Need advice from experience for an M42 rebuild

[jaredmac11]

Shouldnt the chain be replaced at this stage or is the chain an unnecessary replacement?

[roguetoaster]

Since your head is coming off, no need to worry about cam TDC being kept after you take the cam gears off, but you do want to keep bottom end TDC (which I see you did not mention) set if possible. Remember, you set TDC on the bottom end and use the top end to verify that you are at TDC1, not 180 out.

From experience, don't bother wiring the gears to the chain, rather prevent the chain from moving where you can't easily access it (it can bunch if allowed to go slack). You can do this by gathering the chain and zip tying it away from your work area without letting the bottom move. Be certain to note the position of the dowel pins on the gears (only where the cam sensor matters) are when removed. A good approach there is to mark the cam gear to cam interface with a scribe tool or anything sharp (always use separate and unique marks where precision is desired).

Tying the chain to the gears is also fine, but they just get in the way more than needed.

Edit:

To remove the cams/buckets just carefully and evenly loosen the fasteners. When reinstalling you will have more difficulty as the cam will probably not sit flat, but just use some pressure and go slowly. Or if you are really nervous your machine shop can reinstall the cams in the worked over head.

[JonsE30]

i found a local shop and getting the replacement head resurfaced and valvetrain inspected since it came with valves and springs already installed. i am going to start with the teardown but i had a question regarding the camshafts.

i would need to remove the camshafts off my cyclinder head to transfer to the new head once it comes back from the machine shop right?

is there a proper way of doing this? i saw a youtube video by M3NACE but i think he was doing a 6 cyl S52 head. is it the same process for an M42?

do i have to worry about setting to TDC if i am going to remove it and transfer to new head anyways?

does this change the process of removing the timing components?

i was going to follow the steps set forth in the posts above in sequence:

- remove radiator/shroud/fan+clutch
- drive belts
- intake manifold
- coil packs/plug wires
- valve cover
- exhaust manifold
- set cams to TDC 1
- remove upper timing case/thermostat
- remove all cooling lines to head
- remove chain tensioner
- mark and wire cam sprockets and chain together
- remove head bolts

[JonsE30]

I received a replacement head for a reasonable price off a forum member here. I need to look for a machine shop to resurface the head.


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[DevilDog]

At the rapid easily available rate of an m42 used engine it is definitely not worth to rebuild an engine with so many miles especially not to have just buy another used engine bro

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[roguetoaster]

Toby probably had to remove the AC bracket in order to remove the crank sensor wire.

[slowmoe30]

Nope. Just take the belts off. The only pulley to remove is water pump.

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[TobyB]

You should be able to leave the A/C system pressurized. You might (I forget why I had to)
have to unbolt it from the block but that's not too hard...

t

[jaredmac11]

I would just say get in there and remove what makes your life easier. You certainly dont have to strip down the whole engine.. Anything you remove, save the bolt and whatever else in a baggy, label it, and keep them together.

Helps to take pics before, during, after disassembly to make reassembly easier.

[JonsE30]

When prepping to swap the head, it was mentioned to remove belt and pulleys. Does this mean to remove the alternator and power steering pump? Do I need to touch the a/c compressor and tensioner pulley other than remove its drive belt?


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[TobyB]

Brutal around here. You can find an M50 (with car attached) for not more than that.

As to your milkshake, don't worry about that yet.

When it's all back together, bring it up to temp, do all the things you should do hot,
then drain and refill the oil, and a new filter. You'll be fine with that.

hth

t

[JonsE30]

awesome, thanks for the quick responses. this is helping me a lot. still trying to source an m42 head locally, before hitting up roguemaster for his stock m42 head.

i was browsing craigslist and also came across an m50 (no trans) engine for around 1k. is that expensive?

[bmwman91]

Don't worry too much about getting things perfectly clean prior to disassembly. You can flush the cooling system with hose water, and for the oil passages, run some cheap oil + a detergent additive like Rislone for a few minutes once it is all back together. Drain it, put in good oil and you are set.

[jaredmac11]

If youre taking your head in to get inspected, they will likely include a wash with that so I wouldnt worry about it. As for the block, I'll wait for someone wiser than me, but I imagine it shouldnt be a significant concern.

[JonsE30]

From an environmental perspective alone, DEFINITELY drain all the fluids. From an ease of cleanup you should do it as well. Ill never forget when I had my M42 on the engine stand and turned it upside down and lost another quart of fluid.

I had about 6 bags of kitty litter in my garage for that project...

no doubt, but what i meant was since i have the coolant/oil/mixture already in the head/block, do i need to run a few oil changes (i can just use cheap oil), just to get all that gunk out? when i look under the cap, theres still light colored oil in the grooves which makes me think there's gotta be more throughout the head and block.

or is that unnecessary at this point and just start to take the head off since i already drained the oil? then do the oil flush cycle when i replace the head with a good one?