blown99 Posted December 10, 2011 Share Posted December 10, 2011 02 f-350, blueish colored smoke out the tailpipe on a cold start, much more noticeable with temps below 40 degrees. Will smoke for several minutes while at idle. Once I begin to drive it, I no longer see the smoke. There is no misfire/skip,each glow plug pulls 20-25 amps. Oil changed every 5k with synthetic 5w40. Uses 2-3 qts during that time period. Fuel additive used at every fill. Injectors have a very strong buzz even when temps are in the low 20's. The smoke is not a consistent flow out the tailpipe - seems more like one or two cylinders. It had this issue last winter but has now gotton a little worse. I removed the fuel filter - I did not see any signs of oil in the filter housing but this oil is always clean - looks new type of clean, so I may not see any oil in the filter housing. I am still leaning towards an injector o-ring. What do you guys think? Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted December 10, 2011 Share Posted December 10, 2011 Quote: I removed the fuel filter - I did not see any signs of oil in the filter housing Once the fuel is in the heads it can't get back out. One way to rule out oil intermix with the fuel would be to remove the plugs in the back of the head and catch a sample while it drains out. I just pop the plug out and let it drain, you can tell if it's clean fuel or not. The older ones that returned fuel out of the heads back to the filter housing were much easier to pinpoint an issue with injector "o"-rings. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted December 10, 2011 Share Posted December 10, 2011 Injector o-rings are definitely possible but with oil consumption that low I be suspicious. If you put a FP gauge on both heads and watch FP on startup it might give a better clue. Being that the test ports are downstream of the inlet checkvalves (that might work), if an injector o-ring was leaking it would show an indication in elevated FP on that head. Also, if it were an o-ring, one complete head would be smoking terribly on startup. If this were in my bay, it would get 2 FP gauges and a mechanical compression test. Low compression will also cause this symptom- incomplete combustion and white smoke. Poor injector atomization can also cause it. Rule out the basics first! Good Luck! Quote Link to comment Share on other sites More sharing options...
blown99 Posted December 10, 2011 Author Share Posted December 10, 2011 I will check the drain plugs in the rear of heads for the oil. As far as compression being low - I did block the breather and removed the oil cap prior to a cold start. No blow bye out of the fill cap or dip stick tube. If it was not firing due to low compression, then I should have a skip to it. I will try the two fuel pressure gauge idea and see what the results point to. I wonder if I would notice a difference in heat with a ray tek gun if it was burning some oil on one bank vs straight fuel on the other?? Quote Link to comment Share on other sites More sharing options...
ktmlew Posted December 11, 2011 Share Posted December 11, 2011 Intake air heater working? Quote Link to comment Share on other sites More sharing options...
blown99 Posted December 11, 2011 Author Share Posted December 11, 2011 Have not checked the intake air heater. I thought those only came into operation when it was below 0? Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted December 11, 2011 Share Posted December 11, 2011 I'd have a hard time believing the IAH would cause this. Most trucks in northern climates have this "Cold Climate Package" option, but not all of them. The ones that don't have it start and run just like the ones that do in my opinion. I never saw smoke from any 7.3 connected to performance of the IAH and the only IAH problems I've ever seen are codes for open circuit. (For those that have forgotten, the IAH is not for startup but for elimination of smoke during cold warmup. It does not operate before starting but after starting. This allowed FMC to market this engine as a "smokeless diesel".) The inconsistent nature of the smoke leads me to believe 1-2 cyls have low push or bad injectors. As these engines get older I'm finding that a large majority of customer complaints can be traced back to low compression, therefore I am recommending a comp test on nearly all driver complaints. The results speak for themselves once the test is completed. What is bizarre is how a 7.3 with horrible compression can run so well and pull so strong once it gets up on boost. I've had them be so worn out, wrecked pistons, dusted cylinders, broken rings, scored cylinders, 1/2" piston ring gaps on teardown, needing ether to fire every day, and still pull quite respectably on boost.... Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted December 11, 2011 Share Posted December 11, 2011 I will check the drain plugs in the rear of heads for the oil. As far as compression being low - I did block the breather and removed the oil cap prior to a cold start. No blow bye out of the fill cap or dip stick tube. If it was not firing due to low compression, then I should have a skip to it. I will try the two fuel pressure gauge idea and see what the results point to. I wonder if I would notice a difference in heat with a ray tek gun if it was burning some oil on one bank vs straight fuel on the other?? I wouldn't hang my hat on "should have a skip to it" when determining compression characteristics. Compression that is low across the board could leave you with a smooth running motor. Additionally, watching for blowby at the oil filler is going to be inconclusive, IMHO. A properly done crankcase pressure test (with the correct size orofice) is going to give a better indication of ring seal - dont forget to block off the crankcase vent. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted December 12, 2011 Share Posted December 12, 2011 I wouldn't hang my hat on "should have a skip to it" when determining compression characteristics. Compression that is low across the board could leave you with a smooth running motor. Additionally' date=' watching for blowby at the oil filler is going to be inconclusive, IMHO. A properly done crankcase pressure test (with the correct size orifice) is going to give a better indication of ring seal - dont forget to block off the crankcase vent. [/quote'] Agreed on all counts with an asterisk on the crankcase pressure test. Through training research I have had 2 known good 7.3s fail this test with over 6" shown. I remember FMC changing the spec a couple of times from 3" to 4" to 6" or something through TSB/SSMs. I came to not trust it due to this fact. If you have done this test passing good engines please comment, I now take the time to do a compression test. Also, if you do a crankcase pressure test, you need to use/make a slack tube manometer (5 minute job). The gauge bars are usually inaccurate due to misuse in the shop or shipping. Quote Link to comment Share on other sites More sharing options...
blown99 Posted December 12, 2011 Author Share Posted December 12, 2011 I have very little faith in the blow bye test numbers. I use my eyes and hand and watch for a steady stream of blow bye. Any signs of a worn cylinder will be felt and or seen with a steady, then a heavier puff out the dip stick/ road draft tube. I had a DT that had an eaten up piston, misfire, heavy heavy white smoke that passed the blow bye test with flying colors. Anyway, I had limited tools today (and time) but messed with the scan tool a bit. Found today that I do have white smoke and a miss while snapping and or running the engine at high rpm, when the engine is cold (30 degrees) (I don't do this in the morning when going to work - I'll wake up the neighbors) Took to about a 76 degree oil temp before I no longer had any smoke at all when snapping the throttle. My mass fuel is at 10 when at operating temp. Bruce - didn't you say in a recent post that 12 would be the limit? Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted December 12, 2011 Share Posted December 12, 2011 [Agreed on all counts with an asterisk on the crankcase pressure test. Something I see far too often is somebody trying to run a crankcase pressure test on a motor with an obvious misfire. As long as that cylinder(s) aren't contributing (sorry for the mixed metaphor), the CCP might be more than acceptable. Obviously, a misfire should be addressed to some degree of certainty ( a mechanical compression test and/or a cylinder leak test can offer some food for thought ) before we condemn the engine. At the same time, a cylinder that doesn't contribute to engine power/smoothness is likely a cylinder that isn't (but probably would) contribute to excess crankcase pressure if it only could.. DUH!! I think we are on the same page and I hope I my post didn't infer that a crankcase pressure test would, by itself, offer a solution. This test is simply one test of many that will help a tech deduce the internal condition of a motor BY TAKING THE SUM TOTAL OF THE RESULTS into consideration. Like doctors, we should add the results of test A to the results of test B to the results of test C ad infinitum to achieve a logical determination of our next step. I wouldn't add an asterisk to the CCP test.... but I would take the test results in context with other observations. The minute you add that asterisk, you are tempting someone to overlook a simple, quick, unintrusive test that has the possiblity of shedding some light on the concern. Once you have even as much as removed a valve cover, the test becomes harder to perform. Something else to consider.... while the crankcase pressure spec has been a moving target in the case of the 7.3 (in all honesty, I have considered using the 6.0 orofice and the 6.0 spec in a comparison trial but haven't had the time or opportunity), we are left with the thought that "what makes 6" acceptable and 7" unacceptable"..... indeed, when we are given any spec we need to consider why one particular number can = less is good/more is bad. And we need to take that into context regarding what we are working on. In an age when engine electronics can readily identify a non-contributing cylinder, the compression gauge has become more a means of verifying relative compression results rather than a first step diagnostic aid (and isn't that what most of our test procedures are?). If my compression is even, where do I go next? I've already done a crankcase pressure test because it is quick, easy and unintrusive and the results of it AND the compression test will go hand in hand. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted December 12, 2011 Share Posted December 12, 2011 My mass fuel is at 10 when at operating temp. Bruce - didn't you say in a recent post that 12 would be the limit? Yes, I like between 8 and 10 with 12 the ballpark limit. A recent 7.3 I helped on was 20something, I think we led to replacing the injectors.... Quote Link to comment Share on other sites More sharing options...
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