Engine rebuild questions!!??!?!!!

[jackbombay]

So I was hoping that I just needed a head gasket, but I need a lot more than that, first off the head has cracks between 4 of the 5 cylinders between the exahaust and intake valves, from what I read here these cracks are not a big deal, unless they reach the water jacket.

 
 
   
  The other 2 are very similar to the second one.

   One of the cylinder walls is in bad shape as well, here is a pic of some bad pitting in the #2 cylinder


 

  In the same #2 cylinder is also a grove that is worn into the cylinder in a spiral, this grove also has some pitting, great.

 


  From the prices here it looks like I will be at about $500 for pistons, rings, connecting rod bearings and crank bearings.

  What is a ball park price for machine shop work? I assume it needs cylinders bored, crank ground, and the block decked. If the block needs decking what would I do for a HG, this engine already needs a 3 notch HG, does the crank get offset ground to lower piston height?

   AAARRRRRRGGGHHHHHHHHHH!!!!!!!!!

  PS here is an overview



  And oddly enough only the #1 piston had this pitting on the surface

 

[jackbombay]

I just checked the head witha  straight edge and feeler gauges adn it is .016" (.406mm) out of flat from end to end, if it was sitting valves down ona  flat surface the middle would be .016 off of the flat surface. Max distortion according to the Bently is .0004"  (.1mm) so I will need to get the head machined as well for sure.

[chrissev]

the cracks between the valves are fine and normal.  Don't bother about them.  There appears to be some coolant leaking out of the valve in the first picture.  That might be a problem.  The pitted cylinder wall is also a problem.  You can only bore those cylinders out so much.  The pitting appears to go quite deep.  I wonder if it is past the limit?  The pitting is interesting (especially the spiral pitted grove).  I wonder if the injector was dumping fuel into that cylinder at low pressure and it was burning up and damaging the cylinder walls?  Definately have that injector checked before you put it in your rebuilt engine.  Warped cylinder head = somebody overheated the engine.  That's why they warp.  Never any other reason, except if someone torques them wrong putting them on.

[jackbombay]

There appears to be some coolant leaking out of the valve in the first picture.  That might be a problem.  The pitted cylinder wall is also a problem.  You can only bore those cylinders out so much.  The pitting appears to go quite deep.  I wonder if it is past the limit?

   The coolant was just some from removing the head.

   As far as the pitting goes I am hoping that a machine shop can fill the pitting with a welder and then bore it .020" over to clean it all up. Even if it was bored .040" over the pitting would not get removed, the worst is about 1mm deep...

[srivett]

Perhaps the engine was sitting on an angle with water in that cylinder?  I would take it to a machine shop for free consultation.

Steve

[racer_x]

As far as the pitting goes I am hoping that a machine shop can fill the pitting with a welder and then bore it .020" over to clean it all up. Even if it was bored .040" over the pitting would not get removed, the worst is about 1mm deep...

Check with the experts at the machine shop. They will be able to tell a lot more from inspecting the actual block than we can looking at pics over the internet.

But from the pics, I'd say you're looking at sleeving the cylinder with the pitting. I could be wrong, but I wouldn't try to weld inside a cylinder bore like that if I could avoid it. Yes, it's theoretically possible to weld a cast iron block. But the stress from welding would not be something I'd want that close to the combustion chamber in a turbocharged diesel engine. And getting the block stress relieved after the welding operation will add significantly to the cost.

As far as milling the block deck and the head, the tolerances are really tight there. You might need an equal amount cut off the piston crowns, or custom pistons with the wrist pin bores slightly higher to reduce the height of the pistons above the block deck when installed.

[jackbombay]

I'l get it pulled this week and see what a machine shop reccomends.

  Thanks.

[Dr. Diesel]

As far as milling the block deck and the head, the tolerances are really tight there. You might need an equal amount cut off the piston crowns, or custom pistons with the wrist pin bores slightly higher to reduce the height of the pistons above the block deck when installed.

If the piston projection is too high, there are easier ways to deal with it than custom parts. For example, you can shorten the rods somewhat by grinding material off the rod cap-rod mating surfaces and machine the bearing housing back into round. There is actually a bigger window than some people expect as far as piston projection is concerned. Last summer, I had an engine with .041" projection and it still had a good deal of clearance. (can't remember the exact number now, but it was in the neighbourhood of .030")
I'd imagine you could machine the head and deck the block and still have clearance. Have you measured your piston projection? Perhaps the engine doesn't need a 3 notch. Best bet, I'd agree, is to take it in, have them check it out.

[fspGTD]

The head might be salvageable if you have a very experienced engine builder.  Beware of just shaving the head flat (which is not recommended by the VW service manual by the way), not just because it takes special head milling setup to work with the hardened prechambers, but also because the cam bores will not be aligned afterward either.  So you'd need the cam bores align-bored as well, I'd think.  If you just shave the head and bolt the head on, the cam bores will not be in a straight line due to the warping so the cam will be distorted and the cam bearings will live a very high friction life.  Alternatively, junk the head and find a different core, or perhaps buy a brand new one (I know 4-cyl VW Diesel heads are available at reasonable cost... maybe new 5-cyls are being manufactured as well?  Maybe check with the US head manufacturer, "Topline".  Also check out overland parts / overseas distributing for new cylinder head source, and maybe "parts place" out of michigan as well.)

The block I agree hard to determine if it's rebuildable just by looking at the pics, but based on those I'd say the bore condition looks pretty bad, enough to think really serious about a rebuilt bottom end (unless you were *really* strapped for cash...)

The max overbore (to 77.5mm) like it seems you have already figured, will only punch the radius out by .5mm, and the pitting in the bores may be too deep to be cleaned up.  I don't know about sleeving these engines or welding to recondition badly pitted area, but they seem like good questions to ask a very knowledgeable machinist.

You *might* consider getting 5 matching 79.5mm 1.9lTD pistons and having the block overbored to accept those, although I don't know if the rods would work and what it would do to piston projections.  I have heard of them being installed before in a 1.6l 4-cyl diesel (making it a 1.7 liter 4-cylinder diesel.)  The question is whether the rods and crank from a 1.9 liter were required or not.  Going this route, I would budget in at least for a custom one-off headgasket, unless VW made some european-only factory 79.5mm 5-cylinder IDI diesel.

Cheapest option will probably be finding another block to use as a rebuildable core and keeping the stock bore sizes.  Those piston tops look really clean by the way, usually they have lots of carbon all over them.

My recommendation is to remove the block from the vehicle as it's apparently no good to re-use, and find and bring it to a good machinist who really knows their VW Diesels, and ask their advice.

A good thing to ask a machinist to check their competency is whether they are experienced in planing the VW diesel head (with the hardened prechamber inserts), and also whether they are experienced in welding closed the cracks in the head between valves.  You might ask others on this board for a good machinist to use in Oregon, IIRC they knew of someone who might fit that bill.  If you strike out down in Oregon, I know a good machinist here in Seattle that you could call and ask questions on the phone, or use if you are willing to make that long drive.  He can definitely rebuild VW Diesels properly and do some demanding jobs required to revive a bad head like what you've got.

In the meantime, keep your eyes peeled, and jump on if you can find, a good used 5-cyl TD out of a wrecked car.  Good luck!

[jackbombay]

Thanks for the response, the news seems to get worse and worse.

  I look for a machine shop that is knoledgeable WRT the VW Diesels.

[Dr. Diesel]

do you think there's enough room to wedge the inline 6 from a diesel volvo?

[jackbombay]

The 5 is already a snug fit.

   I'll get some prices for machine shop work on monday.