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Discussion Starter #1
Good evening, all-
I’ve got some issues with my Unicorn.
I’ll begin by mentioning I do all my own maintenance on my vehicles. With a 20+ year career in aircraft maintenance I have gradually gathered the tools and the expertise/skills necessary to tackle pretty much any issue that presents itself….with that said I will also admit that I damn sure don’t know everything and from time to time I still get stumped while troubleshooting. Miraculously, however, I still enjoy the challenges and the satisfaction when I’m able to fix things that would otherwise cost quite a bit if taken to a shop. What I’ve got going on currently has me kinda stumped though…..enough to create a forum thread to see if anyone has experienced similar problems.
First, the car in question is a 2004 Passat GLS wagon, with the 1.8T, (AWM) 4Mo, and 5 speed manual. I’ve owned it for just about a year and it’s got around 242k miles on what I believe is the original, non-rebuilt engine. Until a week ago, it ran fine….well, like any 15 year old car with a bunch of miles on the clock it has a couple of minor squawks, but no problems that would negatively affect the operation. It doesn’t smoke or burn/consume oil. It has a newly-developed very small crack in the bottom of the coolant expansion tank which made it necessary to fill it about every 5-7 days, but I planned on ordering another tank in the next few days and I monitored the coolant level regularly. Oh, and about 6 months ago I performed a timing belt replacement which included new water pump, thermostat/housing tube, and new belts. There wasn’t any reason to expect what occurred the Saturday night before last:
I was on the freeway at about 65-70mph, on a slight incline. I noted that when I depressed the accelerator pedal there seemed to be a lack of power, but due to the incline and because the car was more loaded that normal, with the A/C on, I didn’t think too much. A few seconds later though, and the red ‘OIL PRESSURE LOW / STOP ENGINE’ warning annunciator appeared. I immediately made a move for the offramp that I was luckily just coming to, and got the car off onto the shoulder and shut down. It was dark outside and unfortunately I didn’t have a flashlight with me, but when I popped the hood to investigate the first thing that caught my attention was the turbo which was glowing red hot. Aside from that there was nothing out of sorts, to include the oil and coolant levels. I didn’t have my laptop with me to perform a VCDS download, and because it was getting late I needed to figure out a ride home for the night. The next morning my Dad and I loaded the car onto a flatbed trailer and hauled it to my Dad’s shop, where I had the chance to take a look at the stored faults. Here’s the relevant downloaded data:
Sunday,03,November,2019,13:46:12:46767
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 7 x64
VCDS Version: 19.6.2.0 (x64) HEX-NET CB: 0.4508.4
Data version: 20190930 DS308.0
www.Ross-Tech.com Dealer/Shop Name: JET CITY AVIATION, LLC

VIN: WVWVD63B04E298701 License Plate: BKV1998
Mileage: 388490km-241396mi Repair Order:



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Chassis Type: 3B (3B - VW Passat B5 (1997 > 2005))
Scan: 01 02 03 08 15 16 17 19 35 36 37 46 47 55 56 57 58 75 76 77


VIN: WVWVD63B04E298701 Mileage: 388490km-241396miles
-------------------------------------------------------------------------------
Address 01: Engine Labels: 06B-906-018-AWM.clb
Part No SW: 4B0 906 018 DP HW: 8E0 909 018 A
Component: 1.8L R4/5VT G 0002
Coding: 0016701
Shop #: WSC 65728 1018 854933
VCID: 72A8D7076C198EDFA1-5160

12 Faults Found:
16795 - Secondary Air Injection System
P0411 - 002 - Incorrect Flow Detected
16804 - Catalyst System; Bank 1
P0420 - 002 - Efficiency Below Threshold - MIL ON
17733 - Knock-Control: Cylinder 1
P1325 - 001 - Regulation Limit Exceeded
16712 - Knock Sensor 1 (G61)
P0328 - 001 - Signal too High - Intermittent
16717 - Knock Sensor 2 (G66)
P0333 - 001 - Signal too High - Intermittent
17735 - Knock-Control: Cylinder 3
P1327 - 001 - Regulation Limit Exceeded
17736 - Knock-Control: Cylinder 4
P1328 - 001 - Regulation Limit Exceeded
17734 - Knock-Control: Cylinder 2
P1326 - 001 - Regulation Limit Exceeded
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 -
16687 - Cylinder 3
P0303 - 001 - Misfire Detected
16688 - Cylinder 4
P0304 - 001 - Misfire Detected
16706 - Engine Speed Sensor (G28)
P0322 - 004 - No Signal - Intermittent
Readiness: 0000 0000

The P0411 and the P0420 aren’t new but the misfires/knock sensor faults/speed sensor fault are all related to that night’s event, I believe. In fact, I kinda zeroed in on the G28 Engine Speed Sensor fault because I knew that it would cause the symptoms I experienced AND the other faults with a failure of that sensor. A resistance check of that sensor, per Bentley manual, should produce 400-1000 ohms. When I put a multimeter on it I saw an open circuit, which to me means it was failed internally. So I ordered a new Bosch sensor, confident that I had correctly diagnosed the problem. Also, since the part was gonna take a couple of days in transit, I used the time to look for other stuff that needs or will soon need to be addressed. I discovered that pretty much the entire PCV system needs to be replaced, which isn’t shocking after doing some very basic forum searches to find that the system is inherently failure-prone and mine is no different. Every hose/coupler/elbow/etc. that started its life as a supple, flexible rubber piece has now become so hardened and brittle that you’d swear they crumble to dust without having actually touched them physically. One ‘breather’ tube in particular, which comes out the top of the oil filter housing and goes who-knows-where was split open so far that on first glance I actually thought that it was molded that way from new. The more I looked at the PCV system the more confusing it got, and apparently 034 Motorsports has developed a kit which simplifies and replaces the system. If anyone has experience with that replacement kit and/or has any tips, let me know…
Well, the G28 Speed Sensor arrived on Thursday and it didn’t take long to install. However, it didn’t fix the issue as the car would not start. I should note that the starter engages normally, although it sounds strange to me. More on that later…
In the interest of condensing this already much too lengthy thread, here’s an outline of the troubleshooting procedures that I have done since installing the new Speed Sensor; note that this isn’t necessarily in the order I did things:
-Verified fuel is being supplied by the injectors to each cylinder. I removed the injectors still attached to the fuel rail and connected electrically, then put each fuel injector in a Ziploc bag and cranked the engine over, first with the new Speed Sensor disconnected which correctly resulted in no fuel present at the injectors, then cranked with the sensor connected. Had fuel from each injector.
-Removed and inspected spark plugs, which looked normal. While the plugs were out I made sure the cylinders have compression…..due to a faulty swivel connection on the pressure gauge I couldn’t get an accurate pressure value but I did verify that compression does at least exist…
-Removed the valve cover. Why, you ask? Well, due to some of the oil sludge I encountered when checking out the PCV system, I wanted to make sure that the valve cover and cams weren’t caked with sludge. Plus, I wanted to verify the cam tensioner looked normal and that both cams rotated without any problems. I’ll be cleaning the valve cover in a hot tank, but otherwise everything looked normal at the top of the head. Oh, and I double-checked that the timing marks weren’t out of whack. All good.
-Because I was in the area, I removed the Coolant Temp Sensor between the firewall and the back of the head to check for condition and to perform a resistance check. Problem #1 was that the Bentley instructed checking resistance between contacts 1-3, 2-4, etc. Not sure if my CTS is unique but it is a Bosch and the contacts are labeled A B C D, not numerical. Problem #2 is that no matter what contact to contact measurement I attempted, the multimeter never budged from an ‘open’ circuit reading, which I found to be strange. I ordered a replacement just in case.
-I noted that oil has pretty much made its way throughout the induction system…..I found oil at the coupling just below the turbo’s outlet, as well as at the intercooler inlet and all the way up at the throttle body inlet. I don’t know if this is just a continuance of the trashed PCV system or if it’s something different, like a turbo that’s leaking oil past the bearings and downstream toward the throttle.
-Because the breather tube which exits the top of the oil cooler/filter bracket and heads aft to the tee with the PCV valve was broken to the point that it left chunks of solidified rubber down in the filter bracket, I removed the oil cooler and filter bracket to clean it out and inspect for further damage.
-Although I just replaced them about 6 months ago when I did the timing belt, I opted to replace the thermostat and the housing/tube just simply because I happened to have the new ones on hand from when I ordered them in error some time ago. I figured I had things torn apart to the degree that it would be easy to do, so I shotgunned a new t-stat at it.
At this point I had comprised a pretty lengthy list of items that needed to be replaced, and that’s not including whatever I’ll need to actually repair the original issue that caused the car to shut down. Here’s what I ordered thus far:
  • Reinforced silicone breather hose kit from 034 Motorsports. Hopefully this will simplify and restore the crankcase ventilation issues.
  • Coolant Temp Sensor
  • Intake Manifold Gasket
  • Valve Cover Gasket
  • Coolant Expansion Tank w/Cap
  • 6 qts. Liqui-Moly “Molygen” 5W-40 and Bosch oil filter
  • 2 liters of G12
Parts should start arriving tomorrow. It’s damn sure frustrating that I haven’t found the cause for the engine quitting, especially because with what happened I fully expected something obviously catastrophic, like a broken timing belt or worse. My only option is to put it back together with the new parts, even though I don’t think any of them will fix the issue.
If anyone has any input, please don’t hesitate to post! Thanks!
 

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Have you checked the condition of the catalytic converter? Considering the age and mileage it could possibly be clogged or coming apart and blocking the exhaust.
 

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First off, I think that hu vw may be on to something with the collapsed cat idea. That could have caused the loss of power and the glowing turbo.

Second, I wouldn't put any work into the pcv/breather system until you can get the car to run properly and know you have good compression AND good oil pressure. Before that happens you can't rule out: bad cat, ruined turbo, low compression, ruined engine or cam bearings.

The low oil pressure warning is often a sign of a clogged oil pickup screen, so you need to drop the oil pan and inspect it. With that mileage it will likely have bits of the plastic dipstick tube and/or bits of cooked oil from the turbo lodged in it, restricting oil flow.

Shutting down the car with a super-heated turbo, also likely cooked all the oil present in the turbo and in the turbo oil feed line. You will need to remove that feed line to make sure it is not clogged.

Bottom line, the pcv system is the least of your worries. With 242k, you are already in an uphill battle against a lot of internal, oil and wear-related issues that may have recently gone fatal.

Good luck and keep your fingers crossed, but also consider what kind of big-money repairs you are willing to stomach here.
 

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Multiple knock sensor's indicate overheating, either from an issue with the coolant system (doubtful) or the oil system (most likely). I would test the oil pressure with a mechanical gauge and then remove one cam bearing cap and inspect for damage. If pressure is low and no damage is found, a new pump an screen should be installed. With low pressure, it's possible the lifters collapsed to the point of lowering compression, causing the no start issue.

Other possible future issues are the turbo and the cat failing. Both happened on the 1.8T I picked up for my swap. The car had a plugged pickup tube, leading to the oil pressure warning. I replaced the pump and screen, checked damage (none), pressure (was great) and flow at the turbo (also great). Despite that, the cheap Ebay turbo died shortly afterwards. The CEL came on for the cat, but that could also be due to the oil the bad turbo was dumping in the exhaust.
 

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Discussion Starter #5
Thanks for the suggestions on what to look for; I figured I would post an update to let you know what I discovered! After replacing the G28 Engine Speed Sensor with no help, I ended up buying a gauge to check compression. Well, it didn't take long to discover that at least the head gasket was bad because I had compression leaking between cylinders. So, I went about removing the head. I had noted earlier when I had removed each spark plug that all looked pretty normal except for the #4 plug, which looked like it had some weird metallic deposits on it. After getting the head off I found that the metallic substance was actually molten aluminum from where part of that cylinder's combustion chamber had melted, probably due to detonation:
98027

98028
Check out the missing aluminum between the exhaust valves, holy crap!! ALL of the exhaust valves had some pretty heavy carbon deposits on the back side & stems, but for whatever reason the #4 combustion chamber just disintegrated. I found a used/rebuilt head on eBay that I snapped up and removed the short block, which I took to a local machine shop to have inspected for any further damage. I got the "new" head a couple of days ago and it's in great shape; it included all new valves and some mild porting. I need to call the machine shop today to see if they have found anything that I'll need to replace....

Hope everyone has a great Christmas or whatever holiday you happen to celebrate!!!
 

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Wow that's crazy the way that melted! Looking forward to some updates on this, got to save the unicorns, you don't see those very often and i always wanted one, all wheel drive and 5 speed! Good luck with it and Merry Christmas to you!

Thanks for the suggestions on what to look for; I figured I would post an update to let you know what I discovered! After replacing the G28 Engine Speed Sensor with no help, I ended up buying a gauge to check compression. Well, it didn't take long to discover that at least the head gasket was bad because I had compression leaking between cylinders. So, I went about removing the head. I had noted earlier when I had removed each spark plug that all looked pretty normal except for the #4 plug, which looked like it had some weird metallic deposits on it. After getting the head off I found that the metallic substance was actually molten aluminum from where part of that cylinder's combustion chamber had melted, probably due to detonation:
View attachment 98027
View attachment 98028 Check out the missing aluminum between the exhaust valves, holy crap!! ALL of the exhaust valves had some pretty heavy carbon deposits on the back side & stems, but for whatever reason the #4 combustion chamber just disintegrated. I found a used/rebuilt head on eBay that I snapped up and removed the short block, which I took to a local machine shop to have inspected for any further damage. I got the "new" head a couple of days ago and it's in great shape; it included all new valves and some mild porting. I need to call the machine shop today to see if they have found anything that I'll need to replace....

Hope everyone has a great Christmas or whatever holiday you happen to celebrate!!!
 

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This begs 2 questions; what was the root cause of such damage and, what other systems/components besides the cylinder head were damaged in the process?

My advice, proceed with great caution and everything is suspect.
 

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Discussion Starter #8
This begs 2 questions; what was the root cause of such damage and, what other systems/components besides the cylinder head were damaged in the process?

My advice, proceed with great caution and everything is suspect.
Yeah, I hear what you're saying and I'm actually concerned about a possible over-fueling issue, especially on the #4 cylinder. While I wait to hear from the machine shop regarding the condition of the block and rotating components, I'm looking into at the very least testing the fuel supply and delivery system. The Bentley manual has procedures for checking out the injectors and the fuel pressure regulator, as well as the MAP sensor. I'm contemplating upgrading the injectors anyway to something larger because I am seriously thinking about diving all the way in on a big turbo setup.... the way I see it, I have already spent a ton of time and a decent bit of money to get this far, and there's no better time to go all the way since I've got the engine out.

Someone talk me out of it, would ya? 😉
 

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throwing this out there for discussion....on a timing belt change,mechanic/individual was slightly off when he thought #1 cylinder was at TDC, Assumes all is good, then manually cranks (or maybe even attempts to start) the #4 cylinder I believe is at its exhaust stroke at this point and the piston now crashes into the two exhaust valves slightly bending the heads, The stems of the valves are still straight, but the valve heads are no longer "square" to the stems (almost unnoticeable) The valves still return to their seats but do not seal properly/tight leaving a gap , (maybe 1 mm (.040")). Realizing something is wrong , he resets the timing after feeling the positive stop/resistance , never doing a compression check assumes all is good, car runs fine with little realization that #4 cylinder is now running super lean and slightly drawing hot exhaust gases back through the exhaust valves..... a forensic exam of "run out" of valve stem to head mating surface with a dial indicator would be interesting
 

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I'm contemplating upgrading the injectors anyway to something larger because I am seriously thinking about diving all the way in on a big turbo setup.... the way I see it, I have already spent a ton of time and a decent bit of money to get this far, and there's no better time to go all the way since I've got the engine out.

Someone talk me out of it, would ya? 😉
I don't think I am a good influence to stop you. I started the manual swap over 5 years ago simply because I wanted to keep the car for another 9 years (at that time) and I knew the tip trans would not last that long. If I had kept the V6, I would have stopped there and been happy. Since I had to swap the V6, I found the 1.8T did not have the torque I wanted (and HP), so I slowly bought parts. I picked up a built 2.0 block almost 18 months ago. Then I unexpectedly retired a year ago, 5 years earlier than I had originally planned on. I still am buying parts and intend to do the swap sometime next year.
If you like the car, it's in decent shape overall and can afford the cost, I suggest you do what you want to the car.
 

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Discussion Starter #12
I don't think I am a good influence to stop you.
...
If you like the car, it's in decent shape overall and can afford the cost, I suggest you do what you want to the car.
Now, see? I like the way you think, my man! A month ago when the car died on the freeway, I remember my Dad asking me what my plan was in the case that something catastrophic had occurred....he was basically probing to see at what point I would consider the project too costly or complex and start looking at other (read: newer/more reliable or economic) vehicles instead of expending the time, effort, and money to repair the Unicorn. Honestly, I never even considered replacing the car, and I still don't. Yeah, it's somewhat of a rarity but beyond that I just really like the car! The way I see things, this is the opportunity to become just that much more familiar with it, considering all of the maintenance and mods will be done with my own hands.

I'm still waiting for the call from the machine shop regarding the block and rotating bits. In the mean time I found an engine stand on OfferUp for $20 and I've been researching & compiling a list of what I'm gonna need for the rebuild. I'll post periodically as the project continues! Hope everyone is having a great holiday season!
 

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any thoughts or word on your engine?
Nah, not yet. I called the machine shop about a week ago and they still hadn't had the chance to look at it, at least at that point. Apparently the shop owner had been in Indianapolis the prior week at a racing/engine builder's convention and was playing catch-up. I'm getting impatient, but I've got stuff I can address until I get an idea what to expect on the lower end.
 

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Liking the car, lack of rust, lack of heat damaged paint and interior; put anything you want into the car. I only wish mine had a nicer interior, but that can also be done (apart from the cracking dash parts).
 

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Got a text from the machine shop earlier today with instructions to give them a call tomorrow morning... apparently they got the crank/pistons and rods out and have taken some measurements and are ready to discuss things with me, which I'm anxiously stoked about. I will post again tomorrow after I talk to them.
 

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Discussion Starter #16
Also, I am curious about this clutch kit or one that is similar. Anyone have any experience with this or one like it?
Screenshot_2020-01-15-20-37-26.jpg
 

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I haven't heard good or bad about the eBay ones, but i have the Valeo solid flywheel setup. It chatters a little, but it is smooth as stock.
 

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Talked to the machine shop this past Friday. They say that the block & cylinders look remarkably good for 242k miles, to include the deck which surprisingly wasn't warped or cracked. Crank looked good and will not require any regrinding. So after discussing things with the shop's owner I felt that even though it looks like best-case scenario, it couldn't hurt to have a +.020" bore & subsequent hone performed on the cylinders. I ordered a set of new oversize pistons and rings, which were delivered today and I will take them down to the machine shop Monday morning because instead of just doing a cylinder re-bore on verbal instructions, they prefer to have the new parts on hand to perform a piston-to-cylinder wall clearance. Oh, and I also requested that they take some measurements and inspect the con rods. I don't mind reusing them if they are in tip-top shape, but if there's even a hint of anything questionable I'm gonna fire a new set of rods at it.

Oh, and I ended up also ordering that "Stage 2" single-mass flywheel clutch kit which also arrived today. First impressions while unpacking the kit are pretty favorable; the components all appear to be of good quality and the kit was complete with everything you'd expect from a higher-priced Sachs or similar kit. I'll snap some pics tomorrow to post.

While I was at it, I ordered a new catalytic converter and a standard cylinder head gasket kit, which includes all necessary top end gaskets as well as new head bolts and associated bits.

Will post updates soon!
 

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Are they upgraded pistons or stock style? If upgraded, I would just replace the rods with upgraded too. That way you can upgrade to a larger turbo in the future without having to pull the rods. The stock are usually good for around 300hp, but there have been a few bent rods on even a K04 with the high torque down low.
 

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Are they upgraded pistons or stock style? If upgraded, I would just replace the rods with upgraded too. That way you can upgrade to a larger turbo in the future without having to pull the rods. The stock are usually good for around 300hp, but there have been a few bent rods on even a K04 with the high torque down low.
I got some stock-style pistons, albeit at +.020" with a set of rings to match. The machine shop got the cylinders bored and the top of the block decked straight. Oh, and they were also able to remove the broken remnants of the bolt that I broke off in the hot side of the turbo housing...

I picked up the block a little over a week ago and I have been meticulously working on reassembly each morning since, to where I now have it just about ready to go back into the engine bay! I elected to watch the football game yesterday...I needed a break from it for a day. Tomorrow morning though, it's going back to its home! Some pictures: IMG_20200128_115007.jpg IMG_20200130_105140.jpg IMG_20200131_120935.jpg IMG_20200202_140951.jpg
 
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