Thread: Help rear head gasket swap

HEY EVERONE,I HAVE A 98 3.8 AND DO ANYBODY HAVE A GOOD POST ON A REAR HEAD SWAP?
I THINK I BENT A PUSHROD BECAUSE I HEAR IT KNOCKING. THANKS

So how do you know its the rear head?

And why would you need to swap heads if you bent a pushrod?

Amazingly enough, the post RIGHT above yours in the same section you posted in has instructions for a head gasket job.

http://www.grandprixforums.net/f17/t...lots-7763.html

Originally Posted by beastin1
THIS WAS WRITTEN AND POSTED BY A BUDDY OF MINE ON MY OTHER SITE, FIGURED IT FIT IN WELL SO I'M POSTING IT HERE...HOPE IT HELPS...
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This manual should give someone a good idea on how to successfully do a top end swap on any 3800 Series II powered vehicle! (Buick/Chevy/Pontiac/etc)

***This swap intended for a swap retaining the L36 Harmonic Balancer. Although you can change it out, I did not. You cannot run anything smaller than a 3.25 SS pulley with the stock GT balancer***

**Basic hand tools and a torque wrench will be required for this swap. Alot of mechanical knowledge is not needed, but it sure does help. If yuo need any torque specs, let me know in this thread.**

1 - You will want to plan at least a 3 day weekend to do the swap. So make space in your garage/cover/etc. DO NOT CHANGE OIL BEFORE SWAP! You will be out the cost of a new oil change in the end if you do.

2 - Pull the fuel pump relay fuse, and start the car. It will die, releasing all fuel in the system for fuel rail removal. Start the car again to remove any more fuel. Disconnect the negative battery terminal and position it so it doesn't come in contact with the battery. Reinstall the fuel pump relay fuse.

3 - Using a 15 MM socket on the idler pulley, remove the accessory belt. Place aside.

4 - Jack up the car and place jack stands underneath the car then remove your downpipe, there are two bolts that are corroded and need to be broken loose. WD40 or a torch will break the bolts loose. They will probably break, but its okay, old rocker arm bolts can be used here. Disconnect the Oxygen Sensor harness.

5 - Go ahead and drain all of your coolant, I found that pulling off the lower radiator hose is easiest. Then lower the car and remove the jackstands. More coolant will pour out, so do not remove whatever you are using to catch the coolant.

6 - Fuel removal is the next step. Disconnect the fuel line and fuel return. Gas will come out of these, so have a catch can or rag ready. Disconnect each fuel injector harness, and label them if you would like. Remove the vacuum line going to the fuel pressure regulator. The rail is held down to the LIM on 4 studs. Remove these nuts. The fuel rail should now lift out of the engine. Be careful, gasoline will still come out of the rail. Handle with extreme care.

7 - Remove your existing air intake system, and the IAT sensor. Then, remove the brake booster hose that goes to the master cylinder. Disconnect the throttle cables and cruise cables, then disconnect the MAP, MAF, IAC, and TPS sensors and label them if you would like. Remove the support bracket on the throttle body and bend it out (not going to be used again.) Remove the throttle cable bracket and save it. We need to now remove the Upper intake manifold.

8 - There are many bolts holding the UIM do the LIM. Be careful when removing, and use a cross pattern for removal to reduce stress on both the UI and LI manifolds. The intake manifold can now be removed. Expect coolant to flow out of the throttle body. Set aside.

9 - Remove the alternator. Pull the positive supply and sensor plug from the alternator. Set aside. We can now access the heater core lines. Remove the core lines. Coolant will spill. Then remove the bracket, the core will hang from the plastic coolant elbows and will probably break, but if your careful, you can salvage it and save you a trip to the store for a new one. If it does break, try your closest GM dealership or a new one. Coolant will flow from the lower intake manifold. Place the bracket aside for now.

10 - We can now continue on to the removal of the LIM. Remove the EGR flex tube from the LIM. Remove the upper radiator hose from the thermostat housing, catching any coolant that flows. Now carefully, remove all the studs holding the LIM to the block, and once again, remove in a cross pattern to reduce stress on the block. Some of the bolts will be covered in sludge and hard to see, but they are there, hidden. Grab the thermostat housing and lift up, this may take some force to break the LIM free from the block. Hold the LIM level to avoid spilling coolant down inside the engine. Place aside.

11 - Removal of the exhaust manifolds is next. Remove all plug wires and set aside, label them if they are not already. Remove the left dogbone motor mount and ignition coil bracket and coil control module. We need to remove the rear manifold first, so that we can keep the front right dogbone motor mount in place for maximum clearance. Remove the rear valve cover and set aside. Disconnect the Oxygen Sensor plug from the rear manifold and remove the EGR tube from the manifold as well. Remove the crossover pipe from the rear manifold as well. These bolts will require heat/oil to get loose, but will probably break in the long run. Old rocker arm bolts work well here. Remove all manifold studs at this time. Lifting the rear manifold out is a pain, so take your time and think it out. I found it best to bend the transmission dipstick tube out of the way a bit. Now, remove the upper right dogbone motor mount to remove the front manifold. Remove all studs and disconnect the front manifold from the crossover pipe. These bolts will more than likely break, but that's okay, old rocker arms bolts can be used here as well. Remove both the front exhaust manifold and the crossover pipe. You can either choose to keep the old metal gaskets or use new ones. Either way, both can be used or reused.

12 - We need to remove the rocker arm's from the head assemblies. They are held down via rocker arm bolts. Remove these bolts and each rocker arm should lift out with ease. Remove the corresponding pushrod to each rocker arm and make sure to label them. Check the picture below for an idea on organizing the assemblies. Once all rocker arms are removed and labeled, the rocker arm pedestal can now be removed as well. Place aside. We now have access to all the head bolts on both heads.



13 - Now for the removal of the heads! There is one stud on each head blocking one head bolt. Remove this stud. We can now access all head bolts. Each head has 8 bolts, remove them in the same order as the tightening sequence. These heads are VERY heavy and filled with coolant, so handle with extreme care. If you are unable to lift the head out and have access to an engine hoist, don't be afraid to use it. The rear head is a real pain! Place these heads aside and discard the old gaskets as they will never be used again. Soak up any coolant that entered the combustion chamber of the engine.

14 - The swap is basically half way done, now a lot of prep work is necessary. Clean the heads however you would like, but the heads have to be in near perfect condition before reinstalling them. The heads should almost have a mirror like image to them. I found that using brake cleaner and a free hand razor blade is perfect for this. Just be EXTRA CAREFUL if you decide to use a razor on the heads, as one small scratch in the heads can and most likely will cause a head gasket leak. If you have another cleaning method, use it. Heads must be oil free before re installation. Use soap and water after the initial cleaning and dry with compressed air or a lint free cloth. I assure you, the more time you spend cleaning the heads, the better chance you have of not having a head gasket leak, which would be a very bad deal.

15 - Just like previously, we need to clean and prep the block as best as possible. Once again, near perfection. I cannot stress enough the importance of clean mating surfaces!

16 - *Prior to the rear head installation, you might want to position your rear manifold/header in place so it is alot easier to install. Just place it in the rear of the engine bay, I found this easy.*

Go ahead and place your head gaskets on the block to ensure the right gasket, and a good fit. The arrow on the gasket should face the front of the motor, or towards, lets say, the alternator. Remove the gaskets and spray them both, on both sides of the gasket with copper spray, but do not spray too much or the spray will run and drip. We cannot install head gaskets that have sealant dripping on them. CAREFULLY, place the gaskets on the engine block, with the arrow facing the correct way. Now, go ahead and place one L67 head at a time on the block. If you place the head on the gasket and remove any spray, you MUST remove the gasket and respray it. This is very important, we do not want any head gasket leaks on first startup! Once you have both heads in place, go ahead and place in your new head bolts. You should coat all bolts with a decent amount of APR bolt lube from hear on out. The 4 short bolts go into the intake side (top) of the head and the 4 longer bolts go into the exhaust side (bottom) on the head. Tighten down to these specs and in this sequence.

Cylinder Head Bolts - 50 N-m + 120° | or | 37 lb ft + 120°

===Intake===
5 1 3 6 <---Shorter Bolts
7 4 2 8 <---Longer Bolts
===Exhaust===



17 - Double check everything once that is done. This step is one of the most vital of the entire swap. Once you are confident you did everything correctly, go ahead and position your old/new rocker arm pedestals onto the heads, your old/new pushrods into the motor and your old/new rocker arms onto the heads. You should be using new rocker arm bolts, as the old ones cannot be used.

Torque to: 11 lb ft + 90° going from the inside towards the outside, every other bolt. In other words, just don't torque two bolts that are next to each other one after another.



18 - Put some new spark plugs into the new heads. I recommend AL103's or AL104's, as they are cheap and help prevent knock. Gap around .052-.055'. Reinstall the EGR bracket and valve onto the rear head at this time.

19 - Reinstall both exhaust manifolds/headers at this time now. Do the rear manifold first. Torque down to specs and make sure to reinstall the studs you had to take out to access the head bolts. Re-attatch the Oxygen sensor to the rear manifold, and connect the crossover pipe to the rear manifold at this time. Position and tighten down the front manifold to the head and the crossover pipe. Torque everything down to specs at this time. Old rocker arm bolts can now be used for the crossover pipe.

20 - Install your new coil bracket to the front head using the old studs. Go ahead and put on the Ignition module, the extra idler and S/C belt tensioner. Install the ICM ground as well. Tighten everything down. Now, we can move on to installing the new LIM.

21 - Prep the surface of the new LIM just as you would with the heads. Remove any build up on the surface, as well as the intake side. DO NOT forget to clean the intake side, it is easy to skip! Place your new LIM gasket onto the engine, use RTV anywhere you'd like to seal good. I found that placing a bit in each corner where the LIM gasket meets the lower block gaskets is useful and will help prevent boost/vacuum leaks. Now put your new LIM into place and torque to specs and using the proper sequence.



22 - Go ahead and position your valve covers on at this time.

Torque to: 89 in lbs.



23 - Attach the EGR flex tube to the LIM. Now is the time to put in a thermostat. A 160* or a 180* is great here, up to you though. Knock will be against you after this swap, so choose carefully. Install the thermostat, gaskets and re-attach the upper radiator hose.

23 - We can now start to put together the "boost half" of the engine. Go ahead and attach your old/new L67 or aftermarket (with adapters) throttle body to the supercharger. A new gasket should be used here, rubber preferably.

*If you are doing an intercooled top swap, now would be the time to install the core*

24 - Prep the bottom of the supercharger like you did the heads, and the LIM, near perfection. Clean up the LIM one last time before laying down new gaskets. Now, put new coolant O-Rings and the new S/C gasket onto the LIM. Place carefully. Use copper spray if you would like. Place the supercharger down carefully onto the new S/C gasket. You should use new supercharger bolts at this point. Torque to specs and sequence. Be very cautious here, I could not get my blower to torque properly without the blower binding for a while. After you torque each bolt, spin the blower to ensure a free spin, and no binding. After all the bolts are torqued and the blower is bind-free, you have torqued it properly and can move on.



25 - Put new coolant elbows back on the water pump and the LIM without breaking them, it is a bit tricky. Slide the heater core elbow back into the plastic coolant elbows.

26 - Reinstall your alternator. Connect the sensor plug and the power source wire.

27 -Put on the extra idler pulley and mount.

28 -Place your new L67/new aftermarket injectors into the heads with new o-rings. Gas leaks can occur due to a cracked o-ring. Place your new L67/new aftermarket fuel rail onto the injectors. Transfer the injector clips from the old rail onto the new one. Tighten down the rail to the 4 studs coming out of the LIM. Attach the fuel line and fuel return to the new rail. Re-attach all the injector harness plugs onto the marked injector.

29 - Install the throttle cable bracket and throttle body and cruise lines onto the throttle body. We can now install the air intake system. This should be a cold air intake system, to help reduce knock. You can reinstall the factory system, but a CAI setup is ideal. At this time, attach the MAF, IAT, IAC and TPS sensors.

30 - Run a vacuum line to the fuel pressure regulator and the MAP. The fuel pressure regulator needs to see boost in order to operate correctly. Go ahead and attach the Boost Bypass Valve to the supercharger. It's held on with a bracket and two bolts. Run a vac line from the tree on the supercharger to the top nipple on the BBV. The bottom one needs to see ATMOSPHERE, because our L36 PCM's cannot control the BBV.

31 - We can now put the exhaust back on. First, connect the HVAC, EVAP and Brake booster vacuum lines. For the exhaust, a 3 inch downpipe should be used to get the most out of your swap. You will need a new gasket for the manifold-downpipe and then downpipe - resonator. Transfer your oxygen sensor and hook it up to the harness.

32 - Go ahead and fill up the car with coolant. Reconnect the lower radiator hose. 50/50 coolant/water mix is fine. Once all the coolant is bled, put coolant in the overflow tank.

33 - Now is the post swap oil change to get rid of any coolant that may have spilled into the motor. Pretty straight forward.

34 - Go ahead and put on an SS pulley from ZZP of your choice, according to mods you have now. I would start off with a large pulley so the motor can get used to boost. Then put on the accessory belt.

35 - Fill the supercharger snout with specific GM supercharger, ZZP (etc.) oil.

36 - Reconnect the negative cable back onto the battery and double check you put in the fuel pump relay fuse into the fusebox panel.

Look over everything once again, making sure everything is connected properly. Now, start the car. It should run rough while the PCM is learning the new swap. Add coolant as needed and bleed the system. Drive the car carefully for the first 300-400 miles.

Enjoy your new swap and feel free to show it off!




Author - Marc M. Chandler
Published - Marc M. Chandler (Sept. 11th, 2008)
Copyright - All Rights Reserved

Now if you read all that... technically thats for a top swap, but you'd just have to reverse the first half of the instructions to reinstall.

THANKS BUDDY

NOOOOOOOOOOO problem.

Also note I take zero responsibility for you blowing your engine up.

Hey everone I started back working on my GP, and i just took off the rear head.Which was a pain in my hands. I looked at the block and I see 3 pistons the one on the left was down,one in the middle was up,and the right one was down.Is that how it supposed to be? Also how can I test the block to see if it turns? what should i do?

you could use the starter but disable spark and fuel

or get a ratchet and a 15/16's socket and have fun.

And yes, they're all supposed to be at different positions.

I'm kinda amazed you took your head off when you didn't know that.

So how can i tell my heads are bad or not i see nothing bent or anything? Do also need new rocker arm bolts?

Yeah new rocker arm bolts or order the reusable ones from the vendors.

its a dollar more for reusable ones.

Best bet is to have a machine shop look at the head.

Also, its possible its the bottom end thats knocking, not the valvetrain....