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1.6 TD rebuild questions by dl_sledding on 12 Jul, 2011 17:23
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While driving on the interstate late last year, my beloved diesel started screeching horribly and the oil lamp/buzzer contraption started wailing. So, I rapidly got if off of the road and ended up towing it home, where it slept for a few months until I had time to work on it. I have pulled the engine and trans, and have found that the IMS bearings are flaked out and toast. The PO had "some head work done", and I think probably the timing belt was too tight. Neither here nor there at this point. Been cleaning and disassembling for a while now, and noticed that instead of #1 being at TDC, #2 now was... so it called for the head to be pulled as well.
Noticed that just one of the rod lobes had some blueing:
So took off the head and started checking things out. First, noticed the bearings are toast:
So, new bearings are in order. They are all marked std, but have been replaced at some time since there is an engraving on the underside that is not shown here dating the bearing to 2006.
Piston tops all look like this:
All the rings are free and the cylinder walls still show a slight bit of cross-hatching, no deep scores in any of them. Also, it doesn't look like the pistons have ever impacted the valves, so I was worried about nothing there. As far as I can tell, none of the valves are bent either.
Next, the head:
And above piston 1:
See the crack? All 4 cylinders have it. Here's a closer view of #4:
Finally, a quick pic of the head gasket and deck:
Questions:
1. Do I need to replace the pistons? Is this "normal"? Personally, I don't think it can be a good thing, but I am not a mechanic... I think they are original pistons; they do have the Audi logo on the inside of the skirt.
2. Is the head shot? Those cracks all bother me, but I have read on the Vortex that this cracking is pretty common. Is it a deal-breaker? I have a feeling that the valves are fairly new; the PO said that there was head work done on the motor.
3. Is this the proper head gasket? Seems that some of the water jackets are plugged by the gasket, most noticeably to the right and left of the oil drain-down passage.
4. Is this what they call a "two groove" gasket? Is that what the two notches out of that tab on the gasket mean?
5. Been reading about ARP head bolts. Necessary? Or will the "normal" bolts from {insert your favorite supplier here} work as well on a "normal" build? Not going to go for 200 horse or anything, just a daily driver for me...
6. And what about head gaskets? Will the "normal" ones work as well also?
Thanks all! Hope someone has some good advice for a newbie! -
#1 by rallydiesel on 12 Jul, 2011 19:22
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Pistons should be fine if the bores look good. I wouldn't waste my money on new ones at this point. Cracks in the head are a little on the big side of acceptable. Check to see how deep they go and if they might allow gases into the ports when the valves are closed. Stock head bolts are fine as is the stock gasket, as long as the head is flat and you don't run high boost/fuel.
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#2 by R.O.R-2.0 on 14 Jul, 2011 09:22
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Pistons should be fine if the bores look good. I wouldn't waste my money on new ones at this point. Cracks in the head are a little on the big side of acceptable. Check to see how deep they go and if they might allow gases into the ports when the valves are closed. Stock head bolts are fine as is the stock gasket, as long as the head is flat and you don't run high boost/fuel.
if you can fit a penny in the cracks, there too big. -
#3 by silentdub on 14 Jul, 2011 09:50
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Damn, does every cylinder have a crack between the valves? Does anyone weld them up anymore?
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#4 by R.O.R-2.0 on 14 Jul, 2011 10:04
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Damn, does every cylinder have a crack between the valves? Does anyone weld them up anymore?
most all IDI heads ive seen are cracked.. ive seen 1 head that was NOT BRAND NEW and did not have cracks.. -
#5 by dl_sledding on 14 Jul, 2011 11:29
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So, as long as the crack doesn't continue under/through the valve seat, everything should be OK then?
What about hot spots and such, would I be better off filing the edges down so that the crack has smoother edges?
In other news, it looks like new mains are in order too... the bearings are worn down to the brass, copper, bronze, or whatever the underlying material is. Probably going to have to bring the crank into a machine shop and have it mic'ed to see if I need oversize mains or not.
Thanks for all the responses... It's appreciated! Can't wait to get this back on the road again. -
#6 by southernman on 14 Jul, 2011 22:23
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dl,
I recently went through the same scenario as you and here's a few things I'd verify to ensure you're happy with your finished project.
Questions:
1. Do I need to replace the pistons? Is this "normal"? Personally, I don't think it can be a good thing, but I am not a mechanic... I think they are original pistons; they do have the Audi logo on the inside of the skirt.
IMHO, you need to have the block checked to ensure that your cylinders are not at the outer limits once the block is honed for new rings. Remember, excessive ring gaps WILL rob you of power, and while you noted you're not a HP junkie, I'm sure you'd be very disappointed to spend considerable time and money to end up with an under powered engine, and/or one with excessive blow by.
Also remember, rings installed at the 'outer' spec, will soon be out of spec, resulting in excessive ring gaps. Please note that for every .001 of cylinder wear, your ring gaps open up .003. You'll see .001 of wear in the first 100 miles of driving - if not sooner.
Spend the money on new pistons and rings. Next to the heads, they determine engine output and final HP.
2. Is the head shot? Those cracks all bother me, but I have read on the Vortex that this cracking is pretty common. Is it a deal-breaker? I have a feeling that the valves are fairly new; the PO said that there was head work done on the motor.
As noted above, most of these heads have cracks. Have it tested to be sure you won't have issues later, and verify the cam is still in good shape (spec).
3. Is this the proper head gasket? Seems that some of the water jackets are plugged by the gasket, most noticeably to the right and left of the oil drain-down passage.
Gasket looks correct and most will have some holes that appear to be 'blocked off.' Just be sure to take the old head gasket to the machine shop so they can order the new parts and machine accordingly.
4. Is this what they call a "two groove" gasket? Is that what the two notches out of that tab on the gasket mean?
See above.
5. Been reading about ARP head bolts. Necessary? Or will the "normal" bolts from {insert your favorite supplier here} work as well on a "normal" build? Not going to go for 200 horse or anything, just a daily driver for me...
I went with the ARP head studs because a stud offers clamping forces far superior to a bolt, however, I understand why most builders shy away from studs - primarily cost. At the end of the day, if you want to 'bias' your results, head studs, in my opinion, are worth every cent.
6. And what about head gaskets? Will the "normal" ones work as well also?
Yes, they will work fine, but I was considering going with a MLS type gasket for my next build, which requires the head and block to have a >50RA finish. The only reason I didn't this time was because I couldn't get the gasket in time, but rest assured, MLS technology offers a huge advantage over the old composition type gaskets - especially in boosted applications.
Again, just my 2 cents and I hope it helps.
Southernman
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#7 by dl_sledding on 15 Jul, 2011 16:59
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Southernman,
Thanks for the advice... It's very sound. Basically, measure everything and make darn sure it's still in spec, and not near the outer edge of the spec. Actually, that really helps make the decisions for me. And, have someone who knows WTF they're doing check things out too!
Thanks!! -
#8 by dl_sledding on 16 Jul, 2011 11:24
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Do these motors *not* have camshaft bearings? It looks to me like the shaft rides directly in the cradles and blocks, without anything there to protect the aluminum...
Looking for a recommended machinist locally to check out the block and crank. Hopefully someone around here is familiar with metric stuff. -
#9 by R.O.R-2.0 on 16 Jul, 2011 11:31
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Do these motors *not* have camshaft bearings? It looks to me like the shaft rides directly in the cradles and blocks, without anything there to protect the aluminum...
Looking for a recommended machinist locally to check out the block and crank. Hopefully someone around here is familiar with metric stuff.
no, technically, there are no cam bearings.. -
#10 by silentdub on 18 Jul, 2011 08:08
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A machine shop should be able to weld those cracks shut. Does this make sense as a preventive measure? I have seen heads welded up before and they worked very well, not sure if that is an option for this head.
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#11 by R.O.R-2.0 on 18 Jul, 2011 10:30
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A machine shop should be able to weld those cracks shut. Does this make sense as a preventive measure? I have seen heads welded up before and they worked very well, not sure if that is an option for this head.
a shop will rip the valve seats out, weld them, re cut the seats, and then there just gonna crack again once you run it for very long..
kinda pointless to weld a VW IDI head if its not cracked into the coolant passages.. -
#12 by dl_sledding on 18 Jul, 2011 16:38
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Why do the heads crack so badly? Is it because the area is so small, and between two pieces of steel (the two valves), which would have different cooling rates? Is it possible that the cracks are closed during running temperatures, and then open up once the head cools off?
Just curious what the theories are.... -
#13 by J Z on 18 Jul, 2011 17:55
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Just curious what the theories are....
Me too.. -
#14 by dl_sledding on 20 Jul, 2011 15:05
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Sad day...
Took the crank to the machinist. He looked at it for a total of 15 seconds and gave it back. No charge, of course.
Thrust landings are gone. Crank is toast.
Anyone have one for sale?
Gonna look through the fs forum too...