Head Retorque After Running Engine
Thread Starter
Pro
Joined: Jan 2004
Posts: 503
Likes: 0
From: Forney Texas
Head Retorque After Running Engine
As some of you may remember, I recently lost a head gasket due to my lack of "cycling" the new head bolts and not retorqueing the heads after running the engine. I have now finished the head gasket replacement and have run the engine through several heat cycles and everything appears to be good. I think I am now ready to disassemble for the final torque.
Before I begin the disassembly is running the engine through several heat/cooling cycles, basically at idle, good enough? Is there any reason to put the car on the road?
I don't dislike working on my car, I do however dislike doing things over. Any thoughts would be appreciated.
90Indy
Before I begin the disassembly is running the engine through several heat/cooling cycles, basically at idle, good enough? Is there any reason to put the car on the road?
I don't dislike working on my car, I do however dislike doing things over. Any thoughts would be appreciated.
90Indy
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Design and specs are a one time deal and the only thing more twist is going to do is ruin the sealant on the head bolt threads. Assuming you had the typical leak at #7, you need to make sure it didn't wear a groove between the coolant passageway and the cylinder and you want to make sure the deck is square and that the heads aren't warped. Otherwise, following the correct torque sequence and values the first time should keep it leak free.
Thread Starter
Pro
Joined: Jan 2004
Posts: 503
Likes: 0
From: Forney Texas
Design and specs are a one time deal and the only thing more twist is going to do is ruin the sealant on the head bolt threads. Assuming you had the typical leak at #7, you need to make sure it didn't wear a groove between the coolant passageway and the cylinder and you want to make sure the deck is square and that the heads aren't warped. Otherwise, following the correct torque sequence and values the first time should keep it leak free.
I don't mind torqueing the heads again, I just want to make sure I am getting the most bang for the buck.
90Indy
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
I have always done one heat cycle
Get it up to full oil and water temp & let it run for 20-30 minutes,
shut it off for a full cool down,, all the way to cold, like the next morning,
then re-TQ sequentially to spec
Get it up to full oil and water temp & let it run for 20-30 minutes,
shut it off for a full cool down,, all the way to cold, like the next morning,
then re-TQ sequentially to spec
Melting Slicks
Joined: Oct 2000
Posts: 3,426
Likes: 4
From: Heidelberg PA
Cruise-In V Veteran
If they are NEW - retorque, not really necessary if heads are seasoned. Don't ask me how I know
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Melting Slicks
Joined: Feb 2004
Posts: 3,307
Likes: 111
From: Tucson AZ
Most of the new Fel Pro head gaskets do not require a re-torque, but a lot of us do it anyway. I am not sure what Cometic recommends, but we always retorque them.
The idea to this is not that the bolts have backed out, but that the heat expansion of the head has crushed the gasket slightly. The bolts require a certain amount of stretch to maintain the pre-load crush on the gasket. A re-torque after it has been thoroughly heat cycled insures this stretch pre-load is maintained.
Usually the culprit in head gasket problems is a surface that is slightly warped, or a lean mixture condition.
The idea to this is not that the bolts have backed out, but that the heat expansion of the head has crushed the gasket slightly. The bolts require a certain amount of stretch to maintain the pre-load crush on the gasket. A re-torque after it has been thoroughly heat cycled insures this stretch pre-load is maintained.
Usually the culprit in head gasket problems is a surface that is slightly warped, or a lean mixture condition.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Ive never had to retorque heads, think the mfr prints it on the pkg...I did double check twice and all was well. your results may vary though.
On a copper head gasket I definitely would fwiw.
On a copper head gasket I definitely would fwiw.
Thread Starter
Pro
Joined: Jan 2004
Posts: 503
Likes: 0
From: Forney Texas
I guess it basically comes down to what you are most comfortable with. The ARP bolts were "cycled" 5 times before the final torque which is what ARP recommends. The AFR Eliminator heads are new and if I remember correctly AFR recommends a retorque while Fel-Pro does not.
Since replacing head gaskets is a real PITA in my opinion, I will take the time to retorque the heads. Doing this project a third time would not be good for my marriage in the near term.
Thanks for replies.
90Indy
Since replacing head gaskets is a real PITA in my opinion, I will take the time to retorque the heads. Doing this project a third time would not be good for my marriage in the near term.
Thanks for replies.
90Indy
Safety Car
Joined: Oct 2001
Posts: 4,763
Likes: 1
From: Connectivette
This story sounds hauntingly familiar...
http://forums.corvetteforum.com/show....php?t=1785319
At any rate....after cleaning up the above mess my process of "rolling-in" my new ARP bolts consisted of torquing the bolts down and letting them sit over night for 5 straight nights. I let my final torque sit for a week while I was on vacation and checked them again when I returned and dropped my intake base back on the motor.
I went through about a 1/2 dozen(50 miles or so)heat cycles before I checked the bolts. I checked all the bolts I could reach without dropping the exhaust or removing my rocker arms....non of them budged so I buttoned it back up
http://forums.corvetteforum.com/show....php?t=1785319
At any rate....after cleaning up the above mess my process of "rolling-in" my new ARP bolts consisted of torquing the bolts down and letting them sit over night for 5 straight nights. I let my final torque sit for a week while I was on vacation and checked them again when I returned and dropped my intake base back on the motor.
I went through about a 1/2 dozen(50 miles or so)heat cycles before I checked the bolts. I checked all the bolts I could reach without dropping the exhaust or removing my rocker arms....non of them budged so I buttoned it back up