Fresh rebuild; starts fine, then rough, then died... - page 1 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• Fresh rebuild; starts fine, then rough, then died... by sparkoid on 27 Aug, 2012 14:26
• Hey folks, need to tap your experience, as I am lacking, this is my first engine teardown (1.6na, 80K mi).  On first engine start after rebuild, idled sweet and smooth.  As I let it run (~5 min), idle slowly got rough, flooring it yielded virtually nothing, roughness got worse till engine died.
  
  Popped the valve cover and retimed everything again.  Still rough idle.  Made an "IV bottle" of fuel to feed the pump directly and sidestep any tank/filter issues.  No luck.  Engine runs (poorly) only if I keep my foot halfway into the throttle.
  
  Recently rebuilt my 1.6 na after discovering head gasket leak, warped cylinder head.  Purchased a remanufactured mechanical cyl head.  Honed the cyl's, washed and washed, then put in new rings.  New gaskets, head bolts.  Injectors are only a few months old.  Left the pump untouched, as I had no issues with it pre-build.
  
  Anyone recognize symptoms?
  
• #1 by ORCoaster on 27 Aug, 2012 19:34
• What are your valve clearances now?  Did you check them after tightening the head down to spec torque?  I replaced a head a bit ago and had issues I am still dealing with.  Mechanical clack from intakes being 2-3 thousands off from minimum clearances.  Valves open to long.  Hoping they wear in and I don't have to reshim but that is easy to just get the next shim thicker and plop it in. 
  
  Oil pressure OK?  Delivery positive? 
• #2 by rallydiesel on 27 Aug, 2012 19:58
• Sure you got the fuel feed line going to the IN banjo? Sometimes, even old-timers, mess this up.
• #3 by sparkoid on 28 Aug, 2012 09:52
• I thought that banjo thing was a brake line! 
  
  No, seriously, I've made mistakes like that; not this time - the output thingy has an extra nipple for the injector return and goes on the very top of the pump (right?).
  
  On this machine, I mistook Newton-Meters for FootPounds (or visa versa, can't remember) and literally pulled the threads right out of the block on head bolt number one.  They were still wrapped around the bolt.  Hello, TimeSert.  Hopefully, that was the worst mistake in this particular project.  Hey, I'm an electrical guy; still looking for an ECU on this engine.
  
  I bought the "remanufactured" head from a local machinist, and trusted him to get the valve shims right.  Off to the garage to check 'em now.  What baffles me is, why did the motor run so sweet on start up, then slide into the abyss over the next 5 min?
• #4 by Rabbit79 on 28 Aug, 2012 11:15
• I've never had it happen on my VW, but I have seen it at work a time or two where we had air in the lines between the pump and injectors and it just didn't want to come out until we loosened up the lines at the injectors and turned it over a few times. Might give that a try.
• #5 by ORCoaster on 28 Aug, 2012 11:38
• Yeah it is like the air between the fluid coming in from the pump acts like a cushion and absorbs the pressure that would be necessary to push the nozzle up.  Cracking the nuts at the injectors has always given me positiive results.  Odd that it fired up, ran then went off like air sucked up into the system. 
  
  Clear line on that OUT banjo fitting would tell you if you have air going into the return side of the IV bottle.  Any chance something fell in there and plugged the incoming line and collapsed it with the vacuum the pump produces? 
  
  Having tight hoses on fittings is my problem at times.  The heat in the engine bay and though the hoses makes them loosey goosey.  They are WVO laden as well.  So I have to keep an eye on connections or they suck air. 
  
  That's all I can ponder now.  Maybe others later and thoughts come out.
• #6 by sparkoid on 28 Aug, 2012 14:50
• Thanks, guys, for the injector fitting tips. 
  
  Turns out I tried this, but probably tightened stuff up too soon to in attempt to avoid a mess.  Guess I need to get out the paper towels and crank some more. 
  
  Local oracle says it sounds like a fuel problem; I pulled the return lines off a few injectors, and they are all dry.  The pump sat disconnected in the engine bay for a month or two while I was dealing with the other stuff, I'm wondering if it is full of air and if there is a way to prime it up without wearing out my starter...
  
  BTW, I checked the valve clearances (cold), and they are in spec.
• #7 by rallydiesel on 28 Aug, 2012 15:16
• I use a pela fluid extractor on the out line. That fills up the pump. Usually IDI's will fill up the injector lines quick. If you have the unions cracked it will go faster.  You can also use a mityvac on the pump.
• #8 by theman53 on 28 Aug, 2012 16:49
• Pull it in gear with the key on works too.
• #9 by damac on 28 Aug, 2012 17:46
• how was the pump pumping when it ran?
  
  i have seen this happen twice.  one was crazy because i opened the system to do diesel purge and adjusted some lda stuff.  car wouldnt make it a mile and wouldnt restart.
  
  i ended up opening it and not really finding anything wrong.  cleaned everything reinstalled and it still works.
  
  another pump sat in junkyard and appeared to have fluid in it.  i got this one to start but it seemed to pull fuel the wrong way.  i resealed that one, it was dirty.  that one also still works.
  this is with electrical push pump to.
  
  i also got an engine recently that was running but then parked for fuel restriction.  this pump did get fuel to injectors and the stock screw collars were intact, but it would not start and run on car although there was smokeout thepipe.
  
  so i have seen some wierd stuff.  now when i get pumps i take them apart to clean and resealfirst.  there is a guy on ebay that only charges like $20 to the door for bosch kit
• #10 by sparkoid on 28 Aug, 2012 18:09
• The pump was pumping fine prior to the cyl head issues; I kept up (eventually) with all the high-end LED-running-light -(other)- German vehicles on the parkway.
  
  So I put the pump back on the IV.  Had all the lines cracked, #3 took forever to juice up.  Heard a "pffft" from I assume #3, saw the dribble, tightened up the lines and was back to a nice sweet idle.
  
  Put it back on the reg. fuel system, and lo and behold, the idle got rougher and stalled after about 5 min.  Must be how long it takes to dry up a pump at idle.  Looks like either a failure to suck, or maybe air leaks.  I use a Mighty Vac to draw fuel from the regular line to fill the IV, didn't notice any bubbles in the catch can.  Going to try a new filter and filter-to-pump intake hose.  Also noticed a metallic squeal just as the engine quit, couldn't hear it over the clack.  Something else to replace, I suspect...
  
  Anyone have any good rules of thumb for breaking in a new set of rings / valves?
• #11 by Rabbit79 on 28 Aug, 2012 18:56
• Are you seeing any air bubbles in the line from the filter to the pump? Sometimes they're kinda hard to see unless you hold a light behind the line. 
• #12 by ORCoaster on 28 Aug, 2012 19:16
• If you could fill the IV without a problem and you can fill the pump at first start I think you have a filter problem.  Once it starts to draw and the vacuum builds you are either up against a restriction limiting fuel or grabbing air in place of fuel.  Did you recondition the copper washers on the sides of the fuel banjo fittings.  Polish lightly with 600 grit sandpaper and oil and then hold with needle nose pliers over the tip of a flaming torch till they turn blue. 
  
  If you can't add a short piece of clear line to the front of the pump you will not know if air is coming in there or from the front seal or elsewhere on the pump.  If there is solid fuel coming in but then you have bubbles going out then you know the pump itself is leaking and not some fitting or a line.
  
  Keep at it.  It does take a bit to get the air out of an empty pump and you have to rev it some to get it all. 
• #13 by sparkoid on 29 Aug, 2012 13:39
• Looks like it's upstream of the filter; new filter, new fuel line, new copper washers.
  
  Finally got it to the point (on the "IV") where it will rev on demand like it should; there must be a lot of nooks an crannies in that pump for air to hide.  Put the Mighty-Vac on the return banjo and sucked for awhile, but I think in the end it was just keeping it running long enough to for the pump to do its own thing.  Gonna have to remember to pick up an extra jug of patience next time I fool with mechanical fuel injection.
  
  Put the IV upside down on the floor to take gravity out of the equation, the pump had the (clear) hose full and bubble free before I could get out of the truck and get around front to watch.
  
  Looks like a tank-ectomy is next...
• #14 by theman53 on 29 Aug, 2012 20:38
• Did you try blowing out the return and feed lines? I put pressure on the tank filler and use a rag to make a better seal. On the return just go easy on it with the cap off, blowing back to the tank. If your lines are just a little clogged it will help. Also, do you have the water separator? If so delete it with some fuel line and you should be one step closer. I wouldn't pull the tank until you have to.