Author Topic: 1966 230SL Re-torque issue  (Read 1533 times)

dnadanny1

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1966 230SL Re-torque issue
« on: February 15, 2020, 01:38:07 »
Hi All.

I have recently replaced my cylinder head and gasket. And, I heard that the cylinder bolts should be re-torque. However, I dont know how many miles should I drive before I re-torque my cylinder bolts.
Also, if I dont do the re-torque, what is the consequence that I should concern?

Any comment is appreciated.

Thanks,
Danny

Tyler S

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Re: 1966 230SL Re-torque issue
« Reply #1 on: February 15, 2020, 02:48:11 »
The Retorque should be done within 500 miles. This is done because the torque value will change after a few heat/cool cycles. Failure to retorque the head bolts can result in a blown head gasket down the road. Be sure to retorque the head when the engine is hot. Then adjust the valves the next morning on a cold engine.
1968 (67) 250sl. 4 speed manual. DB180 Silver
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ja17

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Re: 1966 230SL Re-torque issue
« Reply #2 on: February 15, 2020, 15:44:30 »
The head bolts on these cars are not "stretch type" so occasional re-torque will keep things to spec. Re-torque will also prevent head bolts from locking or rusting in place. Hopefully you oiled the bolt threads when you had the head off. Dry and oiled torque values will vary quite a bit. Lightly lubricating the threads will also prevent bolts from seizing. Be sure to release the radiator cap so there is no pressure in the cooling system before you begin. Loosen then re-torque each bolt one at a time in proper sequence. 
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

dnadanny1

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Re: 1966 230SL Re-torque issue
« Reply #3 on: February 16, 2020, 05:59:35 »
Thanks for input from both of you.

1) I have a tightening sequence graph provide by elring. Can I also follow the graph for re-torque?

2) When I re-torque, I should loose the bolt by how much? a turn? half a turn?

3) As I cant find graphite oil, I used ROCK PASSION's graphite grease lightly, e.g. between bolt and washer, thread of bolt. Is that ok?

Thanks again.,
Danny

Pawel66

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Re: 1966 230SL Re-torque issue
« Reply #4 on: February 16, 2020, 08:53:48 »
You are a Full Member, please take a look here in our Technical Manual: https://www.sl113.org/wiki/Restricted/ValveAdjustmentTour#HeadBolt
Pawel

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dnadanny1

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Re: 1966 230SL Re-torque issue
« Reply #5 on: March 04, 2020, 13:31:50 »
Thanks for your information. I have finished the reading. Is that mean I need to drive 15000 miles before re-torque?
However, Tyler S. said The Retorque should be done within 500 miles.
Which one is correct?

Thanks,
William

mrfatboy

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Re: 1966 230SL Re-torque issue
« Reply #6 on: March 04, 2020, 13:59:27 »
After the first retorque at 500 miles after replacing a head gasket it is advisable to retorque every 15,000 miles.

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ja17

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Re: 1966 230SL Re-torque issue
« Reply #7 on: March 05, 2020, 05:32:03 »
When replacing a head gasket  torque down the head and adjust the valves. This first sequence is done on a freshly assembled, not runnable, cold engine with a new head gasket. After first warm-up (full operating temperature) of a freshly assembled runnable engine,  loosen the radiator cap and re-torque the engine while still warm. Use correct tightening sequence, but loosen the bolts one or two turns, one at a time and re-torque to spec then move to the next. Adjust the valves again when engine cools. The last re-toque sequence is done after 500 miles approximately, on a warm engine, adjust the valves again when engine cools. Always relieve the pressure in the cooling system before loosening any head bolts. Normal maintenance should include the re-toque and valve adjustment every 12,000 to 15,000 miles. Engines with leaky head gaskets, stuck head bolts and rusted head bolts are usually those engines which have not ever had head re-torqueing maintenance. Oiling the head bolts during the original engine assembly is critical for getting correct torque specs. Some bolt torque charts give different values for torqueing bolts oiled or dry. Naturally it is not necessary to remove the bolts and oil them during re-torque in most cases since the original oil from engine assembly, should still be present on the threads. In addition, just the act of loosening the bolt for re-toque, on a warm engine will allow some oil to migrate under bolt heads and down along the bolt shaft to the threads. On rare occasions, during re-torque service, I have come across issues of rusted head bolts and stuck head bolts from dry assembly (no oil) on bolt threads. During these instances, I have removed each bolt one at a time, in sequence, and cleaned and oiled the threads then re-installed and torqued to spec. Do not fail to loosen the radiator cap before loosening any head bolt. The pressure in the cooling system could allow some coolant leakage into the threads of the loosened head bolt or worse.
« Last Edit: March 05, 2020, 05:37:38 by ja17 »
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback