Cylinder torx stretch bolts

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Pedro 70
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Cylinder torx stretch bolts

Postby Pedro 70 » Sun Sep 09, 2018 6:29 pm

Hi All. Have just removed the head from my ‘86 2.8i (water leak from jacket into the cylinder 6). Can anyone tell me if the Haynes sequence for torquing the head down is correct. I will be using new torx six point stretch type bolts and running the engine until hot then undoing a stretch bolt and retightening seems wrong to me. The Haynes manual does’nt seem to go as far as the change to torx bolts. Any info much appreciated

Dansta
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Re: Cylinder torx stretch bolts

Postby Dansta » Sun Sep 09, 2018 8:36 pm

Take a look at this link

https://www.google.co.uk/url?sa=t&sourc ... mvusH38hCN

Torx settings are there.

Pedro 70
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Re: Cylinder torx stretch bolts

Postby Pedro 70 » Mon Sep 10, 2018 6:11 am

Thank you very much for taking the time to do that Dansta. That makes it very clear. Did not think you wold untighten a stretch bolt. Will download this information for any future reference. Peter

Dansta
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Re: Cylinder torx stretch bolts

Postby Dansta » Mon Sep 10, 2018 7:50 am

No problem. I'm rebuilding mine at the moment. I am undecided whether to stick with hex or move to stretch bolts. Have you found somewhere that does not charge > £120 for a set of torx bolts?

Ref the loosening stage. This is quite common these days in vehicle assembly and it is only the final stage that "stretches" the bolts. The loosening stage is to ensure you are applying the correct torque and not having to overcome running torque or other settling factors.

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Stroker
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Re: Cylinder torx stretch bolts

Postby Stroker » Mon Sep 10, 2018 9:31 am

Dansta wrote:No problem. I'm rebuilding mine at the moment. I am undecided whether to stick with hex or move to stretch bolts. Have you found somewhere that does not charge > £120 for a set of torx bolts?

I'm sure you could use 2.9 head bolts. I've been buying from this outfit lately and have been very good. Hell of a lot cheaper than 120 pounds.
https://www.rockauto.com/en/catalog/ford,1990,bronco+ii,2.9l+177cid+v6,1106198,engine,cylinder+head+bolt,5308

Dansta
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Re: Cylinder torx stretch bolts

Postby Dansta » Mon Sep 10, 2018 10:17 am

I have a set of used 2.8 hex and torx bolts are similar in length placed side by side. But I also have 8 2.9 torx bolts and they are a good 10mm longer...... So I'm not sure about using them.

Pedro 70
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Re: Cylinder torx stretch bolts

Postby Pedro 70 » Mon Sep 10, 2018 10:27 am

I have just purchased a set of torx bolts along with a head gasket set for my 2.8i. Not got them yet,tomorrow. Bought them from - Gaskets for classics. Milten Keynes. £38.00 the gasket set and £23.00 the torx set

Dansta
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Re: Cylinder torx stretch bolts

Postby Dansta » Mon Sep 10, 2018 10:27 am

Marvellous. Will look them up.

Dansta
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Re: Cylinder torx stretch bolts

Postby Dansta » Mon Sep 10, 2018 11:14 am

Turns out their bottom end set is already in my watch list. Can't find bolts but have messaged them.

Pedro 70
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Re: Cylinder torx stretch bolts

Postby Pedro 70 » Mon Sep 10, 2018 11:34 am

Yes they did’nt List the bolts on eBay so I contacted them direct. Can give you the number if you have no luck messaging.

Pedro 70
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Re: Cylinder torx stretch bolts

Postby Pedro 70 » Wed Sep 12, 2018 2:40 pm

Quick update on torx head bolts. Classic gaskets couldn’t supply the bolts after all - disappointing. Tickover haven’t got any, Burton have genuine Ford ones at...........£9.+ each bolt - obviously gold plated. So I have ordered 8 from Rockauto in America as mentioned in an earlier thread. Roughly £22 odd with all taxes and shipping. These are for a 2.9 so fingers crossed they will be the same!!

Dansta
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Re: Cylinder torx stretch bolts

Postby Dansta » Wed Sep 12, 2018 3:35 pm

Yep. I got the same answer from them.

2.9 bolts are 6mm longer. The 2.8 shaft length ie excluding head is 81mm and 2.9 is 87mm.

See comparisons below. 2.9 torx top, 2.8 torx middle, 2.8 hex bottom.

Image

If 6mm makes all the difference :shock: then surely there must be other M12*81mm ISH head bolts on the market...........

When you say you bought 8 bolts from rock. Are you doing only 1 head?

Pedro 70
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Re: Cylinder torx stretch bolts

Postby Pedro 70 » Wed Sep 12, 2018 5:30 pm

Yeah just one head where water was leaking into No 6 cylinder. Car was running really well until the leak so do not want to disturb the other side.

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Re: Cylinder torx stretch bolts

Postby Stroker » Thu Sep 13, 2018 8:42 pm

My bad :sorry: . Looks like you'll have to hacksaw 6mm off them. Still a hell of a lot cheaper than 120 pounds.

Dansta
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Re: Cylinder torx stretch bolts

Postby Dansta » Fri Sep 14, 2018 6:54 am

I'm going to measure the block and head dimensions to see how much space there really is. I'm presuming that the depth in the block will have some gap at the end.

Pedro 70
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Re: Cylinder torx stretch bolts

Postby Pedro 70 » Fri Sep 14, 2018 7:57 am

If the available space below the bolt is that close I could maybe use a suitable size washer under the bolt head, what do you think?shouldn’t interfere with the torque settings.

Dansta
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Re: Cylinder torx stretch bolts

Postby Dansta » Fri Sep 14, 2018 9:05 am

Some engine heads (generally speaking) have washers and some do not Therefore I would avoid a washer unless you have one that is sufficiently strong like the bolt and perfectly parallel. More of a shim. Also I dont know what effect torquing against the washer will have Vs the head surface. Reaching the specified torque may result in too much or too little bolt preload due to the different friction between the relevant faces. And I dont know enough of the science behind it to work it out.

And ford didn't put a washer there in three first place.

Pedro 70
Posts: 37
Joined: Sat Feb 17, 2018 3:17 pm
Car(s): Ford Focus titaniumX daily driver.
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Location: Suffolk

Re: Cylinder torx stretch bolts

Postby Pedro 70 » Fri Sep 14, 2018 11:26 am

Yes, makes sense that Ford didn’t use a washer. Head is coming off this afternoon, just got a torx smokey through the post. Been stripped down to this stage for a few days now. Will measure what length I have in the block for a longer bolt. All good fun a! Not. Thanks for all your input.

Pedro 70
Posts: 37
Joined: Sat Feb 17, 2018 3:17 pm
Car(s): Ford Focus titaniumX daily driver.
Ford Capri 2.8i. Superb, dry days only. Kawasaki GPZ 900R.
Location: Suffolk

Re: Cylinder torx stretch bolts

Postby Pedro 70 » Fri Sep 14, 2018 4:29 pm

Right, cylinder head off and there is no way a 6mm longer bolt is gonna fit down the block holes. If when the bolts arrive they are 6mm longer it’s out with the hacksaw. The good news is that it looks like a genuine 50000 miler, standard bores with no ridge at the top of the bores. Should the waterways in the back of the block/head behind No 6 cylinder be blocked off by the gasket not been cut away. Old and new gaskets? Strange.

Dansta
Posts: 62
Joined: Mon Aug 17, 2015 4:36 pm
Car(s): 1985 2.8i Special
Land Rover Discovery 5 (daily driver)
Location: Abingdon

Re: Cylinder torx stretch bolts

Postby Dansta » Fri Sep 14, 2018 5:57 pm

Could be some sealant from the water pump. My galleries were blocked by an over liberal application by a previous owners rebuild.

Ok if you're trimming the bolts then make sure you run them down a suitable nut to ensure the first thread is ok. Otherwise it will interfere with the running torque and give you too low a preload.