can i re-torque stock head bolts

supraluver4life · 12-10-2009, 08:31 PM

so my head gasket is in excellent condition (engine only has 51,000 mi) and i was wondering if i could just go in and tighten the head bolts down to 75ft/lbs instead of leaving at 58ft/lbs or whatever toyota had it at stock. i want to know if this is ok to do because if it is ill do that and not have to worry about getting a new hg before im actually wanting to rebuild it.

any help is fantastic

cre · 12-10-2009, 10:13 PM

There are two negative factors to retorquing after so long... I'm going off memory here so forgive me if either isn't completely accurate. The first is that the jackets may have hardened and could be compromised; I don't think this is very likely. And the other is that now that the bolts have sat in place for so long you're not going to get an accurate torque value for each and may not get them uniformly tightened or you may not even be able to tighten them due to artificially high readings from seizing.

Now, with that out of the way, I think you're fine to do it. Just crack each bolt loose in the correct order by 1/4 of a turn and tighten them in order in multiple passes.

Do keep in mind that it is possible that whoever did the HG last did use a higher torque level... don't go higher just because...

supraluver4life · 12-10-2009, 10:29 PM

ok and i have never built a 7mgte only honda b16's so is there a specific bolt pattern thati should follow when tightening them and visa versa for loosening??

cre · 12-10-2009, 10:54 PM

Yes, there is an order and it is critical.

Here's the service manual's complete section on the head and related work: http://www.cygnusx1.net/Supra/Librar...ection=EM&P=32
Pay attention to all torque values.

The third image down shows the order for removing/loosening the bolts. Use the opposite order for tightening.

supraluver4life · 12-11-2009, 02:00 AM

oh and is there any risk of the head bolts sheering off because theyre kinda old?

oh and thanx

cre · 12-11-2009, 02:04 AM

I would be flat out amazed if that happened. Worst thing I've ever seen is people stripping the sockets out from not ensuring the driver was in all the way. The stock head bolts are VERY robust.

steves 86 supra · 12-13-2009, 12:48 AM

you can reuse your head bolts as long as there not pitted

to retorque your head back each bolt off about a quarter of

a turn before you retension it, make sure you drop the coolant first

you will find an engine drain bung at the back of the block behind the

turbo,

i had a head gasket start to leak on my old NA motor about 1500 Ks

from home, retorqued it out the back of a servo & ended up putting

about another 50K on it while i built the turbo engine

ps dont use your tension wrench to back bolts off !

cre · 12-13-2009, 04:26 AM

Quote:

Originally Posted by steves 86 supra

you can reuse your head bolts as long as there not pitted

Stretch is the primary concern (the TSRM has details on measuring the bolts to determine if they're healthy). Sure, if they're pitted, cracked, flaking, etc. you don't want to reuse them. You can't check either without pulling them and compromising the HG so it's a moot point in this discussion.

A re-torque usually won't last long if the HG has already started leaking... the longer it leaks the more the gasket material is subject to erosion. Catching it before it happens is key.

supraluver4life · 12-16-2009, 12:11 AM

i believe it hasnt began to leak yet because compression is still great. and by completely pulling the head bolts i risk comprimising the head gasket?? because i want to replace the eventually but if it isnt necessary then i wont

pablo94sc · 12-18-2009, 06:59 AM

If you have have the head off, replace the gaskets and do not re-use the head bolts. They are most likely torque-to-yield and will have stretched the first time installed and torqued to spec. Buy new ones and save yourself the pain of a blown HG when the bolts fail to properly keep the head mated to the block and lift under heavily acceleration (or boost if you have a turbo).

12-10-2009, 08:31 PM	#1
supraluver4life 3" Exhaust Join Date: Nov 2009 Location: Santa Fe, NM Posts: 135	can i re-torque stock head bolts so my head gasket is in excellent condition (engine only has 51,000 mi) and i was wondering if i could just go in and tighten the head bolts down to 75ft/lbs instead of leaving at 58ft/lbs or whatever toyota had it at stock. i want to know if this is ok to do because if it is ill do that and not have to worry about getting a new hg before im actually wanting to rebuild it. any help is fantastic __________________ Cusco front, Tein Rear coilovers Massive DDP, 3'' custom catless exhaust, Tsudo muffler 4.5'' outlet, Apexi cold air intake, Act stage 3 clutch, ct26 turbo (stock)- 10psi +300rwhp "Not driving a car because its too nice, is like not fucking your gf so shes still tight for the next guy"

12-10-2009, 10:29 PM	#3
supraluver4life 3" Exhaust Join Date: Nov 2009 Location: Santa Fe, NM Posts: 135	ok and i have never built a 7mgte only honda b16's so is there a specific bolt pattern thati should follow when tightening them and visa versa for loosening?? __________________ Cusco front, Tein Rear coilovers Massive DDP, 3'' custom catless exhaust, Tsudo muffler 4.5'' outlet, Apexi cold air intake, Act stage 3 clutch, ct26 turbo (stock)- 10psi +300rwhp "Not driving a car because its too nice, is like not fucking your gf so shes still tight for the next guy"

12-11-2009, 02:00 AM	#5
supraluver4life 3" Exhaust Join Date: Nov 2009 Location: Santa Fe, NM Posts: 135	oh and is there any risk of the head bolts sheering off because theyre kinda old? oh and thanx __________________ Cusco front, Tein Rear coilovers Massive DDP, 3'' custom catless exhaust, Tsudo muffler 4.5'' outlet, Apexi cold air intake, Act stage 3 clutch, ct26 turbo (stock)- 10psi +300rwhp "Not driving a car because its too nice, is like not fucking your gf so shes still tight for the next guy"

12-16-2009, 12:11 AM	#9
supraluver4life 3" Exhaust Join Date: Nov 2009 Location: Santa Fe, NM Posts: 135	i believe it hasnt began to leak yet because compression is still great. and by completely pulling the head bolts i risk comprimising the head gasket?? because i want to replace the eventually but if it isnt necessary then i wont __________________ Cusco front, Tein Rear coilovers Massive DDP, 3'' custom catless exhaust, Tsudo muffler 4.5'' outlet, Apexi cold air intake, Act stage 3 clutch, ct26 turbo (stock)- 10psi +300rwhp "Not driving a car because its too nice, is like not fucking your gf so shes still tight for the next guy"

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12-10-2009, 10:13 PM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	There are two negative factors to retorquing after so long... I'm going off memory here so forgive me if either isn't completely accurate. The first is that the jackets may have hardened and could be compromised; I don't think this is very likely. And the other is that now that the bolts have sat in place for so long you're not going to get an accurate torque value for each and may not get them uniformly tightened or you may not even be able to tighten them due to artificially high readings from seizing. Now, with that out of the way, I think you're fine to do it. Just crack each bolt loose in the correct order by 1/4 of a turn and tighten them in order in multiple passes. Do keep in mind that it is possible that whoever did the HG last did use a higher torque level... don't go higher just because...

12-10-2009, 10:54 PM	#4
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Yes, there is an order and it is critical. Here's the service manual's complete section on the head and related work: http://www.cygnusx1.net/Supra/Librar...ection=EM&P=32 Pay attention to all torque values. The third image down shows the order for removing/loosening the bolts. Use the opposite order for tightening.

12-11-2009, 02:04 AM	#6
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	I would be flat out amazed if that happened. Worst thing I've ever seen is people stripping the sockets out from not ensuring the driver was in all the way. The stock head bolts are VERY robust.

12-13-2009, 12:48 AM	#7
steves 86 supra Stock Join Date: Dec 2009 Location: port macquarie Posts: 4	you can reuse your head bolts as long as there not pitted to retorque your head back each bolt off about a quarter of a turn before you retension it, make sure you drop the coolant first you will find an engine drain bung at the back of the block behind the turbo, i had a head gasket start to leak on my old NA motor about 1500 Ks from home, retorqued it out the back of a servo & ended up putting about another 50K on it while i built the turbo engine ps dont use your tension wrench to back bolts off !

12-18-2009, 06:59 AM	#10
pablo94sc Stock Join Date: Dec 2009 Location: TN Posts: 3	If you have have the head off, replace the gaskets and do not re-use the head bolts. They are most likely torque-to-yield and will have stretched the first time installed and torqued to spec. Buy new ones and save yourself the pain of a blown HG when the bolts fail to properly keep the head mated to the block and lift under heavily acceleration (or boost if you have a turbo).