ecupstid
Louisisana
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Joined: 10/21/2008
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I am looking at a 1995 38' Monaco Dynasty with the C8.3 300hp mechanical engine. The MH has 66000 miles on it and was purchased new by the owner. It has always been stored and appears to have been well taken care of and serviced. The owner has not used the MH during the last two years, but says he has cranked it monthly during that time. I have owned two other motorhomes with the newer electronic diesel engines, but have no experience or knowledge regarding mechanical engines. What are the pros and cons of purchasing a MH with the mechanical diesel engine. And would also like to know what the torque rating is for this engine. Thanks
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Fishinghat
Western Washington, USA
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Joined: 10/03/2002
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With that much mileage, the engine was well broken in and it is unlikely suffered any damage.
The mechanical 8.3 Cummins engines are very reliable and get better fuel economy then the electronic versions. You should get at least 8 or 9 mpg, and could get 10 or 11, depending on the usual factors. The 6CTS8.3-BUS(300)engine produces 820 lbs of torque.
Holiday Rambler Navigator DP, Hummer, and Honda VT1100C Shadow
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robatthelake
Vancouver Island
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Joined: 08/24/2003
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Love Mine! Have been told that they are the most reliable engine ever built by Cummins! Of Course that was what, I wanted to be told!
Mine has less Mileage than Your's I'm told that by 50~60 Thousand the Valves may need to be adjusted and the Anti Freeze should be changed!
Rob & Jean
Dutch Star Diesel Pusher ..Tracker 4X2
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Innkeeper
Washburn, Wisconsin
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Joined: 01/14/2008
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We have the 8.3, absolutely love it and it is as Fishinghat described.
1995 Beaver Patriot Trenton
300 HP Cummins
6 speed Allison
Beaver Ambassadors Club
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ccxnola
Wherever the rig is - I'm there too!!
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Joined: 07/02/2003
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I have the c8.3 too - and on our recent 11,000 miles Alaska adventure over 10 weeks, up hills and down, (not towing) we averaged 10.2 MPG!! Better than any gasser I have ever owned!! I am told this engine with the Allison MD3060 transmission like on our rig is just about the best ever you can get - including later computer controlled models.
1997 Rexhall Rolls Air - mid-entry DP w/cummins c8.3
Look for the Mardi Gras 'Gators
Laissez le bon temps roulez - Let the good times roll !!
Click to see the Best View of our rig - That's ME, Going Away!!
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SCOMP225
Brownsburg,Indiana
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Joined: 12/08/2002
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My Old 92 Eagle has 115K miles and is as strong as the day I bought it with 47k miles. I think servicing it is the key to longevity and running it on a regular basis.
Chuck
1992 American Eagle
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Don in Niagara
Niagara Falls, Ontario, Canada
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Joined: 01/14/2004
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Not a problem engine. Just goes and goes! Change the oil and filter every 5k miles.
Don
1990 Barth Regency 34'
Spartan/Cummins 8.3
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chastho
arkansas
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Joined: 07/27/2005
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The last 8.3 I owned had 155k miles on it when I sold it. When I changed the oil in it the oil would stay clear for about the first 1000 mile before it started getting dark. Never had a problem with it.
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dieseldave56
central oregon
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Joined: 08/25/2007
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I also have the C8.3 12 valve mechanical. I would describe it as the '327 small block Chevy' of the diesel world. With no ECM to control the engine , hp uprates are easy bolt-on and adjustments.
To get an accurate spec on your particular engine you need the CPL# ( the tag label is on top of the timing cover , right hand side of the engine as you face the engine from the rear access door).
The Cummins C8.3 mechanical was last produced in 1997 but inventory engines were installed till mid-1998. The 325 hp version was also available as well with the major differences being the cam and fuel injectors. The 300hp version has a max torque of 940ft#s ( if I recall the oEM spec correctly).
The Bosch 7100 fuel pump gives a lot of versatility to producing increased horse power . Factory hp rating is far from maximum usable hp that can be attained. (1)The Holset HX40 turbo can provide increased boost by adjusting the wastegate actuator ( which most shops overlook or are not familiar with). (2) The fuel cam plate can be adjusted and /or replaced to provide the extra fuel to match the increased boost. (3) The AFC is also adjustable to help give an extra "shot" of fuel needed for initial acceleration 'off-the- line'.
(4)The Cat/muffler can be R&R with a muffler that has less backpressure and weight ( OEM CAT/muffler weighs 75lbs vs newer freeflow muffler at 8 lbs) Also the OEM exhaust pipes are 4' dia and can be repalced with 5" dia. with NO increase in decibels.
If you do any fuel /boost modifications it is a MUST that a pyrometer gauge be installed ( either pre or post turbo location)to monitor the EGT ( exhaust gas temperature). Also a boost gauge is convenient to help diagnois any problems and drivability.
The Cummins C series service manual is available.
My C8.3 engine #45484615 CPL#2102 puts out 370hp/ 1150ft#s. My 40' American Tradition TVS has a GVWR of 31,000 , 125 gallon fuel tank, plus we tow a 2500# Saturn SL2. Our MPG average is 9.2
Here's a Banks PDF link that will provide some illustrations and more detailed description of what I've been rambling about. PS I do not endorse the use of the Banks Stinker ( Stinger) for the DIY as 99% don't have knowledge or equipment to properly adjust the 7100 Bosch fuel pump which is crtical to keep the EGT under the maximum of 1350 degrees ( pre turbo).
http://assets.bankspower.com/manuals/45/96381.pdf
The Allison MD 3060 is a great tranny. You'll need to know if the oil pan depth is 4" or 6" to get the proper filters . Also swap the AFT for synthetic oil ( Allsion uses Castrol TranSynd ATF in later years) I use Red Line High Temp Synthetic ATF ( I like Red Line products in general  )
Also I recommend upgrading all the filters; Fleetguard LF9009 lube filter, Fleetguard radiator coolant filter WF 2077 with Fleetguard's premixed Compleat or Extended service Compleat ( both have the DCA4 that is needed to reduce cavitation and are a 50/50 mix to keep the SCA level )
Fuel filters: Fleetguard primary FF 5052 and either Fleetguard FS 1000 or newer FS1015B (with sight bowl) water separator filter.
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ecupstid
Louisisana
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Joined: 10/21/2008
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Thanks to Dieseldave56 and others for the replies and information...I am scheduled to take another look at the MH on Monday and take it out for a test drive. When the owner cranked it up yesterday the oil pressure was very high as it should be, but the owner tells me once it warms up the oil pressure drops down to the 8 to 10 range....this sounds TOO low to me, is this something I should be concerned about or is this normal for the C8.3 mechanical engine?
The MH has a 8kw Onan diesel generator with only 31 hours on it. The owner says they just never had a reason to use the generator. We always used the generator in our two previous MH quite a lot and would plan on using this one, should I be concerned about the low hours on the 15 year old generator, it cranks up and seems to run ok. Thanks
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