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#15
by
rabbitman
on 26 Feb, 2021 16:43
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I think I am understanding you correctly that if I have the flywheel at TDC and the pump at TDC and I use the cam lock when I put it all back together I will NOT have to re-time the injection pump? I will be able to simply re-tension the belt and be all good?
It will most likely start but you'd most likely need to time the injector pump to make it perfect.
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#16
by
intramural
on 26 Feb, 2021 19:00
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Okay great, thank you. I'm starting the removal tonight. Wish me luck.
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#17
by
intramural
on 27 Feb, 2021 14:31
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Okay I did lot more reading and all of this makes waaaaaaaay more sense now. I feel a lot more comfortable with the project.
When I removed the valve cover both the camshaft and flywheel were about 5deg off TDC from the injection pump. My dad and I timed the IP about 15k miles ago. Is this a normal amount of variance after that much driving, or did we just not do a very good job of timing? The engine always seemed to start right up and ran great.
Also where do you all buy your valve cover gaskets? The only place that actually seems to have a 1Y/AAZ valve cover gasket is tectonics tuning. The other parts stores always pull up something closer to an AHU gasket.
Cheers. Thanks for helping me.
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#18
by
libbydiesel
on 27 Feb, 2021 14:52
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If you do not loosen the injection pump mounting bolts and return the belt to the same tooth, the injection pump timing will be the same before/after.
The tube of hylomar is a bad idea for use on a head gasket. No way to spread it evenly and lightly enough. You'll get blobs in the cooling system.
On the other hand, the spray cans of hylomar are EXCELLENT for head gaskets. IMO the copper spray is a poor substitute. A very light spray of the hylomar on all four surfaces (head, block, both sides of gasket) eliminates the pesky weeping oil leaks at the drains and the high pressure port to the head between 3 & 4. When I say a very light spray, I mean it. Not enough to make the surface look blue. Just enough to make it look kind of wet.
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#19
by
intramural
on 27 Feb, 2021 16:40
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If you do not loosen the injection pump mounting bolts and return the belt to the same tooth, the injection pump timing will be the same before/after.
The tube of hylomar is a bad idea for use on a head gasket. No way to spread it evenly and lightly enough. You'll get blobs in the cooling system.
On the other hand, the spray cans of hylomar are EXCELLENT for head gaskets. IMO the copper spray is a poor substitute. A very light spray of the hylomar on all four surfaces (head, block, both sides of gasket) eliminates the pesky weeping oil leaks at the drains and the high pressure port to the head between 3 & 4. When I say a very light spray, I mean it. Not enough to make the surface look blue. Just enough to make it look kind of wet.
Thanks I was curious about that in regards to spray vs. tube. That makes perfect sense.
I'm going to verify the pump timing regardless at this point, since it seems like the whole engine was just a little off. I remember now that my dad and Installed the timing belt without the transmission attached. which explains why the flywheel was a little forward.
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#20
by
intramural
on 27 Feb, 2021 20:36
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#21
by
libbydiesel
on 27 Feb, 2021 22:40
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Just a heads up, that location for your EGT probe is not good. That is a very stagnant area. It renders the reading from the gauge meaningless. You want the probe directly in the exhaust flow and preferably where all 4 runners have come together.
The cracks in the precups can either remain the same for a long time or they can grow quickly and cause the insert to crank in half and fall into the cylinder, ruining the engine. If you can find them, then replacing them is a good idea, IMO.
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#22
by
intramural
on 27 Feb, 2021 23:00
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Just a heads up, that location for your EGT probe is not good. That is a very stagnant area. It renders the reading from the gauge meaningless. You want the probe directly in the exhaust flow and preferably where all 4 runners have come together.
The cracks in the precups can either remain the same for a long time or they can grow quickly and cause the insert to crank in half and fall into the cylinder, ruining the engine. If you can find them, then replacing them is a good idea, IMO.
Meaningless, as in way to low? Or just absolutely meaningless?
The prechamber cracks are a bummer. I am worried about the cracks in the valve seats as well. It doesn't seem like there is an obvious place to even buy the prechambers.
I'm going to take the head to a local VW machine shop on Monday and see what they say. I need to get it checked for straightness any way. I might reach out to Thomas at quality as well and see what he has for heads. $900 is pretty steep but I don't want to do this again.
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#23
by
libbydiesel
on 27 Feb, 2021 23:12
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That EGT probe location causes both a low reading and a additional lag to the reading. It is a dead-end location for flow. Imagine placing a thermocouple in a tin can with open end aimed at the flame but to the side of an oxy-acetylene torch vs. having the probe actually in the flame. In other words, your pistons or turbine fins could be melting for a minute or more while the gauge still reads safe. I doubt you ever see near actual peak temps with that probe location.
Here's where I installed an EGT probe into a VNT15:
It looks like Brickwerks in the UK sells the inserts. Pricey, but certainly less than a new head:
https://www.brickwerks.co.uk/diesel-pre-combustion-chamber-1-9td.htmlA few years back NAPA actually sold them although I haven't checked in a while. I have no idea if they still do.
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#24
by
intramural
on 28 Feb, 2021 00:51
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That EGT probe location causes both a low reading and a additional lag to the reading. It is a dead-end location for flow. Imagine placing a thermocouple in a tin can with open end aimed at the flame but to the side of an oxy-acetylene torch vs. having the probe actually in the flame. In other words, your pistons or turbine fins could be melting for a minute or more while the gauge still reads safe. I doubt you ever see near actual peak temps with that probe location.
Yeah that makes sense looking at this. I pulled out the probe and it seems to be pretty long. long enough where it would be getting an accurate reading... I also readily believe that I could be wrong.
It looks like Brickwerks in the UK sells the inserts. Pricey, but certainly less than a new head:
Awesome dude! Thanks for the part #! I was able to find some other sites selling them. Nothing in the US yet. I'm going to wait to buy them until I have the machine shop look at the head.
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#25
by
RustyCaddy
on 28 Feb, 2021 15:13
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#26
by
intramural
on 28 Feb, 2021 15:42
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If all else fails and you decided to replace the head there is a new cylinderhead on from Topline on ebay now:
https://www.ebay.com/itm/1-9-1992-1997-VW-AAZ-NEW-BARE-CYLINDER-HEAD-TURBO-NON-TURBO-DIESEL/274695551628?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649
You might be able to swap over the valves. No mine or anyone i know.
I don't think I am prepared to rebuild a head. Camshaft swap seems easy enough, but the valves and lifters look complex and like they require tools I don't posses. Right now quality has a new made in Germany head. Seems way more expensive and way easier. I think if the head is bunk I'll probably go with the new one.
I'm concerned that when I take the head to the machine shop they might tell me they need to weld the seats together. From the research I have done it's more likely this will make things worse and I am better off putting the $ towards a new one.
This is turning into quite the project. Although, I'm glad I am able to do it myself. It's easy to imagine that a repair shop would have simply replaced the 3 notch gasket and called it good. Then again, who knows.
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#27
by
intramural
on 01 Mar, 2021 16:12
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As I am prepping the head for the machine shop. I am starting to ponder what could cause the head gasket to fail in the first place. I have done a bit of research, and this seems to be a lot more common on the IDI engines.
My mind initially goes to running EGT too high, especially given Libby's comment on my probe location. I have the boost set for 10PSI, no inter-cooler. The engine has never overheated.
Before I removed the head when it was running I would get a somewhat loud intermittent crack/tap from the engine, but I didn't think much of it. The fuel pulley was a little advanced... could this at all be related?
Curious if y'all have any ideas. Thanks again for all the help so far.
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#28
by
intramural
on 01 Mar, 2021 19:49
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Well I took the head into the machine shop and the block *( edit: head)* is warped. Scheiße
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#29
by
libbydiesel
on 02 Mar, 2021 18:21
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How did you determine that the block is warped? How warped is it?