Author Topic: Stretch bolts  (Read 4426 times)

Offline naffsharpe (Nathan)

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Stretch bolts
« on: June 21, 2015, 06:38:18 PM »
Here's a question for everyone !
I'm part way through the rebuild of my VW T4 ABL engine, for the second time, but this time because of an overheating problem rather than the traditional and well documented crankshaft/timing pulley failure.
Having removed the cylinder head and after stripping it down to just the head I tried it on a sheet of glass while applying hand pressure only and was, in some places, able to ( just ) insert a 0.10 mm/ 0.0039in feeler gauge blade. This is the maximum that VW say is acceptable as deviation from perfectly flat/non warped. I then took a cast iron truly machined plate, wrapped it with 400 grit W+Dry paper, lubricated with WD40 and tried to flat out the areas where the 0.10mm blade would not insert. This took me down to 0.08mm, repeated took me to 0.65mm. This all took me about 2 hours, 1/2 sheet of W+Dry and a few calories. I blued the glass and tried the head but with only 0.35mm to play with the blue coloured the whole head.
Having given you the preamble my question is this: The head is fitted using stretch bolts fitted in four stages, stages 1 and 2 are torqued, stages 3 and 4 are "quarter turn 90 degree" no mention is made of using an actual/accurate angular device. Stage 2 torque is 40nm. What torque figures should I be looking at for stages 3 and 4 or is everyone's quarter turn the same?

Before any one asks , I have both printed manuals available and VW's dealer electronic manual (Elsawin) and none of them mention tolerances with stretch bolts!!

Nathan.

Offline doubleboost

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Re: Stretch bolts
« Reply #1 on: June 21, 2015, 06:53:18 PM »
Make sure the bolts are well lubed  CV grease is the best stuff to use
Nice even 1/4 turn on each one
Most cylinder heads have stretch bolts now
It is very rare that a engine is repaired
John

Offline naffsharpe (Nathan)

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Re: Stretch bolts
« Reply #2 on: June 21, 2015, 07:00:37 PM »
Just seen my C--k up! Should read 0.065mm as a final read and 0.035mm as "leeway". Blame the Fathers day wine/Jim Beam, the fact that my son AND his GF remembered and any other excuse you have all used in the past !!

Nathan.

Offline naffsharpe (Nathan)

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Re: Stretch bolts
« Reply #3 on: June 21, 2015, 07:25:06 PM »
John.
Thanks for your reply. I've not put a car into a garage for repair since October 1976 (Hillman Imp thrust bearing), unless I've been working away from home. If I can do it myself- I do!
My feeling I is that I should go "JUST" past 90/o in the centre to take up that small amount.
I worked for SLD pumps for years so diesel engine rebuilds are nothing new to me, anything from Lister AA singles upto multi cyl Volvo/Ford/Kubota/Perkins and now whatever we have!
The only reason I posted was to find out how much tolerance was in that last quarter turn.

Nathan.

Offline DavidA

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Re: Stretch bolts
« Reply #4 on: June 21, 2015, 08:13:25 PM »
Nathan,

Just cut a cardboard disc to fit on your socket or extension. Make 4 marks at 90 degrees on the disc.  Mark some place fixed place as a reference and,  when you have taken up the slack, just turn the bar 90 degrees.

One mans 90 degrees is the same as the next mans,  or one of them is wrong.

Dave.

lordedmond

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Re: Stretch bolts
« Reply #5 on: June 22, 2015, 02:22:41 AM »
Nathan

I am sure that those bolts are single use only and new ones should be used for a rebuild but is sure DB will correct me

Stuart

Offline naffsharpe (Nathan)

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Re: Stretch bolts
« Reply #6 on: June 22, 2015, 05:09:43 AM »
Thanks for the replies. I will be using a home made protractor as per your suggestion David. Stu, you're correct they are single use and I'm fitting new.

Nathan.

Offline ieezitin

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Re: Stretch bolts
« Reply #7 on: June 22, 2015, 04:02:03 PM »
Nathan

is that motor the 1.9ltr turbo they put in golfs / Jettas?

Anthony.
If you cant fix it, get another hobby.

Offline doubleboost

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Re: Stretch bolts
« Reply #8 on: June 22, 2015, 04:17:38 PM »
You will be able to "feel" when the bolts are starting to stretch on the last 1/4 turn
Like you say  only use the bolts once with plenty of lube
John

Offline dawesy

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Re: Stretch bolts
« Reply #9 on: June 25, 2015, 04:21:38 AM »
You can get an angle torque gauge for a few  pounds. They are easy enough to use.
At the garage I used work at we had a Snap On tech wrench that did traditional torque and angles. You could go 45 back of and go another 45 and it would know. Don't ask me how. Great bit of kit but not cheap.
Angle gauge like this.
http://www.eurocarparts.com/mobile/ecp/p/tools/car-service-tools/general-engine-tools/torque-gauges/?SEAVS530&0&t5_428
You can get them cheaper as that is a sealey one
Lee.
wishing my workshop was larger :(

Offline naffsharpe (Nathan)

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Re: Stretch bolts
« Reply #10 on: June 25, 2015, 03:12:38 PM »
Thanks for the continued interest! Cyl head is fitted and torqued/stretched down, timing was, as usual, a pain but it's there and cranked round to check several times. I've got one porous hose to replace, fuel filter to replace and radiator fans to check in operation then I can fill with oil/water ready for test running. The oil and oil filter will be replaced after an hour or two running at the correct temperature just to be sure all of the oil/water emulsion is gone.
It's not much different to the Golf/Jetta 1.9 tdi but is indirect injection, the 1.9 tdi will fit the T4 and give major power increases but also needs the front wiring loom changing. In fact all VAG 1.9 engines will fit with greater or lesser messing around mine has a Seat 1.9 head as the only available ABL heads were far too expensive for my (non existant) buget!
As John said you can feel the bolt stretch in stage 4 tightening, bits of your anatomy get twitchy around then and start to pucker !!
It will hopefully be on the road this weekend, but, being an old van you can never be certain!
I was going to scrap it but swmbo soon changed that idea when she added up the time I've spent and cash I've used to rebuild the engine and transmission from the ground up. The gasket failed because of a seized cooling fan and a son who was determined to bring Dad's van home after a weekend climbing in Pembroke- should have called the recovery earlier .

Nathan.

Offline naffsharpe (Nathan)

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Re: Stretch bolts
« Reply #11 on: June 27, 2015, 06:29:03 PM »
Well it's back together and runs O/K, had 1 minor leak on a cooling water flange but no oil leaks. I did however reuse the hydraulic tappets and it is now sounding a bit dry on the top end. As VW say they can be refurbished I'll dig my spare (old) set out and work on them so I can do a minimum cost swap , the currently fitted set will have gummed/varnished with the overheating. I know our favourite auction site has loads of cheap pattern part followers but that is what they are - cheap and not very good quality, I will not use them again.
I know also that most people will think I'm crazy for doing my own repairs but I still can and also enjoy it even if parts of my body tell me I'm not!!

Nathan.

Offline vtsteam

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Re: Stretch bolts
« Reply #12 on: June 27, 2015, 08:47:57 PM »
Crazy? Repairs?  On Mad Modder?  :drool:
 
:zap: :headbang:  :ddb:

I love it when a Plan B comes together!
Steve
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Offline dawesy

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Re: Stretch bolts
« Reply #13 on: June 29, 2015, 04:25:28 AM »
Good work buddy.
There's a real sense of satisfaction from repairing things yourself rather than handing over cash for someone to do it for you.
Lee.
wishing my workshop was larger :(

Offline naffsharpe (Nathan)

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Re: Stretch bolts
« Reply #14 on: October 18, 2015, 07:04:34 PM »
Just an update.
The T4 is still in use and has covered about 2000 miles since rebuild, most of it my son's mileage. I've had no major problems apart from the timing/cam belt starting to climb off the intermediate shaft pulley. This was caused by 2 out of 3 mounting bolts falling out! I bought some new threadlock and refitted them/re timed and problem solved. I have 1 annoying but minor oil leak to sort then all "should" be good. Now I can start on the suspension upgrades that I want.
Nathan.