| Author |
Message |
Jack Tucci (Tuccitown)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 09, 2006 - 1:42 pm: | |
Well, I posted a couple of weeks ago about my fuel leak. I thought I had determined it was coming from the fuel pump but after replacing the fuel pump I still have the leak. After trying some of the other suggestions I think I have narrowed it down and am 99% sure that it is coming from an exhaust leak where the manifold connects to the exhaust system. Any ideas what might cause fuel to pass through the engine? I have setup a time for Seattle Truck repair to look at it. Any ideas if driving there will cause further issues? It's about a 3 mile drive.
Thanks for any help in advance.
Thanks,
Jack
H8H649-053 |
David Hartley (Drdave)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 09, 2006 - 3:04 pm: | |
Unburned fuel will collect* in the exhaust system if you have been idleing the engine too much. That is normal on Detroits that have sat around and not been driven hard enough to clear out the leftovers from running cold.( the airbox will load up too sometimes. )
*( Usually on ones with lots of wear! )
It also depends on how bad the apparent leak is. The question would be what color is the puddle or drip that makes you think its a fuel leak.
If it's charcoal black sooty looking its unburned fuel and oil residue dripping from the exhaust due to the reason I stated earlier.
If its clear liquid it's likely a fuel leak that you may be misidentifying the location of the leak. such as a secondary fuel bypass line that runs bwteen the cylinder heads. a line runs from the output of the pump to the secondary filter and back up to the end of one cylinder head. there is a second line that bridges that fuel supply to the other head.
If you look down in there and either head is wet around that area you may just have a pinhole leak in a line.
If you can't find the leak and it's definately black colored, simply let the bus warm up for about an hour and then go drive it hard for about 20 miles and let the smoke clear out. You probably will look like a fog machine until you get all the unburned fuel and oil residue out of the airbox and exhaust system. ( Loaded Up! )...
Note about engines that "Load Up" There are many factors why this happens. Wrong Oil, Too much idleing without getting up to temperature, Not enough driving, Leaky seals in the blower or turbo allowing oil to seep down into the airbox and into the engine to get diluted by fuel, Stuck injector(s) you can tell if you get bluish or white smoke a lot after the engine is up to operating temperature. and many more....
Hope that helps.... |
Chuck Lott (Chuckmc8)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 09, 2006 - 4:26 pm: | |
Jack, Your DD is designed to run in the 180-200 degree range to completely burn the fuel. As operator, your goal is to get the engine temp in that range asap after starting. Cooler temps won't allow complete combustion of the fuel, (causing other undesirable effects) thus making the goo that you describe.
Avoid cold idling as much as possible. Unless you have a way to block the radiator air flow (by shutters, a peice of card board or whatever) you will take a very long time to reach the temp idling (from cold start)Big Generator sets that use DD engines run about 30 seconds (or shorter) and are hit with full load. The longer it runs below temp without complete combustion, more goo dripping. (and shorter engine life)
It is best (IMHO)that as soon as you have safe air pressure (assuming you have done proper pre-checks) put her in the road and get er done!
Not suggesting that you abuse your engine, but one of sayings about Detroits that come to mind is "run it like you stole it". The DD's in marine applications often run at governed speeds for extended periods.
RPM Up and optimum temps make her happy.....cold temps and lugging the engine makes her sad...
No traffic, good straight road, 180 degrees on the temp and engine speed right on the governor. SWEEETTT
May or may not be your solution....I hope this helps! |
Jack Tucci (Tuccitown)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 09, 2006 - 5:33 pm: | |
Hi all,
Thanks for the replies, I think its a little more serous that a load up situation. Very good suggestions however I was not fully aware of the points maid. I normally am in the habit of when the ol'girl gets fired up she usauly gets worked. I find myself going to Tacoma just for coffee.
The fuel leaking is not black it is clean fuel therefore making me think that is was a line or cross over tube and/or fuel pump as I originally thought. This leak appears also when I pressurize the fuel system; it is more of a stream then when the engine is running and where the fan can blow it around. It makes me think it has to be a external leak but I am unable to find it with some very careful inspection of all lines and tubes. I had a friend look it over this weekend for a second opinion and he also thought it had to be coming from the manifold.
So instead of beating my head over it any longer I am planning to take it in and was concerned that if this was internal leak (injector or something) will the 3 mile drive cause problems?
Thanks again,
Jack
H8H649-053 |
Chuck Lott (Chuckmc8)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 09, 2006 - 5:51 pm: | |
Jack, have you determined if fuel is mixing with the engine oil? |
Jack Tucci (Tuccitown)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 09, 2006 - 5:54 pm: | |
I do not beleive it is, however I have not run the engine for any period of time in this condition.
Thanks again. |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 09, 2006 - 6:23 pm: | |
I once spoke with a mechanic at Stewart and Stevenson in San Leandro, CA - he told me about a quick and dirty trick that they use to test the oil for fuel before opting for the full-on oil analysis.
Simply pull the plug in the pan and let out a half pint of oil (you shouldn't have to fully remove the drain bolt for this). Then you drip one drop of oil into the center of a standard white piece of printer paper. If a wet ring around the oil drop immediately begins running away from the paper (absorbing into the sheet via surface tension) then you probably have fuel in the oil). Running an oil analysis would be good (and you would have already pulled the required quantity of oil for that test). Also if the oil is very black and grimy, it's gonna’ be time for an oil change anyway. If the main bearings in the block aren't damaged by fuel/oil mix, new connector pipes to the injectors are less than $150. Even if they aren't bad - if you pull the valve cover off the engine, I'd recommend replacing them. DD typically used copper lines for this, and they become brittle and crack after years of use.
I hope your problems are very limited. With the fuel lines pressurized have you held a piece of paper near the hoses to check for high-pressure mist spray (this isn't usually visible)?
Cheers!
-Tim |
Chuck Lott (Chuckmc8)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 09, 2006 - 7:54 pm: | |
Jack- I doubt that anyone here will tell you its OK to drive it in without being able to physically look at the problem.
Since you are only 3 miles from the repair shop, What I'd do is to go to the shop and ask the foreman which person would be doing the work on your bus. Then find the guy and tell him the situation and see what he says.It would be worth a tip to get him to come by on his lunch break and have a look before you take the bus in. |
Jack Tucci (Tuccitown)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 09, 2006 - 8:22 pm: | |
Understandable, I was really looking for a no don't do it or the engine will lock etc. I have talked to the foreman of the shop and unfortunately I am at work during the day and can't meet with him. He did discourage me at first to driving it but more for an environmental reason that anything else as it is leaking fuel on the ground. I did just change the oil just prior to this happening (same day) so there can't be to much fuel in the oil if that is the case. I think the 3 mile 2 3/4 of it being down hill shouldn’t be a problem. I think I am going to go ahead and drive it down tomorrow morning.
Thanks again for all the advice.
Jack |
mel 4104
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 09, 2006 - 9:26 pm: | |
Jack be sure and post the answer that you get when you find the trouble so that the rest of us came gain by what it was if you wold please. thank you . mel 4104 |
Jack Tucci (Tuccitown)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 10, 2006 - 12:32 pm: | |
Hi all - I drove the bus into the shop thids morning without issues and besides the James Bond smoke screen it ran very well. I will provide an update with the shops findings.
Thanks again,
Jack
H8H649-053 |