Lot of talk about these online for TDI but not a ton for IDI, and the unfortunate name of the company makes it difficult to sift through the google results too so I thought I'd toss in my two cents for anyone later.
I don't know if any of this applies to anything other than an AAZ head from them. FB groups suck for preserving findable info so figured I'd toss it up here.
My OG head on my perfectly running 250K-ish mile motor was off for an external oil weep that's been doing so for ten years I finally decided to fix and I noticed several
cracks between the prechamber and the valve and I just couldn't bring myself to put it back on there like that.
The casting and machining seems to be overall quite good. I'm not a machinist but I'm a 45 year old guy that's been neck deep in car crap since he was a child so take that for what it's worth.
They did make an effort to deburr the sharp edges but they also left casting flash that was bad enough you could pull small pieces off with your bare fingers, lower part of the cam towers and a few
other areas.
The aluminum is noticeably softer than the stock head. FedEx managed to ding the valve cover sealing surface and it was trivial to tap it flat with a hammer. I banged on my
factory head in a similar manner and it didn't deform so take that for whatever it's worth. No issues with installing any of the studs or other bolts.
I wonder if a softer material might deform somehow rather than crack like that factory ones do but I'm no metallurgist.
It's not like butter or anything, just a little softer than whatever the stock one was made of.
I pulled the cam and lifters just out of curiosity. The cam looked fine and the lobes appeared to have parkerizing or something like it on them, I assume for breakin, the overall lobe size matched
my factory cam.
There was a very light coat of oil on everything, I put cam assembly lube on before reassembling.
The lifters are stamped INA underneath, I'm a distrusting sort so I wonder if they are "real" INA but at the same time I don't really think a company this big that puts their name on everything and
barcodes and serial numbers their products would jerk around with sketch fake parts.
One thing of note is one of the lifters was stuck, and none of them were pre-filled with oil at all. I know opinions vary on the oil thing but I always like to get at least a little oil in there.
The stuck lifter I put in a bench vice carefully and with a very small amount of pressure it became free and seemingly normal. I ran it and nothing bad has happened. I'm glad I pulled them
and checked, maybe it would have come free on it's own, maybe it would have kissed a piston with a valve, I don't know.
I would have plastigauge'd the cam journal if I'd had any handy but did not.
The intake and exhaust ports were near enough to identical to my stock head.
The lifters fit properly in the bores, none too loose, none too tight.
Did not pull a valve spring off, the locks looked just like my factory head looking from above.
The valves were 8mm same as my factory head.
The valves and prechambers are non-magnetic. I assume the valves are some sort of stainless, maybe the prechamber is as well, maybe it was inconel, I don't know any way to tell for a layman.
I've read that VW used both stainless and inconel. I do not know if the exhaust valve is sodium filled as the factory turbo one is supposed to be. Looking at the valve seats under and open valve they
looked to be well machined.
I've heard complaints of low oil pressure from a few people online with these heads on IDI's but see no evidence of it here, if anything my oil pressure which was already fine is up a little.
Overall it seems fine as far as a visual and 50 miles of beating on it go. I doubt I'll ever put miles on this one like I have before as I don't drive all that much these days.
The guy that rebuilds TDI heads on the other forum has a pretty low opinion of them but you don't just go out and buy an uncracked AAZ head in the US these days so
it was this or spend who knows how long trolling the internet to find something and then trying to find someone that can rebuild it correctly, so I just bought the new
aftermarket one. Generally speaking I detest aftermarket parts and my opinion has not changed on the matter, if there was a new factory head available at twice the price I'd have bought it.
I paid $908 shipped for this one from Cascade German and it took them a week to ship it but it got here quickly once they did.
Startup was uneventful. I've wound it out pretty good and run the interstate for 20 miles at speed and nothing has exploded.
I had to re-torque one injector that was leaking around the threads in the head which was the first time I've seen that, I pulled
them all and used a swap to clean the mating surface in the head that I should have done to start with, seems fine now.
If anything falls out of it I'll report back but I just don't put enough miles on this thing anymore to really test it much I suppose.
