AAZ vanagon project thread

[Renax]

Check that the valves are straight and fully close, contact might have happened while just slowly turning engine to get timing correct. That is not a problem...

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[zuhandenheit]

Thanks for the reply, Renax.

I'm pretty sure that the markings were caused by more severe valve-piston contact, which motivated the PO's head rebuild. The markings line up with the new valves in the head.

What should I check on this motor before I consider bolting on a new head?

[vanbcguy]

Make sure piston protrusion is the same on all cylinders, that way you know the rods aren't bent. Other than that you are probably good to go.

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[zuhandenheit]

Would it be worthwhile for me to check out the crank bearings, or anything else, while I've got it on the bench?

[zuhandenheit]

. . .

[theman53]

What exactly did he rebuild in the head? That looks pretty rough for a fresh non ran head. I would take it all back or ask for the money required to fix every time you find something wrong. I bet he did not do much.

Piston to valve contact is no big deal if the rod isn't bent and all valves are replaced. Bent rods and valves that "look" ok can come apart after several miles and cost lots of money.

[zuhandenheit]

I'm not sure what was done to the head, but I guess you're right - not too much.

I've been trying to check piston protrusion with a feeler gauge and a straight edge. Everything seems to be the same, but around one 1 mm, which is surprisingly low, right?

[zuhandenheit]

Okay, nevermind - I found some info in the FAQ. I will do a more careful measurement with a dial gauge.

[92EcoDiesel Jetta]

Was the head skimmed? The pre cups are suppose to stick out a little. If pre cups same level as head, then it was skimmed.

[Gizmoman]

 ???I don't see anything wrong -
I believe the cracks between valves are "normal". I also don't see any cutter marks on anything so I would bet it's not been skimmed (even grinding will leave some signs). To me, the cups do look like they protrude a bit and I also see no cracks in them either.

I'd take it to a machinist and ask him to measure the bores of the cam bearings with the caps bolted on and torqued to spec. Then mic the cam journals (did you ever polish them with emery?).

What am I missing?

[theman53]

The valves look burnt to me. The rest of the head looks "ok", but if he didn't do valves, then I would suspect the rest of the vavletrain is junk too. You don't just slap valves in one and say it is OEM either. You need to do the whole deal before they act as they did new.

[zuhandenheit]

Gizmoman:

I haven't tried polishing the journals yet, although I really appreciate your advice.

I'm ordering a Kolbenschmidt head from Bora Parts.

There are a couple of reasons: One, I'm pretty much convinced that the PO put the wrong caps on this head, because they are all about equally the wrong size (around .2 mm), and I'm concerned that the cam will be eaten. Two, I wouldn't worry so much about it if I were able to drive this van around town for a long time (because I could always replace the head later if it doesn't work out), but I'd like to have it ready for a long trip in about a month, if that's possible.

So, I'm ordering a new head in the hopes of getting the van going, and then I can take my time going through the old head, or will maybe sell it here to someone who can put the work into it.

My concern at the moment, therefore, is the block. I've got it on my bench and would like to poke around and check whatever tolerances can be checked without taking it apart, unless that seems to be necessary.

The piston protrusion seems close to even, by my straight edge and feeler gauges, but I will try to check more closely with a dial indicator.

I'm learning as I go along here. Most of this is relatively new to me. So, one more time, thanks again for all the help! I'd be lost without it.

[Gizmoman]

Hard to beat new

[vanbcguy]

I wouldn't be too worried about the block really. You can put new rings in now with a minimum of hassle but as to whether it is "worth it" or not...

These engines rarely have bottom end problems. They do get stuck rings, they definitely eat valve guides but it'd have to be run with no oil to do much to the bearings.

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[zuhandenheit]

Well, I discovered that I can slide a feeler gauge past where the ring should be on the burned side of the piston . . .

I've taken more pictures and talked to several knowledgeable friends, and the consensus is that the pistons are fried, at least.