Head Bolts/ What in the @*^ are THESE?

[Johnbro]

Some modern engines use head bolts that are designed to stretch slightly under the spec torque settings. The "stretching" provides a secure seal to prevent vibration from loosening the bolt. for this reason the bolts cannot be reused.

So a "normal" (ie not a head bolt) fastener might have a generic recommended torque setting to be tight enough not to loosen up and not so tight as to risk damage to threads. But a head bolt torque setting might be different.

I'd order new head bolts from the same source you got the head from, or at least find out the designation and get them from a commercial fastener supplier, then torque to the setting specified in the workshop manual for head bolts, not other bolts.

 

[SpudHauler]

Here is a bolt chart showing the 8.8/10.9/12.9 bolt hardness.
Metric Bolt Torque Table - CNCexpo.com
F100, you are not going to be happy until you talk to a dealer mechanic.
Is that possible?
Otherwise I stick to what I said earlier 47-57 ft lbs per your manual.
When give a range I always shoot for the middle, in this case 52.
And the bolt chart says 53 dry, so 52 should be good to go.
Besides the head torque probably had no bearing on the trouble you had in the first place. It just an assembly issue and being this close I can't imagine any problems.
I'll be most torque wrenches are not that accurate.
I have 5 different torque wrenches and I'll bet if they were tested, none would be bang on.
So, in conclusion, so you can get this thing back together, 52 ft lbs, and follow my previous instructions.
It's a Chinese build right? They probably follow their own rules. Or copied everyone else's and then made their rule.

 

[F100Panel]

Mistubishi is Japanese... & they make NICE stuff. It's a shame Cub Cadet got swallowed by MTD & Cubs are now made by others. Mitsubishi makes Catepillar's D3 Bulldozer.....OUCH, another American Icon outsources....but a testimony to Mitsubishi quality... The Cub dealers around here gave up Cub after MTD got involved & quality took the MTD route..

I may indeed have to talk with a Dealer.....except most don't know what engine I have based on the style of injector... I REALLY believe it's a late model CUB Repacement engine due to how clean the engine is coupled with fresh/flexable/clean gasket sealers that oozed out & something made the head crack. Either it was over heated or was doomed from the start by a bad casting... I can still see the cross hatching in the cylinders & there is zero ridge buildup on the tops of the cylinders...but I'm just guessing. I asked the guy who got me the head what the engine was just to verify the Horsepower. He had no clue. He just used the serial number & any other numbers I had especially the numbers from the head & pictures of the head..& he took all that to his source in Japan " WHO ( the supplier in Japan) was quite proud of himself that he could FIND/supply a head but it would take the 7 weeks" The repair Manual gives 3 differernt torque specs for the bolts in a VERY different ranges- 47-57, 72-80 and 108-116.... THATS huge....

I have encountered head bolt stretch in the past & re-using the bolts not advised. When I bought the head I ordered a Head Gasket Set/anything I might need to change the head & the seller never mentioned bolts & the manual don't either but it's a point well taken. IF I can GET a set of bolts I'll make that priority ONE...I don't wanna do the job again cause I scrimped on ( guessing from Mitsubishi ) probably $75 or so in bolts...

But I still need to figure out which of the 3 torque requirements I should use...

 

[F100Panel]

Took the drive to the nearest Cub dealer today. He's been selling Cub Cadet for 30 years/his father was selling International Farm all back to the 50's..... He laughed when I told him the head was no longer available from Cub.. then he looked it up & sure enough, the Head & BOLTS are no longer available. His shop manual is the same one posted here on this site for the Cub Cadet 7000 series tractor. He don't know what to tell me about the head bolts either... Then he called his mechanic in who laughed looked at the shop manual for a few minutes & he scratched his head & said he didn't know what to tell me either.. I saw a web link someplace to talk to a Cub Technition.. I think I gotta find that link.. Does anyone recall seeing that link anywhere?The Dealer & the mechanic were at a loss to explain the numbers 10 on some bolt heads & 13 on the others...

 

[wrenchturner]

I cannot help you locate a head but I sure can explain the numbers on the head of the bolt.

First it is important to understand that when metal is stressed it flexes. Even concrete does as can be felt inside a car setting on a bridge as a heavy truck passes. Ever bent a coat hanger then let it return to the orignial position? Bend it more and it stays bent. When you tighten a bolt it stretches. Try it. Measure the length of a bolt with a micrometer then tighten it and measure again. Release the tension and measure it again and it will return to the original length just as the coat hanger did. However, tighten the bolt enough and it will not return to the original length. It has reached its yield strength, it has given up so to speak just as a coat hanger does when bent too far.

Now for the numbers. Let's observe a bolt a see M 7.8 on the head. The M tells us this is a metric bolt but will not always be there. The 10 is the bolt strentgh classification just as grades 5 and 8 are commonly used for SAE (standard) bolts.

For the mysterious number after the decimal (.7 in this case) it tells us something about the force needed to permanently stretch this bolt just as in bending a coat hanger. For simplicity, lets say this bolt will hold 10,000 pounds before breaking in two. Once we reach 70% of 10,000 pounds of force or 7,000 in this case the bolt has stretched enough that it will not return to the orignial length. Keep tightening and at 10,000 lbs it will reach its tensile strength and break. You will always notice that higher strength clssifications such as 12.9 will reach a higher percentage of the tensile strength before being permantely deformed. The bolt is stronger but in a sense will not stretch as much before breaking. So, in summary the .7, .8 and .9 on the head a bolt tell us the percent of tensile strength (breaking force) needed to permanently stretch (yield strength) a bolt.

 

[SpudHauler]

F100,
Just thought of something else. Did you check the block for flat and true with a good straight bar and feeler gauge?

New head needs a good flat/true block to sit on.

Looks like you still need to keep calling around to dealers for the one that has more info on torque and head types.

If you have new head bolts that would also be a good thing, given you have so much invested in the head. And they may have different numbers or the same as one or the other which will help. Does anyone have a parts book and are the head bolt part-numbers different?

Perhaps some other owners can steer you to their dealers if they think it would help.

 

[PILOON]

There is also a pattern to torquing head bolts.

Generally you start in the center and work your way outwards, kinda going in a spiral pattern.
While a specific manual generally shows a pattern, the spiraling method will prove safe.

As to torque values, that is generally to SAE standards (or metric equivalents) and charts will give that info.

The general idea is as tight as possible but not to weaken the bolt, hence the charts for that grade/strength of fastener.

Also the correct method is clean threads and no lubes as lube will give false torque readings and you'll risk snapping a bolt/stud.

 

[PILOON]

F100,
Just thought of something else. Did you check the block for flat and true with a good straight bar and feeler gauge?

New head needs a good flat/true block to sit on.

Looks like you still need to keep calling around to dealers for the one that has more info on torque and head types.

If you have new head bolts that would also be a good thing, given you have so much invested in the head. And they may have different numbers or the same as one or the other which will help. Does anyone have a parts book and are the head bolt part-numbers different?

Perhaps some other owners can steer you to their dealers if they think it would help.

Some shop manuals (specific products) actually specify new bolts for every head installation, might not be the case on your engine.
But could well be as diesel engines create high pressures.

Generally a head warps but rarely will a block be out of wack.

 

[boxygen]

It is my understanding that much of the current 15 series lineup of Mahindra tractors is almost identical to the 7000 series CC tractors. They are very similair in appearance and I know they are both mitsubishi contracted machines. You may want to do some research on the 2615 and 2815 Mahindra tractors because I think there is a good chance that one of them is identical to your machine. If you can confirm this then a Mahindra Dealer should be able to give you more specific information regarding your engine. :thumbsup:

 

[F100Panel]

Well.... I'm sitting rereading everything in the reponses... I think the answer is in there to be had, it just needs to be sorted through in my thought process pattern. Coupled with that on the way back from the Cub Dealer I stopped & saw my cousin, a retired machinist from a farm family who LOVES equipment... I think he too may have thrown a piece of the key into the pile. This morning I'm looking at the head bolt tightening pattern. My cousin thought 45 foot pounds for a diesel head gasket kinda light for a diesel. Hmmmmm... I'm thinking that is one strange head bolt tightening pattern in the diagram. Bolts 1 to 3 out of eleven get tightened first, in a row all down the side and on the head away from the cylinders over the exhaust port section of the head. The other 8 bolts surrounding the cylinders get torqued in a sucession that looks like a more appropriate pattern to torquing a head.. WELL..... The 3 dirty bolts/outside the valve cover with #10 on top are away from the cylinders.. NOW I'm thinking the key to the puzzle- Torque the #10's to the low torque setting and the number 13's surrounding the cylinders to the middle torque setting.. I'll debate that a few days, see what you guys think & maybe take a shot at it middle of next week.... Any thought out there? The bolts are all the same size & length. The numbers on top, 3 with #10 and 8 with #13 even though the #13 is an odd number for hardness has to be hardness designation?