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Title says it all. I know todays engines are brokin at the factory so your just seating trans clutches and diff gears. What mileage do they recommend before you tow anything?

Thanks
Mike V
 

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No, even the big engines (Cat etc.) are normally run on a load cell when new, it isn't until their overhauled which often happens in place you have to worry about ring seal over much. You were correct that the primary concern is the diff and the trans, engine, brakes etc to a lesser extent.

If you talk to someone like Motive who actually makes them they will tell you to take it easy and alter speeds, preferably with heat cycling (stopping to allow a cool down) for the first miles. It's been a few years since I installed gears but I remember it being 50 to 75 miles more or less. Then just don't flog the bejesus out of it till 300 and you're done. Those instructions are for hardened gears that have been shot-peened and all that good stuff. Passenger cars typically come with softer gears that are more forgiving. The result of improper break in will be increased noise (gear whine) and weaker gears.

For me bottom line is going a few hundred miles isn't all that onerous, after that I'm not to awful worried about it.
 

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If the factory wants you to drive a certain way... thats part of the breakin process. I forgot that diesel engines are not broke in at the factory due to the longer process.

Mike V
I'm just quoting the instruction manual :)

"ENGINE BREAK-IN RECOMMENDATIONS
The diesel engine does not require a break-in period due
to its construction."

That is not to say there isn't a break in PROCESS. I find this explanation extremely lacking and would love to see more detail about this. I was just trying to provide you with the best available information.
 

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Discussion Starter · #7 ·
I'm just quoting the instruction manual :)

"ENGINE BREAK-IN RECOMMENDATIONS
The diesel engine does not require a break-in period due
to its construction."

That is not to say there isn't a break in PROCESS. I find this explanation extremely lacking and would love to see more detail about this. I was just trying to provide you with the best available information.
Thanks for clearing it up. I want to tow an empty 18 foot open trailer home from picking up the oil burner. I can easily drive it 300 miles before I tow the trailer. Some vehicles want at least 500 to a 1000.

Thanks, Mike
 

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I would imagine an empty trailer is nothing to worry about. This is no worse than putting a couple linemen in the back seat.
 

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I finally found this. From page 520 of the owners manual:

• Do not tow a trailer at all during the first 500 miles
(805 km) the new vehicle is driven. The engine, axle
or other parts could be damaged.
• Then, during the first 500 miles (805 km) that a
trailer is towed, do not drive over 50 mph (80 km/h)
and do not make starts at full throttle. This helps
the engine and other parts of the vehicle wear in at
the heavier loads.
 

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I finally found this. From page 520 of the owners manual:...
Maybe you should read page 7 & 8 from the Diesel Supplement. :D

The diesel engine does not require a break-in period due
to its construction. Normal operation is allowed, providing
the following recommendations are followed:
• Warm up the engine before placing it under load.
• Do not operate the engine at idle for prolonged periods.
• Use the appropriate transmission gear to prevent
engine lugging.
• Observe vehicle oil pressure and temperature indicators.
• Check the coolant and oil levels frequently.
• Vary throttle position at highway speeds when carrying
or towing significant weight.

NOTE: Light duty operation such as light trailer towing
or no load operation will extend the time before the
engine is at full efficiency. Reduced fuel economy and
power may be seen at this time.
 

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Maybe you should read page 7 & 8 from the Diesel Supplement. :D
I have. The diesel supplement is not contradicting the OM. Reaching "full efficiency" is further along than the first 500 miles. Note that the diesel supplement is addressing the engine. The OM is addressing engine, axles, and other components (such as transmission and transfer case).
 

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Guys you can search break in on ring and pinion and other gear types, cut and paste follows...

In order to make them run cooler and quieter, new gears are lapped at the factory. However, they are not lapped under the same pressures that driving creates. The loads generated while driving force any microscopic high spots on the gear teeth back into the surface of the metal. This is called "work hardening". Work hardening is similar to forging in the way that it compresses the metal molecules into a very compact and hard formation. This can only be accomplished if the metal surfaces are lubricated and the gear temperature stays cool enough that the molecular structure does not change. If the temperature of the metal gets hot enough to change the molecular structure, it will soften the surface instead of hardening it. The greatest damage to a new gear set results from running for ten minutes or more during the first 500 miles when the oil is very hot. Any heavy use or overloading while the oil is extremely hot will cause it to break down and allow irreversible damage to the ring & pinion.

Recommended procedure for breaking in new gears: After driving the first 15 to 20 miles, stop and let the differential cool before proceeding. Keep the vehicle at speeds below 60 mph for the first 100 miles. I also recommend putting at least 500 miles on the new gear set before heavy use or towing. During the first 45 miles of towing, it helps to go about 15 miles at a time before stopping to let the differential cool for 15 minutes before continuing. This is necessary because not all of the gear tooth is making contact until it is heavily loaded. When towing, the teeth flex to contact completely, and cause the previously unloaded portion of the teeth to touch and work harden. It is very easy to damage the ring & pinion by overloading before the teeth are broken-in.

...End cut and paste. While this tidbit applies to ring and pinions specifically much the same is true for most gear types. Overloading during the initial break in phase is not good for your gears, running extended break in periods does nothing. Once the gears have broke in they are broke in and no amount of directed break in procedures can change the gears from what you made them when they were actually in the break in period.
 

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Guys you can search break in on ring and pinion and other gear types, cut and paste follows...

In order to make them run cooler and quieter, new gears are lapped at the factory. However, they are not lapped under the same pressures that driving creates. The loads generated while driving force any microscopic high spots on the gear teeth back into the surface of the metal. This is called "work hardening". Work hardening is similar to forging in the way that it compresses the metal molecules into a very compact and hard formation. This can only be accomplished if the metal surfaces are lubricated and the gear temperature stays cool enough that the molecular structure does not change. If the temperature of the metal gets hot enough to change the molecular structure, it will soften the surface instead of hardening it. The greatest damage to a new gear set results from running for ten minutes or more during the first 500 miles when the oil is very hot. Any heavy use or overloading while the oil is extremely hot will cause it to break down and allow irreversible damage to the ring & pinion.

Recommended procedure for breaking in new gears: After driving the first 15 to 20 miles, stop and let the differential cool before proceeding. Keep the vehicle at speeds below 60 mph for the first 100 miles. I also recommend putting at least 500 miles on the new gear set before heavy use or towing. During the first 45 miles of towing, it helps to go about 15 miles at a time before stopping to let the differential cool for 15 minutes before continuing. This is necessary because not all of the gear tooth is making contact until it is heavily loaded. When towing, the teeth flex to contact completely, and cause the previously unloaded portion of the teeth to touch and work harden. It is very easy to damage the ring & pinion by overloading before the teeth are broken-in.

...End cut and paste. While this tidbit applies to ring and pinions specifically much the same is true for most gear types. Overloading during the initial break in phase is not good for your gears, running extended break in periods does nothing. Once the gears have broke in they are broke in and no amount of directed break in procedures can change the gears from what you made them when they were actually in the break in period.
My mechanical know how does not approach this level. We purchased a 6100 lb trailer prior to taking delivery of the EcoDiesel. It's sitting at the RV dealership 90 miles away via southern California freeways. I will have over 500 miles on the Jeep before driving up to bring it home late next week. I've been varying speed and letting the Jeep idle for a few moments after stopping. It would be difficult to pull over every 15 miles or so for the first segment of the trip back. Would appreciate advice, including the real risk to the long term health of the Jeep by traveling that 90 miles at about 55mph. Thank you.
 

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My mechanical know how does not approach this level. We purchased a 6100 lb trailer prior to taking delivery of the EcoDiesel. It's sitting at the RV dealership 90 miles away via southern California freeways. I will have over 500 miles on the Jeep before driving up to bring it home late next week. I've been varying speed and letting the Jeep idle for a few moments after stopping. It would be difficult to pull over every 15 miles or so for the first segment of the trip back. Would appreciate advice, including the real risk to the long term health of the Jeep by traveling that 90 miles at about 55mph. Thank you.
I'm an engineer but not the smart guys, think trains and boats, in my case boats. I have a lot of experience but its down in the dirt seeing the results of your actions (or lack thereof) experience. Break in is not something that you can get back with anything. Once you have failed to load a hard liner motor (many commercial diesels) failing to attain proper ring seal you cannot load it up after words and fix it. You have made an oil burner and must live with the results. Similarly if you over heat your gears you will at the least make yourself a whiner, how loud depends on how much damage you do. The gears will be weaker, how much weaker can only be proven out by breaking them.

I'm not saying this to scare you I'm telling you what the worst cases might be, the worst would be catastrophic failure. If you lunch your gears they will often take out the case, axle(s) etc. on the way. If you're towing some of those parts my end up hitting your tow. They may end up hitting some cars behind you. You could lose control of the vehicle. The fix is going to be expensive and I have no guess as to whether Jeep would pick up the tab considering the rather vague instructions in the manuals. This is worst case, I don't actually believe you will face any of that though.

Most likely as millions of other owners in many vehicles types over the years you will hook up and tow your trailer home just fine with 500 miles already on the clock. This is well past the critical early miles where towing would be much more likely to cause real damage. Again this is only what my experience tells me, I am no expert.

I will say what I would do. It's a good idea to stop after 15 minutes or so with a new trailer anyways to check the bearings (on the trailer) for overheating and other tidbits. I would have a look see inside and make sure you didn't have any free range objects inside the trailer doing their best imitation of a wrecking ball as you drive while you're at it. Thats your first stop. I would not skip it even without the break in questions. Then I would make all of the rest of the stops as directed. Your tow is going to be more load than the entire vehicle itself has been providing. You are not in a full size truck weighing 7500 lbs contemplating towing a bass boat that weighs 2500 all in trailer/motor/boat and your gears are going to face significantly more loading than they have previously. What I did with my last truck when dealing with the same problem was to look up the dealership on google street view and map out a short route leaving the lot where I was picking up the tow to an on ramp further down the road and picked my spots where I could easily pull over. It was painless outside of adding the extra hour and change for the stops. Then I just stayed in the slow lane where traffic was already going 50ish anyways. In my case I was going from Oregon to up north of Seattle and completed the entire recommended break in with that one tow. Were I in your shoes I would just take it easy, on your next outing using the same slow lane stratedgy till I had a few hundred on the clock towing, take it easy for a few hundred more miles but not worry about keeping the speed in the 50ish range and not worry about it after. But thats me.

Others may disagree or have other advice but this is what I did myself with my own money on the line.
 

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We don't tow anywhere near what people do elsewhere with these. I think you guys should look at the Aussie threads.... They pick up their new diesels, grab the Caravan and take off for weeks in the mountains. Go somewhere overseas where they really tow a lot, they don't drive around in Circles for 500km waiting to use their diesels (BMW has specific break in instructions for the Gas engine but not the diesel).

I have never broken in any of the diesels that I have purchased in the last decade Duramax, Mercedes or otherwise and I have towed pretty well the Max weight with most of them. I have also Spec many fleet vehicles including sprinters etc for businesses and none of these guys have ever waited to load them up and use them.

I agree that putting 200-300 miles on before towing a load and not beating the nuts out of it is probably very good advice. I also wish to note that most of the vehicles I noted above never had a major failure such as loosing a rear end or tranny or any any major engine work (not even injectors). The most problematic diesels I have ever seen where ones that were not worked a little (sat too much). Also when I say most I mean I didn't keep track of all of them but the ones I did, they all had 200,000 miles plus without major concern.

Once my JGC had 300 Miles on it, I towed a 7100 pound trailer because that is what it does. I have a 5 year 100k warranty which I usually get but I am concerned about the air suspension and touch screen 5 years from now, not the drive train. If I get gear noise or some other problem they won't question fixing it, it would be warranty, but like I said I don't get those issues.
 

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I have never broken in any of the diesels that I have purchased in the last decade Duramax, Mercedes or otherwise and I have towed pretty well the Max weight with most of them. I have also Spec many fleet vehicles including sprinters etc for businesses and none of these guys have ever waited to load them up and use them.
This always reminds me of a smoker saying that his uncle lived to be 100 so he isn't worried about smoking. Math doesn't lie however and smoking really does take years off your life on average.

I'm actually self employed but have worked for the same owner for most of my life. He is Cats second largest customer by dollar spent. We have extensive data on hundreds of engines that have been run their entire life cycle many times over. In other words they have been in-framed (overhauled, on boats they rebuild the engines in place and this is called in-frame) in some cases more than a dozen times per engine. We also have extensive data on hundreds of various gear boxes used for reduction, drive, etc. Pumps, same thing except these would run in the thousands. Compressors for air, refrigeration, again logged. There is absolutely no question that proper break in of gears will lead to longer life. There is no question they will be less likely to fail. There is no question that properly broken in equipment will have lower service costs over the life of the equipment. When I say no question I mean that each one of these pieces of equipment has their operation thoroughly logged including their break in procedure and the data has been collated across millions of hours of operation when considering all the equipment.

I'm too old to be smart and my experience seems to have mostly served to show me how little I know. That said in my mind break in is worth doing especially in light of how easy it is to simply not flog something for a brief period.

One last thing folks need to keep in mind is that diesels aint what they used to be. My main engines were designed in the late 60s. The actual engines were built in the late 70s. The lid to the oil filter housing is 5/8 steel. It weighs probably 75 lbs. It will stilll be here after a nuclear war and assuming you could find such an engine be installed on top of the filter housing and work just fine. Buy an engine with similar hp now and you will have an array of spin ons just like the filters in most cars. Cept a wee bit bigger. :)

Where I'm going is that not just diesels but all engines used to be designed in a pre computer modeling world to be not strong enough but with some extra meat just to be sure. Nowadays every ounce is accounted for and eliminated if Mr Smarty Pants computer says so and it shows. Our newest engines are also our least reliable. The term we use is high strung. Many of them are lucky to make a few thousand hours up compared to older engines which usually have maintenance scheduled by 10s of thousands of hours. It isn't just that but they are far more complex and more things to go wrong almost invariably mean more things will go wrong. And last we are pushing them harder. The power you have in your GC is similar to what you could get from a Cummins in a 3/4 ton not all that long ago but that engine was significantly larger, less complex, and tasked with producing less power per cube. Less high strung.

My guess would be that as we go forward diesel engines in cars are going to see this same trend, they wont be lasting as long.
 

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Crabman,

I do not in any way disagree with your logic on the large engines and I did not really touch on that at all. I have some experience with the MaxForce, Mercedes Business, CAT, Cummins and Isuzu engines. Certainly when the diameter of the main gear in the rear end is more than 3 times the size of our entire diff, I can see where the break in will take longer and there are certainly procedures in the big stuff that is important. You are also comparing units that have a standard expectation of half million miles as a low average in operating expectancy. I would love to see everyone average 500,000 miles in their Jeeps as a low average as well but I am not sure that the standard use of towing will allow the rest of the vehicle to hold up to the same expectation as the drive line.

Again, a lot of respect for when you are saying, I am not a mechanic or an engineer. Also the first time I tow below 1000 miles I am very good about it... lower speeds, easier acceleration careful braking and I try to avoid the bad stop and go stuff for the first little bit. I maybe didn't put that very well but when I say not to beat the nuts off of it I mean respect the machinery.

I am not sure I like the smoker comment though as that indicates long term abuse of the system and sure that adds to component failure absolutely. I am of the complete opposite thinking and that is that I will always maintain my truck the best I can. Long term wear in the small diesel towing world is more often associated to abusing the equipment and or very often poorly setup trailer systems that are not braking properly and or distributing the loads. The common early failures I see is braking components and suspension, again from improper long term use.

Most of my experience is in the small diesels that we are talking about here. I work mainly for car dealers and many of them, so I get to spend lots of time in shops seeing all the vehicles being repaired. Most of my comments were about the 3 liter diesels of Europe and my experiences with them not the large trucks you speak of.

I guess the point of my post is that I do believe that you are correct in your position especially as it relates to big trucks. You are correct as well that in the big rig world certainly there have been a lot more problems over the more recent years. With the exception of the introduction of Urea systems though, the small diesels in the Passenger vehicles have been outlasting their predecessors by a long shot. There were some initial issues with the AdBlue stuff in 2009/2010 but not anything to do with the engine or transmission etc.

The small diesels have been a different animal for a while and back to the smoker comment as my data and experience with these smaller blocks is more global (using places like Sweden, my wife's families' home where half of all passenger vehicles are fitted for trailering) there are not millions of these vehicles dieing of cancer globally because they were not broken in specially. In Fact, the only thing that you often see in the passenger vehicle Diesel towing notes (which I didn't see in the Grand Manual) is that the brakes needs about a 300mile/500km break in. Which is also why I wait for this point before towing.
 

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lol I didn't actually mean it that way. My point was people will often look at a small group and then extrapolate that subset as a expectation of performance or result in a larger group. In other words the number of people I know with diesel trucks/cars etc and my own ownership experience is not really that large and I cant apply my experience with that subset to the greater whole and know its going to hold up. It might, but it might not. The smoking comment was a poor example but one people are commonly familiar with. At any rate I hadn't had the intent you speak of and I apologize for that.

Also a misunderstanding is that my latter comment simply refer to diesel engines as a whole, trailering or not. Many people here seem to expect that this engine will go well up into the 100s of thousands of miles relatively reliably. But this seems to be based on their experience with older engines which were less stressed, more overbuilt, and far less complex. I would personally be surprised to see these engines attain the same long term reliability as those engines as a group. We do have modern engines (high pressure, pulsed injection, etc) used for house power (keeps the lights on when the boat is stood down at the dock) going all the way down to 4.4 liters and their reliability and up time is a sad fraction of those they replaced.

In the end I hope you are right because I'm buying in, my wallet has cast its vote. I would still make those stops on the tow if I was doing the driving just as directed. It isn't that hard to make a few stops and then just take it easy from there for one tow. Plus a panda cries every time a mechanical bit isn't given the proper love and care. :)
 

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Yes, I didn't think you meant that but I did want to make sure you knew my sample group was pretty large.

I am super pleased they went solenoid injection for much of the "complex" system issues you speak of. Hopefully the issues we encounter will be external of the core components and simple to correct. If anything it will be like my Mercedes and the biggest concern might be a turbo air flow sensor 4 years down the road ;)
 

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I am an engineer, and so is my father who is a strength of materials expert. But I am not giving opinion based on education, experience, or knowledge. The owners manual says in big bold letters "Caution! Do not tow a vehicle at all in the first 500 miles."
 
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