Today at Atelier Kaz - ex-Honda R&D, F1, Indy/CART engineer

Hi Kaz,
It's hard to understand how a bolt of these dimensions could go into the hole cross threaded! I look forward to the next installment to see how you will you repair the female thread.

BTW looks like you got it all nice and clean.

Peter

Dear Kaz,

Some mechanic stripped the threads in my engine block that the upper forward mounting bolt of the A/C idler pulley is supposed to screw into – the same one that is damaged in the NSX you’re just working on. I don’t know whether the mechanic cross-threaded the bolt first or just completely over tightened it but even a factory new Honda bolt cannot find anything to hold on to in there anymore.

Do you know whether there are any oil or water passages immediately around or behind the A/C idler pulley mounting points? I’d like to have a Time-Sert installed in the engine block but don’t want to damage any oil or water passages in the process.

Originally Posted by PeterW

Hi Kaz,
It's hard to understand how a bolt of these dimensions could go into the hole cross threaded! I look forward to the next installment to see how you will you repair the female thread.

BTW looks like you got it all nice and clean.

Peter

Hi, Peter.
No surprise and easily understandable from the point of TB cover design.
Also, the workshop manual doesn’t tell any know-hows for this kind of task.


These two long bolts need to pass through the small diameter metal collar bonded to the TB lower cover before reaching the female thread on the engine side.

TB cover itself has rubber seal all the way around its edge so in order to install it in the right position, you must press it down to hold it against the force of rubber seal trying to go back to its free load shape.

Therefore, installation of any TB covers will be pretty tight and if the TB Lower cover was not aligned perfectly, the bolt won’t be aligned square to the female thread.

Normally, people won’t install these bolts until after the TB Lower and Front covers were installed because it just gets in the way and this is the bad idea. You won’t have enough space and tolerance to move the lower cover to align the bolt holes.
I normally install all of the bolts including these two long ones without installing the A/C idle pulley bracket just for the alignment purpose before tightening other bolts to the spec.
In this way, by the time when I install the actual bracket, the metal collars are already aligned and you can re-install the bolts with ease.

Originally Posted by greenberet

Dear Kaz,

Some mechanic stripped the threads in my engine block that the upper forward mounting bolt of the A/C idler pulley is supposed to screw into – the same one that is damaged in the NSX you’re just working on. I don’t know whether the mechanic cross-threaded the bolt first or just completely over tightened it but even a factory new Honda bolt cannot find anything to hold on to in there anymore.

Do you know whether there are any oil or water passages immediately around or behind the A/C idler pulley mounting points? I’d like to have a Time-Sert installed in the engine block but don’t want to damage any oil or water passages in the process.

Hi, greenberet.
Not sure the level of your damage so it’s not easy to find the best method in repairing your female thread.

I had a quick look at the engine block and there is more than enough meat left around the circumference of the bolt hole so enlarging the diameter by 1mm or so is not a problem.
Although I didn’t measure it accurately, the depth of the hole looked to be more than 5mm deeper than the actual length of which the bolt is threaded in.
In fact, it looked as if the hole was not threaded all the way to the end of the blind hole.

Therefore, if you can use the small diameter short length TimeSert, you should be fine.
The biggest challenge would be how to attach the drill bit square to the engine block in that limited space and actually drill the hole.

I’m planning to use the metal collar of the old TB cover as the straight line guide when rethreading the bolt hole.

Let’s see how it goes….

Kaz

Dear Kaz,

Thank you very much for the information. I don’t know whether re-tapping the threads would be enough but I’d feel better if a Time-Sert were in there the next time a mechanic torques down the A/C idler pulley. Since there is so little space in that area, I’m planning on having the work done the next time the engine is out of the car.