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VVC screw-up 
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Joined: Thu Nov 22, 2007 10:31 am
Posts: 132
Post VVC screw-up
Afternoon all,

So after getting the Libra on the road a few month back I thought I was winning at life, but that would be too easy! Loss of power, only 60 psi compression test on cylinders 3 and 4, compared to 120ish on 1 and 2.

Found that the VVC exhaust pulley wheel dowel pin had sheared out of and damaged the cam - allowing the pulley to move slightly and mess up the timing. :shock: Took the head off expecting to find other damage, but I seem to have narrowly dodged that bullet. I can only assume I did not install the pulley correctly, or incorrect torqued the bolt.

So I needed a new exhaust cam... Not such a big deal, there are a few on eBay...

When I was dismantling the head I removed the inlet VVC mechanism! When it all started to fall to bits in my hands I thought I may have a problem getting them back together. After reviewing the overhaul manual it states:

CAUTION: During the following
operations, it is essential to ensure that
front and rear inlet camshafts are retained
in their respective VVC assemblies. If camshafts
are removed from their VVC assemblies, then
complete assembly must be replaced; it is not
permissible to refit camshafts to VVC
assemblies.

S**t.

Has anyone ever made this same stupid mistake and managed to put them back together? Any diagrams or aids available?

Really don't want to fork out for a new head for the sake of putting these things back together again.


Attachments:
VVC.JPG
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Sheared pin.JPG
Sheared pin.JPG [ 33.05 KiB | Viewed 2463 times ]
Sun May 24, 2020 2:58 pm
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Location: Worksop
Post Re: VVC screw-up
I removed my cams as I was going to do the seats but found my spring compressor isn't long enough, I did fit them all together again but so far not put the head back on the engine. I have 2x docs but I can't attach them as they are over 1Mb, if you send an email to gtmoc at phaeton.plus.com then I will send you them over.

Alan..


Mon Jun 01, 2020 5:04 pm
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On the Road

Joined: Wed Aug 11, 2010 9:27 am
Posts: 541
Location: Sheffield
GTM: Libra
Post Re: VVC screw-up
That warning is a bit of an ass-covering thing by Rover so dweeb mechanics don't faff with them.

The units can be put back together, long as it's done properly.

I think this is about the best guide on VVC stuffs https://wiki.seloc.org/a/VVC_Information

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2000 GTM Libra 1.8VVC 145BHP


Mon Jun 01, 2020 9:18 pm
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Joined: Thu Nov 22, 2007 10:31 am
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Post Re: VVC screw-up
Thanks. With the guide I managed to get them back together. Fingers crossed it all works out ok.

I previously put some water behind the valves and there was no water leak, but I've had another go and now there does seem to be a leak. Only minor / slow, a drip after about a minute, but I'll need to remove and check if they are bent or damaged and lap them if they're not. Oh the joy.


Thu Jun 04, 2020 9:38 pm
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Post Re: VVC screw-up
I've lapped two of the valves that were leaking, one inlet and one exhaust on the same cylinder, opposite each other.

My first thought due to their mirrored location was that they were bent, but after removal, inspection and checking vs a straight edge I see no evidence of damage.

The inlet valve has sealed up ok after the lapping, but the exhaust valve is still leaking slightly. I came back after a few hours and a couple of drips had gone through.

Would you expect to have a perfect seal indefinitely with metal to metal surface? Is it worth replacing the valve even though it's not physically damaged? I'm torn because I dont want to keep lapping and lapping until I damage the seat.


Sat Jun 06, 2020 11:19 pm
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Post Re: VVC screw-up
Can I ask what valve compressor you have mine is not deep enough to get the collets out.

As to your leak problem, not too sure, think I'd be tempted to swap 2 valves over, don't lap them in & see if you still get the leak, if the leak remains then it's likely to be the head, if the leak moves then it's the valve. Looking on Rimmers a new exhaust valve is only £10 + post, I know it's going to hold you up 4 days but I think I'd be tempted to buy a new one.


Sun Jun 07, 2020 8:29 am
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Post Re: VVC screw-up
https://www.ebay.co.uk/itm/10pcs-Valve-Spring-Compressor-Kit-Remove-Compress-Tool-For-Cars-Van-Motorbikes/263442024611

I used one of these sets on my VVC head. Cheap as chips and worked a treat.


Sun Jun 07, 2020 9:19 am
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Joined: Thu Nov 22, 2007 10:31 am
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Post Re: VVC screw-up
I'm sending my compressor back because its naff. Doesnt hold the compression as the handles move back when you apply pressure (photo attached). I've had more success with the hammer + socket technique seen on youtube.

So I've taken another one out, given it a coarse lap and I see pits. Should I carry on lapping or should I dump them and get new ones?


Attachments:
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Screenshot_20200607-102056_Gallery.jpg
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Sun Jun 07, 2020 10:23 am
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Post Re: VVC screw-up
sanzomat wrote:

Thanks just ordered one, then realised although they say Manchester it's coming from China on a 2 week delivery, Barstools!!!!


Sun Jun 07, 2020 11:08 am
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Post Re: VVC screw-up
tonygerrard(1049) wrote:
I'm sending my compressor back because its naff.

That's similar to the one I've had for years, but my pocket bit isn't long enough

tonygerrard(1049) wrote:
So I've taken another one out, given it a coarse lap and I see pits. Should I carry on lapping or should I dump them and get new ones?

That's going to take a hell of a lot of lapping to clear up, I think I'd be tempted to buy new, but I am no expert so others may have a different view


Sun Jun 07, 2020 11:12 am
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Joined: Thu Nov 22, 2007 10:31 am
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Post Re: VVC screw-up
Lapped it pretty well I think (see photo). Took ages. Still leaks :lol:

I'd need 5 exhaust valves and two inlet valves. Very tempted to put it back together and just see how the compression is using the tester.


Attachments:
Screenshot_20200607-131753_WhatsApp.jpg
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Sun Jun 07, 2020 1:21 pm
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Post Re: VVC screw-up
Is that the same valve? The pitting looked really deep so was going to say you'd be lucky to bring that one back but looking at the second pic it looks like you have. Was that just with paste and a stick with suckers or did you use something more powerful?


Sun Jun 07, 2020 2:15 pm
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Post Re: VVC screw-up
tonygerrard(1049) wrote:
I came back after a few hours and a couple of drips had gone through.


If you are only getting a couple of drips in a few hours I wouldn't worry, especially now you've lapped off those pits. When I last rebuilt a head mine was leaking past some of the valves with a drip probably every 10 minutes and when I ran it up the compression was fine with no obvious difference in compression between the ones that appeared to leak a little on the water test against those that hadn't leaked at all.


Sun Jun 07, 2020 2:22 pm
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Joined: Thu Nov 22, 2007 10:31 am
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Post Re: VVC screw-up
That was the same valve yes - just a wibble stick by hand using coarse and then fine grinding paste. Took about an hour though, so the thought of doing 7 more makes me want to cry, especially as it still leaked afterwards.

I've seen some people use a drill on youtube but I feel the risk of causing damage is too high.

Reading up on the cause of pitting there would be water in the combustion gases, likely from an untreated headgasket issue. Suppose this is what you get with an unknown history Ebay engine.


Sun Jun 07, 2020 3:57 pm
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Post Re: VVC screw-up
Tony think I would look for someone local with a valve grinder to reface them all should not cost much
Ian


Sun Jun 07, 2020 4:14 pm
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