M42 freshen-up and partial rebuild

[Jaredmac11]

I am performing an update to an m42 from a '95 e36 318i.   I've targeted the following areas for my freshen up/rebuilds.

• Gaskets
• Rubber hoses
• Water Pump
• Thermostat
• Oil pressure relief valve update
• Valve stem seals
• lap valves
• dip piston heads
• timing case rebuild

The one thing Im not 100% sure about is the timing case rebuild.  There is TONS of info out there for e30 M42 timing case rebuilds, but I heard the late M42 (e36) and the M44 had built a stronger timing case.  Does this mean I need new timing guide rails, sprockets and chain?  This is easly $200 worth of parts.. not a ton, but that is like 30% of my parts list price.  Just trying to get my head around the update and if its necessary to rebuild this

Here is what my sprockets look like:
http://imgur.com/a/ScpDH

I found this post by changing up my search a bit:

I'm the one who originally asked the question via PM.

All M42 use the same oil pump. The M44 uses a larger capacity oil pump.

Cross referencing the early M42, late M42, and M44, there are differences between them all:

• early M42 and late M42 share same cam sprockets (1121124733811311721887); M44 uses different ones (11361247951)
• early M42 and late M42 share same slide guide between the sprockets (11311721641); M44 uses a different one (11311743046)
• late M42 and M44 (11311743262) have a different chain tensioner guide than the early M42 (11311727342)
• late M42 and M44 (11311734694) have a different chain guide below the crank sprocket than the early M42 (11311721419)
• late M42 and M44 (11311739130) utilize a guide in place of the deflection wheel/gear found on the early M42 (11311727569)
• M44 uses higher capacity oil pump (it's thicker) than early and late M42
• the M44 uses a different crank position sensor than the early and late M42. The mount location is also different. Looking at pictures, M42 chain cases have a mount for the M42 sensor, however the M44 don't. Does anyone with a very early M44 have this mount?

Given I have to replace the chain case, I'm going to get a late M42 style at a minimum to get rid of the deflection wheel. However, if it's not too much hassle, I would love to use the M44 and get the larger oil pump.

Chain case part numbers:
early M42: 11141727191
late M42: 11141739699
M44: 11141739800


Here is a picture of the mount (where 11 fits into 1):


What can I do to use the M44 chain case?

[1998ccc]

 How many miles do you have on your engine?  As good as your sprockets look, you may be ok for a while with just a tensioner.    ECS sells a complete OEM kit for ~$500.  If on a budget, I would replace chain,  curved guide and slider.  Check all the other guides for cracks in the plastic.  The little two are cheap, The long straight guide is $$$ now.

[Jaredmac11]

How many miles do you have on your engine?  As good as your sprockets look, you may be ok for a while with just a tensioner.    ECS sells a complete OEM kit for ~$500.  If on a budget, I would replace chain,  curved guide and slider.  Check all the other guides for cracks in the plastic.  The little two are cheap, The long straight guide is $$$ now.

155K on the motor, so its an early refresh. I just never got to see the engine run so Im being proactive. Its swapping in to a weekend toy, so it shouldnt see many miles. 

The straight guide is quite a bit of money like you said, I think almost $50.. which is nuts.  I'll give a good look.  I'll look for cracks and see what to do from there.  Tensioner is another $100 or so.  All those rails would bump up the rebuild $200 easy.  When should tensioner be replaced?

I've been happy with what Im seeing.  At worse, it had a bad leak either at the timing case or the valve cover, which left a lot of dried up oil.  Rubber hoses down the DISA air tank are rotten in half which probably gave it bad idle issues.  Otherwise, everything is visually looking OK, but I havent pulled out any micrometers or gauges...

[1998ccc]

Just the straight guide is closer to $200 for genuine BMW.

You will hear a rattle on cold startup when the tensioner starts to go.

I believe I would leave the TC components alone if everything checks out.  155k if the oil was changed and not overheated is not bad.  New timing cover / filer housing gaskets should cure any leaks.

[Jaredmac11]

Im edging near a full rebuild, but what about a new oil pump and main bearing set?  Bearing sets are nearly $100 and an oil pump is $50, but I wonder if its worth skimping on some of these items..


Ive been reading more posts about converting to the 360 thrust bearing sets but Im not 100%.   Ill have to see how mine are first

[1998ccc]

You can check crankshaft endplay with the engine fully assembled.  Some of the ones I've had had massive play, others were fine.

[Darky]

I'm going to add my 2c in here

Do not skimp on oil of bearings, think about what could go wrong.
You definitely want to get rid of the early m42 timing wheel, that's a must!
When they fail and where known too, things go so wrong!
Also the 360 oil grove in the main bearing while not a must, it is another known point of concern.
Easy to do just buy m50 or m52 bearing set and only use what you need.
M44 oil pump is a nice to have basically it's 1.6 mm wider from memory, which allows it to get more oil to the head quicker when the engines cold. Probably required for the m44 style head. But not really necessary for a m42 and its hydraulic lifters.
If you are going to replace the hydraulic lifters go with the vw ones as they are 20g lighter, or there's the s50 cam tray mod if you want to go lighter again!

Cheers Rohan

[Jaredmac11]

Alright.. I think I will broaden scope a bit.  I removed the flywheel, but I was able to grab the crankshaft pulley and there was a biiiit of play back and forth, I dont think there should be any.

Do I need to get the M50 bearing?  Seems like a waste to away 1/3 of the bearings.  I heard newer bearings are 360 but I cant confirm.  I'll do some more research on this and see if I can find more

edit:  It appears m50 bearings are $15 cheaper on pelican parts over the m42 bearings... go figure..

[Darky]

Hi

What you mean 2 bearings, 5 on m42, 7 on m50!
Cheaper that's just odd!
Check that the new bearings have the 360 deg oil grove, if not find some that do!

Regards Rohan

[Jaredmac11]

I'm looking at the connecting rod bearings and I see a scratch/line down each of the bearing.  Is this common? Plastigauge is reading .036.

I read on a comment spec is .03 - .07 .  Is this accurate?  Should I replace the bearings?

[Darky]

Conrod bearings have no scratches or groves on them.
Oh and please stat the units your working with!

[Jaredmac11]

Conrod bearings have no scratches or groves on them.
Oh and please stat the units your working with!

yikes you shouldnt even have to ask.
its .038 mm, per the plastigauge guide.  not exact but it feels like a close fit to their guide.  and the scratch is down the middle but certainly not from the factory, however, i believe the bearing is in spec.


I also ran in to this today.  I measured the spec of the main caps and they all passed, but I fear I missed or mis-measured one.  The bearing and the cap looks totally different.  I cant determine if those grooves are wear or from the factory.
http://imgur.com/a/jBSpY

[Jaredmac11]

Hi

What you mean 2 bearings, 5 on m42, 7 on m50!
Cheaper that's just odd!
Check that the new bearings have the 360 deg oil grove, if not find some that do!

Regards Rohan

Im looking at my new bearings now..  they look identical to what is in the engine.  The lower main bearings have a groove down the middle, but the upper ones look identical to stock, with just small grooves at the edge.  Either the bearings were already upgraded or these are not 360 bearings.  What do the 360 bearings look like?  I read the M50 bearings are 360 bearings and fit the M42, so I picked those up.  I hope I didnt get the wrong ones..

Also, I think one of the main bearing caps is worn?  Im not sure.  The crank on that bearing has a smoothed wall, where-as on the other caps it has a slight lip.  I put together an album to show all this.  I checked the clearance between the crank wall and the cap and they all passed.. I must have missed this one however.

http://imgur.com/a/jBSpY

[Darky]

Hi

Just checked your latest photos. That's just weird must have some forward or backwards movement!
But I don't understand how or why!

But note how the oil grove disappears after 270 deg total.
Your trying to get that all the way around.
I got my 360 deg oil bearings from MM,
I think they where Malve bearings and there using 2 top sets if that makes sense. To get the 360 deg grove.

Cheers Rohan

[Jaredmac11]

Well that's a bummer.  The m50 bearings I picked up look just like these so they aren't 360 bearings... I had read the m50 bearings were 360...

And this bearing must be the main thrust bearing. either it'd a unique bearing and the crank was machined or it wore down completely.

I have a friend with a bottom end, whole, so I will just use that.  Fun fun.