11/24/2014
Remember, simple stuff first. Had to share this shop issue. We had a customer purchase a new used truck, that he brought to us to repair before putting on the road. During that process, I suggested that he install a new set of injectors as there was a slight miss, hard start and fuming at idle. Engine ran well after injector install. Shortly after getting truck back, customer contacted us indicting that the engine was making oil. (crankcase oil level was rising not falling) We looked at engine, checking for cut o rings on injectors, fuel restriction, etc. and found nothing wrong. No change. We then replaced 2 injectors that were suspect. No Change. Customer was frustrated with our efforts to solve his issue, so took truck the the engine manufacturers distributor. They checked and said that they had found a rolled o ring on one injector. They then replaced all o rings on all injectors. No Change. They then replaced the injectors we had installed saying that they were bad. No Change. (We warranteed these injectors) They then suggested the cylinder heads be replaced as that is the last possibility. Customer asked that we take another look at this issue. We remove the fuel supply pump and found the shaft weep hole was wet, so had pump rebuilt. (this style pump is rarely and issue) No Change. We then ran engine on a dyed fuel mixture from an enclosed tank. This indicated that all of the (new) (new) injectors were leaking fuel from the top where the plunger enters the barrel. (This style injector has no seal at this location, and relies on a class fit (very tight tolerance fit) to control fuel flow at this point. This indicated a fuel return circuit restriction. We had checked this previously, but looked at it again. We again found no return circuit restrictions. We did identify a substandard fitting that we replaced. When replacing the fitting it was discovered that there was pressure in the tank as I took a fuel bath when disconnecting this fitting that was 1 foot above the fuel level. I checked with the customer and he indicated that he heard a hissing noise when removing the tank caps to fuel the truck. He said that he thought that it was suction noise not pressure. We tested a little further and found that two $30.00 tank breathers that were plugged, was the cause of thousands of dollars needless repair costs and was probably the reason that the truck was for sale in the first place. Patience and persistence will usually ultimately solve most problems. But the little things, overlooked, often cannot be solved with any amount of time or parts.
