Head Re-torque

[pfrederi 17,700]

After overhauls or repair Kohler service manual and everyone here specifies re-torquing head bolts after warm up.  Never heard it mentioned in the WH or Kohler User manuals  anywhere about re-torquing on a new machine...wonder why that wasn't directed...

[ebinmaine 67,397]

I've wondered the same thing. I've run it by friends that are technicians.

 

I can't speak for the specific Sciences behind it. Hopefully somebody with a better understanding than me will pipe up.

 

I've had discussions in both directions of yes it's always necessary or no you never need to do it.

 

My thought process is, too many to similar materials for my comfort level are in play so I'm always going to retorque a cylinder head.

 

In the case of a big block Kohler. The block is cast. The head bolts are steel. The cylinder head of course is aluminum.

Some serious differences in the rates of expansion and contraction there.

 

 

I've had the cylinder head off of maybe a dozen engines? I was probably two or three deep into that when I learned that they needed to be rechecked.

When I go back and tighten up 10 bolts, one to three of them will move.

 

 

 

[Pullstart 62,831]

31 minutes ago, ebinmaine said:

My thought process is, too many to similar materials for my comfort level are in play so I'm always going to retorque a cylinder head.

 

In the case of a big block Kohler. The block is cast. The head bolts are steel. The cylinder head of course is aluminum.

Some serious differences in the rates of expansion and contraction there.

*dissimilar materials*   I agree.  It’s worth doing!  

[Fordiesel69 263]

It depends on the head gasket used.  If you re-use the old one, no you do not have to re-torque.  If you use a brand new one, either OEM or aftermarket, you will absolutly need to retorque after some thermal cycles.  

[ebinmaine 67,397]

I know it's not the original discussion but I'd also like to add that replacing the cylinder head BOLTS probably does not get done often enough.

 

 

None of the engines I've been into are less than 30 or 40 years old and I've started replacing the cylinder head bolts and washers on every single one of them.

 

 

 

[ri702bill 8,311]

48 minutes ago, ebinmaine said:

When I go back and tighten up 10 bolts, one to three of them will move.

 

And there you have it folks. AND if it's the 2 closest to the exhaust port...  guess what?? That is the most common spot for the gasket to fail, as that area see the greatest thermal swing in temperatures. The Kohler K Series Manual mentions to retorque as necessary - no number of times given. I take it that means until it holds torque on all bolts when cold.

 

 

KohlerKseriesManual.pdf

[Skwerl58 704]

When I got my 1054 going,unstuck the exhaust valve,  removed the head, cleaned it all up, smoothed it up and replaced the head. Torqued it down per specs and after running for a short while I retorqued it and was surprised how many bolts needed it. I then ran it again and retorqued and a couple bolts definitely needed it. I was surprised but rechecked because of post here on Red Square concerning doing it. It takes maybe 10- 15 minutes so why not?

[8ntruck 6,998]

One does wonder what the proceedure at the Kohler factory was for torquing head bolts at initial engine assembly was.  Maybe they did a test run on the engine, then retorqued the bolts?

[pfrederi 17,700]

1 hour ago, 8ntruck said:

One does wonder what the proceedure at the Kohler factory was for torquing head bolts at initial engine assembly was.  Maybe they did a test run on the engine, then retorqued the bolts?

 

 

That was really my point.  I do not think they test ran them  and they are new head gaskets which might compress some... just puzzled

[squonk 41,051]

Dissimilar metals. Expand and contract at different rates. Head gaskets shift. A 68 small block Chevy could run over 20 years on steel head gaskets with iron blocks and heads with no issues. An 82 K car with an aluminum head and iron block and composite gasket will pop it's cork within 5 years mostly from this movement. Aluminum wheels need to be retorqued after 50 miles of installation. Because of movement between the steel hub, lugs and nuts. I service a Jeep in upstate NY. Rotated the tires. Lady drove to Washington D.C. and halfway home a wheel became loose. They tried to blame me. Sorry. over 300 miles since I touched it and she never brought it in for a re torque. Big bold letters on the invoice:

 

Aluminum wheels must be re-torqued within 50 miles! 

[clueless 2,983]

28 minutes ago, squonk said:

Dissimilar metals. Expand and contract at different rates. Head gaskets shift. A 68 small block Chevy could run over 20 years on steel head gaskets with iron blocks and heads with no issues. An 82 K car with an aluminum head and iron block and composite gasket will pop it's cork within 5 years mostly from this movement. Aluminum wheels need to be retorqued after 50 miles of installation. Because of movement between the steel hub, lugs and nuts. I service a Jeep in upstate NY. Rotated the tires. Lady drove to Washington D.C. and halfway home a wheel became loose. They tried to blame me. Sorry. over 300 miles since I touched it and she never brought it in for a re torque. Big bold letters on the invoice:

 

Aluminum wheels must be re-torqued within 50 miles! 

Did a K car ever make 5 years.

[Handy Don 12,204]

2 hours ago, squonk said:

An 82 K car with an aluminum head and iron block and composite gasket will pop it's cork within 5 years mostly from this movement.

I learned this when I asked why the head gasket on my Dodge Caravan failed. Car overheated badly and it was way beyond worth repairing the complete damage at that point but a preemptive head gasket replacement would have been a lot less and worth doing. Sigh, I liked that car, too!

Edited 7 hours ago by Handy Don

[8ntruck 6,998]

2 hours ago, clueless said:

Did a K car ever make 5 years.

There is a maroon K car wagon still roaming around Sedalia MO.  See it a couple times per month.

[ebinmaine 67,397]

2 hours ago, clueless said:

Did a K car ever make 5 years.

 

Given actual maintenance they would...

The 2.2 Liter in particular was a pretty decent engine considering the times.  

 

 

[953 nut 55,163]

7 hours ago, pfrederi said:

 

 

That was really my point.  I do not think they test ran them  and they are new head gaskets which might compress some... just puzzled

Just out of curiosity I checked the head bolt torque on a Kohler Magnum 10 engine. The manual calls for 25 to 30 foot pounds, I started at 25, no movement, went to 30, still ne movement, change to 40, nothing. At 45 foot pounds a couple of the head bolts did move a bit, most didn't. My guess is the factory torques them to 45 knowing they are using new bolts and no owner is going to retorque them.

When torqueing head bolts I lay this little memory aid on top of the head so I don't have to look up the sequence.