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  #211  
Old 11-08-2013, 12:23 PM
David S.
 
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The compression for the cylinders was something like #1 360 #2 350 #3 320 #4 310 and number five was about 295. The engine was cold when I did the test. The injectors seemed to be fine. My cousin checked their spray patterns a little over a year ago. All seemed to be firing ok.

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  #212  
Old 11-08-2013, 12:49 PM
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Well, there is a 20% difference between the worst and the best. Other's here will have to weigh in, but I think that's not great news. Of course on a cold engine it's hard to really know for sure, it's best to test a warm engine, maybe some of that spread will diminish. I understand that's hard to do, until you can get it to run right. Compression, would probably be a later issue to deal with. Check vacuum, valves, glow plugs, etc...I know much of this is over and over, but it's amazing how often redoing what you are sure is fine ends up solving the problem.
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  #213  
Old 11-08-2013, 01:28 PM
David S.
 
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I thought that the compression I have is not bad for a 300k engine? I will pull the valve cover off again after school and see if anything is wrong.
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  #214  
Old 11-08-2013, 04:12 PM
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It's not so much that any one number is really all that bad, (well #5 is down there) but is the amount of variation in the numbers. Again, though I'd like to see numbers with a warm engine, this might change the variation a lot.
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  #215  
Old 11-08-2013, 04:23 PM
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Answer

Quote:
Originally Posted by MrUkrainian View Post
The compression for the cylinders was something like #1 360 #2 350 #3 320 #4 310 and number five was about 295. The engine was cold when I did the test. The injectors seemed to be fine. My cousin checked their spray patterns a little over a year ago. All seemed to be firing ok.
Piston cylinder compression test numbers are:
#1. 360 PSI
#2. 350 PSI
#3. 320 PSI
#4. 310 PSI
#5. 295 PSI


The cylinder head would be coming off if this was my engine.

The numbers are indicating (at least) a failing cylinder head gasket.
Diesel cylinder head issues thread

om615, 616, and 617 head bolt torque sequence


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  #216  
Old 11-08-2013, 04:55 PM
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Interesting, why would you pull the cylinder head? What would you be looking for? Very inquiring minds want to learn.
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  #217  
Old 11-08-2013, 05:20 PM
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Originally Posted by crazy4diesel View Post
Interesting, why would you pull the cylinder head? What would you be looking for? Very inquiring minds want to learn.
I would expect to find at least a bad head gasket on 4 - 5, and would do extreme cleaning to look for possible

Cavitation
Cavitation

1980 240D CRACKED cylinder head + cavitation damage
1980 240D CRACKED cylinder head + cavitation damage

1985 300TD head gasket repair
1985 300TD head gasket repair


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Prototype R&D/testing:
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Noise Vibration and Harshness (NVH).
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  #218  
Old 11-08-2013, 06:48 PM
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Ugh, I think I'm going to have nightmares!
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  #219  
Old 11-09-2013, 11:51 AM
David S.
 
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Is there anyway to test if it really is a bad head gasket, 100%?
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  #220  
Old 11-09-2013, 12:35 PM
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I don't think so, you just have to pull the head and look. If it's cavitation is more than a head gasket.
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  #221  
Old 11-09-2013, 12:42 PM
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No

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Originally Posted by MrUkrainian View Post
Is there anyway to test if it really is a bad head gasket, 100%?
Sorry, no other way.


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Prototype R&D/testing:
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  #222  
Old 11-09-2013, 04:29 PM
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There were few problems prior to the valve adjust, redo the valves. I always rechecked the valves after I did them and invariably found one or 2 amiss.
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  #223  
Old 11-10-2013, 01:15 AM
David S.
 
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I don't feel like it is a bad head gasket. I drove the car about 80 miles total today, and the car drove fine the whole time. It just smokes. It definatly stopped misfiring when it warmed up all the way.
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  #224  
Old 11-10-2013, 05:00 AM
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I'm always wary of compression test results. You're not only measuring the compression / pressure created in a small section of tube between a schrader valve and the gauge but also the health of the battery and the starter (among other things). If you start at cylinder #1 and work your way to the back of the engine there is always the possibility that the last measurement is made when the "system" really could do with a rest!

You could try the test again on a warm engine but this time starting at cylinder #5 (for the situation described above) to see if it makes a difference.

Alternatively a leak down test is a superior - albeit slightly more complicated - method of assessing the sealing properties of a cylinder.
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  #225  
Old 11-10-2013, 08:50 AM
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Quote:
Originally Posted by MrUkrainian View Post
I don't feel like it is a bad head gasket. I drove the car about 80 miles total today, and the car drove fine the whole time. It just smokes. It definatly stopped misfiring when it warmed up all the way.
I know that "feeling". Since it has 300k on it,assess the rest of the car, if you want it as a daily driver, then r&r the compression. If you just want to run it till it dies and then get something else, you'll be surprised how long it takes.

"Driving fine but it smoke" isn't driving fine. A warm 616/617 shouldn't smoke unless you are flooring it. Low compression causes unburnt fuel in the exhaust. It's the compression that burns the fuel. High compression = efficiency. Eventually it will be all smoke and no burn.

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