AAZ - sudden excessive oil consumption - Updated

[phil_b]

Our hard working and reliable AAZ has possibly reached the end of its life, it was fitted 55,000 miles ago (it already had 112k miles under its belt in a Golf) and other than an oil pipe and head gasket failure in the first 1000 miles of fitting has been 100% reliable with just routine servicing etc.

However, in the last five or so thousand miles oil consumption has steadily increased and driving back from Spain this week has increased dramatically, I needed to put in at least 5L of oil over the last 1000 miles. Bone dry underneath, definitely not leaking out.

Other than excessive oil consumption it starts and drives as usual, a puff of blue/white smoke on start-up which clears after a few seconds. No obvious smoke when driving even on full load up long inclines, although maybe slightly down on a power on steep hills. At night a very slight haze can be seen in following cars lights if they come close. Exhaust has dry soot in tailpipe, no oil spots on tailgate. Fuel consumption has recently improved but that’s probably because I’ve been driving slower in an effort to reduce oil consumption – without success, or because it’s using engine oil as extra fuel? but no running on etc.

My first thought’s were turbo seals but having taken the turbo inlet pipes off I was surprised how little oil was in the turbo just a stain really, and no play in the shaft, however the inlet pipe after the connection with the crank/top hat breather pipe did have a significant amount of oil in it. I have since plugged this connection and vented the crank/top hat breather into a temporary catch bottle, when running there is a significant plume of grey mist coming from this? Is this normal or does this suggest blow past due to worn bores/rings?

Any thoughts on what else to check/test before looking for another engine?

Anyone know where to source a good engine?
Cheers Phil

[ELVIS]

AW Engineering. Me mate fitted one and ive fitted two. Appear to be a quality remnaufacturer at good prices. If they dont have an AAZ in stock they can turn your engine around PDQ.

[Timburrows]

Valve stem oil seals cheap and easy to do can be done with the head on I think with the right tools

[phil_b]

Thanks for the replies, would be great if it was just worn valve guide seals, could they alone result in oil consumption of approx a pint every 100 to 150 miles? Anybody done this job without taking the head off on a VW diesel engine?

Cheers Phil

[Timburrows]

Done it on a 15degree engine don't know how good your access is at 50degrees,piston at TDC to stop the valve dropping out,there is a rail that bolts onto the rocker box studs and a spring compressor that hooks under it enabling you to compress the spring to remove the collets.check with your local vw dealer you may be able to borrow it from them

[phil_b]

Update - found a good used AAZ at very good price which I fitted over the Easter weekend, did a 200 mile round trip yesterday and everything seems good again, also much quieter mechanically. Going to strip the old engine at leisure and repair as a spare.

[phil_b]

Further update on the state of my old AAZ engine - now partially stripped

This is what I found so far - signs of very heavy valve contact on piston No 4, light contact on No3, both carboned up, this has not occurred in my ownership so it had been running like this for at least 55k miles, I'm guessing timing belt snapped in the past and repair done with just new belt/valves.

Slight piston erosion on No. 4 and top ring worn extremely thin and with a 4mm end gap! lots of signs of blowpast, other rings stuck in grooves with carbon. So this will be why it was using so much oil....

Any thoughts on whether this is typical wear on an engine with approx 180k miles or could the excessive ring wear have been caused or related to the heavy valve contact. Other than the recent oil use issues the engine had run perfectly and reliably, it has been regularly serviced with oil and filter changes at 6k mile intervals.

Cheers

Ps. my cheap Ebay engine has now done almost 4k since install, with less than 0.5 litre oil consumption, and returning average 35mpg so well pleased

[stys0n84]

I'd be very interested in picking your brain about this. My bus seems to be firing oil out of the exhaust and leaving it on the tailgate and on the floor! What usually causes this blowby?

[jebiga41]

I'd be very interested in picking your brain about this. My bus seems to be firing oil out of the exhaust and leaving it on the tailgate and on the floor! What usually causes this blowby?

Sounds like one I have which I just changed with another could be either one of three things from what I can see,
1 Turbo oil seals 2 valve stem seals and possibly guides or 3 worn piston rings.
I tried 3 turbos which seemed to run ok on other engines so kinda ruled out number 1 on mine. I havent managed to do a compression test yet but appears to run fine and starts on the button so Im kinda ruling out piston rings although in the process of ordering a compression tester with an injector adapter as seems fairly impossible to get the glow plug adapter in behind the pump so will see what that does.
I'm hoping for valve seals going to take the head off and decarbonise and replace valve guides and seals while I'm at it plus can have a look at the rings and pistons whilst the head is off and replace if necessary.
Hope this is of help

[stys0n84]

yea cheers mate gives me something to go at. :thumbs up: