the engine.Additional guides will follow for engine disassembly and rebuild as well as the re-install.

We started the process by having Suncoast pull the transmission and place it into storage.You can certainly pull the engine first but we liked having the additional access with it removed and it allowed us access to the flywheel with the engine in the truck rather than attempting to do the removal on the hoist or engine stand.The flywheel bolts are torque to yield and are definitely difficult to remove.You wonít be able to use a cheap flywheel tool and a Ĺ inch drive to break the bolts free.At a minimum you need a Ĺ inch breaker bar with a cheater pipe or a ĺ inch breaker bar.

With the truck up on the ramps you have plenty of clearance to get the job done.A lift would make the process even easier but this guide is geared towards the garage enthusiast where you donít typically have access to a lift.In addition to the breaker bar, we used a propane torch to heat the flywheel bolts.The flywheel bolts need a 14MM hex tool, we used an excellent impact set from Sunex Tools.You can see it attached to the air impact here.


The flywheel bolts are exceptionally tight, we had one person heating while the other applied the breaker bars to get them moving.We snapped a ĺ to Ĺ inch adapter pretty easily before trying the heat application so be careful during this process, busted knuckles can happen at any time.

Once broken free, the impact will remove them with ease.

The flywheel and flexplate is a three piece assembly, with locator pins.

This photo shows the correct orientation and order of assembly for the three pieces.It is practically impossible to hold the flywheel in place without the Kent-Moore flywheel tool for the Duramax.It can be seen bolted in place to the starter location in these photos and was worth the 100 bucks we paid for it.

You can also see the 17 MM flywheel housing bolts that secure the flywheel housing to the engine.This extension has to be removed before mounting the engine to an engine stand.It serves multiple duties including coolant and turbo oil return flows.More on this later.

The rear seal is a two-piece seal that slides directly over the crank and it also requires a special Kent-Moore tool for assembly.The metal side of the seal faces the crank / engine assembly and the foam / plastic side faces the rear of the truck.

The seal has been pulled apart in this photo and you can see damage on the sealing surface.It is unknown if this damage was from the factory, from wear over time or if it occurred during the rear seal failure due to crankcase over pressurization.

After the flywheel was removed we began on the prep work to clear the engine bay connections so we could pull the engine.The GM repair manual has an engine removal procedure that does a good job of stepping you through the process.It is a good idea to have a digital camera handy to snap before and after photos so upon reassembly you have some reference points.We also used baggies with the write on strips to store nuts, bolts, etc. as well as masking tape markers for hoses, lines and electrical connections.The more you can document along the way the easier the reassembly will be.A simple notebook makes a great work log to take notes of what has been done, things to remember upon reassembly and other notes for torque values, things to recheck, etc.

First order of business was to remove the air intake assembly.The MAF connector is pulled here.

Once the air intake tube was out we began the AC system recovery.

While that was in-progress we also opened and drained the coolant from the radiator and surge tank.

While the coolant was draining we removed the wheelhouse liners for access to sides of the engine and plumbing.GM wants you to remove the front wheels, which certainly can be done if you are working on a lift.We needed to keep the truck mobile so the wheels stay on.You still can pretty easily access everything you need with them on.A screwdriver, a cotter pin pull tool, and a push fastener tool all make short work of the pesky liner fasteners.Work the center pin out and then pull the main fastener.

With the wheelhouse panels open you have easy access to the myriad of plumbing on the Duramax.

With the wheelhouses opened up you have fairly easy access to the block coolant plugs.There is a plug for each side, the driverís side plug is towards the front of the block and the passenger side plug is to the rear, behind the starter.The plugs are painted yellow on my block and were easy to locate.

Driver side:

Passenger side:


The block drains pretty quickly once the plugs are removed, when the coolant stops flowing put the plugs back in, make sure to not miss the washers on each one.The plugs do not require sealant and should be torqued to 13 foot-pounds.

With the coolant drained, the surge tank can be removed.The smaller line clamp can be moved but the larger line clamp is integrated into the hose body.The tension can be released and it must be removed with the line.

The surge tank also has an electrical connection for the low coolant sensor, it is on the same harness as the AC pressure cycling switch and the mass airflow sensor.With those connections labeled and disconnected you can move on to the front of the truck to start removing the stack.You can see the harness here as well as the plugged turbo inlet.Capping off lines as you go will help avoid contamination as the removal progresses.With those items out of the way and with the wheelhouse panels removed now is a good idea to remove the CAC pipes as well as any thermocouples you have installed.


The upper stack shroud removes easily one the push fasteners have been pulled.The grill is removed next; it has four turn fasteners and two spring fasteners.With the grill removed you have full access to the cooling stack.

Next we tackled the TCM and upper fan shrouds.The usual 10MM bolts for the TCM and push fasteners for the upper shroud.A small screwdriver pries up the center pin and then the fastener comes out easily with pliers.

With the fasteners and TCM out the upper fan shroud comes out easily exposing the fan assembly.

Make sure to take a few snapshots of the belt routing.A breaker bar on the belt tensioner is all you need to remove the belt.

The fan clutch assembly comes out pretty easily with a strap wrench and a large crescent.GM sells a Kent-Moore tool for this as well.The Kent-Moore tool locks into the holes on the water pump pulley.

Here is a front shot with the fan clutch removed.

Next up is disconnecting the transmission cooler and oil cooler lines.They use a wire snap ring to secure them in place.Slide the shield back, use a small screwdriver or pliers to remove the snap ring and then pull the lines out.Put the snap ring back in place so you donít lose them, the lines just snap back in during reassembly.

Then you can disconnect the upper heater hoses.

Simple hose clamps are all that need to be removed, plus a few tie down bolts on the hard-line portion.When the line is loose, lay it over to the side for engine clearance.GM wants you to pull the heater hoses from the quick disconnects, they are buried far under the firewall and really are not necessary to remove.Just undo the hose clamps on the engine side instead.

You then can move to the interior to disable the SRS system, you donít want an airbag blowing up while working on the front end.Pull the 15 amp SIR fuse in the driver side panel; disconnect the airbag connector on the steering column and behind the glove box.The driver side is easy to find, the connector in the glovebox is a bit more challenging.

The driver side connector:

This is the connection in the glovebox.It is hard to locate behind the dash support metal.It is pulled down here so you can see it:

We then moved to the left and right headlight assemblies.Remove the pins on the main headlights and disconnect the bulbs.The running lights have tabs holding them in their frames.Release the tabs and pull the bulbs.

Be sure to take photos of the wire routing for reassembly.

With the headlights pulled out and the bulbs removed you can then remove the plastic housing for the upper and lower lamp assemblies.These are a mixture of 10 MM bolts and T-25 bolts.The housings also have some push fasteners for the fairing panels around the bumper.They pull out easily for removal.GM recommends you remove the bumper; again this is an unnecessary step provided your engine lift has enough vertical capacity to get the oil pan clear of the bumper.As a side note, there is enough clearance to remove the engine without disturbing any of the wiring harness, the fuse blocks or loosening the fenders.Loosening or removing any of these items like recommended in some write-ups is just an invitation for disaster when attempting a reassembly.

Here are the plastic frames removed.Whenever possible, reinstall the fasteners for the part, that way you know exactly where they go and you donít have to bag them.

Here is the removed frame.

With the headlight assemblies pulled you can begin on the stack removal.The upper bolts for the radiator and CAC are removed.

The upper crossbar bolts are 10MM and have three on each side.

Remove the hood latch, and the crossbar support containing the transmission cooler.I used a Sharpie marker to scribe the hood latch location to make things easier on reinstall.Then remove the AC condenser connections and lift it out.The radiator and CAC come out as one assembly.

AC Condenser line connections:

Radiator and CAC stack:

With the stack out, you have the entire front of the engine exposed:

A view from the side:

There are a myriad of connections to tackle next including wiring harness, fuel lines, fuel filter lines, fuel regulator lines, nitrous lines, power steering pump, FICM connectors, glow plug power, AC compressor lines, power and ground.This series of photos cover that process.Also, with the stack removed and the harmonic balancer exposed we put the flywheel assembly back on the truck, locked it in place and then removed the harmonic balancer bolt.We used the ĺ breaker bar; it takes some muscle to break away the bolt when it is torqued to 273 foot-pounds.You do not want to attempt this on the engine stand if at all possible.Keeping it in the truck is the best bet.

The harmonic balancer bolt is a big one, we used a 36MM socket.

Here the fuel lines are being disconnected from the bypass regulator:

The fuel lines feeding the engine filter are disconnected next.You can see the harness for the MAF and for the coolant bottle sensor in this shot as well.


Here is a shot with the coolant reservoir and air filter housing removed:

Capping off the lines with aluminum foil or line caps as you go prevents contamination.Foil is cheap, easy and abundant:

The driverís side nitrous line is disconnected here as well as the boost tubing that normally resides on the SuperDiesel manifold:

Disconnect the power lead from the alternator as well as the control harness connection.The leads for the AC compressor will be disconnected here as well.Masking tape labels make for easy reassembly.The common harness for the alternator and AC compressor will be removed from the engine, just pull it out lay it to the side by the fuse box area.

Disconnect the bale connectors on the CAN-BUS.If you have ever installed a Juice, this is an easy part.

Disconnect the ground bracket mounted on the engine for the power box and ground tab:

Disconnect the fuel lines located on the driverís side head near the glow plug relay assembly.The Lisle fuel line disconnects work well for this purpose:

There is an oil pressure sending unit that needs to be removed here.Remove the bolt, be mindful of the copper sealing washer.

Remove the nut holding the fuel line bracket in place:

Disconnect the compressor lines and cap off the connections.You can remove the AC compressor and lay it over to the side as well, however this does put a good deal of stress on the lines.I preferred to remove it and recharge the system later so I did not have to worry about line clearance when the engine was coming out.

Here is a shot of the alternator and AC compressor harness mentioned earlier:

Remove the bolts holding the power steering pump in place.With the engine computer removed you have room to wire the power steering pump out of the way:

You can see the main nitrous line disconnected here as well as the heater hose hard line moved over for clearance purposes:

Various connections are documented here, the more photos the better for reassembly:

With the minor connections all removed you will want to begin working on removing the upper major components from the engine.This will expose the front of the cylinder heads which is where you will attach the chain hoist to remove the engine.The AC compressor and second CP3 pump have been removed here.

With those components removed you can begin working on the alternator support bracket containing part of the PCV system and belt tensioner.The alternator does not need to be removed.Disconnect the hose clamp for the PCV line and remove the 15MM bolts holding it in place.

Here is a shot with the Alternator bracket removed, you can clearly see the runners for coolant flow to the heads:

Repeat the process for the AC compressor bracket:

Now the front of the engine is clear for attaching the chain hoist.You can also see in this photo the loose harness wires for the battery crossover and various ground connections.The Duramax has several ground connections on each side that need to be removed as well as ground connection near the glow plug controller on the driverís side head.It runs from the rear of the head to the firewall.

The removed accessories:

Here is a shot with the oil pressure sensor removed:

Each cylinder head has threaded holes for the engine lift tabs.GM recommends their Kent-Moore lift tabs to be attached to the block with a ďsuitable boltĒ, however they donít give you any idea what that bolt might be.While investigating whether or not we had to remove the engine coolant heater as GM recommends, we did remove the passenger side engine mount.Turns out the bolts that mount the engine block to the engine mount were a perfect fit.We used the existing engine lift tab from the factory on the rear of the passenger side head and two holes on the front of the driverís side head.

Raise the hood the service level position for extra clearance on the boom of the engine lift:


Moving the chain hoist into position:

The rear and front chain mounts are made here connected to an engine leveler.While an engine leveler is not required it certainly makes removal and installation easier as you do have to angle the engine to remove it.

Loosen the engine mounts and begin hoisting slowly.You should be able to move the engine around to get it free of the engine mounts while hoisting it up and moving it forward.Go slow, be methodical looking for any missed connections and raise the engine enough to clear the bumper.The oil pan is deep so you will need plenty of lift on the boom.You can remove the wheels if necessary to gain additional clearance.

Once you swing clear of the truck it is a good idea to get some support underneath the engine for good measure.The engine will be on the hoist until the flywheel cover can be removed.The flywheel cover cannot support the weight of the engine on an engine stand.Begin by removing the flywheel cover bolts.


Removing the heat shield and driverís side turbo up-pipe will give you access to the turbo drain nuts and studs.Remove the nuts and then use a reverse torx socket to remove the studs.

Continue the same nut and stud removal process for the oil cooler gallery connection to the flywheel housing.

The turbo up-pipe has been removed:

A good shot of the back of the engine and turbo:

Bag and mark the bolts:

A handy tool for working on the tighter engine spaces are the ratcheting box ends.These are the swiveling Gear-Ratchets and they also have a nifty ratchet conversion kit to make a low profile ratchet for any socket.You can also see the reverse torx socket.You will need these to complete the job and a set can be bought at Sears.

A few shots of the temporary engine support until the upper and lower oil pans can be removed.When the upper and lower pans have been removed use a seal cutter to cut the sealant holding the flywheel cover to the block.At that point you can attach the block to the engine stand.

Here is a good shot of the rear chain hookup:

The end result:


Look for part two of the guide, covering the engine rebuild process to begin soon.We will keep you posted on every step along the way as the build progresses.