kridd12 Posted February 25, 2009 Share Posted February 25, 2009 We've gotta strange one here wondering if iny one has had one like this. 2008 6.4l job one truck. came in for running rough and smoking. performed diag crank case over full and found when doing relative compression #2 is 0. removed glow plug and tip is gone. removed head found #2 injector tip gone and hole burnt in exhaust valve. cylinder looked ok and did not show signs of shortened rod. replaced head injector and glow plug. truck ran like a dream. customer took truck and returned 300 km later doing the same thing. # 2 missing now found # injector leaking again from tip. replaced injector and put truck back together. 20 minutes after this john guy from ford phoned and said replaced the other 7 injectors as they were part of the suspect injector range.( this was 2 days before recall came out). replaced the other 7 injector and retested. ran good on first road test. second road test engine began to make a knocking noise. shut truck off and restarted ran fine no noise. Mr Jim Warman started it up and it ran like crap. missing on 5 cylinders knocking away and smoking like crazy. shut truck off and restarted ran like a dream. smoked black for about 2 km on road test and never missed a beat again. knock is almost gone but you can hear a slight bit mostly at idle. the manual compression readings were 300-315 on most cylinders except #2 it was at 280 psi. cylinder walls all look ok. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted February 26, 2009 Share Posted February 26, 2009 Quote: the manual compression readings were 300-315 on most cylinders except #2 it was at 280 psi. cylinder walls all look ok. Compression is too low. A healthy 6.4L should have over 400 PSI. The ones I have performed a manual compression test on had an average of 425 PSI on good cylinders. Remember, these engines have individual injector fuel trims and can compensate and mask problems. Ask me how I know. Quote Link to comment Share on other sites More sharing options...
OHNO60 Posted February 26, 2009 Share Posted February 26, 2009 kridd, same exact issue here. Glowplug obliterated and exhaust valve melted to hell. The one i had actually had cylinder damage and prior gave 6007 drop in bomb. Amazing they can tell you the exact cylinder the bad injectors they want replaced, but cant give you an answer on how to keep these from "exploding" Quote Link to comment Share on other sites More sharing options...
kridd12 Posted February 27, 2009 Author Share Posted February 27, 2009 now this frickin truck runs like a dream. approx 3oo km put on it not a lick of issues. no noise runs like a dream unable to duplicate concern. i really have no clue what the issue was. cold start and warm start now everything fine. -37 degree c yesterday and it started like a dream. hotline has nothing, but i really don't know what to look for on something running fine. customer of course wants an engine ford says no for obvious reasons. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted February 28, 2009 Share Posted February 28, 2009 Somewhere along the line, I pissed somebody off bad enough to be handed the keys to this truck.... It will, at it's own discretion, either run like an absolute bag of shit (5 noncontributing cylinders at one point) - run like a top... or decide on some middle ground. You can take a motor that misses like a bastuhd and make it run smooth simply by turning the key off and restarting the motor. This motor can have a steady "TAP" at idle.... when this happens, it is beginning to emerge that the fuel trim for #2 MIGHT be adding - the concern is that transitory. It might "TAP" when it misses.... but then, it might NOT. The last time I ran the motor warm, there was a VERY intermittent miss on #2 in enhanced mode.... SFTs were fairly tight to zero except for #2 at between 15 and 18 plus. So... the big question is..... when I submit my application as a burger flipper at MickeyDs, can I use you guys as references? Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted February 28, 2009 Share Posted February 28, 2009 Do you have ANY DTC's or test data to go on or share with us? The only strange 6.4L story I have was that one with fuse #74 that screwed with me and the Field Service Engineer from Navistar... but we did not have melted engine parts. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 28, 2009 Share Posted February 28, 2009 Compression is too low. A healthy 6.4L should have over 400 PSI. The ones I have performed a manual compression test on had an average of 425 PSI on good cylinders. At sea level. I don't know the altitude at Slave Lake, maybe it's really high. Thin air would explain some of Grandpa's remarks.... Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted February 28, 2009 Share Posted February 28, 2009 Hmmm, good point Bruce. I hadn't thought of that. Now that you have brought this to our attention, how much can altitude affect compression numbers and other than testing a like vehicle, how would we know if our readings are normal for our altitude? Ask a Hot-Line engineer and you won't get an answer. Perhaps there is a chart or a formula somewhere that would provide a ballpark figure? I am sure guys that build and prepare racing engines have to know this to set up engines right? Thin air would explain some of Grandpa's remarks.... I just caught onto that! Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted February 28, 2009 Share Posted February 28, 2009 Bruce is quite right... we are at about 1900 feet above sea level... This affects manifold vacuuon gas engines and it also affects absolute compression numbers... We have never had our compression gauge read anywhere near 400 PSI (that I can recall, anyway). FWIW, I don't like to rely on compression readings in terms of "absolute" numbers - I do prefer to look at compression test reults in terms of relative numbers. As it stands, the engine runs very smooth when it wants to, it starts very easily - even in -30C without being plugged in. The left head was just off and there was nothing abnormal on the cylinder walls... but the concern(s) is/are intermittent - and this is going to limit any possible mechanical concerns pretty much to "sticky shit". It is going to be a matter of looking at the right stuff at the right time.... Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 28, 2009 Share Posted February 28, 2009 It will, at it's own discretion, either run like an absolute bag of shit (5 noncontributing cylinders at one point) - run like a top... or decide on some middle ground. You can take a motor that misses like a bastard and make it run smooth simply by turning the key off and restarting the motor. This motor can have a steady "TAP" at idle.... when this happens, it is beginning to emerge that the fuel trim for #2 MIGHT be adding - the concern is that transitory. It might "TAP" when it misses.... but then, it might NOT. The last time I ran the motor warm, there was a VERY intermittent miss on #2 in enhanced mode.... SFTs were fairly tight to zero except for #2 at between 15 and 18 plus. I have no idea where to start on this POS, but here's some weirdness I have experienced in the past with "make it run smooth simply by turning the key off and restarting the motor". Vehicle #1: Some kind of Ford truck, might have been a 7.3PSD. Sometimes the truck would run like an absolute POS, shut it off and restart it, and it would purr like a kitten. After changing boatloads of parts, the culprit was found to be an aftermarket starter solenoid/relay on the fender well without a spike suppression diode built in. The release spike was backfeeding up the trigger wire to the PCM and sending it on a drunken rampage. (sidebar: On a slow day I scoped several regular Bosch style 5 pin relays. Suppressed relays had a release spike in the 30-50VDC range, non suppressed relays had a spike in the 400VDC range! These were small relays. I haven't tested large starter style relays yet....) Vehicle #2: Some kind of luxury Ford product, might have been a Lincoln Navigator. Hard to start, and once it started it would sometimes run fine and sometimes run like a POS. Problem was found to be a bad starter, emitting massive EMI/RFI and pissing off the crank sensor. Problem was solved with a scope watching PCM inputs, in where there was huge interference (electrical hash) on all circuits when cranking. Replacing the starter fixed the problem. Oddly enough, cranking RPM and sound was fine with the old defective starter. (This is a pattern failure with some Nissan products, I hear) Too bad there's no BOB for a 6.4. If your 6.4 was in my bay, I'd start by scoping the CKP/CMP waves. I have known good captures if you need them, I think they're the same as a 6.0. I might have already posted them here, but I'm old now and CRS. If your CKP was pissed off, it could conceivably answer why cyl #2 was overfueling. So... the big question is..... when I submit my application as a burger flipper at MickeyDs, can I use you guys as references? Are you really sure you want to do that? Aren't you afraid we'll tell them what we think of you? Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 28, 2009 Share Posted February 28, 2009 how much can altitude affect compression numbers and other than testing a like vehicle, Huge differences in compression readings, I can assure you. how would we know if our readings are normal for our altitude? Have a "known good" on file mentally for your altitude. Ask a Hot-Line engineer and you won't get an answer. Perhaps there is a chart or a formula somewhere that would provide a ballpark figure? There is somewhere, I'll see if I can find it. Damon usually knows shit like this, maybe I'll ask him. I am sure guys that build and prepare racing engines have to know this to set up engines right? Heavy cams lower compression significantly, so their experiences may not apply. Grampa, what's your MAP/Baro read KOEO in your area? Sea level is 14.7psi, Cleveland is 14.2 unless it's raining. In higher altitudes like Denver, I see 12ish. I've seen as low as 13.8 in a rainstorm on a truck in Cleveland that's usually 14.2. (yea, you can forecast weather with the Baro/Map sensor readings) Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 28, 2009 Share Posted February 28, 2009 FWIW, I don't like to rely on compression readings in terms of "absolute" numbers - I do prefer to look at compression test reults in terms of relative numbers. Bad move if you ask me. How are you going to diagnose a dusted engine? Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 28, 2009 Share Posted February 28, 2009 Found on the 'net, no guarantees it is correct, but it looks good: Altitude and temperature also affect the compression readings. Manufacturer’s specifications are almost always given at a specific altitude (14.7 psi at sea level), and 59° Fahrenheit. Both temperature and barometric pressure change as you go up in altitude, so you will need to correct your measurements if you wish to compare it with a factory specification. The following chart provides conversion factors for correctly compensating for changes in altitude: Compression Test Altitude Compensation Factors Altitude Factor 500 0.987 1500 0.960 2500 0.933 3500 0.907 4500 0.880 5500 0.853 6500 0.826 7500 0.800 8500 0.773 A standard compression reading of about 150 psi at sea level in Los Angeles would measure significantly less in the surrounding mountains. For example, at an elevation of 6000 feet, the expected reading would be 150 psi X .8359 = 125 psi. The cylinders would be reading low if compared to sea level measurements, yet perfectly fine at this altitude. At your 1900 foot altitude, this should translate a (sea level 100%)425psi reading into 402psi, but you still say you've never seen 400psi??? Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted February 28, 2009 Share Posted February 28, 2009 Cool Bruce. This chart you posted accounts for altitude only as I see it and it does not account for weather changes in barometric pressure - I see accounting for temperature as being more difficult to factor in on top of it all. Wouldn't it be more accurate to just compensate using a baro reading? Heck, you could even use data logger to obtain that value real time, no? Compensating aside, I can't think of any time or place I have seen Ford publish a specification for compression testing. (I do hope that I didn't miss anything along the way - ) Yes, we know to compare cylinders: determine a baseline and measure variances between cylinders but it is the baseline that sometimes comes into question. Knowing what readings to expect for healthy engine at seal level is the key here. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted March 1, 2009 Share Posted March 1, 2009 Bruce, on a really "good" day, we may see as high as 13.7 PSI but 13.5 would be closer to normal..... If I suspect a dusted engine, I can perform a crankcase pressure test or a cylinder leakage test. FWIW, there are caveates to consider when performing a crankcase pressure test on a motor with any non contributing cylinders. I feel there are too many other conditions that can affect compression readings to use this as an "absolute" test. It's not that I don't use compression test data - I just don't try to read too much into it. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted March 3, 2009 Share Posted March 3, 2009 OK.. so I took a truck with 75 kms on it.... and I checked compression on 2 cylinders (numbers 1 and 3). Rolling the engine over 6 or 7 times gave compression pressures in the 280~300 range. Rolling the engine over until the gauge stops moving yields closer to 360 psi... The engine was warm but not hot. How much is related to altitude and how much is related to the gauge, I can't say. All things considered, relative information is all I will infer from a compression test. Running relative compression tests on the subject truck is futile - walk away from the truck for a half hour and repeat the test - there is little, if any, relation to any other test. Tomorrow, we will repeat a course of relative compression testing with the "control" group. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted March 3, 2009 Share Posted March 3, 2009 I almost went nuts with a 6.4 and relative compression... that one with the missing wrist pin retainer and the burnt piston. The bastard ran like shit and smoked badly. I went through the diagnostics end ended up putting 2 injectors in the offending cylinders. In retracing my steps I THEN discovered different relative compression readings... which I repeated several times getting inconsistent results. I cant explain it Jim. At that point a manual compression test was the only test I would trust. After pulling this thing apart the damage I found should not have produced erratic results. I was thinking I was going to find a valve train issue... this engine may yet make the 6.0L look good. I may get to swing that engine in the next day or so. The truck has only been around since January. It would be funny if it wasn't so sad. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted March 3, 2009 Share Posted March 3, 2009 Years ago, I was the (sort off) proud owner of a Sun Interrogator (and later a Sun MCA3000) which performed relative compression testing using starter draw as the comparitor. No, I must assume the PCM uses the CKP as the comparitor (is that even a word?)... Ford says 4% is THE number.... the fat old man thinks this test is only good at finding holes that are very, very close to comatose - for anything else.... too many variables. We still have a significant number of other tests that are as good as a manual compression test or will serve to discover things that a manual compression test can't. Wet and dry compression tests, cylinder kill test (interestingly, both the MCA and the Interrogator automated this test... to the point that NINE cylinders would be killed to ensure that every cylinder measured had a killed cylinder precede it - and it would include gas bench measurements in the data) and my particular favourite, the cylinder leak test... this is accepted practice with both piston powered aircraft engines as well as top alcohol drag teams. One thing that I am having a real hard time dealing with is the insistance that so many have that this is a base engine concern.... It don't feel like one and I can't say it acts like one. Let us not forget what a fuel washed cylinder can do for compression testing.... More to come after the next round of testing. Quote Link to comment Share on other sites More sharing options...
DwayneGorniak Posted March 3, 2009 Share Posted March 3, 2009 Not only that, but FUBAR injectors can cause erratic relative compression readings. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted March 3, 2009 Share Posted March 3, 2009 Let us not forget what a fuel washed cylinder can do for compression testing.... Since I trusted my testing and the initial relative compression results I assumed that was the reason for the change after the repair. Having replaced injectors on other trucks that dumped fuel into the cylinders and noticed a fuel knock and roughness afterward I thought it would clear after driving it hard as usual. Not this time. Quote Link to comment Share on other sites More sharing options...
GregKneupper Posted March 3, 2009 Share Posted March 3, 2009 We had one here a while back that came in running rough and smoking realk bad. Was also low on coolant. After running relative compression it showed multiple cylinders low. We feared the worst of course. On tear down we found a broken rocker arm on number 2 cylinder. We contacted hotline and they said replace the rocker arm first and them perform manual compression on all cylinders. Well that was all the damn truck needed was one rocker arm. Put it on and all compression was good. Put it back together and performed another relative compression test and it passed. We could not believe one rocker arm was causing it to do what it did. Hotline informed us that they have been seeing this issue with the relative compression test on the 6.4. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted March 3, 2009 Share Posted March 3, 2009 Well it was the Hot-Line that suggested to me that I had a valve train issue... having repaired one 6.4L with some seized valves it seemed a possibility but i n reality things turned out strangely different. On the subject of valve train concerns, any malfunction there can and likely will affect other cylinders beside the cylinder with the problem. Case and point, a stuck exhaust valve on #8 caused #6 to miss worse than #8. Yeah! Fun huh? Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted March 3, 2009 Share Posted March 3, 2009 We have seen more than one engine with a valve train concern on #2 that causes the power balance to flag #4. If the spent gases from #2 can't enter the exhaust, they will infiltrate the intake manifold and dilute the fresh air charge... Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted March 21, 2009 Share Posted March 21, 2009 Update.... I finally found some time to return to this heartache... In the few hours that I have had it run, oil level is once again on the rise. It actually ran good this last time other than having too much white smoke when cold. In as much of a rush as I can generate with the way some days go, I removed the four front glow plugs... bear in mind that this engine is at room temp. #1 glow plug has a tip that is nearly pure white.... Cranking the engine 6 firing strokes per cylinder, yielded about 220 PSI for #1, 200 PSI for #2 and #s 3 and 4 at about 280. Rolling the engine to achieve "absolute" compression yielded about 280ish the two low cylinders and 320 on the others... (from comparing to a new unit that was still hand warm when I checked it - I will assume that the 320 PSI cylinders are typical). #2 shows strong misting when the engine is cranked (key off, powering only the starter solenoid at connector C-139). So.... we have established that we do have a base engine concern happening.... however, looking at it realistically, it isn't the cause of our running concern... and it doesn't explain away the differing relative compression results. More on my take on relative compression later.... Hotline has informed me that these engines enjoy high crankcase pressures... but an overfill as little as two quarts can be the "beginning of the end". This engine is into it's third time overfull. Of course, the compression test results do not support or explain the random nature of the misfires or why cylinder #2 is such a big player. Hotline informs me that this concern appears to affect #s 8, 4 and 2.... in that order (memory warning) - so, does that make #1 a different concern, a red herring or a related symptom? And why the white glow plug tip - I don't ever recall seeing that before... So often, we try to read too much into things - relative compression is one of those areas where I feel we try to put lipstick on a pig. If we have a steady miss at idle, performing a relative compression test can HELP us determine if our concern lies inside the cylinder or if we should concentrate our efforts outside the cylinder. Performing a relative compression test on an engine that does not have a steady, easily identified miss at idle can and will lead us astray or even have us misdiagnosing a concern. I have compression pressures that are obviously "off" on at least two cylinders, yet relative compression cannot identify these cylinders with any regularity nor accuracy. Don't get me wrong.... relative compression is a good test... but we need to use it in an appropriate manner... Stay tuned for our next episode... will our hero perservere and find that "magic silver bullet"? Or will he be driven to spend the rest of his days in an engineer induced alcoholic stupor? <Insert advertising jingle here> Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted March 21, 2009 Share Posted March 21, 2009 Jim I feel for you as I just went through the same kind of runaround if you recall my posts on it. I had the same inconsistent results with relative compression that caused me to head down the wrong path during my diagnosis. Had the test indicated the two problem cylinders the first time my experience would have been much different. I think we may have discovered that for the IDS relative compression test to be accurate the engine must be at operating temperature. With my engine cold or only as warm as 5 or 10 minutes running in the shop had gotten it, the worst reading I saw was -2% on cylinder #2. After warming the engine up and then driving the hell out of it for 10 minutes I saw a much different picture. Cylinder #2 dropped to -8% and cylinder #8 suddenly showed -5% in relative compression. If you recall, #2 had a missing wrist pin retainer and #8 had a piston crown beginning to melt and score the cylinder. What does this tell us? I'll repeat this: Perform engine performance diagnostics at full operating temperature. Quote Link to comment Share on other sites More sharing options...
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