Community Forums

sirpurrcival · 03-11-2020, 01:15 PM

I am looking into purchasing a 2011 Tiffin Phaeton RV (40' Single Axle) with the above Cummins and relatively low mileage at about 27000 miles. The coach is beautiful and has clearly been well maintained. The owner says he has all the maintenance records and that service has been done at or before the regular intervals. For the moment I will take that at face value. Comes with an Allison 6 speed.

What are opinions of this motor? I am new to diesels in general and would like to avoid engine/tranny issues. Are there any real red flags to these motors? Things I should ask about? I know they are common as spit which I take to be a positive.

At bare minimum I would think an oil analysis is in order.

Any suggestions greatly appreciated.

Ljwt330 · 03-11-2020, 01:22 PM

My only caution would be that the engine is a 2011, but it may be as old as a 2009 and it would be good for you to check, not because of the age, but because of the DEF. Having a DEF system, per se, is not bad but most of the issues with these engines has to do with that emissions system. An engine built prior to 2010 MY will not have the DEF system. I wouldn't let it be a deal breaker, but be aware of the emissions issues with post 2010 engines.

That is a reliable engine and transmission combination and you should have no concerns in that department, aside from the emissions.

Fiesta48 · 03-12-2020, 10:03 AM

A 380hp, 1050 torque is a ISL9 8.9L.

Ljwt330 · 03-12-2020, 10:58 AM

Quote:

Originally Posted by Fiesta48

A 380hp, 1050 torque is a ISL9 8.9L.

Not necessarily.

The ISC has a horsepower range from 240-400, but the torque is maxed at 1075 ft/lbs.

The ISL, of course, falls within the same range for the motorhome in question. However, the Tiffin information for that year/model coach lists the 8.3 engine which is the ISC.

2011 Tiffin Motorhomes Phaeton 40 QBH Motorhome : Reviews, Prices and Specs : RV Guide

vito.a · 03-12-2020, 03:18 PM

The Cummins ISC 8.3L engine is great as long as you keep the gross weight reasonable.
The Cummins ISL 8.9L engine has a slightly longer stroke crankshaft and is better in higher gross weight coaches, especially when towing. It is rated up to 1250 ft lbs of torque.

Try to think torque ratings in these diesel engines instead of HP. The reason I say this is because some coach builders will use the small Cummins ISB (used in Dodge pickups) in large motor homes to save money. Some of these small engines are rated at 360hp, but the torque rating is low (can be as low as 610 ft lbs).

I agree that oil analysis on both the engine and transmission would be a good idea.

Make sure you check nationwide pricing on RVT.com and RVTrader.com. Include coaches both 1 year older and 1 year newer. Used coach pricing is all over the place.

Best of luck!

sirpurrcival · 03-12-2020, 06:02 PM

Some great advice, thanks everybody. I'm pretty sure that it is an ISC 8.3.

I would probably be towing some kind of light toad and I do live in mountainous regions (western Canada). Hopefully that won't be an issue. I would be happier with a somewhat bigger torque horsepower combination but Class A rigs are a bit short on the ground up here in Canada. Trailers/5th wheels and Class C's are all much more numerous than Class A's.

The GVWR for the coach is 36600 lbs but of course I can't find the CCC.

Thanks for the responses. If anyone else reads and comments I will be checking back.

Ray,IN · 03-14-2020, 02:41 PM

Quote:

Originally Posted by sirpurrcival

Some great advice, thanks everybody. I'm pretty sure that it is an ISC 8.3.

I would probably be towing some kind of light toad and I do live in mountainous regions (western Canada). Hopefully that won't be an issue. I would be happier with a somewhat bigger torque horsepower combination but Class A rigs are a bit short on the ground up here in Canada. Trailers/5th wheels and Class C's are all much more numerous than Class A's.

The GVWR for the coach is 36600 lbs but of course I can't find the CCC.

Thanks for the responses. If anyone else reads and comments I will be checking back.

Visit a local weigh scale and have your MH weighed, front axle and rear axle separately. The total of those subtracted from the GCWR is your CCC.
The axle weights may be used to determine minimum tire inflation; 60% of each axle weight is used to find minimum air pressure for both tires on that axle.
If your engine is an ISC or ISL it will have that identification on the camshaft cover on the front of the engine.

zproud · 03-14-2020, 07:52 PM

Some things to check
Coolant SCA levels, or was it changed to Elc coolant?
Age of air cleaner
Was the air dryer filter changed for the the air ride/air brake
Greasing of drive shaft ,slack adjusters, front suspension
Age of tires..

Best of luck!

vsheetz · 03-14-2020, 08:04 PM

We have 2011 Phaeton 40' with the ISC 380. Nearing 50k miles on it. Has been troublefree (knocking on wood). We tow a 5000lb jeep. Plus we travel heavy. We are often in the mountains of the west. Power is good enough.

It is a wet cylinder engine, subject to cavitation, so be sure the coolant chemistry has been maintained. If not already done, suggest to convert it to ELC type coolant.

Bill2 · 03-15-2020, 06:26 AM

If you have the serial number of the engine you can call Cummins and they will tell you exactly which engine it is I done that about a week ago to find out I have the 380 with an I SL wet sleeve engine. I checked it because I wanted to know what kind of coolant to put back in when I flush the radiator.