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Author Topic: '78 Rabbit head warped; What would you do?  (Read 1976 times)

August 28, 2018, 09:41:16 am

Gnarlodious

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'78 Rabbit head warped; What would you do?
« on: August 28, 2018, 09:41:16 am »
Progressing on my '78 Rabbit restoration...

Machine shop says my 1.5D head is warped 9 thousandths. Is that an acceptable amount of warpage? Should I put it on and give it a try? Will the newfangled gasket sealers like Hylomar hold pressure where the old ones didn't? How long is it likely to run?

If I put in the studs and really tighten it down will that seal it?

If that's a no-go, can the head be surfaced? Anywhere that does it?

Is it possible to find a new/used head? 55K on this car. Parts Place has it for $500, but is it even worth it?

Or should I give up now and throw a 1.6TD in there? What would you do?




« Last Edit: August 28, 2018, 09:43:05 am by Gnarlodious »


’83 Vanagon 1.9TD, 78 Rabbit, '81 Caddy (no engine)

Reply #1August 28, 2018, 11:53:21 am

libbydiesel

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Re: '78 Rabbit head warped; What would you do?
« Reply #1 on: August 28, 2018, 11:53:21 am »
Maximum warpage spec is 0.004.  At this point I'm not a proponent for having the head milled.  I believe it loosens the pre-chamber inserts with potentially disastrous results down the road.  I've had success with hand lapping heads using sandpaper on a large piece of polished granite but .009 is a LOT of warpage.  Likely the cam journals are warped out of whack also. 

As I mentioned in your last thread, I won't even do a head gasket on a 1.5 or an early 1.6 with the 11mm head bolts.  Don't even bother with it.  Even if you do everything right, the block has a tendency to crack when installing the head bolts.  There's no way I'd dump money into rebuilding a 1.5 head.  There's also no way I'd put down $500 for a replacement head.  At minimum you should source a 12mm 1.6 engine.  1.6TD is even better.  A mk1 with a well-running 1.6TD is a really fun car to drive.  AAZ or 1Z/AHU will also bolt in but are more than I need in a Mk1.


Reply #2August 28, 2018, 12:05:03 pm

Gnarlodious

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Re: '78 Rabbit head warped; What would you do?
« Reply #2 on: August 28, 2018, 12:05:03 pm »
Thanks, Andrew. I'll abandon this engine and look for a TD.
’83 Vanagon 1.9TD, 78 Rabbit, '81 Caddy (no engine)

Reply #3August 29, 2018, 09:55:55 pm

fatmobile

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Re: '78 Rabbit head warped; What would you do?
« Reply #3 on: August 29, 2018, 09:55:55 pm »
Yeaah Andrew is more picky than most on his 11mm blocks.
 Check here, the vortex and vwdieselparts,.. even the Samba for a used head.
 With headstuds you'll be fine.
 My machine shop scrapped a 1.5 head,.. they only fit the 1.5 and 1.5s are getting so rare they can't sell them.
So you should be able to get one cheap.
 You can take a 1.6 and there is a spacer you can put in the front hole so it will seal on the 1.5 block.
Tornado red, '91 Golf 4 door,
with a re-ringed, '84 quantum, turbo diesel, MD block

Reply #4August 30, 2018, 08:33:07 pm

libbydiesel

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Re: '78 Rabbit head warped; What would you do?
« Reply #4 on: August 30, 2018, 08:33:07 pm »
The last head gasket I installed on an 11mm block, I scoured the block for cracks and it was totally fine.  I purchased the 11mm head studs and was hyper meticulous on the install.  Block cracked.  Never again.  I remember Justin Soares from Greaseworks had a similar 11mm story.  When you spring for the studs and it cracks anyway that's a doubly bitter pill.   

Reply #5August 31, 2018, 02:44:43 am

fatmobile

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Re: '78 Rabbit head warped; What would you do?
« Reply #5 on: August 31, 2018, 02:44:43 am »
 11mm studs from a gasser will work and I've been able to get them used for pretty cheap on the vortex.
 I'm sure I would avoid them too if I had the same experience but I've had no problems with studs.
Even with the VNT-15 boosting over 30 (those precontoller days).

 And I've never had any problems with an 11mm block cracking even with stock bolts,..
 and they are known to be too short and put too much stress in a small area.

  I've heard of it happening maybe 4 times counting both of Andrew's.
  I think the chances are 1 in 20 and that might be high.

 Funny story: The dealership had an '81 rabbit diesel in there that needed a head.
 They bought a new vw head, maybe the last in the country, this was about 9 years ago.
 Then stripped out all the threads in the block.
  I think they torqued it using 12mm torque specs because you can't strip out every one using the right torque, even with stock bolts.
The 11mm has a finer thread so lower torque.
Tornado red, '91 Golf 4 door,
with a re-ringed, '84 quantum, turbo diesel, MD block