HE LIVES!!!! …And His Name Is Freshie

Freshie 2

At long last I finally dove back into my A4.  Armed with my premonition from a dream and a deep desire to hear the engine purr, I set out to find the source of the awful noise and dead misfire.

With the noise coming out of the right bank, I started by taking off the valve cover on that side.  Per my dream, I checked the clearance between the intake cam and the lifters, but it was to no avail as everything was within tolerance.  I did notice (through luck) that the engine had stopped PERFECTLY on Top Dead Center for cylinder 1.  My exhaust cam on bank one, which is driven by the timing belt, was dead on the money.  Perfect.  My intake cam, however, looked a little off.

Chain Links

So, as the timing procedure outlines, I checked the number of chain links between the intake and exhaust cams (see photo above) and realized I was at 14 links rather than 16.  Boom!  That solved the misfire concern.  But what about the noise???

I thought to myself that regardless of what the noise may be, I had found something that had to be corrected.  The course forward would be to re-time the cams on bank two, check compression, and reevaluate.  And that’s exactly what I set out to do.

I removed the bearing caps for the intake cam and compressed the cam chain tensioner hoping to have enough wiggle room to make the needed adjustment.  I didn’t.  Then I loosened the exhaust cam, but still no dice.  Ultimately the timing belt, cam gear, and timing cover (behind the cam gear) came off to make the correction.

With the cams out I decided to check the lifters again for good measure.  What I found was an intake lifter on cylinder two that did NOT want to move.  This was the area with the noise!!  With a little persuasion the lifter came free and I found debris (almost like a dried up engine sludge) between the lifter and the bore in which it travels.  It wasn’t much debris, but it was enough to prevent the lifter from freely traveling.  Boom!  Here was my noise!!!!!!  I cleaned all the contact surfaces, lubricated them with new oil, and confirmed there were no more restrictions.

At midnight I was finally ready to hit the key, and to my delight the engine was quiet as a mouse once the lifters pumped up.  Needless to say I’m very happy to have the A4 road ready.  And, with the all-wheel drive drivetrain, I can weather through the snow to EXAIR for your application needs all winter long.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Also, about the name – I acquired a VW Jetta much in the same way I came to own this A4.  When I towed the Jetta home my son saw the crunch in one of the fenders and named the car “Crunchy”.  This one, being very clean and sporty, has been named “Freshie”.  Because he’s fresh.

I’m Back! But My A4 Isn’t…Commence Troubleshooting

Last week I enjoyed the company of Airtec Servicios, Dansar Industries, and Global Automation (EXAIR’s distributors in Mexico and parts of South America).  We met in San Luis Potosi, Mexico, for an EXAIR training event that covered all topics of EXAIR products.

Following my return to the States, I dug into a project at home that I’ve been working on here-and-there; my 98 Audi A4.  In an earlier blog post I showed the damage done to the cylinder head when a valve-train component failed and a few valves were bent.  After rebuilding the cylinder heads on a bench here at EXAIR, I finally got the engine back together and hit the key for the first time since I bought the car.

Fortunately, the valve timing was perfect and the engine fired right up.  Unfortunately, however, was the terrible knock from the bottom half of the engine – the half I left untouched during the initial repair.  (See image below for my feeling on the issue)

Lie_down_try_not_to_cry_cry_a_lot_cleaned_525Now I’m faced with a dilemma of the best course to take, and after chewing it over, I’ve decided to open up the bottom half of the engine and make the repair.  The most likely cause for the noise is a defective wrist pin or connecting rod.  When I open it up, I’ll be sure to take pics and share for those interested. I had thought repairing the top half of the engine would make the fix because most of the time that is the case. Similarly, we occasionally experience reduced performance in our Reversible Drum Vac. Most of the time (I’d speculate 95%-99%) a simple cleaning is all that is needed (see video demonstration here) because this product has no moving parts there is little to go wrong. Occasionally it is another issue that is causing reduced performance; for these times we have the Reversible Drum Vac troubleshooting guide:

lit6203-Reversible Drum Vac Troubleshooting

So, sometime soon I’ll run through the next troubleshooting steps for the engine in the A4. If you need help troubleshooting an EXAIR product or a compressed air application, please contact EXAIR.

In the meantime, the A4 is relaxing, hanging loose at home – and I am too.  Mexico was wonderful, and the people were more than kind.  But, it feels good to be home.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

One For The Gearheads

EXAIR Application Engineers are geeky about compressed air, but there’s a few gearheads at heart among us, too.  I’m one of them.  Read through my blog below for a dive into my most recent gear-driven fun!

1998 A4

Recently I took on a new project at home.  One of my friends called me to tell me about an A4 with a potentially blown motor that might find a happy new home for the right (low) price.  Seeing as how I’ve procured many a vehicle in just the same way, I’m always optimistic about these kind of things.

So, I made the trip to look at the A4 and found a clean interior, 80k on the clock, and a no-start condition.  After sitting at the dealer for over a month without an accurate diagnosis, the owner had it towed to his house where he put it on the market as-is.  Unsure of the problem, but confident I could find and fix whatever is needed, I bought the car.

AHA DOHC

Cranking the engine (2.8 AHA code) over, I could hear a lack of compression, so I pulled the plugs and confirmed with a gauge.  Bank one (cylinders 1-3) had virtually zero compression on any cylinder, and bank two (cylinders 4-6) was perfect.  Interesting…  My first thought was that there was a timing belt failure and valves were bent when getting readings on bank one.  But the perfect readings on bank two made me second guess.  Nevertheless, I pulled the front carrier/core support and tore down to the timing belt.  Sure enough, the teeth of the belt were chewed off at the crank!  But, the story goes on…

The repair in a case like this is to pull the cylinder heads, check all the intake and exhaust valves for leakage, and replace those that are faulty (or all the valves depending on their condition).  Some people call this a rebuild of the top half of the engine, which is pretty accurate.

When I removed the cylinder heads and began to disassemble them, I could tell something wasn’t right.  There’s a camshaft adjustment unit used to advance or retard valve timing that has a special landing and thread for a service tool.  On the bank one cylinder head, this landing was missing (see the photo below).  Strange!  And, normally, the camshafts can be removed fairly easily once their bearing caps are removed.  But, on this cylinder head, no dice.

VVT Unit

Ultimately I found that the landing for the camshaft adjustment unit broke off and wedged on the exhaust cam of bank one.  See the photos below for the gouge mark on the casting.  This cam seized, locked everything on the head, and forced the crank to chew the teeth off the timing belt.  Miraculously, the valves on bank two avoided any damage and triple checked out when disassembled.

Head Gouge 1

Head Gouge 2

This failure led to the damage of (5) valves.  Some of them are visible to the naked eye as seen below.

Bent Valves

Now comes the fun part of getting the engine back together, knowing that there’s a “new” car at the end of all the work.

Lee Evans

Application Engineer

LeeEvans@EXAIR.com

@EXAIR_LE