Yanmar 3GM30 valve clearance adjustment question

[jfkal]

Hi Guys, the manual does not specify the torque required to tighten back the locking nut after adjustment. Any recommendations?
Thanks
Joerg

 

[rotrax]

Common sense-tight enough not to come undone, loose not to strip the thread and to be able to loosen it next time

In my extensive experience, few manuals give a torque for adjusting nuts.

 

[jfkal]

Ok. Shall be careful then .

 

[tjbrace]

My downloaded manual gives ‘general torque settings’ for each metric sized bolt/screw. Pm an email address and I will try to send the pdf.

 

[VicS]

From the Yanmar manual, but you have to counter-hold the adjusting screw while you tighten the lock nut making the use of a socket on a torque wrench difficult.

 

[rotrax]

Agree with the rule on the general torqueing of bolts, but a conventional tappet adjuster is like two nuts used on a stud to remove it-it only has to be tight enough to do the job, locking the one internal and one external thread together to hold the adjustment.

Dont lets overcomplicate it.................................................

 

[Skylark]

Dont lets overcomplicate it.................................................

I’m aware of your background and not meaning to contradict, nor troll, but..........

The older I get the more I want to tighten any nut and bolt to a correctly prescribed torque. My last 10 years of work was spent with gearboxes. We designed and manufactured mechanical transmission product for niche applications, mostly for military vehicles.

Working with different materials, ferrous and non-ferrous, different thread sizes and different grades, we couldn’t afford to leave anything to “common sense”. One persons definition of “tight” can be very different to another. The consequences of over or under tight didn’t bear thinking about.

In the boat yard a few years ago a bloke came up to me and said “you’re an engineer, aren’t you?” I asked him why he asked and he replied that he’d never seen anyone else torque the prop fixings.

 

[rotrax]

I’m aware of your background and not meaning to contradict, nor troll, but..........

The older I get the more I want to tighten any nut and bolt to a correctly prescribed torque. My last 10 years of work was spent with gearboxes. We designed and manufactured mechanical transmission product for niche applications, mostly for military vehicles.

Working with different materials, ferrous and non-ferrous, different thread sizes and different grades, we couldn’t afford to leave anything to “common sense”. One persons definition of “tight” can be very different to another. The consequences of over or under tight didn’t bear thinking about.

In the boat yard a few years ago a bloke came up to me and said “you’re an engineer, aren’t you?” I asked him why he asked and he replied that he’d never seen anyone else torque the prop fixings.

Totally agree.

But the locking nut on the adjusting screw is a completely different animal to a retaining bolt or a retaining nut on a fixed stud or shaft. The nut is tightened to retain the adjustment that has just been made. To use a conventional torque wrench would require crowfoot sockets, otherwise the adjusting screw might move when the locknut is tightened. Not many non pro mechanics have a set of those. Using a conventional torque wrench or torque screwdriver does not allow the screwdriver to stay in the adjusting screw while the locknut is being tightened.

As to torqueing propshaft nuts-whenever I've done it the split pin hole did not line up..........................................

 

[RichardS]

To use a conventional torque wrench would require crowfoot sockets, otherwise the adjusting screw might move when the locknut is tightened. Not many non pro mechanics have a set of those. Using a conventional torque wrench or torque screwdriver does not allow the screwdriver to stay in the adjusting screw while the locknut is being tightened.

Vic correctly covered the issue earlier in the thread.

Basically, we can forget about using a torque wrench on a rocker adjuster. I've tried using a conventional socket by allowing enough latitude in the adjuster to give the correct tappet clearance once the socket is removed. After a frustrating 10 minutes I gave up. :ambivalence:

Richard

 

[Skylark]

Totally agree.

But the locking nut on the adjusting screw is a completely different animal to a retaining bolt or a retaining nut on a fixed stud or shaft. The nut is tightened to retain the adjustment that has just been made. To use a conventional torque wrench would require crowfoot sockets, otherwise the adjusting screw might move when the locknut is tightened. Not many non pro mechanics have a set of those. Using a conventional torque wrench or torque screwdriver does not allow the screwdriver to stay in the adjusting screw while the locknut is being tightened.

As to torqueing propshaft nuts-whenever I've done it the split pin hole did not line up..........................................

Can’t argue with any of that, either

I have a torque spanner set, can be very useful at times (such as the case in point).

The very well made Flex o Fold prop fitted to a Saildrive does not use a split pin design.........hence I use Loctite and the correct torque

 

[VicS]

At least the valve clearances dont have to be adjusted while the engine is running , like they did on one car I owned back in the 1980s

 

[penberth3]

At least the valve clearances dont have to be adjusted while the engine is running , like they did on one car I owned back in the 1980s

Oh yes, the fun we used to have!

 

[rotrax]

I had access to free use of a rolling road dynomometer in the early 70's.

By adjusting the valve clearances on MGB'S with the engine running the manifold vacuum improved, it was easier to balance and tune the carbs and up to 4 BHP extra was seen on the dial a couple of times. Normal improvement 1 to 2 BHP.

Adjusting them this way required special feeler gauges-hardened ones. You also got splashed with hot oil...........................