Starting M42 Rebuild......The Damage is Found

[Kedge]

Right I'm finally getting off my arse this weekend and striping down my old engine, the only problem with it that I know of is that the chain guides started breaking up, although the chain had supposedly been recently changed, the engine certainly ran very well and very smoothly with no rattles.

I have decided I am going to rebuild this engine as the head has had some shoddy welding done to it in the past and I'd like to increase performance (in the future. After speaking to Ant last summer I still feel that the turbo route will be the route I will eventually be going, although this will be some way off. Baring that in mind I want to strengthen the bottom end somewhat, even though Ant assured me that M42 can comfortably handle 12psi (iirc) on standard internals a little extra help won't hurt. He also advised me that I would be wasting my time doing any head work as the M42 head is efficient enough for a turbo and I would really notice the difference as I'm more interested in useable torque rather than really high peak powers.

My current plan is to get hold of an M44 crank (anyone got one?) to increase capacity to 1.9, I seem to remember being told this is a straight swap but can someone confirm this as that will have an affect on my final decision. I will then obviously be replacing all of the bearing shells and bolts. I have already had a quick look in to ARP bolts and currently they only offer a kit for the main bearings so is there another alternative I can use for stronger con rod bolts? Also i will need to reduce the CR a little, Ant mentioned either taking a couple of mm off the pistons or using a plate attached to the head, what have people found to be the best method, i like the sound of the plate on the head as it means the head won't need to be skimmed if it has to come off at a later stage thus raising CR again (I think I'm right with that anyway).

Any advice on all aspects of the rebuild will be greatly received as I haven't done anything of this nature so it will be a massive learning curve for me. I will up date this thread after the weekend with pics of the stripped engine and current progress, I suspect this will be a fairly slow progress build as I think it may start getting expensive. Fingers crossed my current M42 can hang on long enough!

Here's a couple of pics of the car i'm doing this for.




Cheers
Dave

[ed325i]

Have alook here >> http://www.metricmechanic.com/pdfs/M42_ ... Series.pdf

[bmwscorpion]

Car sits very well, Good luck with the build.

[odbod]

I re-built an e36 low mileage engine that had been sitting for some time, couple of places I have had headaches with on the oil leaks front. the timing case gasket to block needs some additional sealant along the bottom edge I worte up quite alot on fitting the egine into the car somewhere...

[1an]

looking good their Dave,

good to here your finally on your way to what you want, certainly went well last year going to leman.

[agreen]

ot but that exhaust is very nice looking what is it dude

ps good luck witht the build a quick search on www.m42club.com for (rebuild ) should see you on the right track mate

[appletree]

Dave, IIRC the M44 chank in not forged like the M42 and also doesnt have the counter weights, good for high revving N/A but not so good for the F/I route.

Tim_s had alot of info about the m44 m42 crank differentces

[Kedge]

Cheers for the links guys, M42club is certainly a good forum but there seems to be such a differing opinion on how to do everything, plus they seem to have a few variations to UK cars. MMs pdf is awesome, if only they were in the UK, will certainly be in contact with them for advice.

agreen, the exhaust is just a Powerflow one, not the best quality in the world but sounds and looks ok.

Cheers for the info Matt, didn't realise that, could certainly do with getting in touch with Tim, sure knows his stuff.

[Kedge]

Partly striped down the old engine today, hit a snag with the crank bolt to not been able to get the lower timing case off yet but so far everything looks fine and as it should be. Surprised how cleaned everything looks and the guides i can see with the upper casing off all look fairly new.

This gives an idea of cleanliness, on the right is the upper casing off another engine with approx the same mileage and on the left is the one I removed today.


Nice new looking chain, sprockets and guides. Will hopefully be able to reuse these so that'll save some money or is that a little risky?


The reason why i am seriously considering throttle bodies again, such a fiddle working with the standard inlet and throttle body on these!


The pigeon shit welding on the head.


Will get some better pics p as i only had my phone and the was pretty crap by the time i got round to taking these pics.

[Kedge]

Some more pics,

Damage inside the thermostat housing, first is the underside of the welding,


To the left of this pics you can see where some of the metal work has broken away, seemed like someone had tried sealing it back on, this pic just shows the hole it left.


Close up of the guides.

[Kedge]

Finished stripping the engine today and was a little shocked to see what i found, turs out there was nothing wrong with the guides, so the plastic i found must of been from some previous broken guides cuased by what i found.

I'll let the pics do all the talking but WHAT A BODGE!



Shame the heads been welded in the past, least amount of damage i've seen around the profile gasket area.

[Sanchez]

Dave i suppose your keeping that exhaust but give me a pm if you thinking of selling.

[appletree]

That could have done some real damage

[ShakeyC]

Surely better in the long run if you source another engine and rebuild that if need be?

For price of a 1.8 engine never worth the risk bodging a bodge for a future bodge

[Kedge]

The cars on the road with another engine in it so won't be getting rid of any parts.

There's no reason why this engine can't be rebuilt, all i need is to get hold of an undamaged timing housing.

[maxfield]

[ShakeyC]

Sure it can be rebuilt, maybe pictures made out the damage is far worse to me, bare in mind these engines are not expensive is it worth the risk is my only point.

[Kedge]

I won't be using any of the parts you can see in the pictures with the broken sproket and mount, thats all in the bin.

The timing casing just bolts up to the front of the block so can easily be replaced.

[ShakeyC]

Easily sorted then good luck with the build.


PS any similar bits to the Nissan CA18DET which is interchangable could provide cheap aftermarket resourses? only asking as they look very alike

[uzdubmwe30]

Kedge, A new timing casing from zimmer bimmer (paul) is around the 150 mark, I priced one up a few months back as I have an m42 sitting in the wings wating to be rebuilt (cracked casing getting water pump out!) I'm just trying to warrant spending more than i paid for the engine on rebuilding the thing! Got all the other parts but it's the casing thats the big money.

Anyway good luck with the project and i'll be keeping an eye on your progress as hopefully I intend on going down the turbo route but using standard internals and just a bloody good rebuild.

matt