| Author | Message | ||
| visitor Rating: N/A |
Hello could somebody tell me if these pressures seem normal? (6v92) : At idle ~ 18lbs (not high idle) At higher 'cruising' RPM ~ 39lbs Just looking at a particular bus... seems to run well enough. Only a little white smoke @ start-up and a little bluish gray when pulling a hill. This happens to be a mc9 I am thinking about buying. I noticed that when test driving, it seemed to be very sluggish - seemed to be lacking power. My Gillig skooly (w/ 3208 turbo and Allison auto) would smoke this thing off the line - and probably on the freeway as well! (it will do over 70 mph w/ no problem) I did not drive the mc9 on the highway(freeway) just around town. I was told that possibly the reason it felt sluggish to me was because of the design ... it was meant for passenger comfort. No quick take offs (jackrabbit starts)! Anybody have any thoughts on my obvservations? I am quite possibly going to purchase this bus. Just concerned about the above mentioned things! Thanks again for all your good answers, advice, criticizm, encouragement, recources, discouragement, humor, concerns, and most of all: motivation! Mark (aka s'Coolbus nut) mc9 wannabe! | ||
| T. (Bluegrass)
Rating: N/A |
Mark I would have someone check out the engine that knows something about a Detroit Deisel, It would be money well spent to do so. Tony | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
Standard Running Oil pressure from Da Book is ~50-60 psi. If she's burning blue while you're underway (and the temp-gauge says it's in the 150+ degree range) then you probably have bad blower seals or turbo seals (if equiped) on the intake or the piston rings are finnished. Has the bus been sitting long? When I bought my 84' gillig with a 6v92, it had been sitting for about 10 months without being run - and a little moisture got into the cylinders and created a fine rust ring where the rings met the cylinder walls. The first time you fire up an engine with this problem and you can kiss your compression and your rings good-bye! This may explain the symptoms you experienced with the MCI (i.e. it may need a re-build) Cheers! -Tim | ||
| Dale Waller (Happycampersrus)
Rating: N/A |
Take the bus to a REPUTABLE garage that has seen Detroits before. It is worth a small investment to get someone to check the bus over good before you hand over your money to the seller. With that said, Tim is 100% right. The sluggishness can be a worn out powerplant. The blue or bluish smoke could be worn rings or valve guides or both. The oil pressures you gave are little low for that engine. But on the other hand she may just need to have the rack adjusted and change the wrong oil out. The wrong oil will cause smoke and leaks. So unless it is a GREAT selling price I would have the ole bus checked out. | ||
| David Hartley (Drdave)
Rating: N/A |
Wow Guys... Why not just tell him to walk away.? My MC9 is not a drag racer. If you compare a schoolie performance to a normally equipped MC9 which weighs more and has a different gear ratio it will seem sluggish. Geeezzz.. They are not powered nor geared for stop-n-go driving the are setup for cruising at a respectable speed. Sure it takes a while to get there but stuff won't break off the driveline for having too much horsepower. Detroits ( 6V92T ) in the coach version mostly were de-tuned to 277 hp. To get the 350 you have to change the injectors and timing, Makes it go faster and have more torque. A 6V92TA will run from 10 to 60 lbs of oil pressure, Mine rides at 25-35 psi on the road and is just fine. It doesn't smoke,leak or drip so far and cruises nicely on the highway. The guy said he didn't drive it down the road so it probably never got warmed up properly and of course if it has been idled a lot it is probably a little loaded up. And, "Visitor" Just who are you and why are you hiding under an alias? Fess Up guy.. Register and use your name please! Makes people want to help you more too!  | ||
| Mark R. Obtinario (Cowlitzcoach)
Rating: N/A |
I have owned a MC-7 with an 8V-71 and a Thomas 40' with a 3208T. Both had Allisons. The Thomas was geared for highway use and had a top speed in excess of 80 MPH. The -7 topped out at 75 MPH. On the flat the Thomas would leave the -7 in the dust but any hill and the -7 would catch up. Even though the Cat had a turbo, the gears were so long legged that she was really pokey on the hills. If the Thomas had had the same rear gears as the -7 I don't think the -7 would have been able to keep the Thomas in sight. Around town, the Thomas would take off about the same as the -7. Neither could be described as jack rabbits. When I purchased the -7 it hadn't been run in some time. After about 5k miles it used less oil, used less fuel, and smoked a whole lot less. In fact, it smoked a whole lot less than the Thomas, particularly on start up. So while neither of my buses are identitcal to your buses they are similar. My advise is if the price is right, all things being equal it doesn't sound as if the -9 is a bad choice. But before I purchased it I would definitely take it out on the highway and up a good grade to warm it up and see what she will really do. Out on the highway, particularly on a good hill, a -9 with a 6V-92T should pass a 3208 without any problems. Good luck. Mark O. | ||
| H3-40 Rating: N/A |
Dave is that 25-35 psi in a hole or out? Just kidding but you did have a nice one until you moved! Ace | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
Sorry, now that I'm home I can give you the direct quote from the book (Detroit Diesel pub. 6SE266). If you end up getting the MCI, go out and get the "Field Service Data Book - 6SE266" it has invaluable information about your engine. These are the most useful tidbits in Da Book: "1.6 - Oil Consumption: (all units in "quarts per 10 hours of run-time") 6V-92 (Naturally Aspirated) 0.45 @ 1200 RPM 0.60 @ 1400 RPM 0.85 @ 1600 RPM 1.15 @ 1800 RPM 1.40 @ 2000 RPM 1.60 @ 2200 RPM 1.80 @ 2400 RPM 2.10 @ 2600 RPM 6V-92T 0.90 @ 1200 RPM 1.15 @ 1400 RPM 1.40 @ 1600 RPM 1.55 @ 1800 RPM 1.80 @ 2000 RPM 2.05 @ 2200 RPM 2.25 @ 2400 RPM 2.50 @ 2600 RPM..." "3.1 - Engine Pressure (@600RPM): V-92 (Naturally Aspirated) 500psi Minumum, 550 New parts V-92TA w/17:1 ratio 450 Minimum, 500 New parts V-92TA w/15:1 ratio 375 Minumum, 425 New parts..." "3.4.5 - Series 92 Oil Pressure (two variants listed): 6,8V-T, TA Automotive Full Load - 45-65psi Idle - 5psi OR 6,8V-TA Automotive 6V-TTA Automotive Full Load - 50-70psi Idle - 5psi..." As you will probably not see "full load" with an empty rig, I wouldn't be surprised if your pressure was a little lower than what Detroit lists. Although the more I thought about your "idle" pressure, I think your guage may be a bit out of whack... Use an independant guage (like what they use on a manafold) right at the engine. Cheers! -Tim | ||
| Leslie Robinson (Lesrmc9)
Rating: N/A |
for $30 get an oil sample analized ask the owner how many miles from last oil change and what type of oil 40 wt cf-2 or multi-grade [if multi-grade thats why blue smoke] if the engine sat for a long time the oil sample will show fuel dilution as abnormal this will OK as when it is used and warmed up the dilution will not happen! if you buy the unit get oil changed immediatly to 40wt! | ||
| John MC9 Rating: N/A |
The oil pressure is the least of it. Take it to a bus garage, and have it inspected from bumper to bumper. This is a piece of heavy equipment you're buying; any mistake can cost you heavy $$$$$$$$. The "blue smoke" bothers me more than any other color smoke. "Blue", indicates oil. There should be no oil in the exhaust. White, indicates water, and easily remedied. Black indicates fuel, and easily remedied. Other problems, such as rust, or stress cracks around the frame, can be very costly! Take the thing to a bus garage for a complete inspection. If the owner says no? Walk... run, or do whatever, but leave with your bank account intact | ||
| john david lebrun (Davidlebrun)
Rating: N/A |
Good advice, take it to a good shop, unless you know what your looking at, alot of things can be wore out and cost to fix. David 4106 | ||
| Sojourner (Jjimage)
Rating: N/A |
I agree with Dave's post & few others. Visitor quote “I did not drive the mc9 on the highway (freeway) just around town” No-way you can determine engine condition without full temperature range (not under 180º F- 190º F not over). Always little blue smoke while engine is not up in normal operating temperature. Usually incomplete burn fuel at no load with barely warm engine. Turbo equips is less so. Visitor….from what you said mean you need on site inspection before anything answer to you is reasonable to trust. Hope everything is reasonable good condition. By the way, warm (200º - 240º F oil temp) oil pressure is normal at 5 or more psi (mechanical gauge on engine) at idle. To very few others….Suggest not confuse this person with “problem” until have it check with knowledgeable Detroit Diesel mechanic. NO-WAY you can tell the condition about everything unless you are there in person. Too many variables. Too expensive to guest if it needed or not. All the years I work as diagnostician & mechanic (late 40’s to 70’s) on automotive & truck or anything that have piston in it, I NEVER tell them real problem UNTIL they bring to me or go there. Warning to save allot of trouble from unknown, do what most above posts already suggested……..get a knowledgeable MCI & DD mechanic to drive it with you in it to explain what is normal & what is not as well full inspection for condition BEFORE you say yes or no. FWIW Sojourn for Christ, Jerry | ||
| visitor Rating: N/A |
Good advice, fellas I want to be confident with my purchase! Anybody out there able to reccomend / suggest a shop or mechanic in Portland, OR ? The bus is not in my posession, so I will probably have to opt for an on site dude Thanks Mark | ||
| Steve (Steve)
Rating: N/A |
Looking at the engine from the rear remove the right hand valve cover then remove the rack delay valve. this valve stops the rack from moving to full fuel untill the turbo and blower build up the presure before it can move the rack to full fuel. I removed my valve before Detroit tuned it and WOW what a take off from the stop lights. Back in the old days the truckers would remove this stupid valve. be carefull you will start to lose drive tires faster. also you will get a little more black smoke at take off. I like that when I pull away from the toll booth ha ha smoke em!~ oil presure 25- 75 psi hot, water temp 190 , 15 degrees advanced with B90 injectors, 740, 6V92, 3:35 rear, 24" tall rubber, 85 mph @ 6 mpg. | ||
| Bob Damm Rating: N/A |
If this bus has the 5 speed auto in it, it will start out in second gear. It will not jump off the line! You may even need to select 1st gear when stopped on a hill to get it moving. Bob |