Head nut re-torque

Post by **dnac** » Wed Aug 16, 2006 8:42 am

Hi, I replaced the head gasget on my mog a few weeks ago, do I need to re-torque now that it has done a few hundred miles?

Post by **57traveller** » Wed Aug 16, 2006 9:11 am

Yes, 40 lb ft diagonally outwards from the centre. Also check rocker pedestal nuts 25lb ft. Then check and reset as necessary the valve clearances.

Post by **Kevin** » Wed Aug 16, 2006 9:15 am

Yes its normally done after about 500 miles.

Post by **KirstMin** » Wed Aug 16, 2006 10:50 am

This has been discussed before - and ratified by many a specialist - you do not need to re-torque a modern head gasket after 500 miles. The reason this is specified in the manual is because the original gaskets were asbestos no?

Its normal with head gaskets you now buy to fit them, torque, run the engine up to running temp and then re-torque. Job done.

That said, I dont think any harm will come if you re-torque after 500 miles.

Post by **bmcecosse** » Wed Aug 16, 2006 1:17 pm

Do it - you will be suprised how much more it pulls down. Many would say 40 ft lbf is low - but is what the manual says. I use 44 on my Minor engines - and 50 on the Mini which has the Y studs, and flanged nuts with washers.

Post by **Onne** » Wed Aug 16, 2006 1:51 pm

Modern cars use different studs, which shrink after a couple of hunderd miles. So they don't need re-torqueing. They need to be changed every time you do a headgasket though, unlike the Minor studs

Post by **KirstMin** » Wed Aug 16, 2006 2:17 pm

When i was referring to 'modern' I was referring to the head gaskets now used on minis and morris minors not modern cars themselves.

I had my engine re-built by an morris minor specialist (charles ware) last summer and on the head was a big sticker which said:

"RE-TORQUE AFTER INITIAL WARM UP AND NOT AFTER 500 MILES"

I was confused by this as it went against all the things I had read in the manual so when I swapped the head for a fast road one 6 months later I checked this with a different specialist (simon at morspeed) and he confirmed it.

That said, I dont s'pose it will do any harm. And my engine is a 1275 A+ torqued to 50 not a standard 1098 so each to their own

Post by **Kevin** » Wed Aug 16, 2006 2:18 pm

Its normal with head gaskets you now buy to fit them, torque, run the engine up to running temp and then re-torque. Job done.

That doesnt apply if you are using a traditional Copper faced gasket which are more suited to the Moggie engine.

Post by **bmcecosse** » Wed Aug 16, 2006 7:28 pm

Studs that shrink ??? Wow - wonder how they do that ? I'm truly amazed - and sceptical!

Post by **Onne** » Wed Aug 16, 2006 7:32 pm

I don't know exactly what they are called in English, I did my best. Literally they are translated as head stretch bolts.

Onne

Post by **Packedup** » Wed Aug 16, 2006 10:34 pm

Stretch bolts. Yep, lots of modern cars have them. Though I thought the idea was to tighten to a certain amount, then add a few degrees more. I suppose if there's any elasticity in them then the stretch will shrink when possible, keeping everything tight, but never thought of them like that before!

Post by **bmcecosse** » Thu Aug 17, 2006 7:22 am

Ahh - so they don't shrink - they just are long with a good elasticity - but are stretched slightly beyond the yield point, hence need to renew them. Sounds expensive!

Post by **Onne** » Thu Aug 17, 2006 9:54 am

thats what I meant

And I think about £20-£50 per set

Post by **Welung666** » Thu Aug 17, 2006 10:05 am

The head gasket set for Ole Red was around the £35 mark and that included the head bolts. I was told by Vauxhall that they stretch as they are tightened and bottom out in the holes in the block, meaning they can only be used once but they don't need re-tightening. Just torque up and go

Post by **bmcecosse** » Thu Aug 17, 2006 10:37 pm

The warning notice (way up ^^^^ there) is correct - the head should be torqued down after initial warm up - but I suggest it is also a v good idea to do it again after 500 miles.

Post by **Packedup** » Thu Aug 17, 2006 10:54 pm

I do it after a full warm up/ cool down cycle, then recheck after a couple of weeks/ couple of hundred miles later. But I don't do many miles, though sitting in traffic does get the engine warm so maybe 500 miles (for the check, the initial should be done after one cycle IMO) is fine for more normal driving

Post by **Dominic** » Fri Aug 18, 2006 11:00 pm

I understand that more important than just the number of miles elapsed since initial torquing, is the number of cold - hot - cold cycles the engine goes through. The optimum I gather is about 12 fully cold to fully hot and back again.
Dom

Post by **bmcecosse** » Fri Aug 18, 2006 11:15 pm

You're worrying about this too much. It's really not that important.