How hard is it to remove and replace the head on an m50

[rob101]

Well I hear that replacing the head on a SOHC such as an m20 or m30 isn't that difficult because setting the timing can be fairly straight forward. Now I am thinking of perhaps reconditioning the head on my m50 at some stage. Is it a difficult job and do i need any special tools for setting up the timing.

I do have access to some extremely knowledgeable mechanics through my work as well as their tools so it shouldn't be too intimidating. I've always wanted to get into this stuff and now with the winter approaching here (read it will not be 40 degrees celsius during most of the day at work) might be a good time to do it.

I suppose the part that I am most unsure about is setting the timing for the DOHC after putting the head back on. What techniques are used for this?

[grave77]

do you have the Bentley.5er manual? it has everything in it. they explained everything about setting the timing and removal/installation..etc

Edit: it would take you around 1 - 2 days if you're alone and one whole day if you have a partner with the proper tools. that's if you will remove the whole head system and replace the valve seals.

[Dave M]

Prior to the M50, I had never had the head off of a DOHC engine. I thought it would be a bit tougher than it was. No worries, if you follow the bentley, you'll have no problem.

In terms of tools:

you can either buy a 'cheap' $40 cam alignment tool or just use a straight edge to line things up.

Bentleys mentions a secondary chain guide tool, but two safety pins work plenty fine

In order to remove smaller head bolts from the timing cover area, you'll need to modify a torx socket (grind it down to fit into a deep hole).

Otherwise, nothing to special needed.

The trick (if there is one) is not the cam alignment per say, but setting up the bolts in the cam sprockets. There is quite a bit written on this subject and I know I have a post with plenty of pics out there which details this procedure.

In a nutshell, go for it, you'll enjoy it.

Dave M

[rob101]

Prior to the M50, I had never had the head off of a DOHC engine. I thought it would be a bit tougher than it was. No worries, if you follow the bentley, you'll have no problem.

In terms of tools:

you can either buy a 'cheap' $40 cam alignment tool or just use a straight edge to line things up.

Bentleys mentions a secondary chain guide tool, but two safety pins work plenty fine

In order to remove smaller head bolts from the timing cover area, you'll need to modify a torx socket (grind it down to fit into a deep hole).

Otherwise, nothing to special needed.

The trick (if there is one) is not the cam alignment per say, but setting up the bolts in the cam sprockets. There is quite a bit written on this subject and I know I have a post with plenty of pics out there which details this procedure.

In a nutshell, go for it, you'll enjoy it.

Dave M

thanks, for the record i have a bentley, but things can turn out different than what the bentley says sometimes.

[92E34]

You'll need a cam alignment tool.

It wasn't too bad when I did mine. If I totaled up the total days of work, came to 8 days. And I didnt disconnect the header. Just Lock the Flywheel and the rest is a breeze. As for your cams, make sure that you have the 4 dots on the cams facing up and your at TDC. I made a cam alignment tool with a piece of 1/8 steel plate about 10 inches long and 6 inches high. The cam height is the same as the outer lip of the head. Most things are 10 or 11mm. Make sure you replace your head bolts. And If you can get the Victor Reinz gasket set.

[Anton CH.]

You can always do it the "ghetto" way by using a ruler - worked for me. Set the bottom to TDC using the mark on the wheel on the front of the engine. Set the top by using a straight edge. As you move each cam you will see the angle between the ruler and the cam block dissapear. Just make sure your valves on cylinder one are pointing in the same direction.

[92E34]

I almost forgot. You can make a flywheel lock out of an old 3/8ths drive extention. Put it on the grinder and take about 3/32nds of an inch off the square drive. Or you can use a 5/16ths diameter bolt.

[Wiseguy]

I'd absolutely use the Cam Locks! If the car is a Non-VANOS car, then it is much simpler and easier to do than with a VANOS car. VANOS equipped cars require a few more special tools.. get the VANOS timing wrong and you can damage the engine.

Bill

[Ferret]

Bah the three I've done on non-vanos M50s didnt need more than a straight edged steel ruler and a bit of patience

[Hallmark]

The Bentley is very good for disassembly. Reassembly is a little trickier since they guide you to just after setting the VANOS timing and then give the ol "assembly is the reverse of disassembly".

One thing I did was take digital pictures at every step as I took it all apart so I would have a handy reference on putting it back the way it was. I didn't use any of the special tools and I found that there is a four pack of torx sockets available at Autozone for about $8 that covers everything you'll need for the job.