Author Topic: M42 valve adjustment? (Read 8825 times)

dshosu · « **on:** January 15, 2009, 03:03:40 PM »

I'm looking at purchasing my first E30 and there's one on my local CL that simply says

"needs valve adjustment, good condition"

Obviously I'm asking a lot more about it, but what exactly does "needs valve adjustment" mean?, how does that occur?, and how serious of a problem COULD it be?

I saw conflicting statements on BF regarding if the M42 could even have its valves adjusted...and I'll be the first to admit I don't know that much about car mechanics, but I'm willing to learn (hence my creeping around here)

Thanks everyone!

xwill112x · « **Reply #1 on:** January 15, 2009, 03:06:37 PM »

m42 has self adjusting valves...

maybe has a burnt valve?

batsbats · « **Reply #2 on:** January 15, 2009, 03:09:42 PM »

hydraulic valves, which the M42 has, are designed to never require servicing. But this does not mean they go bad, or make terrible valvetrain noise over the life of the car.

However, the M20 found in most other E30s, do require valve adjustments.

The owner probably got mixed information, and is concluding a possible rough valvetrain noise to be fixed by adjusting them to spec.

dshosu · « **Reply #3 on:** January 15, 2009, 03:29:48 PM »

Thanks for the quick replies!

That's what I was assuming form what I've read so far, in terms of the M42 not needing valve adjustment (in the classic sense)

So what could the problem be? Or what questions should I ask to figure that out? Or how might I find that out?

txleadfoot · « **Reply #4 on:** January 15, 2009, 04:36:24 PM »

poor oil pressure, wrong viscosity oil, worn lifters. how many miles on the clock? ask the seller what symptom indicated why he/she made that comment.

-eur04lif3- · « **Reply #5 on:** November 12, 2012, 10:03:30 AM »

Quote from: txleadfoot;64750

poor oil pressure, wrong viscosity oil, worn lifters. how many miles on the clock? ask the seller what symptom indicated why he/she made that comment.

I just passed 200K on my motor, and the oil used is 0W-40.
Will be posting a sound clip later on today.

Could the oil viscosity play such a large role?

PS. Sorry for reviving such an old thread.
Also, the timing tensioner was replaced about 30K ago.

MattBimmer · « **Reply #6 on:** January 07, 2013, 09:21:38 AM »

Quote from: -eur04lif3-;117613

I just passed 200K on my motor, and the oil used is 0W-40.
Will be posting a sound clip later on today.

Could the oil viscosity play such a large role?

PS. Sorry for reviving such an old thread.
Also, the timing tensioner was replaced about 30K ago.

Yes man! I had some valve ticking noise. Use some good gas and a thicker weight 10w40 at least you'll be good when you do that and change you timing chain tensioner

bmwman91 · « **Reply #7 on:** January 07, 2013, 06:53:41 PM »

0W-40 is pretty darn thin for an M42, especially with high mileage. Unless you live somewhere where the temperature is below freezing most of the time, you should really consider 10W-40, or 20W-50 like the manual specifies.

The M42 valve train can get very "ticky" as it gets old and the lifters clog up with varnished old oil. A lot of the time, the valvetrain noise that people hear is actually a worn out timing chain tensioner/guide assembly. That is a much more serious problem than the lifter tick and it usually precedes engine failure from a loose timing chain. It is relatively easy to fix before things get to that point, thankfully.

bmwman91 · « **Reply #8 on:** January 07, 2013, 06:53:45 PM »

0W-40 is pretty darn thin for an M42, especially with high mileage. Unless you live somewhere where the temperature is below freezing most of the time, you should really consider 10W-40, or 20W-50 like the manual specifies.

The M42 valve train can get very "ticky" as it gets old and the lifters clog up with varnished old oil. A lot of the time, the valvetrain noise that people hear is actually a worn out timing chain tensioner/guide assembly. That is a much more serious problem than the lifter tick and it usually precedes engine failure from a loose timing chain. It is relatively easy to fix before things get to that point, thankfully.

deansweet · « **Reply #9 on:** January 07, 2013, 08:39:09 PM »

Quote from: bmwman91;119056

0W-40 is pretty darn thin for an M42, especially with high mileage. Unless you live somewhere where the temperature is below freezing most of the time, you should really consider 10W-40, or 20W-50 like the manual specifies.

The M42 valve train can get very "ticky" as it gets old and the lifters clog up with varnished old oil. A lot of the time, the valvetrain noise that people hear is actually a worn out timing chain tensioner/guide assembly. That is a much more serious problem than the lifter tick and it usually precedes engine failure from a loose timing chain. It is relatively easy to fix before things get to that point, thankfully.

So true it needed to be posted twice! 0w-40 is way too thin for these motors in my opinion.