Head bolt re-torque

[Thousand Dollar Supercar]

I've just done a rough head gasket replacement in my Rover straight 6, which has an alloy head that I'm told is soft and likely to cause the gasket to fail again.

I used a modern aftermarket gasket with some gasket sealer and I re-used the existing head bolts.

The car has been driven twice since, not long trips but enough to get the engine fully up to temperature each time.

Should I retorque the head bolts? If yes, after how long - now or after a few hundred kms?

[Simon]

Yes, after about 800-1000 kays?

Easer that finding another head and changing it...

Just do it.

[fuel]

most head gaskets these days are mono-torque, therefore don't require the head bolts to be re-torqued. For the gaskets which do need re-torquing, it's usually after 100kms or a few hours of running. I probably wouldn't worry about re-torquing the bolts to be honest.

[Unclejake]

I think three things:

1) Headgasket sealant is bad, but it is too late so don't worry about that.

2) A 'soft' head will not exactly make the HG blow, but will give you issues forever. A Rockwell hardness check would be worthy next time.

3) Re-tightening the head is a great idea. Do it as hot as you possibly can. Don't forget to crack the headbolts back a smidge before cranking them up again.

Also - adding anything to your coolant water prior to the re-torque is not the best idea. If you do develop a pre re-torque leake then you can't get rid of is well if there is 'anti-freeze' trapped in there

[fulloc]

Steel and/or graphite head gaskets DO NOT need to be re-torqued.

just had this discussion with the people at NZ Gaskets last week.

also all ACL gasket a mono-torque i believe .

IMO leav it alone.

[KKtrips]

Lots of conflicting statements but I will add my practice to the fore..

I always retorque heads no matter what the gasket is.

I torque the head down as per usual practice and then after 800Km I retorque.

Alloy heads I retorque when cold and Steel heads I retorque when hot <---IMO this is important..

[Thousand Dollar Supercar]

Alloy heads I retorque when cold and Steel heads I retorque when hot <---IMO this is important..

After reading around the net (and finding more conflicting statements), I've decided I agree with re-torquing the Rover's alloy head when cold.

If I do it hot, the metal's expanded (and the block and head are cooling unevenly while I work) - I'll set my torques and later on when the motor's cool / metal's contracted, the bolts will be loose and uneven.

Some people say you back the bolts off before you torque them back up, so that the torque wrench isn't tricked by having to overcome static friction. Others say that if you do this, why did you wait x heat cycles / hundred kms? Backing the bolts off has rendered that a waste of time.

And about the modern gaskets being monotorque - can re-torquing these do any harm other than being a waste of time? I want to do everything I can to get a few miles out of this miserable motor before the gasket goes again.

[KKtrips]

Back off one at a time and retorque it..

Retorquing it will not do any harm in my opinion..

[Unclejake]

Back off one at a time and retorque it..

Retorquing it will not do any harm in my opinion..

100% agree.

[fulloc]

yeah i really dont think it would hurt i guess its just not necessary.

imaging if workshops had to get every head job back in for a re-torque

on a side note have you had the head tested for hardness?

i kinoe for example 3k etc heads go soft when they are cooked.

[KKtrips]

imagine if workshops had to get every head job back in for a re-torque

When I was mechanic this is exactly what I did. Its what I call doing a proper job.

[fulloc]

touche.

i deal with fuckwit compliance yards that replace one brake disc or one wheel cylinder.

its scary.

in reality no workshops i know re-torque, or dont unless they absolutely have to.

[CaMpylobacter]

imagine if workshops had to get every head job back in for a re-torque

When I was mechanic this is exactly what I did. Its what I call doing a proper job.

BLAM

99.999% of customers wouldn't care at all, and would probably be eager to do this as it's seen as a aftersales service/massive PR thing, as well as a bit of security for the workshop in question that they will be less likely to get a claim on the job. plus most headgasket jobs aren't drive in drive out after like a day so often the workshop can keep the car in an extra night and retorque. choice.

i used a monotorque gasket on my 4m. half the bolts were loose after the first running period which was only about 30minutes of coolaning system bleeding and a general bugger around up and down the road a couple of times.

also my old man was lazy and didn't retorque his z18 in his navara and it shat it's pants within 6 months. slamming another gasket in there and doing retorque as per kk's instructions (generic 'proper' mechanics method) and it's going strong after running on all sorts of different shithouse fuels and getting a generally bad life for like 2 and a half years.

[cletus]

i had a fwd 626 years ago, they were well known for blowing gaskets.... i retorqued it about 3 or 4 times and it never blew again even giving it death.

the only engine i wouldnt be doing a retorque on would be later model engines with torque to yield bolts

[KKtrips]

the only engine i wouldnt be doing a retorque on would be later model engines with torque to yield bolts

This is a very valid point - I forgot about them..

FYI - TTY bolts are generally identified by a low initial torque value followed by a series of angular settings

ie 25ftlb then 90 degrees followed by 90 degrees again..

[Thousand Dollar Supercar]

on a side note have you had the head tested for hardness?

Yes, and it failed down one side. And I still reused it, because the only other option was an engine swap and I haven't got my mechanics wings yet.

Hence the concern.

However:

i had a fwd 626 years ago, they were well known for blowing gaskets.... i retorqued it about 3 or 4 times and it never blew again even giving it death.

my old man was lazy and didn't retorque his z18 in his navara and it shat it's pants within 6 months. slamming another gasket in there and doing retorque as per kk's instructions (generic 'proper' mechanics method) and it's going strong ...

So there's hope.

[fulloc]

TTY head bolts are a worry but i rekon youll be ok.

IMO swapping a motor is an easier job than rebuilding one.

[Unclejake]

^ If he was going to do an engine swap I expect it is a fair assumption that the replacement would not be the asthmatic and hard to get parts for, straight six Rover motor

[Thousand Dollar Supercar]

^ If he was going to do an engine swap I expect it is a fair assumption that the replacement would not be the asthmatic and hard to get parts for, straight six Rover motor

Well actually it would have been. There's a 2600 motor up in Whangarei, I was talking to the seller and agreeing that it would be better to stick that motor in whole rather than risk swapping its head onto my block.

The only part that's been hard to get for the Rover so far was the cambelt tensioner (no longer available).

The option always exists to swap to the asthmatic-but-easier-to-get-parts-for V8 Rover motor. If the sixes give me too much grief, I may either attempt this or sell the car to someone who will.

[Unclejake]

Shot down