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M30B35 Head Gasket DIY for Dummies

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    M30B35 Head Gasket DIY for Dummies

    Faced with the daunting task of replacing your head gasket? Don't want to spend thousands to get it done at a shop? Here is a comprehensive DIY on how to do it yourself! This write-up is meant for the wrencher with little to no experience under the hood. I took pictures of nearly every aspect of the job, no matter how insignificant it may seem.

    *This was done on an e30 with m30b35 swap. The same basic process still applies to any b35 equipped car. Minor differences in grounding points and exhaust may be present.

    Tools Needed:

    The picture above shows my entire tool set. Notice the basic hand tool setup available at any Home Depot or auto parts store. (Not all these tools pictured are required)

    - A metric socket set from 8mm-19mm (mine only came 10-19mm, I had to buy an 8mm socket)
    - reducers (3/4"-1/2", 1/2"-1/4") for sockets
    - open ended wrenches from 8-19mm
    - 36mm socket
    - flat head screw driver )long and short ones come in handy)
    - philips head screw driver (same as above)
    - metric Allen wrench set (either individual or ratchet attachments)
    - adjustable pliers - Channel locks
    - needle nose pliers
    - Breaker bar
    - crescent wrench
    - spark plug removal socket (if not already in the BMW tool kit)
    - plastic lunch baggies
    - marker
    - PB Blaster
    - Head gasket kit

    The Procedure:

    Remove the negative cable of the battery for safety purposes.

    Jack the car up properly.

    Drain the oil. Use an 18mm socket and remove the drain plug on the oil pan.

    Drain the coolant. Use a philips or flat head screw driver to unscrew the drain plug on the bottom right hand side of the radiator. This plug is under the lower radiator hose. Remove the cap on the expansion tank for a quicker drain.

    *Note: After draining the coolant, I removed the radiator due to tight clearances in the e30 engine bay. You may or may not choose to do this.

    Now that the fluids are drained, remove the spark plug wires.

    BMW was kind enough to offer a spark plug removal tool in the "tool kit" under the boot lid.

    Use the tool to remove the spark plugs

    Now it's time to remove the intake. First remove the electronics (wiring).

    This is the oil pressure sensor on the back of the head. Remove the clip.

    Sensor wires are removed, hooray! Time to remove the intake itself. First remove the AFM. There may be 3 clips on the underside of the MAF securing it to the valve cover - remove them. Loosen the hose clamp with a flat head screw driver and pull the AFM towards you.

    This is what you're left with:

    Locate the breather line attached to the PCV hose coming from the valve cover. Find it? Good. Remove the line from the PCV hose.

    Unscrew the hose clamps from the PCV hose and the intake boot.

    Pry out the ICV (black sensor attached to the intake boot on the left) carefully, then remove the intake boot with the PCV hose attached. It may be easier to remove the PCV hose from the boot if it is brittle.
    This is what you are left with:

    I recommend you put all the pieces removed from the car into a bin (or something similar) so you don't end up losing them.

    Lets remove the cap, rotor and distributor. Get out your 10mm socket and 3mm and 6mm allen wrenches.

    There are three 10mm bolts holding the cap on, remove them.

    The rotor is mounted with three 3mm allen head screws. Remove them.

    Now get your 6mm allen and remove the distributor.

    Wiring harness removal

    Remove the Spark generator and crank position sensor wires from the plastic cover near the front of the engine.

    Remove the positive wire at the junction box with a 10mm socket.

    Remove the ground wires on the shock tower with a 10mm socket.

    Remove the wires to the ignition coil. Small = 8mm / large = 10mm

    Carefully pry up on the injector connectors (under the large plastic harness cover) with a flat head screw driver to release them.

    After the first few are released, it's fairly easy to pry the cover up with your hands. Do not force it.

    *Note: I did not have the two mounting bolts holding the cover down. Your engine most likely does. Remove them with a 5mm allen wrench.

    Head on over to the other side of the car. Locate the charcoal canister sensor under the intake manifold - most likely mounted to the intake support bracket. Remove the connector.

    *I know I don't have the intake support bracket. It will not fit with the mounts I am running. You will need to remove the 13mm bolt holding the support bracket to the block. You may choose to remove the entire bracket by removing the two (2) 13mm nuts on the underside of the intake manifold.

    Now remove the wiring on the starter - 8mm, 10mm, and 13mm. This will remove all the wiring to the starter.

    Unhook the 02 sensor connector. This is the small round connector near the starter. Also, twist off the large round connector near the firewall.

    Now pull the harness up and out of the engine bay. This is what you should have.

    Lets remove the belts. I only have the alternator/water pump belt on my engine, but the same procedure applies for the others. Unfortunately I only have pictures of the final product here, but it's a simple task. Grab your 19mm socket and a 13mm open ended wrench. Locate the adjuster on the alternator bracket with the teeth. You will be loosening this bolt. (My adjusters were not working properly, so this is how I did it). Secure the 13mm nut on the backside while loosening the 19mm adjuster on the front. Once it's loose enough, pry the alternator toward the engine as far as possible. Remove the belt.

    If your adjusters are working, use the 19mm adjuster to bring the alternator in. *Tightening the adjuster = loosening the belt tension*

    Now we are going to remove the fuel lines. These are located under the intake manifold. Mark the fuel feed line with tape (the line that shoots to the back of the fuel rail is the feed line). Spray some WD-40 on the lines to loosen them up a bit. Mine were on there pretty good. Be careful pulling them off, you may leave some knuckle skin on the motor mount.

    Remove the break booster vacuum line going to the intake manifold. From the factory, BMW secured this hose with one-time-use clamps. I recommend replacing them with the screw style clamps.

    *Some engines do not come with this. If yours does not, move on.

    Reach your hand under the intake manifold. Remove the two vacuum lines running to the ports closest to the cylinder head.

    *Note: the right vacuum line has been removed in this picture.

    Go back to the passenger side of the car. Loosen the hose clamp on the ICV hose where it meets the intake manifold. Pull this hose off with the ICV.

    Locate the charcoal canister vacuum hose. This routes to the intake manifold right under the ICV hose. Pull it off carefully.
    *Don't mind the injectors in this picture

    There are 3 bolts that hold the fuel rail in place. Remove them with a 10mm socket.

    Now that the bolts are removed, the fuel rail is free. Grasp the rail and wiggle it while pulling up. *Inspect the o-rigs on the injectors*

    Lets move on to the Exhaust. This is where a can of PB Blaster comes in handy. You will be removing the down pipes from the exhaust manifold. I am running b34 manifolds which have three 15mm bolts per side. Spray these bolts and let it sit. B35 manifolds have 2 bolts (I believe are 15mm as well) where the same procedure applies. If you choose not to remove the downpipes, you can remove the manifolds from the head.

    After letting the PB Blaster soak, get your 15mm socket and remove the nuts.

    Here is what you are left with when the down pipes are removed.

    *Note: I removed the left exhaust manifold due to tight clearances in the e30 engine bay.

    If you haven't already, remove the radiator hoses. You will also need to remove the top of the water pump hose.

    I ended up removing the entire thermostat block for easier access. It is not required, but I will show the process.

    Get a 13mm socket and an extension. There are three mounting nuts that you need to remove. Pull the block off of the mounting studs. It may be "stuck" to the head. If this is the case, lightly tap it with a hammer then pull it off and out of the way.

    *Note: you need to remove the thermostat cover if you do not decide to remove the thermostat block.

    Lets move on to the upper timing cover. This is held on by eight (8) 10mm bolts. 6 of them can be removed with a socket. The other two need to be removed by an open end wrench.

    *Take note of where the bolts come from. They are different lengths*

    The throttle and cruise control cable mount needs to be removed. First, pull the throttle back to allow slack in the cables. Squeeze the square connectors and push them through the throttle bracket. Then, remove the two (2) 10mm mounting bolts on the intake manifold. Screw the bolts back into the manifold after removing the bracket so you don't lose them.

    Now it's time to remove the valve cover. I waited this long to remove this so contaminants do not accidentally get in the head. There are 8 nuts and 1 bolt holding the cover on. Remove them with a 10mm socket. Then pull the valve cover up and out of the car.

    Remove the valve cover gasket

    Now you can remove the upper timing cover.

    *the Headgasket kit should come with a new seal for the upper timing cover. Tap the old one out and press the new one in.

    You will need to turn the motor to TDC (Top Dead Center). There is an "O I T" mark on the crank wheel. Turn the motor over by the crank nut 36mm socket until the "O I T" mark lines up with the line on the lower timing cover. Yes that is a 36mm. You will have to go to an auto parts store to get one.

    Now that the timing is set, you need to secure the chain to the cam sprocket. This keeps the timing in line while the head is off. Take a few zip-ties ad feed them through the holes in the inside of the cam sprocket. Tighten them around the chain so it's secured.

    There are 4 bolts holding the cam sprocket on. Remove them with a 10mm socket.

    Carefully pry the sprocket off with a flat head screw driver and your hands.

    Time to remove the head bolts! Get out your breaker bar and a 19mm socket.

    Loosen and remove the bolts. The order you remove them does not matter.

    Up till now, you have been doing all the work yourself. Now is the time to grab a friend to help you remove the head. It's a good 75 or so pounds and is a bit tricky removing by yourself.

    WARNING: have a large catch pan under the car for this process. When the head is pulled up coolant will come pouring out. This is all the coolant that was left in the block that could not be drained through the radiator.

    Set it down out of the way.

    Here is what you are left with!

    It may take some light scraping to remove the head gasket from your block. Try to avoid scratching the surface too bad.

    While the head is off, check to make sure it is not warped. If it is, take it to a machine shop and have it straightened.

    This would be a good time to paint your valve cover and intake manifold if you choose. I decided to take advantage of this and painted the god awful color scheme to a more subtle one.

    Now, place your new head gasket onto the block. Grab your partner and carefully mate the head to the block. There are locating plugs in a few bolt holes that help align the head properly. Unfortunately, I do not have any pictures of this, but you will understand once you are at this step.

    Get your NEW set of head bolts and tighten them down in this order*

    Then torque the bolts down in 3 stages. I used the s38 torque specs:

    1st Stage ; 50 Nm = 37 lb-ft

    2nd Stage: 80 Nm = 59 lb-ft

    wait / settling time of at least 15 minutes

    3rd Stage: 100Nm = 74 lb-ft.

    Last edited by yert315; 06-03-2011, 09:04 PM.


      Now you can put everything back together. I will illustrate some areas that may need explaining.

      Upper timing cover gaskets go on one way.

      Now you can put the distributor back on.

      *Note: Don't forget to put the dust shield in before the gear*

      The distributor gear can only go on one way. Line it up with the locating pin and tighten it down.

      I would recommend getting a new cap and rotor since you are there anyway

      To put the injectors back in, line them up with the holes and wiggle the rail down until the mounting holes line up.

      - Refill the oil
      - Refill the coolant

      Bleeding the system:
      1.) Turn the heater inside the car to full HOT (this lets the fluid flow through the heater core).
      2.) Fill the tank slowly
      3.) When the tank looks full, remove the "pisser line" from the radiator side and blew through it until coolant came from the port on the radiator (where you removed the line).
      *Don't let coolant get too low when doing this or you will blow more air into the system
      * reservoir cap is on for the procedure.
      4.) Put the front end on jacks or a steep hill and run the motor. Crack the bleeder screw until the coolant comes out without any bubbles.
      5.) You may need to do this last step a few times as you drive the car. Keep an eye on the temp gauge.

      NOW you are done! and it should look nice and clean:


        This is a great write-up. Wish I had something like this when I did the head gasket on my m10. I vote for sticky.
        85' 318i ~The Bronze Bomber (FrankenM10 with a Forced Future :wgaf:)


          Great writeup! I just did this exact same thing on my m30b35. I would suggest that you add in one step when draining the coolant. Pull the plug on the block near the exhaust manifolds. This will save you from having a coolant mess when you remove the head.


            thanks, will definitely be using this when I o-ring
            '89 335is +turbo


              Wow. Amazing write up. So many good pictures! Probably easier to go by this writeup than the service manual I have.
              89 325i: 86 535i motor+trans, JE forged pistons, MLS head gasket, ARP head studs, Comp turbo, GoodNTight b34 turbo manifold, motor mounts, AKG 75D engine/trans mounts, custom 3" exhaust, intercooler, MS2PNP, Megan Racing Coilovers.


                Good job but was wondering if and where you use RTV or any gasket sealer with or in place of any gaskets?
                Never argue with stupid people, they will drag you down to their level and beat you with experience. -Mark Twain


                  Good job! May also want to add a couple steps to check/replace the front/rear seals (back of the head, and front upper timing cover).
                  Mtech1 v8 build thread -

                  OEM v8 manual chip or dme -


                    Originally posted by Bearmw View Post
                    Good job but was wondering if and where you use RTV or any gasket sealer with or in place of any gaskets?
                    I did not use any RTV or gasket sealer anywhere.

                    Originally posted by Jean View Post
                    Good job! May also want to add a couple steps to check/replace the front/rear seals (back of the head, and front upper timing cover).
                    I would have but I didn't take any pictures of it. I'll update it with that info. Thanks


                      Btw, what was the reason behind this? Was it running hot? Coolant looked clean from the pics....
                      Mtech1 v8 build thread -

                      OEM v8 manual chip or dme -


                        I changed heads 2 times. Each with a different problem.
                        First one snapped a valve in half (no damage other than broken valve).
                        Second one, oil spray bar was clogged/damaged and seized up the cam.
                        Figured I would document it the second time around.
                        Yes, both completely random and uncommon problems.


                          Thanks for the killer write up. I was just starting to break down my m30 last night. Huge help.


                            bump for the people looking for it


                              This is really a great writeup, thank you for putting it together! I'm going to Sticky for anyone who wants to read :)