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06 MACK 690s smoking


Jmackaecker

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I got this here Mack at a job I just started. I'm semi new to diesel engines and to the JalTest software. To start this truck after its been sitting for a week or so I would need to use starting fluid to get it running, after that it runs and starts no problem till it starts. After I get it running to OP temp go to rev it up, 700 rpm all the way to about 1100 is ok, but when I go to past that it will start blowing smoke if I put the petal to the metal.

I've also performed a cylinder test on a known running fine 690s truck in the image below. I'm not sure if those numbers are even up to. The test on the one smoking, the numbers ranged from 29 to 35, also tried a compression test using JalTest. I would be Cranking the engine over and the date would never show up on the screen. So I perform a compression test on the know good 690s and with in 5 sec of cranking I had info right away.

Any Ideas??

Thanks in advance!

 

cylinder test.PNG

compression test.PNG

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I'm not much on all the fancy tools, sounds like you either have a fuel problem or a compression issue, check the engine blow by tube (a monometer test) will tell if you have excessive blow by, if you do the engine needs rebuilt. if it is acceptable then have the fuel system worked on, the high speed smoking could be any thing from a plugged air filter to an injection timing issue, or faulty injector. to an intercooler issue.

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Check the fuel pressure, should be somewhere around 65 psi at idle. Usually when the fuel tansfer pump starts to give up the ghost the engine is hard to start, has white smoke in the upper rpms.  The drive gear is most likely spinning on the drive shaft on the transfer pump.  You might check the oil level as well, it could be diluted w/fuel--another thing the fuel transfer pumps were notorious for.

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Finally  got around to installing the fuel psi gauge. Note that the psi is fluctuating between 55 and 85-90 because there is no in line valve to hold the value. would I still go off of the highest reading? The filters are new and the pump seems to be Farley new. 

20161004_091724.jpg

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Is it still smoking with the gauge in? when you rev it up does the pressure drop off that is the whole point of this exercise! If not your looking in the wrong place!The preasure should drop a tad then jump up with a good stomp on the trottle! 

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ok so I moved the gauge to correct port on the block. The needle is all over the place. It seems to run way better with gauge hooked up, and doesn't really have the problem any more. There is still smoke but more now when I let off the peddle after romping on it. I'm uploading a video to you tube. I'll send the link when it's done. thanks BTW for taking your time to help. 

also is this the check valve to check/replace?

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Yup thats worth a try That will at least nail it down to a hole If the smoke dont go away after that  u may very well have an ECU issue !

Also if you can, check the ambient air temp if you have a means ,we once had issues with sensor readings coming from that sensor which put the engine in a retarded timing at certain temps! its a long shot but something else to try! un plug the sensor see if the problem clears up!

Edited by fjh
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