dongfeng tractor with y385t wont start help

[reelnative]

Nope, you go by the diameter of threaded portion, not the head size. The chart figures are based on a thread engagement of 1.0 times the bolt diameter, (basically, the thickness of a nut) if I'm not mistaken, and in use where there is more thread engagement that that the torque may be higher. Also, those bolts may be grade 12.9, which would have a torque value of 62 ft/lb versus 53 ft/lb for grade 10.9 or 37 for grade 8.8, according to my chart. Another chart have shows values of 70, 60 and 40, respectively, so even the charts don't necessarily agree. Values can also change if the material the bolt is threaded into is different than steel equivalent to the bolt itself. Lots of variables, in other words.

I'd use a torque value from the chart for the grade of bolt you have, and disregard the book. Use a drop of blue Loctite on each thread and you won't have to worry about them loosening from vibration.

I just measured the tread engagement of the bolt and it is about 2 times the with of the head or what a nut would be the thread came in at 20mm long now would that give it a higher torque value ?, asc size the bolt is right at a 3/8ths bolt

 

[Rich Waugh]

I don't think they are TTY bolts based on your description of the aligning collar feature. And steel bolts can easily take double the torque to break free, particularly if they're seated in aluminum which causes dielectric corrosion and welds them in place. Even steel-to-steel will get a little rust and require a big increase in torque to break free.

Most metric hardware has the grade numbers forged into the head. Three radial lines on the head is the standard marking for SAE grade 5 bolts, not a metric designator as far as I know. Metric grade 10.9 is roughly analogous to SAE grad 5, though that means nothing.

Like I said, I'd torque the new ones to about 55 ft/lb and use a bit of blue Loctite to make me feel better. Over-torquing is almost always a bad idea.

 

[Rich Waugh]

If you have 20 mm (~3/4") thread engagement you might be able to get away with a bit more torque without stripping the threads, but I seriously doubt you'll gain any real improvement in security over just using the chart torque for a bolt that diameter and grade. You don't have a gasket crush situation on those con-rod journals so you just need them to pull together and not loosen, right?

 

[Bob Rooks]

There is no such thing as "grade" in metric fasteners. There is no "grade 8.8".

And no, it's not just symantics.
All metric fasteners are Property Class (PC) strength. I thought you guys already knew this!

ASTM F568M - Wikipedia, the free encyclopedia

 

[Rich Waugh]

As noted in that Wikipedia entry Bob, "...property classes, the metric equivalent of a screw grade,..." so yes, I'd have to say it is mostly a matter of semantics for most people. Admittedly, engineers will split hairs over this, but the whole area of classifying/grading/rating fasteners is confused at best. Unless all fasteners were made of precisely the same alloys, there is a need for some system whereby people can reasonably infer certain characteristics of a fastener by its designation, whether you call it a grade, a class or a rating. In the final analysis, most of us just want some designation that tells us what a particular fastener can be expected to do in service.

 

[reelnative]

There is no such thing as "grade" in metric fasteners. There is no "grade 8.8".

And no, it's not just symantics.
All metric fasteners are Property Class (PC) strength. I thought you guys already knew this!

ASTM F568M - Wikipedia, the free encyclopedia

well ok then, but that write up does say, : this property classes, the metric equivalent of a screw grade :, so for us people that still walk a mile and not a killometer calling them grade 8.8 kinda works for us

 

[Bob Rooks]

I'm sorry.

 

[reelnative]

I'm sorry.

hey its all good bob, really i dont care what anyone calls them, just as long as i can find out what torque to put these darn rod bolts at, but one thing i can say is there is no way in **** im only gonna only torque them to 40 ft lbs, if I did that there would be no way i could sleep at night, im kinda leaning toward just putting them in at 80 ft lbs and be done with it, to me even 80 seems a little bit low, heck at 40 I can almost take them back out with my fingers and not even need a wrench hahahah jk

 

[reelnative]

well shes back together, well everything except 2 injectors and oil, water, rad hose and to bleed injectors, ran out of time but ill fire it off tomorrow morning, I torqued all the rod bolts down to 80 ft lbs and head bolts down to 120ft lbs and all went good, i also torqued all the oil pan bolts down to 20 ft lbs, and did the valve train to 20ft lbs, ill add a few pics

 

[reelnative]

well she runs but now i have another problem she wants to run away, good thing i had my hand on the fuel shut off or she might of blown, she fired up and got to about 2500rpm before i had time to shut it down, can i take the part of the ip pump that has the throttle part in it and try to fix it or will there be a bunch of crap that i cant put back together in there