Learning how to rebuild an VW engine

Rings, bearings, seals probably $300USD. Pistons (sometimes they need replaced) are another $300USD or so.

I think doing a teardown and rebuild would be cool. I'm keeping my eye out for a dead motor to do just that. Very good experience, you just need a lot of specialty tools though (micrometers and such). With a good book, I think anyone with patience and care would be successful.

Now, transmission work... that's tough!

Done that a couple of times with my old 1.6gti and last year with my g60 engine (expensive). It's easier then you think. You need a good torque wrench and a special socket (12 point) for the head bolts. Also work as clean as possible when you are dealing with crank and rod bearings. It's a great experience and you learn a lot.......

SFC

"WT" schreef in bericht news:gcz6g.3235$ snipped-for-privacy@newsfe20.lga...

Many parts supply places provide rebuild kits in the form of all the gaskets needed, sometimes the rings and bearings as well. You should replace the cam and lifters while you have it apart. A local parts store is a good place to get a price estimate.

While the Bentley manual is a good source of information, it scares me sometimes on some of the information that is not provided in some dismantling or assembling procedure.

One thing that is sometimes overlooked when rebuilding an engine is the ridge that is formed near the top of the cylinder walls by the top piston rings . If that ridge is not machined off with a ridge reamer, it is likely that the top ring on each piston (assuming new rings) will smash into the ridge the first time you start the newly overhauled engine- breaking the ring and possibly damaging the piston and/or cylinder wall.

Just one thing to be aware of before you start.

It is possible to buy a "stepped top ring" in a re-ring kit for rebuilds which avoids the hammering og the ring and ridge.

Hammering? *Hammering*!? HAMMERING...?????

Sheesh! Listen up: A ridge reamer is an easy to use, low-cost device. Fer cryin' out loud, if yer gonna learn to rebuild an engine, at least learn to do it right! Ream the ridges *before* removing the pistons.

Moreover, IIRC, stepped top rings are designed to extend above the ring land, so that gas pressure (further) aids ring sealing, not below the ring land, where gas pressure will work against ring sealing.

OK, listen, here's engine rebuilding 101 Part 1, Disassembly, off the top of my head (I did not open a book to write this; I really mean it's off the top of my head), as a SUPPLEMENT to what you see in the MANUFACTURER's service manual for THE ENGINE YOU ARE REBUILDING. If this posting and the manual disagree, follow the manual. If any of this is wrong, or a necessary step is missing for your engine and Bad Things Happen, I'm sorry, but it's YOUR engine and YOUR fault for not doing the necessary research and/or having the skills needed to execute the steps successfully.

If I feel like it, I'll write Part II, Assembly. Otherwise, not. No promises.

Take pictures or notes as you go. Label things. When you put the car back together, weeks or months later, your memory of how things came apart will not be perfect unless you have done this a number of times on the same make and model car. Don't trust to memory. MAKE SURE you know how to put it back together, or this WILL NOT be a fun or money-saving experience.

1. Drain the oil, preferably with the engine warmed up, before removing it. (I'm always pissed off later when I forget this step. And there's nobody else to yell at! Damn.)
2. Wait for the engine to reach ambient temperature before disassembly. (For most cars, and nearly all FWD cars, this is a no-op because by the time you get it out, it's cooled off, but I've worked on cars from which the engines could be removed so quickly they might still be warm once out.)
3. Remove the transmission, clutch, and all the engine accessories, covers, PCV breather tubes, oil filter, etc.
4. Remove the timing chain(s) or belt(s), tensioners, etc.
5. Remove the cylinder head. For overhead cam engines, DO NOT put the head valve-side down on the bench or you WILL bend one or more valves.

Check the service manual to see whether the head bolts must be removed in a particular order beforehand. Check to see whether the bolts are reusable. If they are not reusable, mark them in some way or destroy the threads with a hammer so you won't use them by accident, but DO NOT throw them out until you have the new ones in hand. This way, you can make sure you have the right ones. Nothing is unfunnier than a too-long head bolt bottoming out before it reaches the correct tension...except, I suppose, more than one.

1. Remove any dowels from the block deck.
2. Put the engine upside-down on the bench on something that will not scratch the deck surface. Wood, rags, newspaper, etc. will do. Be prepared to mop up the oil with something from time to time.
3. Remove the oil pan. Do NOT pry it off from one side or corner or you will deform it and it will leak when reinstalled. Work your way around it in stages until it comes loose.
4. Measure the flywheel runout. If it exceeds spec, plan to have it resurfaced. Remove the flywheel and crankshaft pulley. If the flywheel bolts are not reusable, mark them or destroy their threads but do not discard them until you have the new ones in hand to compare.
5. Remove the main and rod bearing journals and set them aside in the right order. Make sure they are marked, or mark them, so that they can be reinstalled on the correct main bearing journal saddles in the block and on the correct connecting rods. (The ARE NOT interchangeable).
6. Remove the crankshaft. Examine it carefully for unusual wear, stress cracks (usually at a journal corner), and so on. Put it on V-blocks and use a dial indicator to check it for bend. Measure all the journals at various points around each one. Unless your low-mileage engine inhaled a spark plug or something, it will probably need to be cut due to wear. Bring it to the machine shop and have it cut the minimum amount necessary. Consider having it magnafluxed to detect cracks that could cause a failure in service. If the engine seized at anything above idle speed, do not consider reusing it without this test.
7. Turn the block right side up. Ream the ridges.
8. Turn the block on end. Remove the pistons by pushing them through the TOP of the block, past where the ridges used to be. DO NOT force them. If they do not move smoothly past where the ridge was, make sure it was completely removed and try again.
9. Remove the bearing shells from the block, main bearing caps, connecting rods, and connecting rod caps. If a main bearing has spun, the block must be re-align bored. If a rod bearing has spun, the rod must be reconditioned at a minimum, and perhaps replaced. All require the services of a competent machinist.
10. Inspect the inside surfaces wherever a bearing goes for burrs. Inspect all the main bearing supports in the blocks for cracks.
11. Reassemble the rod caps to the connecting rods, just to make it easier to keep track of them and to help make sure you have the right caps on the right rods later. Remove the rings from the pistons using a ring spreader. (The tool is not optional. You DO NOT want to scratch the ring lands.)
12. Measure everything on the bottom end. The size of the crankshaft main and rod journals, the size of each cylinder bore (minimum of 6 measurements, 3 on each load-bearing surface just below where the ring ridge was, where the maximum load point is in the cylinder (I forget how far down, but a bore gauge or large snap gauge and micrometer will show all), and one at the bottom of the piston travel.

If any bore size exceeds the service limit at any point, all must be rebored oversize. Same if any bore taper exceeds the service limit. Measure the pistons at right angles to the centerline of the engine and in line with it. Any worn or tapered smaller than the wear limit must be replaced. My suggestion is that if this is true you replace them all with an oversize. (Actually, on a more practical level, plan to do this anyway if you expect a long service life.)

If the piston has full-floating wrist pins, remove them and measure the pin and bores for each piston. This will take a VERY good micrometer because these clearances are measured in ten thousandths of an inch. If they exceed wear limits, the pistons involved must be replaced.

Don't forget to measure the pilot bushing to transmission input shaft clearance. If the bushing is worn, replace it. If it's a needle bearing, replace it.

Your trusted machinist (ask around!) will be happy to make these measurements for you if you want them repeated by someone who does it daily (and you do!) or don't have the equipment or skill to make them yourself (and if you're reading this, you're either curious to see if I'm an idiot or you probably haven't got everything you need).

1. In the service manual, find the measurements (lash, end play, etc.) for the oil pump and MAKE THEM. If it is beyond its service limits, replace it.
2. Remove any screw-in gallery plugs. Remove any freeze-out plugs. You should be down to something close to the bare block at this point.
3. Inspect EVERY threaded hole in the block and crankshaft. Chase any burred threads in either with the right tap. Drill and retap or helicoil any that are stripped in the block. (I suppose this will work for the crankshaft, too, but discuss with the machinist first.)
4. Remove the camshaft(s). Remove any rocker arms, rocker arm shafts, cam followers, hyrdaulic lifters, etc. KEEP TRACK of which came from where so they can be reinstalled in the SAME positions.
5. Using an appropriate spring compressor, remove the valve keepers, retainers, springs, spring dampers (in between inner and outer springs), shims (under each spring on an alumimum head), and valves. Throw away any broken springs or spring dampers. KEEP TRACK of which valve came out of which hole. A board drilled and marked appropriately is a big help here. Remove the valve seals.
6. Measure the cam bearing journals and bores. If the clearances between the cam bearing journals and bores are over the service limits, look at your options (new cam and lifters/followers, bearing inserts, new head) discuss with your machinist.
7. Measure the lobe lift of each camshaft lobe. If the cam lobes on a camshaft are worn beyond the service limit, have the cam reground or (perhaps cheaper) buy a new cam.
8. Measure the valve-to-guide clearances. Any over spec require a new guide, valve, or both.
9. Inspect the valve seats to determine whether they can be recut (usually) or must be replaced (sometimes).
10. Measure the unloaded height and spring tension for all the valve springs, inner and outer. Discard any spring that is out of spec and buy a new one.
11. Measure the head surface for straightness and flatness as shown in the factory manual. If it does not meet specs, have it machined.
12. Cart the block, head, crankshaft, and valves to the machine shop. The block to be bored, the head to be resurfaced if needed, for new guides if needed and to have the valve seats cut, and the valves to be cut. If the wrist pins are not full-floating, and any piston must be replaced, bring the pistons and rods, too. For any measurements you cannot make yourself, bring those parts, too.
13. Have the head hot-tanked or dunked in aluminum cleaner, as appropriate. Same for the head.
14. Have the necessary machine work done. Don't skimp too much here or you will not like it later. Pay the bill.
15. Buy all the necessary parts. In addition to whatever had to be replaced above, this will include a complete gasket set, all necessary unreusable bolts, probably pistons, rings (probably oversize), bearings (probably undersize), seals, new thicker shims for the valve springs (cutting the valves and seats raises the valves in the head, and you have to compensate for the loss of spring tension to preserve the maximum safe engine speed, aka "red line"), timing chain or belts, etc.

I recommend going for equivalent to new if you intend to keep the car. That is, make sure that all clearances meet spec, new pistons, rebore, get the crank cut, etc., to yield an engine that is likely to be as durable as it was when new. Everything you economize on here will reduce its life. Everything. Think about that long and hard if the car is good overall but the engine is shot before trying to save a bit here and there.

Assuming you have all the needed tools, you're now ready for reassembly. Unless, of course, I forgot something. (You WILL use the manual, right?)

Engine building is fun if you have the right mindset and enough patience. If you lack either, pay someone else to do it or buy another car. No kidding. I mean it.

JRE

Hi JRE:

Very well said. You obviously have the know-how.

Regards.

OK, here's rebuilding 201, Assembly. (There might be a 202. I have friends coming over tonight and will suspend this when they arrive.)

OK, you've got it all back from the machine shop, and all the parts are in hand. Now the real work can start.

As before, any risks are yours. *Think* about what you're doing and if you think there is any chance at all that it's unsafe or won't have the desired result, *stop* and get a professional to do it. As before, I'm walking the rope without a net--that is, this is entirely from memory. Follow the manual, fer cryin' out loud.

1. Nothing is clean. Clean everything as you go with a cleaner that leaves no residue or. Carb cleaner works great in a ventilated space. (Fer gossakes, don't smoke!)

1. Clean the entire block inside and out. A rifle and/or shotgun cleaning kit works great for the oil galleries, which you want very clean indeed and free of any foreign stuff that could cause a bearing failure. One little piece of grit and lots of hard work (not to mention money!) will be down the drain.

2. Done with the block? Do the head. How clean is "clean enough"? Up to you, but one little piece of grit, and...you get the idea.

1. Cover or wrap the block and head in rags when you are not working on them. If stored in a high humidity area, spray them with something like WD-40 or CRC 5-56 first. (This means repetitive cleaning but it cannot be helped. Rust is The Enemy.)

2. Clean the crankshaft. Don't forget all the oil galleries within.

1. Clean all the main bearing caps.

6a. (Damn. Forgot a step.) Replace oil gallery plugs and drive in any freeze out plugs. Use the right tools...it's easier in the long run.

1. Put the DRY bearings in the DRY block, and into the DRY main bearing caps.

2. Lay the crank carefully in the dry bearings in the block, which you of course placed back on the deck surface on clean rags, right? DO NOT rotate the crankshaft while placing it in the bearings.

1. Put a suitable length of Plastigage on each crankshaft journal at right angles (more or less) to the crank centerline.

2. Install and torque the main bearing caps.

1. Remove the main bearing caps. (If you're staring to wish there were a zipper, just wait.)

2. Compare the clearance indicated by the crushed width of the Plastigage to the required clearance in the service manual. If you had the crank cut and they don't match, swear a mighty oath and cart it back to the machine shop. If you didn't and they don't match, swear a mighty oath and bring the crank to the machine shop in a contrite manner. (The machinist *did* suggest you have it cut, right?)

1. Remove the plastigage from the bearing shells or crank, or both.

2. Carefully, and without rotating it, remove the crank.

1. Assemble the pistons on the rods, if that hasn't been done. If you are replacing them and the pins are not free floating, they need to be pressed out. Don't screw around. If you don't have a press, have it done by someone who does. If you don't have a press or a torch, have them assembled by someone who does. If you have a torch and don't know what "clear" means when referring to color temperature, have them assembled by someone who does.

If the pins *are* free floating, remove the internal snap rings, the pins, and the pistons. Measure and assemble as needed.

If they aren't, after pressing them out there are two choices. You can press them in, or use a torch to heat the small end of the rod enough so that pin will slip in. If you choose the latter method (which I prefer because I'm a cheapskate but others don't, so your mileage may vary), use a cutting head on the torch to slowly but *not* T-O-O S-L-O-W-L-Y heat the small end of the rod until it is "clear."

Then, VERY QUICKLY insert the pin through the piston and rod until it is centered in both. Do us both a favor and avoid burning the flesh off your hands. In about half a second, the pin will warm up, increasing it's OD and its normal interference fit with the rod's ID, which *will* prevent *any* further movement, so do NOT take your time. 'Twas best done quickly.

If in doubt, have someone who knows how do it. A piston pin that scrapes against the cylinder bore is painful to even think about.

1. Liberally oil the crankshaft and the *insides* of the bearing shells. Install the crankshaft using the specified torque (and possibly angle) and procedure (which usually calls for it to be torqued in progressive steps).

Make sure you can easily turn the crank by hand as you torque down each bearing cap. There will be (progressively more, as each cap is torqued, but still not a *lot*) initial resistance from oil shearing force as you go but the crank should move smoothly once started and should not bind through its full 360 degrees of rotation. If it does bind, *stop* and find out why. (You didn't mix up the caps, did you, or put one on facing the wrong way? They are assembled and align bored at the factory. The right one *must* go in the right place and be pointed in the right direction.)

1. Install the rings on the pistons. Use the right tool. It's cheap and we don't need deformed rings or scratched ring lands, both of which will give away compression, power, mileage, and longevity.

1. Liberally oil the rings and piston. There are no points for oil conservation when rebuilding. Some will argue that a "prelube" should be used here and on the crank. I don't think so but have no empirical evidence either way. Make your own decision.

2. Put a ring compressor on piston #1. Put some pieces of rubber tubing (fuel line is good) on both of the connecting rod bolts so they cannot scratch the rod bearing journals on the crank. Make them long enough to be easily removable once the rod's big end is nestled against the crank.

1. Put the DRY bearing shell into the big end of the rod, and the other DRY bearing shell into the bearing cap for that rod.

2. Liberally coat the cylinder wall with oil. Don't get the rod journal wet. (Oil and Plastigage do NOT get along.)

1. Correctly orient the piston to the block. Some pistons have a machined notch, others a punch mark, etc., to indicate the front (usually) of the piston. Look it up! Orient the piston correctly or Very Ugly Things will probably happen. (The piston pin is usually NOT in the center of the piston; most are offset somewhat.) Using the

*wooden* handle of a hammer or a convenient piece of wood or Delrin and a suitable hammer, *carefully* drive the piston into the block. (You did, of course, ream the ridges or have the block bored for new pistons beforehand. Right?)

1. Push the piston down and turn it as needed to get it aligned with the rod journal on the crank. Turn the block around so it rests on the deck surface again. (Ever wonder why pro mechs have muscles?) Put Plastigage on the journal opposite the rod big end. Assemble the rod to the crankshaft according to the procedure. If the rod bolts are not reusable, do this with the OLD bolts. Unless, of course, you bought

*two* sets of new bolts just for this reason. (Why!?)

1. Take it apart and see what the Plastigage tells you compared to what the factory service manual says the clearance should be. If the news is bad, swear a mighty oath and visit your friendly machinist. Again. It it's good, remove all the Plastigage, oil things up liberally, and assemble the rod to the crank using the correct procedure and torque. If the bolts were not reusable, use the NEW bolts.

2. Repeat for the remaining pistons and rods.

1. Install the oil pump, pickup, screen, etc., all of which you have cleaned to within an inch of their lives. Use the right torques, just to show you care. (Besides, you don't want these thingies to come loose later, do you? ;-)

2. Install the oil pan gasket and oil pan. Procedure and torque are important if you don't want it to leak. If it's deformed (which it's not, becauae you removed it carefully, right?), straigten it first.

OK, my friends are here and I'm tired of writing anyway. Next time, if I get to it, Engine Rebuilding 202, Assembly Continued. No promises.

JRE