timing belt skipped a tooth or two,is compression signifigantly changed ?? - Troubleshooting - VWDiesel.net The IDI, TDI, and mTDI source.

• timing belt skipped a tooth or two,is compression signifigantly changed ?? by 2strokesmoke on 20 Jul, 2009 23:32
• Hello to all,  I'm quite new to this forum and absolutely love it ! I own 2 caddy 1.6L n/a diesels.After some time,I'm finally getting around to working on them. I haven't worked on these engines in about 20 years !
  I purchased one about 6 months ago-NOT running-clean body- original owner- He swears it has under 100K ,but odometer doesn't work-so I'm unsure of true milage.
  He said he drove it into a tent garage,for the winter and in the spring it was a no start.
  After cleaning starter connections and a new battery,I got it to crank good.
  I installed a new air filter and fuel filter and bled the filter,filled the IP (was empty),cranked until I got fuel spritzing,with lines loose at the injectors.
  I tightened the injector lines,turned the key and it instantl started and stalled (ran about 2-3 seconds) It did this repeatedly,but wouldn't stay running.
  I pushed down accelerator pedal andf the same thig happens.  Eventually it did start,but would only run at high RPM (above 3000RPM ??) Lowering RPM,results in bad stumbeling and stall.
  I went over the basics and do still own most of the VW tools.
  I replaced the glow plugs (originals were good though) and do have power to them and they work. I installed  new injectors ( prior owner gave me with the truck)
  I did a compression test,dry and wet.I think my comp gauge is bad from sitting all those years (Or  I sure hope its bad)
  cyl  1      2      3      4
      270  275  300  295   DRY  (average of 3 readings each cyl)
      300  300  320  310   WET ( "  "    "     "     "     "    "    "      )
  I know these are far below the spec-but the readings didn't go up too much,with oil in the cyls. ( I added a good teaspoon of oil to each cyl, let it sit 5 minutes,then spun the engine over for 15-30 seconds )
  I then proceeded to pump shop air into each cyl,to" listen" for comp leakage. No leakage from the valves and minimal through crankcase at approx 100PSI shop air..
  At this point I'm beginning to think my Compression gauge might be bad.No one locally had a New one,to double check. My gauge is a SnapOn 500PSI- but 20 years old.
  When unable to get another gauge for this weekend, I figured- lets continue-hope for the best-and see what happens.
  I had previously purchased a new timing belt and tensioner- so lets install it and check the timing.
  I found that the belt --------"was off by 1 or 2 teeth"-------
  After locking the back of the cam,the IP lock pin hole was off a little and pin wouldn't go in.
  The crankshaft TDC mark on flywheel,was way off and not even visable through the hole.
  Ahhhhh---maybe this was the problem !
  To be honest- I never thought it was a compression issue,because the engine would instantly kick and start-then stall-with only a tap of the key---and lets remember -it wanted to run at high RPM
  So I proceeded with timing belt installation-started to install and found that the auto parts store sold me the wrong belt-  New belt was Too short and too narrow-probably for a gasser. So I couldn't complete the install today- will ahve to order another belt and tensioner kit (I used Beck Arnley- I hope  they are still good-they were 20 years ago??)
  So--after all this, blah-blah,blah
  My question is--" will the timing belt being off 1 or 2 teeth,result in lower compression readings,like I displayed ??
  I welcome your thoughts and opions.
  Agian, I bought this vechicle-not running.
  Thanks in advance,Mike
• #1 by Vincent Waldon on 21 Jul, 2009 00:13
• I'd think valve timing might have a small effect on compression... hard to be qualitative unfortunately.
  
  It's much more likely that your running problems were caused at least in part by timing that's way out of whack... I'd be inclined to get the timing bang on and then see how it runs... re-doing the compression test if required.
  
  Full pictorial on setting the timing is available in the HOW-TO link on my sig.
  
  The most important rule is: always always always turn the engine over by hand a couple of revolutions *after* you finish the timing and *before* you hit the starter... as Andrew says these are extremely tight interference engines and you want to find mistakes with a gentle klunk rather than an expensive bang.
• #2 by 2strokesmoke on 21 Jul, 2009 00:39
• Hi and thanks !
  Actually, i never considered the TDC mark to possibly be inacurate.
  I will definately check it as suggested.
  The "V" notch on the flywheel is TDC Correct??
  When I locked the cam in place, the square molded block on the flywheel,was lined up instead.
  (If I remember correctly,there were several of these square blocks on the flywheel,evenly spaced)  But its been a long-long time !!  LOL
  Any opionion,on the compression readings andwet readings?
  Is Beck Arnley a good choice for timing belt and tensioner ?
  Thanks agian,Mike
• #3 by Vincent Waldon on 21 Jul, 2009 01:06
• Yup, there's a picture of the TDC mark on my HOW-TO... the square lugs are on either side of the actual mark.
  
  Can't comment on your wet/dry readings (other than "north of 400 is normal")  since you know your timing is wonky , and I don't recognize the timing belt brand so can't comment on that either.  Doesn't mean it's bad... just means I've never heard of it... which means nothing!!  FWIW, OEM is generally German for these parts... Conitech is probably the most common timing belt supplier.
• #4 by Doug on 21 Jul, 2009 07:36
• Top dead centre on the flywheel is identified as "O" which is short for "Oberen Totpunkt". There are numerous other casting bars and lumps but only one "O".
  
  Your low compression readings assuming that the valves are intact are probably due to seized rings which are common on stored vehicles. It seems that the carbon and oil just turns into a hard cement that does not break up. The good news is that the rings are cheap. Of course that means a head gasket, may as well do the valves and rod bearings while open and a fuel pump is not far off with the new ULSD. Now we're up to a couple of grand just to get the engine where you want it to be. Sounds like you are handy though so maybe you will save a bit there. Old cars are so much fun!
• #5 by burn_your_money on 21 Jul, 2009 08:05
• Lets not sink the ship yet....
  
  TDC can either be a V notch or a 0 with a line through it. I've seen both many times. If your timing is that far out there is a good chance that the valves might have kissed the pistons. You can put it out pretty far on the flywheel and still be in the clear though.
  
  I'd say re-time and see what happens. Do you have the dial indicator for setting the pump timing?
• #6 by jtanguay on 21 Jul, 2009 10:47
• wouldn't sticky valve lifter(s) and sticky rings cause low compression as well?  wynn's sells something you pour into the crankcase to help free sticky valve lifters and rings... might be worth a shot? as well as the above mentioned steps of course   and you can ignore the sticky valve lifters if you have a pre '86 solid lifter engine...  but that would raise another question.  wouldn't out of spec mech lifters cause a problem?
• #7 by rabbitman on 21 Jul, 2009 17:42
• My TDC mark is an O with a A and B on each side, and then some marks for degrees like -10, +10. Can't miss it.
• #8 by 2strokesmoke on 22 Jul, 2009 01:39
• Hello agian, and thanks to all for your input !
  Unfortunately,I won't have the time to install the timing belt,until this weekend.
  Then we'll see what happens- I'll keep you all posted.
  What do you think about pouring some top engine cleaner in the cyls and letting it sit several days ? If the rings tend to stick,when the engine has sat for a while- I thought the top engine cleaner might desolve some of the carbon and help free up the rings.
  I am happy to hear,that I might not have bent valves,while the crank  being 1 or 2 notches of on the timing belt. That would explain why I didn't hear any air  leaks,while pumping shop air into the cyls.  Only a little air leaking into crankcase,past the rings.
  I do still have the injection timing kit,with dial indicator. From what I'm gathering, the pump can be set from .86 to 1.0 and as far as 1.05 @ TDC. Considering this is a 1.6 N/A,totally stock,probably close to 100K and in a Caddy ( = quick as a snail) I was planning to set the pump at 1.0  . I was wondering if you all agree ?  I would be happy with 40-45 MPG.
  I will make other adjustments to IP,when I get it running .
  Seeing as I have to Order another T-belt and tensioner, is continental,or conti, a good quality belt ? I would rather spend the extra $$ and use quality parts.
  20 years ago, I owned many rabbits and caddys,as did my co-workers and relatives. I really enjoyed them and I'm thrilled to own a couple of caddys agian !
  I need to find so good parts resources agian,as I will be restoring these caddys-one at a time.
  They will be daily drivers,with a minimum of 600 miles driven-per week.
  I need to get one up and running soon,covering all the mechanicals top to bottom.
  then I can start restoring the other caddy,which I believe will need an engine rebuild.
  But for now,thanks for all the info and help, it's greatly appreciated !   Mike
• #9 by rabbitman on 22 Jul, 2009 01:48
• Contitech is a very good belt, I've heard it's the best but I don't know of any brands that have failed prematurely.
• #10 by burn_your_money on 22 Jul, 2009 07:45
• +1 for conti.
  
  1.00mm is a good starting point on a used pump. I don't like putting anything but oil and coolant in my engine. I'd just drive it until it clears up. If after a few hundred it still hasn't then I'd try some of the many snake oils out there
• #11 by theman53 on 23 Jul, 2009 07:39
• A little of the old ATF will clean and unstick parts in an engine. I don't like to run it but sometimes you have to. I usually wait until it is down a quart and pour a quart of ATF dexron/mercon III in. Drive it good and hard and hot for 2-3 days and change the oil with no ATF just oil. It usually fixes the sticky stuff.