how good is the m42 block?

[Gadea]

I had a blown head gasket, and after getting the head back from the machine shop, I´ve been collecting seals, hoses, sensors, gaskets, etc. to put it all back together, thinking if I replace all those worn out parts, I´ll probably won´t have to worry about them anytime soon. In theory, that could potentially mean 15 years without any visits to the mechanic´s shop, or so I thought. But then again, I´m not replacing valves, lifters, pistons, and it also comes to mind the question in the title. What do you think?
All input welcome.

[Erick]

I bought my 318iS with a blown headgasket. Turned out I had a cracked cylinder head. I just swapped in a brand spanking new cylinder head, new gaskets everywhere, and called it a day.

My M42 is certainly somewhere above 150k miles, and it runs strong. Burns a bit of oil (like a quart a month? Which to me is 2000 miles), but otherwise legit.

- Erick

[Cobra Jet]

What did the shop do to the head? Did they verify or check it for any type of cracks?

Head cracking is extremely common and the premature death of many M42's after an overheating issue (either caused by profile gasket failure or head gasket failure). These heads have to be inspected very closely, as most of the time the cracks are very minute and hard to catch if not inspected throughly.

The head on my M42 is not the original and was rebuilt due to the original head cracking after the PO ignored a failure of either the profile or head gasket.... The engine was also torn down for inspection at the same time as the head rebuild @ 99k. The engine currently has 130k on it and when it was apart, the cylinders still had all of the factory cross hatching in them as if it were new. The timing system and all associated parts has all been replaced and all gaskets/seals were replaced as well. It's driven 114 miles per day 5x a week - and another 80-100 miles per weekend... It does not burn any oil. It's a pretty stout engine and gets extremely excellent gas mileage (on average an easy 31mpg for me).

Hit up m42club.com and there's tons of tech threads about the M42 engine & head - especially when it comes to putting it all back together...

[gearheadE30]

Mine's running strong on the original head and block at 220k miles and regular autoxs and HPDEs. Doesn't burn any oil. So if they are taken care of, they can last a very long time.

[BadCab]

My 92 318vert has about 200k. I just replaced the clutch/PP and all the timing stuff and gaskets and my cyls. still had the cross hatch on them too. Cams showed no wear or very little. The engine was super clean inside. It's looks like it's been on synthetic all it's life. I think i could probably get another 200k out of her.

[Gadea]

Awesome. I´m glad all of you guys have had great experiences with your 4-wheeled-babies. Makes me feel....relieved. I posted this very same thread on m42club (I actually posted it before doing it here) but had zero responses so far. I´m unfortunately still collecting parts for the rebuild. All I need at this time is the timing chain, tensioner, guides, and water pump. I miss my car a lot.

[Gadea]

to answer cobrajet, the machine shop found a hairline crack on the head surface, and did whatever it is they do to smooth everything out and eliminate cracks or whatever.

[Erick]

Well... it's not AAALL good.

My M42 has already given me a million little small issues. I love the motor to death, but it's a whiny little bitch compared to the SOHCs.

[3bvert]

I had a cracked head between the exsaust port adn the water jacket. water steam cleaned the cylinder, unfortuantely it also damaged the rings as that cylinder is down about 20 pounds over the rest, comes back with oil

[strad]

Mine has 210k miles on it, original head and block. Had profile gasket replaced at about 30k miles -- dunno if it overheated at that time. At any rate, is fine now, and burns about a quart of 20W50 every 3000 miles.

[gearheadE30]

Well... it's not AAALL good.

My M42 has already given me a million little small issues. I love the motor to death, but it's a whiny little bitch compared to the SOHCs.

Out of curiosity, what has happened to you?