| Author |
Message |
Paul Tillmann (Paultillmann) (24.105.194.162)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 26, 2003 - 8:00 pm: | |
Got a question for all you experts out there. Brought my 1978 MCI MC-5C in for a tune-up at the local DD dealer and repair shop for a tune up six weeks ago. Here were the symptoms of the reason I brought it in:
1. Smoked alot (white and grey smoke) at start up and would "run away" on me once in a while.
2. Used about 1 gallon of oil per 50-75 miles.
Other than that it ran great when fully warmed up. Very smooth and powerful. Little or no smoke. Took the 3 mile long, 6% grade near my home at between 45 and 48 mph (third gear). As far as I was concerned it ran great except for the oil consuption and start up smoke. Before I bought the bus I brought it to another DD dealer much farther away and they said the engine was fine, all it needed was the oil leaks fixed and a good tune up. Oil analysis came back with "no corrective actions needed". So I saved my pennies this last winter and brought it in for the tune up some six weeks ago and stupidly told them there was no rush. Here's what they found and what they did.
1. Removed the blower to check it and it turned out to be a recently remanufactured unit and it was dry (no oil inside the blower).
2. Found one of the blower (air?) box drains clogged and when cleared, a lot of oil came out. It was determined that when the engine "ran away" on me that it was ruuning on it's own oil. Made sense to me.
3. Four injectors were bad.
So, DD replaced all the injectors; replaced all the injector connecting tubes; eight injector rocker arms (most of them were worn out); put the newer style injector actuators on it; replaced the linkages from the governor and put it all back together with all new gaskets; called me last Wednesday and told me it was ready to rock and roll (to the tune of $2486) and said it ran great. Picked it up last Friday at around 4PM; started it; seemed fine (no smoke); drove it home. Seemed like it was a little underpowered now and it smoked blue/grey under just about any acceleration, even after being fully warmed up. Hmmmm, it never did that before. It now does 32 mph up that 6% grade. I almost had to shift to second! Acually I have to constantly shift it, now, at every little incline. After running it for a while it seems that it is not running on all 8 cylinders. What could they have done wrong??? Or what new part they replaced is bad. Or could one of the Jakes be stuck open?? I'm clueless and I don't want to touch the engine till they look at it again for fear of being accused of screwing it up. Any input would be much appreciated so when I bring it back tomorrow, I have at least a little knowledge of what may be happening. On the plus side I've driven the bus about 100 miles since the "tune-up" and it hasn't used hardly any oil yet. |
Paul Tillmann (Paultillmann) (24.105.194.162)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 26, 2003 - 8:06 pm: | |
Just read over my post and realized I left out some important info.: the 5C has an 8V-71 with 4 spd. manual transmission. Sorry.
Paul |
Guy Bouchard (161.184.192.147)
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Votes: 0 (Vote!) | | Posted on Monday, May 26, 2003 - 8:28 pm: | |
Sounds as if they didn't balance the fuel control rods close enough. Start the engine cold, and let it warm at an idle. About a minute after starting, run your hand on each exhaust manifold and see if they warm equally. If one warms quicker than the other, your fuel rods should be readjusted(only half the cylinders pulling the load).This is a very basic check, but will give you an idea.
Guy 4905 |
Paul Tillmann (Paultillmann) (24.105.194.162)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 27, 2003 - 3:51 pm: | |
Guy,
You were real close. I used your method this morning to pinpoint which cylinder was not firing. When I brought it to DD I was able to tell them where I thought the problem was and, low and behold, they found a locknut on one of the injectors loose. They re-adjusted the injector and away I went 49 mph up that 6% grade. No more smoke either. Thanks a lot for your input, it helped me out a lot.
Paul |
Tom Caffrey (Pvcces) (64.114.233.50)
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Votes: 0 (Vote!) | | Posted on Tuesday, May 27, 2003 - 10:42 pm: | |
What do you guys think about the amount of power lost from one cylinder not working?
Tom Caffrey PD4106-2576
Suncatcher |
Paul Tillmann (Paultillmann) (24.105.194.162)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 28, 2003 - 8:43 am: | |
Actually I was quite amazed at the power loss from just one cylinder. I didn't ask the technician why but apparently the drag created by a non firing cylinder is quite a bit.
Paul |
jmaxwell (66.42.92.15)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 28, 2003 - 1:48 pm: | |
Guy: Good troubleshooting; can I interest u in being my chase driver? I have 1 injector (#5 on a 6v92)that is slow to pump up in real cold weather (about 30-45 seconds). Another owner found it for me using your method but I try to stay out of cold weather just to avoid changing out the injector. At least I know the problem now and can fix it if it gets worse. |
Guy Bouchard (161.184.176.245)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 28, 2003 - 9:11 pm: | |
jmaxwell;
Three possibilities come to mind on your problem.
1 #5 injector is set on the loose side on the rack
2 injector leaks (check for oil dilution)
3 compression down on #5 cyl
When you get down to checking out your problem, move injector # 5 to another location (interchange) and see if the problem changes cylinder. If it does, injector problem;if not, cyl problem. The time that you indicate is not that serious;probably lots of miles left.
Guy |