Re- torque head bolts?

[Captndrydock]

I was recently advised to re torque the head bolts on my 77 135 hp Chrysler outboard twice a year. My concern is whether they are torque to yield bolts or normal bolts? I'll probably leave well enough alone, but still curious if this is standard preventive maintenance on these motors.

 

[racerone]

Yes , it is a procedure that should be done.-----Simply ignore this modern " torque to yield " stuff.----Many motors have suffered because folks did not know about or do simple stuff!

 

[topgun3690]

Torque spec for head bolts is only 225 In Lbs, or 18.75 Ft Lbs......so they are not really that tight. Main thing is to follow the correct sequence when torqueing them down....and do it in several steps. Do all at like half torque, then 3/4, then full torque.

 

[racerone]

Head bolts are steel.------Block and cylinder head are aluminum.-----Aluminum expands at twice the rate of steel.-----Therefor bolt torque needs to be checked on occasion.----Very few are aware of the concept.

 

[jerryjerry05]

Had twin 88/85hp Forces.
Never retorqued and never had a problem.
Now if I had the head rebuilt?? I'd do that procedure.

 

[lgaytan]

I just rebuilt my motor, and torqued it to spec very low to my feeling and according the sequence, it leaked at the first start, not sure if the torque wrench is accurate or not, it is just a Autozone wrench. I decided to go a little bit higher 22 ft lb, and it did stopped leaking, after the motor warmed up I again retightened noticed they backedup a little, so I kind of makes sense that you should retighten after a couple years of expansion and contraction of the material.

 

[Captndrydock]

Yeah, re-torquing the head bolts as routine maintenance is certainly open to debate. I've been chatting with some very experienced Chrysler guys that are getting a good laugh out of this advice.

 

[Captndrydock]

I just rebuilt my motor, and torqued it to spec very low to my feeling and according the sequence, it leaked at the first start, not sure if the torque wrench is accurate or not, it is just a Autozone wrench. I decided to go a little bit higher 22 ft lb, and it did stopped leaking, after the motor warmed up I again retightened noticed they backedup a little, so I kind of makes sense that you should retighten after a couple years of expansion and contraction of the material.

I'm not a very experienced mechanic, but I'd guess that your gasket was still compressing.

 

[Nordin]

From my experience the first reason you have to retorque the head bolts is if you have changed the gasket, the new gasket will be compressed.
The factory workshop manual calls for retorque after one hour or so and yes absolutely the head bolts should be retorque.
When the power head warms up the head, block and head bolts will expand different cause of different material.
But after one or maybe two retorque you should not have to do it more.