| Author | Message | ||
| bobm (68.35.160.48) Rating: N/A |
My 4104 w/671 will not start without a shot of starting fluid. I can crank it until white smoke pours out but it will not start. With a less that a second push on the starter fluid button it starts. First a black cloud then a little blue smoke for a few minutes then it runs fine. Starts ok when hot. But a cold start, even with outside temp above 80, requires starting fluid. Once started the bus runs fine so I hate to condemn the engine to a rebuild. I know that this is a symptom of low compression but what else could cause this? | ||
| R.J.Bob Evans (64.110.227.72)
Rating: N/A |
Broken rings from too much starting fluid over the years. Around my business we say that diesels get addicted to starting fluid and we simply don't allow anyone to use it. And it gets awful cold here - minus 55 on the thermometer several days last Jan. Fortunately I was in Mexico while that was going on but the point is if we can start diesel engines at -55 with no starting fluid then no one needs to use ether to start them at any temperature. | ||
| John Rigby (24.174.238.253)
Rating: N/A |
Bob Do you have a block heater? Also You could be loosing your prime from the fuel pump to the block/rack. If you have a way to prime her back up(ie a small gas fuel pump and hose) you can disconnect the hose going to the block after its stood a day or two, and see if the line is full. This has been a problem I have had on my 671/4104. I did not use either, I used a block heater to heat everything up. Until I found out I was loosing my prime. John | ||
| Stephen Fessenden (Sffess) (65.134.2.190)
Rating: N/A |
If you must use starting fluid in summer, try WD40. It seems to be gentler than ether and it provides lubrication. | ||
| TWO DOGS (65.179.201.120) Rating: N/A |
or better yet...liquid wrench in the spray can...seems like a 671 o-haul kit was 450.00...but...that was years ago...anybody know...used to read about them in the truck papers at truckstops...where is ol' Brian...he ought to know.. | ||
| Phil Dumpster (24.16.243.37) Rating: N/A |
How fast does the engine crank? If it doesn't crank fast enough then it will be hard to start without starting fluid. Consider 150 RPM a minimum, and the faster the better. Try this - if you can park at the top of a hill, try starting your cold engine by putting the coach into first gear and rolling at about 5 miles per hour. This should spin the engine at something close to idle speed. See if it starts easily when spun that fast. I would say a compression test when the engine is stone cold would give a good indication of what's up. If it had broken rings, then it would probably also have lots and lots of blowby and power output would be down as a result. You said the engine runs fine. When you start talking about individual cylinder faults and a no start condition, do bear in mind that your engine can start on fewer than 6 cylinders. I would be hesitant to think the compression rings have broken into pieces because behavior like you describe would require all six cylinders to have the same problem. Blue smoke is crankcase oil. White smoke is unburned diesel. Black smoke is a lack of air. | ||
| Chuck Lott (68.211.108.62)
Rating: N/A |
This past year, I've added a permanenty mounted 24V electric fuel pump to my MC8 for intermettient use. After pulling the tank and having it vatted and then changing the fuel filters, all I had to do was just flip my toggle switch, listen for it to gets its prime and hit the starter and ,Viola! Odd thing was, even after I started it the first time after the major work, the next time or two that I tried to start it it did as "Bobm" author of this thread, describes.....Just spun and wouoldnt catch. I just hit the switch for the elect pump for a few seconds and it made the sound that an elect pump makes 'till it builds pressure...hit the starter and away she went. Then turned the elect pump back off. It only did that twice and now it starts normally, but I'm sure glad I put that pump in. Its just a big help when changing fuel filters or God forbid, I should run out of fuel. Bobm, This may not or may not solve your problem, but its a great bus project that you would use anyway. I did this setup for less than $100, with info off this board, and would be glad to share photos and info with anyone interested. | ||
| John Rigby (24.174.238.253)
Rating: N/A |
Chuck. do you have a way to post them? That would be great. As I said I have a pump but I sure would like to plumb it in permanent. Thank You. John | ||
| Nick Morris (Nick3751) (69.34.105.21)
Rating: N/A |
I second John's post. I've also got a small leak in my fuel filters that causes my system to leak down in about 8 hours and I have the same symptoms as Bobm does. I can almost just walk back and open the doors with the starting fluid and it will start  | ||
| jose (63.190.80.172) Rating: N/A |
When installing a aux. electric pump be sure it does not slow the fuel to the primary pump. I believe CCC has pictures of a electric fuelpump bypass instlation. The 6-71 must have a flow of at least .8 gal.per minute at 1500 rpm measured at the return line. This flow is necessary to cool the injecters. I don't have the spec here for the 8-71,6-92 etc. but,all need excess flow for cooling purposes. Jose | ||
| BrianMCI96A3 (65.41.248.184) Rating: N/A |
TwoD, depending on the model and other factors, like whether it has a two valve head, I found DD 6-71 overhaul kits from $970 to $1300... they averaged about $1100 Brian | ||
| Chuck Lott (65.3.203.59)
Rating: N/A |
Trying for the first time to post a photo. This is a 24V pump. You'll notice (If the pic comes up) that I used a ball valve instead of a check valve. Lots cheaper. When I want to use the elect pump, I just close the valve. When the engine is up and running, I shut the valve and turn off the switch to the pump. If I can't get the photo to load, I'll email it to someone with computer savvy and let them post it. Chuck | ||
| Chuck Lott (65.3.203.59)
Rating: N/A |
Well, I just emailed the photo to the folks who asked for them. Anyone else who'd like one drop me a note. I just need to figure out how to compress the image so I can post it here. I found a neat thread in the archives, but I'm not sure my computer has the image editor. I'll try that on a rainy day. Chuck | ||
| TWO DOGS (65.179.201.191) Rating: N/A |
sounds like a check valve would help..if it's looseing it's prime | ||
| John Rigby (24.174.238.253)
Rating: N/A |
Two Dogs your right. The DDA shop said for me to put a check valvle just as the return line leaves the head on my 671. With these king pins,I have not had time yet. John | ||
| Jim-Bob (152.163.252.199) Rating: N/A |
Hey John, I don't think the extra check valve in the return line is going to help. That valve will need to be installed so that the returned fuel goes through it & back to the tank. After you shut the bus off it will still allow fuel to go back to the tank. That said, DO check or replace the suction side check valve. Mine is screwed into the inlet of the primary fuel filter. If I had the problem, I would go to the trouble of running the engine from a "Jerry can". Connect fuel hose from the inlet of the primary into the jug & from the return (after the restrictor) into the jug. Run it long enough to get clean fuel all through the hose (maybe 5 minutes) then shut her off overnight. If she starts with no problem next morning then the problem is in the fuel lines in the bus. If it still loses it's prime then it is between the primary and the return fitting. We use this on marine engines. We call it the "Fuel System Substitution Test" and it will narrow down the problem. | ||
| John Rigby (65.112.227.94)
Rating: N/A |
Great Input Jim Bob. I will certainly try it. Thank you John |