New vehicle/towing question

[viv savage]

In a brand new 100 series (less than 100 miles), how many miles should I wait (if any) to tow a boat/trailer combo that weighs 2500 lbs or less? I know what the manual says - and I know what my toyota mechanic says.

Will it really harm the vehicle to tow that much weight right away?

 

[mobi-arc]

Do you really want to run the risk that they're wrong? Could be expensive.

 

[Campfire]

As a former mechanic, I never saw a failure in a new vehicle due to "normal use". Land Cruisers are rated to tow 6000 pounds with the right hitch. But we don't know your whole story. Is this on flat ground to the lake? Or up the Rockies over a 10,000 foot pass to a fishing spot? Are you talking about conservative driving or running that V-8 at a constant 4300 RPM?
And how long does a Indy Car crew leader wait until he lets the driver "open it up"?
You have to be the judge of what your comfortable with. And if you knew how the lot boy, mechanic, salesman, detail guy, and truck driver drove it before you got it, I think 2500 pounds to the lake won't do it too bad.

 

[Tinkerer]

Another factor in deciding:

How do you drive?

If you drive like me, you can tow your 2500lb with new 100, still breaking in engine, with no problem.

If you drive like most people, you might want to wait a few thousand miles before towing.

(I wonder if $6+ per gallon gas would, finally, cause most Americans to practice economical driving habits? In the earlier "fuel crises" of the late seventies, some folks learned. But apparently that collective knowledge disappeared again...or maybe 2-income families don't mind wasting money...dunno...)

 

[viv savage]

I will be towing from Tampa to Key Largo. Mostly flat Terrain and mostly Interstate driving.

 

[NMuzj100]

I doubt it'll do any damage and wouldn't be suprised if the warnings are just a relic of a time when engine break-in was much more important than it is now. It was probably in the "owners manual template" passed down through the years and just hasn't gotten removed because no one in the technical writing section knows whether it's needed or not.

Should be easy to get a couple hundred miles in at least before the big tow. Ride in style at 55 and I can't see any problems.

Can anyone explain how loading the engine in the first 2k miles could do damage that would not occur after 2k?

 

[Tinkerer]

<snip> Can anyone explain how loading the engine in the first 2k miles could do damage that would not occur after 2k?

IMO:

During break-in, rings are seating to the still-"rough" hone (crosshatch) pattern on the cylinder wall. The seating process involves greater wear of rings & cylinder wall, with significant metal particles produced, compared to "normal" (already seated) operation.

If engine rpm/loading is lighter, rings will seat more slowly, with reduced total seating wear and better final result. Also, wear-generated metal particles are generated more slowly, with more oil flow per particle rate, so particles are better flushed away from the site, to minimize scoring and other negative effects from the particles.

If engine rpm/loading is greater during break-in, rings will be seated more aggressively, with higher loadings and greater particle generation rates. Final seating wear amount may be greater, with associated additional negative effects from greater concentrations of metal particles under higher relative speeds & loads (pressures) between the rings and the cylinder wall.

How long to allow for break-in? Good question. I do think it is true that a good engine from a mfg like Toyota is probably more tolerant of shortened break-in period than lesser engines. In any case, I'd advise folks to refer to the owners manual.

(Personally, I still drive mine like it is still in break-in, at 96k. Maybe even more gently than that. Due to a visceral understanding of things happening inside the drivetrain vs. load, I guess. )

 

[NMuzj100]

Thanks, that makes some sense. But why vary the speeds or would X hours of idle be the ideal break-in?

 

[Tinkerer]

Thanks, that makes some sense. But why vary the speeds or would X hours of idle be the ideal break-in?

Simply idling for X hours is probably not a good break-in approach because:

- It might take MANY more hours of idling (vs. wear-equivalent driving time), burning MANY tanks of gas, to achieve break-in wear equal to a couple k miles driving. Not feasible, and wasteful.

- Believe it or not, the piston/rings do not sweep as far upward at TDC, when idling, as they do at higher rpm. It's a very small difference, but nonetheless, there is a tiny unswept part of the cylinder wall during idling, that is swept at higher rpms. (I don't have the exact figure, and it varies by engine anyway.) So, you do want to run the engine at normal rpms, more or less, during break-in, to sweep the entire cylinder that will be swept during normal operation.

(This same idea also applies with other moving parts in the engine.)

- Oil pressure/flowrate are higher at higher rpms, pumping at nominal design ranges: A good thing.

- All other parameters at nominal design ranges at higher rpms, including air/fuel mix, temperatures, etc etc etc.

***********

All the break-in opinions aside, what are the likely outcomes of ignoring break-in and just driving like the typical driver, heavily-accelerating at every opportunity, including with towing loads etc., when the engine is brand-new?

1. Not likely to break anything from it.

2. Break-in oil may need changing sooner.

3. Engine will not last quite as long, ultimately.

(As noted, the "Toyota Agents" who drive the vehicle off the end of Final Line at the plant, and jockey it from place to place, prior to you taking delivery, are driving it pretty hard. But break-in load/rpm vs. wear is a cumulative function, so brief early leadfoot action followed by gentle break-in period, is easier on things than leadfoot action all the way.)

"Won't last quite as long, ultimately" might mean that, say, instead of lasting 300k miles it will last "only" 280k miles before needing a rebuild, assuming good PM during its life. (My guess for this particular Nippon-built Toyota engine.)

It would be neat to find actual testing done on break-in, by a mfg. Say, take 10 production engines, test with various break-in procedures followed by life testing, then tear them down and analyze the wear. Anyone know where to find such data?