M42 maintenance list

[Ryann]

I read about using a 360 deg. thrust bearing on Metric Mechanic's site.

[5ickride]

That's great info there!

[ayemattyyy]

Amen Simon. Who cares what happened with the guy, but that is damn good information.
Matt

[Simon S]

In an effort to make this a balls-out, informative m42 thread on preventative maintenance – it seemed prudent to share a summary by peerless. I would really like to keep this thread free from any forum politics – and just appreciate/share his input for what it is. Take it or leave it.

Here is my experience with rebuilding 2 M42's. One took 3 engines to make one good one.

We will start with the factory flaws and how they should be corrected.

1) Stamped steel chain guide. These fracture and break apart. Replace with upgraded dealer part, its a all nylon/plastic construction. You will need one new 45mm long bolt in conjunction with the new guide.

2) Steel oil pressure relief valve, aluminum front cover. The steel valve can seize causing a immediate loss of all oil pressure - good bye engine. Replace with updated dealer part, made of nylon/plastic. Make sure you get the spring and spacer as well. The spring is slightly longer so it all a matched assembly. You will most likely want to replace the oil pump rotors, front pump cover and bolts. All of this is about $45.

3) Front chain cover. These are known for leaking profile gaskets. The rail that holds this gasket gets corroded and leaks. Every one notices when it leaks outside the block, but no one notices when it seeps behind the block. This creates a rust cavity potentially damaging the front face of the block. Expect to at a minimum to replace the front cover. If the block is damaged, you can surface the front face to clean up any rust damage. .015" MAX.

4) Main thrust bearing. The factory in all their wisdom decided to only use half a thrust bearing shell. This is not capable of handling the high rpm loads created by the M42. You will find the bearing to be rounded and burnt black. The crankshaft thrust surface must be inspected carefully. On the 2 engines I built one crank was scrap and the other barely within spec. To correct this problem you will want to replace with a full 360* thrust bearing. I do not know if the standard replacement bearings come with 2 halves. I use the early eta M20 main bearing set and have the lower main caps custom machined so they fit. This not only gives me a full 360* thrust surface, it also gives me a full 360* oil groove for improved oiling to the rod bearings. As a note, I pulled the oil pan on a M42 with 80K miles, it already had thrust bearing material in the pan, along with 4 oil pan bolts.

5) Crank pulley. While the stock crank chain gear does not wear very much a new upgraded part is available from the dealer. It has 2 rubber rings molded into it. This helps keep harmonic vibrations in check. This may help prevent the oil pan bolts from backing out

6) Rod bearings, I use custom Clevite 77 NASCAR performance bearings. This is a upgrade, the stock pieces should work just fine as well.

7) lock-tite all your upper oil pan bolts to prevent them from backing out. This is a big problem on the front 6 bolts that surround the gasket for the oil pump pick area of the pan gasket. When these back out and fall into the pan the gasket can push out and you lose oil pressure. See number 5.

Regarding valve guides, they should be fine as they have very little side loading due to the valve train arrangement. I did not need a cam removal tool either. When loosening and tightening the cam tower bolts, take your time, do it slow and evenly. Remember the camshafts are hollow and can break easily.

If anyone tells you the stock M42 is a great engine, they are pulling your leg or don't know the M42 very well. The stock M42 is very self destructive.

I have pictures to back up every flaw I just described above. Everything I said above comes from direct experience with the M42 engine.

Expect to pay about $2,500+ in parts and machine work to properly rebuild the M42. If you need help/advice along the way just give me shout.

Again – I know the dude was banned. It’s the information and feedback of a guy who spent time working with these engines – and then took the time to share what he learned. That’s all. It's the value of the information - that inclines me to share it as well.

[Simon S]

Ah - gotcha. Quite right.

And yeah - all the parts add up - and it sucks.
At least you're more-informed now - and can maybe plan/save for more action down the road.

Your guess is right - tensioner and hoses. Good.

[Ryann]

There’s just one head gasket – can you clarify “full set”? (I can appreciate ‘full’ set meaning gasket + head bolts) (head bolts being a one-time use deal)

A head gasket set= everything you need to refurb and reinstall the head. It's got some other gaskets you'll need such as the intake and exhaust manifold gaskets, valve cover gaskets, upper timing cover gaskets, profile gasket, throttle body gasket, etc. etc.

Victor Reinz set pictured below.

[5ickride]

Thanks, and I agree with searching, just get lazy sometimes...

Back to topic. I priced out most, if not all, of the parts I listed and it came out to almost $1k in parts. Sooooo, needless to say, I'm going to have to scale this back a bit. Being that the engine is relatively young (miles not years) i'll stick with the most common issues and do a tune up for now. My guess is the Timing Chain Tensioners should be close to the top of the list? I'm also experiencing some idle bouncing so hoses will also get replaced.

[Simon S]

Search function performs searches !

http://r3vlimited.com/board/showthread.php?t=60069

(this thread was pretty informative - and it's from 05)

[5ickride]

What kind of reinforcement? I'm also tackling a suspension overhaul at the moment by refreshing it and lowering it and then throwing on some wheels. So I certainly would like to prevent anything from happening.

[Simon S]

This is kinda left-field – but it occurred to me that reinforcing the front subframe is another good preventative maintenance thing-to-do on m42 cars. Seems like they all crack/break on the passenger side.

I don’t think it’s so much power-related – lol – but more of a light weight/inertia thing.

Best analogy I can think of is with a shotgun. A heavy shotgun won’t seem to kick as much. A light weight shotgun will kick into your shoulder much more.

[Simon S]

They are lighter and cheaper which is a bonus, there are no real gains besides reducing valve float, I have them in my car they are a direct swap no modifications needed.

Good to know – thanks for sharing this info.

Also if your end up getting a cold air intake and a high flow exhorts with a chip I would recommend finding the 22# injectors that fit our cars.
My car tends to lean out at high rpm.

I wonder if an old/worn fuel pump might play into a possible lean condition?

If you're going to do the profile gasket, you're going to need a full head gasket set.

There’s just one head gasket – can you clarify “full set”? (I can appreciate ‘full’ set meaning gasket + head bolts) (head bolts being a one-time use deal)

Btw, I like your approach, but keep in mind with your ODO you may not need to dig as deep as you're planning just yet.

Yeah – this is one of those tricky, slippery slope things. ~106K is pretty young – no doubt there. I think a majority of objective is preventative maintenance in nature.

I’d like to think replacing chain tensioner and guides prior to ~150K is going to help original chain and sprockets live for up to ~220K.

At this time, with those miles – one can agree that factory profile gasket has been addressed by now – but then one never knows if any possible timing case corrosion condition was addressed. The guides are kind of a fucker because – at this time – it may be more of an age thing – rather than a mileage thing. From what I’ve gathered – original guides start failing between 150-200K.

Ultimately, in terms of owning/driving the car for years to come – the above established list is pretty solid. Otherwise, yeah, you could just drive it till it breaks – but then increased repair expenses and inconvenience are what one should strive to avoid.

[Ryann]

Any details on the "Top end gasket set"?

If you're going to do the profile gasket, you're going to need a full head gasket set.

Btw, I like your approach, but keep in mind with your ODO you may not need to dig as deep as you're planning just yet.

[Massimo]

If your lifters are ticking replace with these http://www.fourseasontuning.com/product.php?id=162&product_code=050109309HBR

They are lighter and cheaper which is a bonus, there are no real gains besides reducing valve float, I have them in my car they are a direct swap no modifications needed.

Also if your end up getting a cold air intake and a high flow exhorts with a chip I would recommend finding the 22# injectors that fit our cars.
My car tends to lean out at high rpm.

[5ickride]

Simon S- Thank you for posting that information. That just made me smarter and it sheds alot of light into subject matter. Maybe more cars will stay off the "part out" threads.

jintermont- Thanks for letting me know, i'll get back to you.

[jintermont]

My best friend is a mustang nut. I can probably get the injectors for really cheap he says they pretty much give them away because the 19# are way too small for their applications. Pm me if interested