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I have Nailing and discolored Diesel Fuel?
For about 1 Month I have been experiencing Nailing till the Engine is fully warmed up.
I removed the Glow Plugs and reamed out the Carbon and found one of the Glow Plug Wires nearly severed and fixed that. Checked Glow Plugs on the Battery and all of them passed.
Subjectively that seemed to give a slight improvement. But after starting and the original heat from the Glow Plugs was gone I had at least one Injector that was nailing obviously louder than the rest; it would clear up after the Engine was well warmed up.
I did the Injector Cut Out Test when the Engine was running but still cold and found when the Fuel was cut off to the #5 Injector the loudest nailing went away.
I decided to pull all of the Injectors (that were rebuilt by Me 26,000 Miles ago with Monark Injector Nozzles) to Pop Test and check the Spray Patterns. The Car Seldom goes on the Freeway except for the last 2 months it about 2 miles Daily with an occasional 10 Mile trip that is about 3,715 miles per Year since I bought it.
I needed Diesel Fuel for the Pop Tester and decided to get it from the Fuel Return by way of the Cigar Hose Barb on the Fuel Filter using a longer used 5/16 ID Hose.
After removing the Cigar Hose and attaching the 5/16 Hose I ran the Engine and had the Fuel from the Fuel return going into a Gallon Jug.
I looked into the Jug and found that the Fuel coming out was tinted a purple grayish color!
At first I thought the cause might be from the Used Hose. But, I removed the Hose and had return Fuel go into an old clean plastic Bottle and it was the same color; see the pics.
My Plastic Filter does have a few chunky Black particles in it but I have no loss of Power.
Things that I know can cause that color in the Fuel.
Oil being sucked into the Fuel Supply/Lift Pump from the Tiny O-ring on the Pump Push Rod.
I rebuilt the Fuel Supply/Lift Pump about 4 Years ago but I used a Tiny O-ring I got from a BMW Motorcycle Dealer. I suppose it is possible the O-ring did not hold up.
On the other hand People who have put Waste Motor Oil in their Fuel say it quiets the Engine down; meaning Oil mixed in the Fuel would not likely be the cause of Nailing.
I don’t believe I am having any unusual Crankcase Oil loss and I have some Seal leaks that would make that hard to track.
On the other hand I have seen Fuel get the same color on Cummins Engines where the Injector did not seat well in the Injector Tube and Combustion Gasses came up around the Body and past the O-rings that seal the Fuel Supply on the Injector allowing the Combustion Gasses to mix with the Fuel right at the Injector.
Bad Fuel from the Pump? I buy from the same place I get 99% of My Fuel. A Truck stop. But, that does not make it impossible to get bad Fuel from them.
If the seat in the Injector Nozzle is bad they have been know to allow combustion Gasses to get into the Fuel Return area in the Injector and of course into the Return Fuel.
I guess I will find out if that is so when I Pop Test the Injectors and find a bad one and take it apart.
Something growing in side the Fuel Tank. While I have seen Fuel Injection Pumps brought into the Shop gunked up from Fuel Tank Growth I have never see the actual Fuel itself to know what Color the Fuel gets. That means I don’t know if the color of the Fuel Sample I have is actually caused by some growth in the Tank.
I did not want to use the discolored Fuel in the Pop Tester but did it any way. The #5 Injector tested Good. Opens at 2000 psi good spray pattern and had no dripping/leaking during the pressure test that checks how good the Nozzle seating area is.
I have not pulled the other injectors yet and tested them but I think I will also do a Compression Test when all the Injectors are out. Compression is not Fuel realated but can effect Nailing.
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84 300D, 82 Volvo 244Gl Diesel
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