Head stamp for JIS TTY bolts??

[JHZR2]

I’m doing a timing belt on our odyssey, and @The Critic advised of some issues with specific bolts on Honda engines. I’ve searched myself and found such info.

One bit of info indicated that there were bolt headstands, JIS or otherwise, that indicated torque to yield. More specifically, this symbol:

Which I have no idea if this is true. FSMs say that many kinds of these bolts are “replacement” items after use.

All the bolts I’ve heard being potentially a softer alloy or similar, seem to be secured with red loctite.

Thing is, one of the “replace” bolts has a different head stamp:

This engine has head stamped bolts all over. Hard to make heads and tails.

Thing is, lots of bolts under there have the first headstamp.

Is there a specific try headstamp that is used for JIS or elsewhere?

Be it this or something else?

 

[Rand]

I thought the bolts with the dash -- or nothing meant regular tension bolt
not sure what the others mean I know in some applications a 10 or 12 means high tension but I don't think its used on cars.

H could just be Honda ?

 

[Trav]

The only bolts I would be concerned with are the tensioner mounting bolts, those would get replaced with OE bolts only. AFAIK there are no TTY bolts on that job. These are really the only markings you need to know. Some Honda bolts use a letter to identify the bolt length, measure the H lettered bolts and see if they are the same length.

 

[Nukeman7]

The only TTY bolt on a timing belt/water pump replacement job on the Honda Odyssey w/J35 motor is the large crankshaft pulley bolt. I have done four of these jobs and learned about two specific concerns:

(1) If you are using the Aisin kit instead of all OEM Honda parts, consider installing the special Honda taper shim on the idler pulley and grinding a relief gap in the aluminum motor mount bracket per TSB 08-045 to prevent the potential chirping noise.

(2) Pay particular attention to Honda's FSM procedure for purging the air from the hydraulic tensioner assembly for the serpentine belt. The tensioner should be rotated slowly a minimum of 4 full-range strokes before and after installing the serpentine belt. Failure to fully purge the trapped air will result in shearing of the bolt in less than 1000 miles! See this Thread about the broken tensioner bolt phenomenon on J35 engines which shows the factory bleeding procedure for the tensioner.

 

[Rand]

The only bolts I would be concerned with are the tensioner mounting bolts, those would get replaced with OE bolts only. AFAIK there are no TTY bolts on that job. These are really the only markings you need to know. Some Honda bolts use a letter to identify the bolt length, measure the H lettered bolts and see if they are the same length.

Nice chart I googled for a few min after posting and couldnt find anything honda specific!

 

[KrisZ]

Knowing high volume manufacturing, I highly doubt these symbols mean anything related to the assembly process.
They most likely represent physical properties which makes sorting at the factory much easier.

Install per FSM and don’t over think it.

 

[JHZR2]

The only bolts I would be concerned with are the tensioner mounting bolts, those would get replaced with OE bolts only. AFAIK there are no TTY bolts on that job. These are really the only markings you need to know. Some Honda bolts use a letter to identify the bolt length, measure the H lettered bolts and see if they are the same length.

View attachment 220189

This is super, thanks so much!! It’s really a missing link to knowing what is there. The H bolt is shorter than the 840MPa bolts. It also has red loctite. FSM says to replace all of them, other schools of thought were that the red loctite bolts are something different and may be TTY or something else. This seems to indicate otherwise.

The only TTY bolt on a timing belt/water pump replacement job on the Honda Odyssey w/J35 motor is the large crankshaft pulley bolt. I have done four of these jobs and learned about two specific concerns:

(1) If you are using the Aisin kit instead of all OEM Honda parts, consider installing the special Honda taper shim on the idler pulley and grinding a relief gap in the aluminum motor mount bracket per TSB 08-045 to prevent the potential chirping noise.

(2) Pay particular attention to Honda's FSM procedure for purging the air from the hydraulic tensioner assembly for the serpentine belt. The tensioner should be rotated slowly a minimum of 4 full-range strokes before and after installing the serpentine belt. Failure to fully purge the trapped air will result in shearing of the bolt in less than 1000 miles! See this Thread about the broken tensioner bolt phenomenon on J35 engines which shows the factory bleeding procedure for the tensioner.

Thanks for those insights.

Im using only OE Honda parts. Except spark plugs.

The serpentine belt on our 2014 doesn’t have the hydraulic design. It’s just a spring loaded unit.


This job has been long. Had to pause because of a bad motor mount. But tbh the hardest thing was pulling the ECU plastic cover. Some have a little visible tab. Mine doesn’t. Blindly pulling stuff like that often will cause a break in plastic, so it makes me grumpy and frustrated. The rest is just lousy access for everything. Nothing too hard.

 

[JHZR2]

I compared the new Honda bolts with the ones off the engine. The Honda FSM says to replace these, and there are stories of these bolts breaking in some situations.

But there is no sign of extension or changes to the threads.

 

[KrisZ]

TTY bolt elongation will be tiny, likely within the bolt length tolerance. You will not detect it when comparing to another. You would have to measure the same bolt before and after to measure the difference.