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DISCUSSION => Engine + Driveline => Topic started by: alpine on December 15, 2012, 05:23:23 PM

Title: m42 replacement engine.. questions on what to replace
Post by: alpine on December 15, 2012, 05:23:23 PM

hey guys so i picked up a very clean 91 alpine a few weeks back. m42 was seized. interior and exterior are near flawless..

anyway, i just picked up a running m42 with 170k miles. gonna start prepping the replacement swap. what do you guys recommend i replace to keep this m42 running strong? valve cover gasket, spark plugs, any sensors? anything that is common to fail on these motors? sorry i dont know much about these guys yet.
ive heard upper and lower oil pan bolts. i know the upper is hard to get to when its in the car, will definitely change that too..
oil pump?

any help is appreciated! ill just start making a list of things to look at/replace

thanks!

(http://i.imgur.com/kalOG.jpg)

Title: m42 replacement engine.. questions on what to replace
Post by: DesktopDave on December 15, 2012, 07:57:34 PM

Sounds like a great project.  Saving another one from a scrapper!

The lower oil pan is easy to remove even in the car, those front upper oil pan bolts can vibrate free.  That lets the upper oil pan gasket slide out of position.  Since that gasket also seals the primary oil passage above the oil pump, you'll lose oil pressure back into the oil pan instead of lubricating the motor.  A bit of blue Loctite on those 3-4 bolts will fit the bill nicely.  Plus you'll get to see how many bolts are sitting in the pan.  They usually engrave scars on the lower pan when they get wedged under the oil pickup.

I'd definitely check the cam chain over very well.  That was another weak point on the early M42.  If it has the updated plastic style cam guides and some decent flats on the cam gears, I'd leave it as-is.

I'd also strongly consider replacing the water pump, plastic coolant manifold and deleting the vac hose pre-heater mess under the intake.  And any motor swap is also a great time to replace the clutch, tranny seals and rear main seal.

As far as cosmetics, I'd also replace the oil filter housing seals - the gasket and o-ring both tend to leak.  An OEM gasket with some Hylomar should button that up nicely.

Title: m42 replacement engine.. questions on what to replace
Post by: alpine on December 15, 2012, 08:54:32 PM

awesome! thank you for the advice!

so far:
valve cover gasket
upper oil pan bolts + gasket
lower oil pan bolts + gasket
cam chain (look over)
h20 pump
coolant manifold
vac hose pre-heater
tranny seals
rear main

anything else guys? ordering parts tonight or tomorrow!

Title: m42 replacement engine.. questions on what to replace
Post by: 92BMW318is on January 13, 2013, 12:09:29 AM

How much did she set you back?

Title: m42 replacement engine.. questions on what to replace
Post by: locknload on January 14, 2013, 07:52:45 PM

What caused it to sieze?  PO have any idea?

Title: Cam Chains
Post by: jimc2 on January 28, 2013, 05:07:22 PM

Based on my sad experience , consider replacing that cam chain at 125k-150k or over regardless of how pretty it looks. Mine has 214k and the chain rollers started fracturing and ending up in the pan. These got sucked up into the oil pump and wrecked the pump and front timing housing. The rollers remaining on the chain still "look" fine. The chain guides are also full of hairline cracks and should have been done long ago too. Expensive parts, but cheaper than another motor.
This one ran really well up 'till it stopped oiling.
Lots of similar posts on this site too.
I'd also recommend a rear main seal while you've got it out.
When swapping these motors,
Beware the two possible M42 transmission pilot bearing sizes in the back end of the crank. some are 12mm some are 15mm, these can make you crazy if you mismatch.
Jim

Title: m42 replacement engine.. questions on what to replace
Post by: alpine on January 29, 2013, 06:48:09 PM

update!parts cost me around 400 dollars, engine 200.... so nearly refreshed m42 for 600... haa

Title: m42 replacement engine.. questions on what to replace
Post by: keflaman on January 29, 2013, 09:37:41 PM

Quote from: alpine;119704

update!parts cost me around 400 dollars, engine 200.... so nearly refreshed m42 for 600... haa

It adds up quick, doesn't it? And every thing you ordered will probably be shipped in a container the size of a shoe box.

Title: m42 replacement engine.. questions on what to replace
Post by: alpine on January 29, 2013, 10:35:21 PM

Luckily i work for a wholesaler.... soo wholesale prices haha. all shipped to me within 2 hours of ordering!

Title: m42 replacement engine.. questions on what to replace
Post by: sfinsf on January 30, 2013, 07:21:01 AM

Quote from: alpine;118405

awesome! thank you for the advice!

so far:
valve cover gasket
upper oil pan bolts + gasket
lower oil pan bolts + gasket
cam chain (look over)
h20 pump
coolant manifold
vac hose pre-heater
tranny seals
rear main

anything else guys? ordering parts tonight or tomorrow!

How far along on this are you? Where in Calif are you?

I would add a bunch of other items, but if you've already gotten this beast in the bay and running then I'll just shut up....
reviewed my list and I'd add:
 chain tensioner
 fuel filter
 Tstat (which hopefully you did w/pump)
while you're doing the mess under the intake,
 delete TB heater
 new intake gaskets
 have those injectors cleaned and tested

I have a huge list of what I've done, mine has 209k