Today I opened my 75 regular bug's block and found that the outside main bearings (especially on the clutch side) have worn a ridge in the case along where normally the oil runs.
I understand that this would be a prime candidate for line boring but am wondering if that is worth it? Would the case be 'as good as new' when this is done or is line boring just a postponement of the inevitable - case replacement. Also, what is the usual fee for something like this? (just so I can compare it against a new case). What do you guys usually do when you run across this problem?
Also, now that I may be looking for a case, I see that both magnesium and aluminum cases are offered. Should I need a case, which would the one to pick for a stock engine?
(I keep replying to my own messages, but I keep coming to conclusions so please tell me if I am way off base)
One weird thing is that the bearings actually look pretty good - clearly used, but no brass showing. It is almost like someone replaced them without looking at the shape of the bearing saddles. I will still replace them out of general principle.
I've had time to read what people suggest when a case is in need of line boring. Most think replacement is the only proper way to go.
If that is indeed the case, what should I be looking for in a good new case? What is a good source for cases for not crazy money? It will remain a stock 1600.
(I keep replying to my own messages, but I keep coming to conclusions so please tell me if I am way off base)
One weird thing is that the bearings actually look pretty good - clearly used, but no brass showing. It is almost like someone replaced them without looking at the shape of the bearing saddles. I will still replace them out of general principle.
I've had time to read what people suggest when a case is in need of line boring. Most think replacement is the only proper way to go.
If that is indeed the case, what should I be looking for in a good new case? What is a good source for cases for not crazy money? It will remain a stock 1600.
for a true stock rebuild having a *competant*(with experience with vw engines) do a proper align bore is acceptable.....if you do not have a local shop that is competant you can end up with never ending problems, such as low oil pressure and improper bearing crush, resulting in a "spun" bearing
If the bearing saddles have a distinct "raised" dark ring in the middle where the back of the bearing was not touching the saddle, then it should be line bored. Note that there is always a dark ring, it's mostly discoloration and if you can get rid of the "step" with just light "cleaning" with very fine (wet) sand paper, you're fine. If there's indeed a step you can easily feel with your finger after cleaning teh surfaces, then it needs to be line bored. Also make sure the big end saddle *sides* aren't worn, the new bearing needs to fit very snug on the saddle. If it has *any* free play sideways, then the thrust side needs to be machined too (they cut the saddle narrower). Then you need a narrower bearing too. Stock size is 22mm I believe. There's a way to eliminate this free play with just a hammer and a punch but I'll keep that to myself, it may shock some of the purists in the audience ;)
FIRST OVERSIZE: Acceptable for all purposes.
SECOND OVERSIZE: if you are building a high performance (race or nasty street) engine with a heavy clutch etc.. and you don't plan on rebuilding it for many years, better find another case to be safe. On the other hand, if you are building a mild street or stock engine, it's OK to use a case that has been bored to 2nd oversize.
THIRD OVERSIZE: The last size you can easily find bearings for. (Availability may be limited to bearing sizes that are meant for re-ground cranks too, OD 3rd oversize and ID first oversize...a shame if your crank is std size and in perfect condition..) Do not build a super high performance engine out of this one, it's your LAST available bearing size and *when* it goes, you have to get another case anyway. All the full flow and stroker clearancing and other machine work performed on a case like this is a wasted effort. WEAR will be accelerated, and continue accelerating at an exponential rate. Mild street engines can be built on cases like these, but it's a gamble. Stock rebuilds are ok if you are not after maximum engine life. Those who want a LONG living engine, should look elsewhere, even if it's a a stock engine. If the car doesn't get driven much and the stock engine beaten a lot, this case might be ok for years to come.
The bearing saddle gets weaker as it starts needing (and receives) line boring. Firstly, the original surface had special treatment done to it that makes the surface harder, so it could tolerate wear better. (wear from the miniscule bearing movement, "vibration" etc. ). This surface hardening doesn't go very deep into the metal. When teh case is line bored, the hardened layer of the saddle face gets thinner, or is removed completely. The resulting nice, smooth and straight surface is now also SOFTER.
Another phenomenon is, that on cases that have seen such use and wear & tear that the bearing saddles need to be bored for the second or third time, has seen so much pounding that the bearing saddles will have started to let go. They will eventually start to collapse, not just wear. You should check used cases before assembly for any signs of this: Bolt the empty case together using only moderate torque on the bolts. Now lift it up and look inside the case from the flywheel end of teh case, against a good light source. If you see the middle bearing saddles allow LIGHT to pass through the contact surfaces, you will know that the case is junk. The saddles have started to separate and collapse.
Shipping cost is nothing compared to all the hassles resulting from a poorly done job by some backyard hack. :)
The bearings are held in place by small metal pins. The pins are seated in a tight hole in the middle of each bearing saddle, with about 1/3 of their lenght exposed. The bearings have a hole on them where this pin goes into. Thus preventing teh bearing from spinning with the crank.
Connecting rod bearing and cam bearing "spinning" is prevented by having one corner of each bearing half end pressed into a groove on the bearing saddle. This "tab" breaks the round shape and prevents the bearing from spinning.
When either the pin or the tab fails, the bearing "spins" around with the crank (or cam). This will result in almost immediate engine failure, as the bearing eats into the saddle and the OILING HOLES no longer match up. (It cuts off all lubrication to the bearing surface on bearings that don't have a groove in their back, and not many have this).
I didn't explain this very well but the bottom line is, it's the last thing you want. :D
for lineboring, I recommend Painter's Grinding in Colorado, they do a MUCH better job then RIMCO for this operation. Certain jobs at RIMCO have taken a nose-dive in quality the last couple years.
a spun bearing is just as it sounds....the bearing spins in its seat...not a good scenario...the main bearings are held by dowel pins that locate the b earings in the saddles...the bearings have an indention in them for this dowel....if the case "bearing crush" isn't good, it allows the normal "vibrations" to cause the bearings to move slightly, which gets worse as the dowel holes in either the case or the bearing become elongated....eventually it can lead to engine seizure....
Since this is my first VW, I think it be best to not take any kind of risk with getting the case machined. Jan's comment regarding sideways slop in the bearing is true in my case so it is more than just line boring to get it up to snuff. I truly am enjoying working on the car, but don't want to put it all together to have to take it apart again in the near future for something I should have done. For me, I think getting a new case is the way to go.
That brings me to my next question regarding a case aircooled net is selling:
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I am looking to make this stock and understand the cylinder and stroke option -- I don't need them for stock. What is that other option: "drill and tap for full flow"? What is that and do I need to worry about it?
Also is aircooledNet a preferred supplier or you guys know better/possibly cheaper ones?
Thanks a lot -- sorry for all the questions, but this is new territory for me.
It allows you to install an external oil filter. in it's stock form, the engine has NO oil filter. It's a very good modification (if done properly) even for stock engines. It involves drilling one of the case gallery plugs open, and threading the hole for a hose adapter. That's the return line, and the hard part of the job. The oil pump cover is replaced with one that has an outlet, and the original outlet hole on the pump is threaded and plugged shut. I also plug the case passage immediately next to it. That little stretch of passage is never used after this mod, but it may allow oil to leak past the pump back into the case.
All case work here must be performed when the case is apart, and teh passages must be cleaned carefully after this, before assembly. Lots of metal shavings will fall into the case oil passage when drilling and tapping it.
If you absolutely positively do not want to modify your case, you can use an oil line return adapter from aircooled. net that attaches to the oil pressure control valve at the bottom of the case (later model cases have this). It however messes with the oil flow a little and you lose the functionality of the valve. (All oil will go through the cooler at all times, if I remember correctly.. takes longer to warm up and cold, stiff oil might blow the cooler if you rev a cold engine up without letting it warm up first)
That's the best place to get parts from. Unmatched service and guarantee on parts. Great return policy, and *very* knowledgeable people who grew into the business through active VW hobby, racing included. The prices aren't the cheapest on the market, but you save yourself the risk of having to deal with inferior parts and faulty junk, or crap that never had a chance of working properly. Unlike most other stores, they don't sell that :)
That Magnesium case from Aircooled.net is a very good way to go. You can rely on it. There may be "cheaper" offerings out there, but I know from experience that Aircooled.net stands behind their products.
At any rate, that is the case you're looking for. Eschew all aluminum cases. They're junk.
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