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#30
by
VWRacer
on 17 Nov, 2004 06:16
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Lookin' good, Jake!
Could you post a close-up of the lower left corner of the pic immediately above? I'd like to see more deatils of the turbo air inlet.
Thanks! Stan
PS - I got a Bandwidth Exceeded msg for the photos above the latest one...
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#31
by
fspGTD
on 17 Nov, 2004 10:00
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Looks like I need a new image hosting provider. :? Got any ideas?
I could just use good ol' Imagestation, but the problem with them is that they will hose out only small images, so I can't really show the details captured by new high-res digital camera.
Stan, there are some pics of that air filter setup in this old hostboard thread... (Let me know if you want me to take shots of any other views.)
http://www.hostboard.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=4037&t=291
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#32
by
web
on 18 Nov, 2004 06:01
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Congrats!
If you know how to use FTP for uploading, I can set you up some image-space on my webserver.
It's not very fast, but for posting a couple pics to this forum it should do just fine. (that's what I use it for anyway, posting pics to various forums)
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#33
by
VWRacer
on 18 Nov, 2004 08:12
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Thanks Jake, I'll check it out tonight. (The LAN-Nazis at work block Hostboard as "Chat".)
But they don't know about vwdiesel.net... :lol:
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#34
by
fspGTD
on 22 Nov, 2004 09:49
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Yes, you could get an audible rod knock if the bearings are damaged. Also, if you have oil pressure and/or oil temp gauges, watch for substantial changes in their behavior since the "incident".
Absolute pressure/temperature readings usually don't mean much, but changes in their behavior can allow you to spot a bearing problem early (greatly reducing the risk of crankshaft damage).
I once had an engine that ate a set of brand new rod bearings in just 20 miles. It didn't even knock although the bearings were down to the backing metal in just 20 miles. I tore it down the 2nd time after the bearing job because it felt sluggish and exhibited high oil temps / lowish pressures after the bearing job. Indicating high friction (and likely excessive clearance). I have NO idea why it never knocked, I consider it one of those exceptions every rule seems to have... Turns out the root cause was an oil supply problem. Live and learn 
But that's beside the point, just an extreme example of gauges being a Good Thing.
Don't let me scare you though ; as you say, likely the VW diesel bottom end is very strong.
Marcel
OK... I've taken the engine through about 3 heat cycles now, and driven it around the street a bit. The good news: it rips! It really seems to like this new head. Power in the high RPMs seems really good (I haven't red-lined it yet, just trying to get a feel for the new performance of the motor.) Really goes like a "buzzsaw" at high rpms. I think this head might be a little bit of a better casting than the old one. I also set the intake cam shims a little tighter to get a little more lift.
The bad news: idle oil pressure when hot is lower now, vs compared to before the over-rev indicent. Before the incident I used to see about 1.8 bar hot idle oil pressure... now I'm reading closer to about 1 bar, almost half the old reading. The weight of oil is the same, and oil temperature is the same, so now I'm suspecting some bearing(s) got prematurely worn from the over-rev incident.
So considering what Marcel had to say, I'm thinking about pulling the pan and inspecting (and replacing if needbe) the rod bearings. Do you think I should worry about the main bearings as well, or is it likely that only the rod bearings got pounded? Also, what are the good brands of bearings I should look for? After I get a bearing removed, will I be able to see stamped on the back of it or something, what the undersize spec of it is in case I need to buy a replacement, so I can duplicate the spec? When inspecting the crank, should I be just looking for a gleaming bearing surface that is free of any bearing metal being stuck to it?
PS - I am not hearing any noises that seem really unusual. If there are any new unusual noises like rod knock, they must not be very loud. Also, the oil pressure at high RPMs is good.
PPS - I plan on abusing this bottom end (IE: winding it above 6k RPM), so what would you guys advise. I'd prefer to make the bottom end reliable if that is possible. Are the rod fasteners re-usable?
Thanks!
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#35
by
fspGTD
on 23 Nov, 2004 15:36
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Congrats!
If you know how to use FTP for uploading, I can set you up some image-space on my webserver.
It's not very fast, but for posting a couple pics to this forum it should do just fine. (that's what I use it for anyway, posting pics to various forums)
I fixed the broken image links (just using imagestation for now) thanks...
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#36
by
web
on 28 Nov, 2004 14:31
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Idle rpm is the same? (just eliminating...)
There's always a possibility the "new" head is using more oil pressure than the old one, but this lower idle oil pressure would worry me enough to at least check the rod bearings.
Just plastigauge one, two or all of them, starting with the worst (and block the crankshaft somehow while you do that, cos if it turns while tightening, it may smear the plastigauge and throw off your reading). Plastigauge should be applied dry ; it is a wax-like substance that does not like oil. Put oil back on after wiping off the plastigauge.
If the rods are OK, most likely so are the mains. Rod bearings nearly always die first. Mains are harder to plastigauge properly so if the rods are fine, it's not worth the effort to look further. Fasteners are reuseable but obviously mind the proper torque procedure both when plastigauging and on reassembly.
On the crankshaft, if in doubt, wipe off the oil and look for wear marks of any kind. Ideally the journals should be polished shiny. Minor scratches don't hurt, but a generally dull surface or blueish "heat marks" are bad.
The bearing surface should look nice and smooth, dull grey. Be careful with them, the layer that meets the crank is soft enough to scratch with a fingernail.
Bearings are best changed all at once (that includes the mains) so if it ain't broke, don't fix it
Marcel
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#37
by
v8volvo
on 29 Nov, 2004 00:27
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Jake--with an oil pressure drop like that I would indeed recommend at least taking a look at things. As Marcel said, all would have to happen at once pretty much or else it would not make much sense to do it at all. If the bearings got mashed badly enough to cut your oil pressure in half, chances are the rod upper bearings and the lower crank bearings were both pretty screwed up.
However, I'm not sure you need to pull the pan yet if more testing can be done. Do you have an A2-style oil filter housing with the oil pressure or temp sensor on the top as well as the A1-style head-mounted sensor? Do you have pressure readings for both from your old engine? I don't know the VW lubrication system well enough to know for certain whether or not this will be possible, but maybe you could localize the pressure loss by taking pressure readings at both the head and the filter housing. If you're good at the filter housing but have low oil pressure at the head, I'd be pulling the cam cover rather than the oil pan. Also, like I said, if you happened to have readings from the motor before the over-rev, you could find where the change was.
BTW, who is this machinist who can cure the 1.6 head crack problem? I will be pulling the head off my motor later this week and will probably at least want to have it checked for warpage and pressure-retention, and if it has the cracks I may want them welded up too. There have been yays and nays with regard to shaving these heads; what's the opinion here? Bentley says it will ruin them, but I and many others see no particular reason a careful decking would be a problem.
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#38
by
web
on 29 Nov, 2004 05:39
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Jake--with an oil pressure drop like that I would indeed recommend at least taking a look at things. As Marcel said, all would have to happen at once pretty much or else it would not make much sense to do it at all. If the bearings got mashed badly enough to cut your oil pressure in half, chances are the rod upper bearings and the lower crank bearings were both pretty screwed up.
Well that's a bit pessimistic, and remember we're only talking idle oil pressure (doesn't take all that much to affect that). Probably pulling the pan is quicker and more certain than anything else now.
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#39
by
fspGTD
on 29 Nov, 2004 10:29
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Thanks for the info, guys... Yes, idle RPM should be and according to my memory is the same since the incident... haven't done any fuel injection changes since before or after the incident, and I don't recall noticing that it was lower (I do have a tach reference.) I don't drive this car regularly, but probably will drive it again for another test run fairly soon and will continue to monitor the oil pressures and will take a close look at the idle RPMs. It seems like if the problem worsens, that chances are that I will get a sign - IE: oil pressure will drop further, and/or I will hear a warning noise, such as a tapping or knocking develop.
I will consider the plastigage test, although I don't have it and haven't used it before. I also am not sure how much I trust it (after running out of oil from a broken aluminum oil pan, mom's Golf TDI got it's bearing clearances OK'ed from the VW dealer - I think they used a plastigage test - and then a few weeks later the engine developed a ticking noise and seized! The dealer screwed up their diagnosis somehow... :oops: ) If I do plastigage the rod or main bearings though, where do I position the plastigage on the journal, and how should the crankshaft be oriented when taking the measurement(s)?
Are you sure that since the rod bearings go first, it might not be a better strategy to just replace the rod bearings if I get as far as dropping the pan and pulling the conrod caps off to inspect them (rod bearings also turn are are pretty cheap for a set... only about $20.) I'd really love to not have to remove the tranny and drop the crankshaft to replace those mains!
v8volvo - I don't have record of oil pressures taken before the over-rev accident at the oil filter flange; only from the head. The machinist I have used for my last couple head rebuilds is Jerry at Northwest Connecting Rod Service - 1705 S 93rd, Seattle 206-763-2487. He seems to do good work at reasonable prices, and also seems very familiar and knowledgeable about VWs and VW diesels in particular. Surfacing the head seems to work OK if the pre-chamber inserts get surfaced properly along with the head (which is apparently a big stumbling block for a lot of machinists when attempting to do this job.) Also if too much material is shaved off the surface, it might give it a greater tendency to warp (either temporarily or permanently) in the event of an overheat, so that the headgasket seal between block and head would be compromised.
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#40
by
srivett
on 29 Nov, 2004 14:54
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Could it be as simple as the blow-off valve on the oil pump? Rat407 rebuilt his engine and still didn't have oil pressure...I'm not sure if he figured that one out or not.
Steve
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#41
by
web
on 29 Nov, 2004 17:58
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I see what you mean about dropping the crank (it's often easier to pull the engine in those cases... so you won't have to work upside down the whole time). BTW in many engines it's possible to remove the bearing caps one by one and replace main bearings without removing the whole crankshaft. You need a little trick to push the upper shell out and in, but it can be done. You still don't want to, though. Which is why I recommend leaving them ALL in if they're allright. If you want to replace the rod bearings only that's fine, but you still need to measure them, so you know whether to look at the mains or not.
Plastigauge is thin wax "wire". Comes in a few thicknesses, at about $1 per ~1ft strip. You take off a bearing cap, clean up, take (cut) about 1/2" of plastigauge, and put it on the crankshaft (when working under the car, you would put it in the bearing cap). It is used across the width of the bearing (parallel to the crankshaft). Put the bearing cap on, torque to spec, remove, and measure how thick the now squished strip has become compared to samples printed on the packaging.
If there's a lot of side clearance on the conrod, try to keep it from moving around as you tighten it. Crankshaft orientation does not matter as long as it is fixed in that position, so just pick a convenient position for each measurement. And mind the oil feed hole, you don't need plastigauge in there
The only way to screw up is squishing/smearing the stuff too much by allowing things to move around or putting too much pressure on the bearing cap somehow. The stuff should be squeezed to the exact clearance and no further. This may be what went wrong on mom's car, or there might have been a completely different reason why bearing failure still ended up happening. If in doubt, measure twice and see if your results are consistent. Do not average, the highest reading is best, you can only err to the small side.
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#42
by
fspGTD
on 30 Nov, 2004 09:54
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Could it be as simple as the blow-off valve on the oil pump? Rat407 rebuilt his engine and still didn't have oil pressure...I'm not sure if he figured that one out or not.
Steve
Steve - I'm almost certain the oil pump is not to blame as I haven't touched the oil pump since the over-rev incident, and can't see it being damaged as a result of the incident... no sign of any metal particles entering the oil pump screen, IE: the pump pickup screen was totally clear.
At least it seems I still have more oil pressure than Rat407
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#43
by
fspGTD
on 30 Nov, 2004 10:19
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BTW in many engines it's possible to remove the bearing caps one by one and replace main bearings without removing the whole crankshaft. You need a little trick to push the upper shell out and in, but it can be done. You still don't want to, though.
That's incredible... wow. That sounds like a tricky job! And you're right sounds like something I'd much rather not risk if I don't have to!
Which is why I recommend leaving them ALL in if they're allright. If you want to replace the rod bearings only that's fine, but you still need to measure them, so you know whether to look at the mains or not.
Thanks for clarifying this. Makes sense to me that either all the mains would need to be replaced at once or none at all, or else the fresh, tight main bearings would probably wear prematurely.
Plastigauge is thin wax "wire". Comes in a few thicknesses, at about $1 per ~1ft strip. You take off a bearing cap, clean up, take (cut) about 1/2" of plastigauge, and put it on the crankshaft (when working under the car, you would put it in the bearing cap). It is used across the width of the bearing (parallel to the crankshaft). Put the bearing cap on, torque to spec, remove, and measure how thick the now squished strip has become compared to samples printed on the packaging.
If there's a lot of side clearance on the conrod, try to keep it from moving around as you tighten it. Crankshaft orientation does not matter as long as it is fixed in that position, so just pick a convenient position for each measurement. And mind the oil feed hole, you don't need plastigauge in there
I was thinking if the bearing is worn egg-shaped, the plastigage even if torqued down carefully without movement might not detect the max wear if it wasn't oriented right. So if it was predictable where the wear would be, then I was thinking the crankshaft orientation and position of plastigage on it could be determined. However, I'm not sure what forces were more likely to have caused bearing wear - IE: high centrifugal force from the overrev (peaking at TDC between exhaust and intake stroke; pulling "up" on the piston/rod), or damage caused by the piston valve interference would be approaching TDC but would be in a downward direction on the piston/rod.
The only way to screw up is squishing/smearing the stuff too much by allowing things to move around or putting too much pressure on the bearing cap somehow. The stuff should be squeezed to the exact clearance and no further. This may be what went wrong on mom's car, or there might have been a completely different reason why bearing failure still ended up happening. If in doubt, measure twice and see if your results are consistent. Do not average, the highest reading is best, you can only err to the small side.
Yeah you're right, mom's car failure isn't really conclusive proof that plastigage doesn't work, I could just be over-reacting. There may have been another problem that they didn't diagnose the problem with it correctly. I hopefully will find out the story about what happened with that motor soon.
You're talking me into the plastigage. I'm going to drive the car some more first, and double check the low oil pressure condition exists and then if it still seems there is a problem, I'll get some plastigage and plan on dropping the pan to check them out. I am recalling now sometimes after driving the car very hard, seeing alarmingly low oil pressure at hot idle, IE: lower than normal even. I need some more driver's seat time to verify the oil pressure isn't up to par, I think.
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#44
by
Rat407
on 30 Nov, 2004 11:06
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The one thing that comes to mind with mine is the head. From reading all the maintenance reciepts in the glove box from the PO there was annotations on some of the maintenance reciepts for when they had the alternator replaced and then again when they had the oil changed as well as the exhaust worked on that the oil light would flicker on. This was only on the reciepts of maintenance done after they had a new head put on due to the timing belt breaking and trashing the head. This was at 105k miles on the engine.
So I'm wondering, since I didn't mess with the head other than to make sure it was flat and had it pressure checked to make sure the valves sealed, that my problem is somewhere in the head. It would only make sense since the bottom half is all new with the bearings installed are to specification to include the intermediate shaft bearings. It is also the second oil pump, since it was easy to change I figured that might be my oil pressure problem. Once I get some funds built up and my garage built, the head is coming back off and I'm going to go completely through it and make sure the cam saddles are not worn out of limits. I got a ton of volume, just 0 pressure at the head port. So far I have 5k miles on the engine and the thing runs great. Just for now it is going to be a while till the money issue comes back to the GREEN level. With Christmas it might be a while.
At least by then I will have a garage to work on it and can leave it without worry of massive dirt/dust blowing around the open engine, like it would in the car port.
I'm running straight 30w now and this morning with the temp at 30F the oil pressure at the head hit a wapping 24psi, then it warmed up and went to ZERO. I can say this much, you kind of get use to the blinking red light/buzzer going off after a while.
My latest trip to the salvage yard I came across an 86 NA diesel Jetta and on the dash was a strip of black electrical tape over the warning lights. I wonder how long they drove it that way.? :shock: The engine looked in good shape and everything was on it so, here in a day or so I'm going in and getting all I can off it.