View Full Version : Avant fix-up thread

05-29-2018, 04:23 PM
Figured I'd make a thread for what I've been working on lately. I picked this up a few weeks ago for $800.

The good: It's a 2001 1.8T Quattro with a 5-speed. It's pretty clean. And it has a few aftermarket goodies like an APR tune, 2.0T coil conversion, decent headunit with GPS and Bluetooth, and best of all, a hot air intake. [:D]

https://farm2.staticflickr.com/1724/28548663118_f2687acecc_z.jpg (https://flic.kr/p/KuKmVC)IMG_0031 (https://flic.kr/p/KuKmVC) by nlions88 (https://www.flickr.com/photos/96246718@N05/), on Flickr
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The bad: Overheating as a result of a blown head gasket with a maybe warped head.

I'll be the first admit I'm a novice with this sort of thing. I've done timing belts on my 1998 and my 2004 1.8Ts but this obviously a bit more involved.

Intake manifold off.... I was shocked by how much more complicated this was compared to my 1998 AEB.
So many more vacuum lines and misc emissions bullshit in the way... and for what? An extra 1 mpg highway?

I already know I'm going to mix up a few lines putting this back together...
https://farm2.staticflickr.com/1737/41519627545_ae448c4734_z.jpg (https://flic.kr/p/26fWWKk)IMG_0047 (https://flic.kr/p/26fWWKk) by nlions88 (https://www.flickr.com/photos/96246718@N05/), on Flickr

Timing belt off...
https://farm2.staticflickr.com/1721/42421851981_3e339d2c91_z.jpg (https://flic.kr/p/27CF5D4)IMG_0046 (https://flic.kr/p/27CF5D4) by nlions88 (https://www.flickr.com/photos/96246718@N05/), on Flickr

- - - Updated - - -

Head removed... lovely.

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05-29-2018, 04:30 PM
This is pretty much where I'm at at this point. I'm curious if anyone knows what is considered "unuseably bad" as far as warped heads tolerances go.

Around cylinder 2 seems to be the worst from what I can tell using my very basic straight edge and feeler gauges... can fit about a .17mm gauge in there. I'm guessing that's considered "buy a used head" territory.

05-29-2018, 07:29 PM
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05-29-2018, 07:58 PM
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05-30-2018, 04:43 AM
So you're at 6 or 7 thousandths distortion there (.006 inches). That's not terrible. If it was .003, you could just bolt it back down with a new gasket (per the Bentley manual).

If you don't have another head lying around, I would get that one cut. It would be best to have it pressure checked first, to make sure it didn't crack anywhere and you can have them check to make sure all the valves are sealing. Distortion in the head can cause the the valve seats to distort and fail to seal with the valves. The 1.8T is slightly more prone to this due to having so darn many valves. You can actually do this test yourself (perhaps before you do anything else) by turning the head upside down (with valves and springs installed) and filling the chambers with water. Something even thinner, like paint thinner, gasoline or kerosene would be an even better test. If everything holds, you're good - cut the surface and slap it back on. If you have leaky valve seats, you should plan on getting the valves and seats cut too (which adds expense to fixing the head and may also require new valve guides if they are too sloppy). That's probably where you'd want to consider a different head.

05-30-2018, 01:53 PM
Thanks as always for the braindump walky!

This is a stupid question, but whatís typically the cost of having a head resurfaced? Never had to visit a machine shop before.

The reason I ask is that I found a rebuilt head fairly local to me and got him to agree on $300: https://reading.craigslist.org/pts/d/audi-cylinder-head/6599877597.html

Itís an AMB off an 05 A4 but my understanding is that itís pretty close to an AWM. Still small port, still has VVT. Iíve read thereís something different with the thermostats or coolant flanges (?) but neither one of those sounds like a huge deal to me.

I figure I could probably get at least $100 for the cams and caps on my existing head, so at that point Iíd really only be out $200 for a rebuilt head with a new cam chain tensioner and an extra exhaust manifold thrown in.

05-30-2018, 02:32 PM
The AMB heads are considered inferior by many. 2002 and up 1.8T heads more often have cracking problems due to them cheapening and lightening some of them in those years. You will notice even on these forums that the B6-era 1.8T have much higher reported occurrences of cracked heads and blown head gaskets. Specifically the castings that bear the "Coscast" mark are the junkier ones - as opposed to the "Germany" marking (which is the good stuff and, as it turns out, is also where Audi's come from [up]).

A resurface only will probably cost between $50 and $75. Some charge extra to clean the head if it's nasty (hot tank). And extra to run the tests that have been discussed above (pressure check cooling passages and valve seats). So you might be $30 to clean, $40 to pressure test, $50 to cut. Something like that. If I'm sending a head I know was working fine and I just want the surface fresh, I'll tell the guy "no cleaning, no tests, just cut it". And I try to wipe it down a bit because he likes to hot tank everything (and charge for it) so he doesn't get dirty. lol

05-30-2018, 07:36 PM
The AMB heads are considered inferior by many. 2002 and up 1.8T heads more often have cracking problems due to them cheapening and lightening some of them in those years. ...

Thanks for the info -- I didn't know that.

My elder son has a 2002 A4 with AMB. My wife has a 2001 Passat with AUG -- what can you tell me about that version of the engine?

05-31-2018, 07:22 AM
Well, if the head says "Coscast", then it's the lousier stuff. Here's a post I made a while back (pics are on photobucket, so I hope they come through):

Good Stuff:

Not Good Stuff:http://i1382.photobucket.com/albums/ah276/walky_talky22/Coscast-Head_zpsimiznma0.png

Really Not Good Stuff:http://i1382.photobucket.com/albums/ah276/walky_talky22/China-Head_zpskxcssoao.png

My pet theory is that that not only the lighter Coscast heads are to blame, but that the rapid temperature deviations of the B6 A4 "mapped cooling system" using the electronically governed ultra-high-temp thermostat is a contributing factor to cylinder head failures on that model.

As for the Passat, a 2001 should probably have a "Germany" cylinder head. And the B5/B5.5 Passats didn't have the electronic thermostats either. So, based on my theories, that one should be in the group with lower cylinder head failure occurrences.

06-06-2018, 05:47 PM
Update post because a box of parts came in the mail today. :)

Head is scheduled to go into the machine shop tomorrow.

https://farm2.staticflickr.com/1760/42631040981_3ced3537fa_z.jpg (https://flic.kr/p/27XaeeX)IMG_0080 (https://flic.kr/p/27XaeeX) by nlions88 (https://www.flickr.com/photos/96246718@N05/), on Flickr

06-09-2018, 06:38 PM
Okay, stupid question time. [headbang]

Getting ready to bolt everything back together- how can I be sure that my timing is not off 180? While I had the head off I rotated the crank a bunch for cleaning purposes, and didn't think of this issue until afterwards. Is there a way to tell if I am at TDC on the compression or exhaust stroke?

06-11-2018, 04:51 AM
Compression and exhaust stroke is determined by the cylinder head only. It is determined by what valves are open. So there is only "TDC" on the bottom end. You cannot be 180 out.

06-11-2018, 03:19 PM
Compression and exhaust stroke is determined by the cylinder head only. It is determined by what valves are open. So there is only "TDC" on the bottom end. You cannot be 180 out.

Okay, that's sort of what I had gathered from some Googling, just wanted to be sure before throwing everything together. Thanks!

06-12-2018, 06:38 AM
Good work LA4! [up]
Good to see a QTM avant live another day.

For all the vac lines on the 01 I know all about it. Not sure what your plans are but you don't all of need them. but if you going for 100% stock then sure replace them. If you plan to clean the bay up a little follow this DYI (Thanks to walky again)[up] Vac line DIY (https://www.audizine.com/forum/showthread.php/442614-*DIY*-B5-1-8T-Vacuum-Check-Valve-SAI-PCV-Delete-amp-Simplification)

06-24-2018, 05:08 PM
Been pretty busy the past couple weeks so wasn't able to make much progress until today.

Got the head back from the machine shop, ended up only being $44 for resurfacing. Got it bolted into the car, and connected up the exhaust manifold.

Something strange happened when it came time to hook up the timing belt though. I didn't really realize it until now, but there is no stud on the block to place the idler over. My old idler has this allen-key bolt going through it to attach it to the block. The new one is meant to slide over my non-existent stud on the block.

From what I can tell it looks like FCP Euro sent me the kit for the later (2001.5?) VIN cars.

https://farm2.staticflickr.com/1773/28122495357_c471ab7ba0_z.jpg (https://flic.kr/p/JR696B)IMG_0120 (https://flic.kr/p/JR696B) by nlions88 (https://www.flickr.com/photos/96246718@N05/), on Flickr

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07-23-2018, 03:32 PM

The car is now up and running, albeit with some issues (wouldn't be a B5 otherwise.)

It starts up and drives fine, actually feels a bit quicker than my 1998 1.8T. Cooling system is working fantastic, I've put about 150 miles on it, all in very hot weather and traffic, with no issues. So the overheating/head gasket woes are definitely resolved. [:)]

However, it has a CEL P0340 (Camshaft Position Sensor). It is also idling a bit rough... you can feel it in the steering wheel/dashboard/cabin. However, the RPMs are steady and a hair under 1000rpm just like every other 1.8T I've owned, so it doesn't feel like a misfire. It also has 4 new NGK BK7REs.

I swapped in a new Cam Position Sensor and the issue persists. I'm wondering if timing is off a tooth?? The cabin vibrations go away after ~1500 rpms or so and the car pulls strong... not sure if this is typical of timing issues or not.