| Author | Message | ||
| Austin Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 70 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
I changed the oil in my 4104 this weekend and there seemed to be more oil coming out then should be. (ended up with about 7 gal of liquid) Upon closer inspection I noticed it had a strong diesel smell and was very thin. What are the more common things that could cause fuel to get into the oil? . | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 580 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
leaky lines inside the valve cover | ||
| Austin Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 71 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
That is one that had crossed my mind. I assume to find the leak you need to remove the cover and run the engine. How messy is it to run the engine with the valve cover off? Or could I install an in-line electric fuel pump and just run it? . | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 581 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
yep...remove valve cover,pressurize fuel line.no need to run engine You can do it with air,remove each line from injecter,do not bend the lines,do them one at a time till you find 'air' leak (Message edited by bob greenwood on January 22, 2007) | ||
| Jim Wilke (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 110 Registered: 2-2001 Posted From: 69.77.151.82 Rating: N/A |
Austin, when you remove the valve cover, take a look at all of the jumper lines. The leaker/s should be VERY clean in the area where they thread into the head or injector. The fuel washes the oil from those spots. Jim-Bob | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 2 Registered: 8-2006 Posted From: 74.32.84.239 Rating: N/A |
Austin take a wrench and tap the fuel lines and they will have a ring the one that does not ring will be the one that is leaking found this out from a old dd diesel man good luck | ||
| Austin Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 72 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
WOW... All great ideas. I hope to be doing it this weekend if the weather cooperates. I can always count on this board for good help. . | ||
| Steveggt (Steveggt)
Registered Member Username: Steveggt Post Number: 6 Registered: 12-2006 Posted From: 71.116.87.220 Rating: N/A |
I've found that, if you have a priming tank, you can remove your valve cover and pressurize your fuel system to check for leaks. A helpful "do-dat" is one of those little round hinged mirrors about 1-2 inches in diameter that's mounted on a collapsible "antenna" so that you can peek around the back (firewall-side) of the injectors. Good luck! - Steve | ||
| Tim Strommen (Tim_strommen)
Registered Member Username: Tim_strommen Post Number: 265 Registered: 11-2004 Posted From: 67.169.47.134 Rating: N/A |
Austin, If you're going to have the valve covers off for an inspection - I'd recommend replacing the lines anyway (but check them before replacing them so you have the piece of mind, knowing that they were in fact leaking...). Cross-over lines are made of copper and get brittle with age, if they haven't failed already, it's >>possible<< that they may fail in the future. Spun main bearings are not fun... (crossover pipes are cheaper than an engine swap). In earlly DDs, the fuel only enters the head after the pump, and leaves the head after the injectors. This means there aren't many places that fuel could enter the oil system (cross-over pipes are the most likely candidates). The fuel rail (that goes to the crossover pipes), is bored through the head - so if you have a cracked head it may leak there. But you'd probably have water in the oil too or oil in the water. Another very remote possibility is over fueling and blow-by on the piston rings (but this would be accompanied with a general "loss of balls (power)", and if your engine oil didn't come out all chared and gummy, then that's not too likely at all. While you're poking around the fuel system, I'd also recommend checking the fuel system for obstructions (especially if your fuel lines are rubberized), as some fuel components can break down with age and clog injectors/return lines. Cheers! -Tim (Message edited by Tim Strommen on January 24, 2007) (Message edited by Tim Strommen on January 24, 2007) | ||
| Sammy (Sammy)
Registered Member Username: Sammy Post Number: 65 Registered: 8-2005 Posted From: 68.237.213.178 Rating: N/A |
Check the fuel cross over pipe stand off fittings. These are the fittings that the crossover pipes attach to. There is a copper washer between them and the head.Look for the "clean" trail on inner head surface,fuel will wash away engine oil.(already mentioned) Good luck with your repair. | ||
| jim morrison (Jim_morrison)
Registered Member Username: Jim_morrison Post Number: 64 Registered: 11-2006 Posted From: 72.142.29.218 Rating: N/A |
i had the same problem last spring leaving south Texas after replacing a head , the mech, forgot to tighten a fuel line in the head cover and 50 miles up the road head'n home the smoke started ' oil blow;n he came to me, found the problem and fixed it, but he replaced the oil with 40 w, now i have to replace the oil and filter again but i know now what to look for , education costs , it how much do ya pay that counts that matters ......... jim | ||
| Austin Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 75 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
Well I removed the valve cover this past weekend and did not find anything conclusive. I looked at all of the areas where there could be a leak and did not find any difference is cleanliness. I taped on every steel line and I did seem to get a ring from every one. I then just went to every fitting and put a wrench to every one and found a few that were a little looser then the others and tightened them up. I will be keeping an eye on the oil level to see if it increases. And also keeping an eye on the viscosity. I hope the few slightly loose fittings I found solve the problem. . | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 611 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
didn't put pressure to lines this is a little more important than just looking,...you will be buying a NEW engine,if you can't find it,...........take it to a shop five to ten thousand dollars is enough to put you in the group:"I USED TO HAVE A BUS" (Message edited by bob greenwood on January 29, 2007) | ||
| Austin Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 76 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
I do plan on putting the lines under pressure and checking again. I didn't have very cooperating weather last weekend. It started to rain while I was working on it. I decided to button it up and try again in the near future. The bus only gets run about twice a week for about 60 miles round trip. I check the oil every time before each run and since the oil change there has not been any noticeable increase in volume or loss of viscosity. . | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 618 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
seriously,I would not drive it till you find the fuel leak,you have already done damage to your engine | ||
| Jim Wilke (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 112 Registered: 2-2001 Posted From: 69.77.151.82 Rating: N/A |
Austin, if your oil level isn't going down as you drive, say 400 miles then you are "making oil" (diluting the oil with fuel). Detroit 2 strokes burn oil, at least a quart in 500 miles, sometimes a gallon in 500 miles so be concerned if the oil level does not drop. Also, many here have posted and my experience has shown me that the 6-71 uses less oil when the level is kept closer to "ADD" than to the full mark. Jim-Bob | ||
| Austin Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 77 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
My oil level is right in the middle of the add and full marks. I haven't driven it but about 200miles total since the oil change, 30-60 miles at a time. (it barely has time to warm up) I have an electric fuel pump and plan on installing it to pressurize the system this weekend, weather permitting. | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 621 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
it's early in the morning, I might be thinking incorectly,but an electric pump,what is that going to do ?where are you going to install it,do you know a lift pump just lifts fuel TO the injectors.maybe I need more coffee. | ||
| Austin Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 78 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
Bob, I have seen that some here have installed an electric fuel pump just above the fuel tank to prime the system after changing the fuel filters. I would think that this same type of set-up would pump the fuel with sufficient pressure to see any leaks. I may be wrong. | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 624 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
I've had more coffee..I think you are wrong... I might be wrong.. if you will look,some of those posts are mine & the elec. pump will pump fuel TO the injector PUMP...BUT....no farther...unless... I need more coffee. (Message edited by bob greenwood on January 31, 2007) | ||
| Austin Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 79 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
The jumper lines under the valve cover should have pressure because the main fuel line in the block is pressurized and they are connected to that passage. I'm not sure about the return lines. . | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 625 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
has nothing to do with return lines...re-read my last post.. I had left out a word | ||
| Austin Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 80 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
Amazing what one word can do to the meaning of a sentence. So the engine fuel pump may prevent the fuel from going through to the second filter, fuel manifold, and injectors..... In your previous post you said to use air to pressurize the lines. How would you suggest to do that? | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 626 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
unless I'm terribly wrong, the injector pump will stop the fuel from getting to the injectors.just useing the 12 volt as a lift pump somebody else help out here !!! The 12 volt pump pumps fuel at about 30 psi to the injector pump,the injector pump takes that fuel & increases the pressure to like 1000 psi, my figures might be off , (Message edited by bob greenwood on January 31, 2007) | ||
| joe padberg (Joemc7ab)
Registered Member Username: Joemc7ab Post Number: 78 Registered: 6-2004 Posted From: 66.38.159.33 Rating: N/A |
Bob You are thinking of the traditional pump system that you would find on an cummings or cat made for those by rosa master or Bosch etc. On the 2 strokes the fuel is high pressurized in the injector and the fuel pump mounted on the engine brings pressure up to about 60 psi if memmory serves and delivers it to the injector. An automotive type pump typically only runs at 5 to 7 psi (carburator application ) Hope this helps. joe | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 627 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
no....it didn't | ||
| Austin Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 81 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
Bob, My bus only has a mechanical fuel pump driven off the blower. (gear type) It pulls the fuel from the tank through a check valve and primary filter. It pushes the fuel through a secondary filter and to the head where it is distributed to each injector via the small jumper tubes under the valve cover. Each injector has a return jumper tube that passes the unused fuel back to the fuel tank. Fuel pressure is normal at 20-40 psi, according to the book. . | ||
| joe padberg (Joemc7ab)
Registered Member Username: Joemc7ab Post Number: 79 Registered: 6-2004 Posted From: 66.38.159.33 Rating: N/A |
Bob Austin has it correct. If you have, or have acces to Da Book V71 Detroit series it describes the operation in detail in section 2.1 and 2.2 Joe. | ||
| Austin Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 82 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
I have both the 4104 bus and 71 series engine manuals on my computer in PDF format. I got tired of not having my books at work when these questions come up. I keep a copy in the bus and my originals in my house. Here is the diagram of the fuel system in my book.  |