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devesvws
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 Posted: Sun Oct 19, 2014 4:50 am Post subject: post diesel runaway running problem.. |
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its my brother in law's 82 we thought the motor broke after a diesel runaway incident and jumped timing. after removing the head we found everything looked normal with the head and pistons, so we put everything back with a new head gasket but now the thing smokes like crazy and runs rough. the two middle injectors don't seem to be firing when I crack those lines to bleed the air out. I even swapped the pump and the two injectors and still the same thing...  any thoughts?? I think I'm going to check the valve adjustments next...
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THE FEW THE PROUD THE ORIGINAL VW WATERBOXER -> looking for a original 91 vanagon owners manual with 1991 on the cover http://www.youtube.com/watch?v=pmuiG2tUsP4&feature=share https://picasaweb.google.com/101290228103300323836/BostonBobFlywheelVideo#5543000332201103922 |
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?Waldo?
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| Posted: Sun Oct 19, 2014 8:43 am Post subject: |
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What do you think caused the runaway? What have you done to address it?
Were there any valve prints in the carbon on the piston crowns? |
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devesvws
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devesvws
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devesvws
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devesvws
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?Waldo?
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| Posted: Sun Oct 19, 2014 10:08 am Post subject: |
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To adequately assess the situation or offer assistance, more information about what happened and how it was addressed is necessary.
Most often runaway is caused by excessive blowby from excessively worn rings. Do you know for sure that it was overfilled by two quarts or is that a guess?
Diesel runaway does not stop when the key is turned off. When the engine was running away did someone turn off the key? Did turning off the Key kill the engine or did it continue to run away?
If turning off the key killed then engine then it was not 'runaway' it was a fuel issue. If turning off the key did not kill the engine then it was runaway and changing the fuel pump would do nothing to affect it.
Again, were there any valve prints in the carbon on the piston crowns?
Have you done a compression test?
Adjusting valves at this point seems a lot like rearranging the deck chairs. |
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devesvws
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?Waldo?
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| Posted: Sun Oct 19, 2014 12:51 pm Post subject: |
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| There 4 other questions in my last post that you did not answer and they are all pertinent to offering any sort of advice. |
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devesvws
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?Waldo?
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| Posted: Sun Oct 19, 2014 2:21 pm Post subject: |
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2.5 quarts might cause a runaway. That means 7 quarts drained out of the engine.
If it continued to runaway after turning off the key then it is not due to the fuel system. When running off engine oil, it will rev up ungoverned until the airflow into or out of the engine is the limiting factor...8000+rpms? How long did it run away? With 7 quarts still in the sump what stopped the runaway?
I'd certainly look at compression.
I gather from what you said that loosening the union at the two middle injectors does not change the running of the engine. Does fuel bubble out when the union is loosened?
Before installing a used head I always tip it so the ports are UP and pour a little solvent into the ports to see if the valves are leaking. Did you do anything like that or any other test of the head other than looking at it? |
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devesvws
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| Posted: Sun Oct 19, 2014 3:45 pm Post subject: |
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''How long did it run away?'' I wasn't there but from what I was told about a minute and then it just stopped and would not turn over....''Does fuel bubble out when the union is loosened? yes fuel bubbles out the two middle ones that seem dead, but from left to right there might be a slight change on the 3rd one over but no change on the 2nd one over... all I did to the head is look at it. I did turn the cam wheel about a dozen times and put a straight edge on it to see if there was any sort of warpage...
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THE FEW THE PROUD THE ORIGINAL VW WATERBOXER -> looking for a original 91 vanagon owners manual with 1991 on the cover http://www.youtube.com/watch?v=pmuiG2tUsP4&feature=share https://picasaweb.google.com/101290228103300323836/BostonBobFlywheelVideo#5543000332201103922 |
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?Waldo?
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| Posted: Sun Oct 19, 2014 4:11 pm Post subject: |
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| Compression check is definitely the next step I'd take. |
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chrissev2
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| Posted: Sun Oct 19, 2014 7:10 pm Post subject: |
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Hi: This is the 1.6NA diesel right? Those are not complicated motors. When they run rough it's usually a very short list of things that could be wrong:
1. Timing - make sure when you put the new belt on, that you crack off the cam pulley bolt and pull the pulley off the cam, so that it moves freely (with the camshaft locked of course - don't use the cam lock to hold the cam when you crack off the cam bolt, you'll break the end of the camshaft off). If you don't do that, the timing will be off by a bit and it'll smoke and run rough.
2. IP timing - make sure you set it. The IP will not be timed correctly when you re-install the timing belt (even if it was when you took it off).
3. Air - the motor needs a lot of it. Have a look and make sure the filter is not clogged.
Other than that, if the valves were working when you took the head off (assuming you turned the cam to check them all to make sure they were actually moving) and the pistons were not damaged, it should run.
From the problems you're experiencing, I would say timing is the issue.
Chris |
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?Waldo?
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| Posted: Sun Oct 19, 2014 7:34 pm Post subject: |
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The most significant thing missing from your list of things the 1.6 diesel needs to run is compression. With low compression a cylinder will not fire consistently and with low enough compression, a cylinder will not fire at all.
Run a 1.6 non-turbo at ultra-high rpms for a while and it may need quite a few other things to run well. A theory that fits the information better than timing being the issue, is that the rings were close to shot before the runaway and the runaway damaged them further so now they are totally shot in one cylinder and bad in the other weak one. A compression check would prove or disprove that immediately.
The head was pulled and replaced and so the cam timing should certainly have been adjusted during that process. Devesvws also mentions changing the injection pump and so pump timing should also certainly have been adjusted during that process as well. Additionally, cam timing and pump timing will affect all cylinders equally. Because of that, an issue with timing does not fit with the statement that the opening of cyl 2 and 3 injector unions does not change the running of the engine. |
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devesvws
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?Waldo?
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| Posted: Tue Oct 21, 2014 6:33 pm Post subject: |
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That tester does not go high enough. Using it will damage it (if your compression is good), or will injure you (depending on how close you are when it explodes). Typical pressures will be between 400 and 500 psi. Wear limit is 377 psi. Max difference between cylinders is 73 psi. Adjust those numbers for higher elevations.
Don't do the 'wet' test. It can ignite destroying the compression tester.
Last edited by ?Waldo? on Tue Oct 21, 2014 9:06 pm; edited 1 time in total |
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devesvws
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devesvws
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?Waldo?
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| Posted: Wed Oct 22, 2014 7:48 pm Post subject: |
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The Harbor Freight diesel compression tester will work, but may not be completely accurate. From what I've seen, the adapter does not have a shrader valve right at the tip and so, even if the gauge is accurate, it will read low. It will work, though, and I know of several people who have used them.
I'm not sure if the vanagon Bentley describes the compression test process for the diesel. Remove all four injectors. You'll need a 27mm or 1-1/8" deep socket that is hopefully deep enough to not damage the return nipples on the injectors. Spray penetrating oil around the threads if the injectors have not been removed recently. Make sure to orient the breaker bar so that you are pushing it *toward the head* or you will break the boss for the injector. Also, make sure to do 1/4 turn out, 1/8 turn in, 1/4 turn out, 1/8 turn in, etc... until you can unscrew them with your fingers or crud can ball up on the threads and pop the injector boss. When torquing them, again make sure to orient the bar so that you are pushing it toward the head.
After removing the 4 injectors, also remove the wire to the stop solenoid and place it so that it cannot short on any metal of the engine or chassis.
No need to hold the accelerator depressed like on a gas engine as there is not throttle plate.
Crank the engine over until the needle stops moving. That is your compression pressure. |
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sorry about the triple post I'll correct that when I get home.: I was surprised how clean the motor looked the tops of the pistons are as clean as I've ever seen one, the valves in the head looked very nice. and yes I needed two oil pans to contain all the oil..I think too many people have been driving this and not paying attention to the oil level, or should I say too much attention to the oil level...