Towing a Sienna Behind an RVby Richard Rowe
Towing a minivan like the Toyota Sienna behind an RV seems like an almost perfect solution for those in search of their next great adventure. While most RV drivers will opt to tow a small car as a "dinghy" behind their land yacht, a minivan makes good sense if you're planning on using your RV as more of a base camp and the tow vehicle is an intermediate-range cruiser to visit surrounding areas. So, a fine notion -- but one not without its fair share of challenges.
The first decision you'll need to make is exactly how you're going to tow your dinghy. You've got three basic options: flat towing, a car dolly, and full trailering. The Sienna, to date, has never used a transmission that would permit flat towing without modifications to the vehicle; a potentially expensive problem, but not an insurmountable one. This does limit your options somewhat, though, especially if you're working within a given budget and you don't want to modify your van. The second major factor involved is the van's dimensions, primarily its length, ground clearance and departure angle -- how much you can lift the front end without the rear bumper hitting the ground. Lastly, you've got operational considerations: how the combination of RV and minivan will drive, ease of loading and unloading, and what you're going to do with a car trailer or dolly if you use one.
Flat Towing the Sienna
Early Siennas used the U-series automatic transmission, and later models used A-series transmissions with optional all-wheel drive. Both of these transmissions used oil pumps driven at the input end; so, if you force the transmission to turn without the engine running, you're effectively running it without lubrication. Several companies, most notably Remco, make auxilliary electric oil pumps to overcome this problem. These pumps pull fluid from a fitting in the transmission oilpan, push it through the transmission cooler in the radiator, and back to the transmission. If you're flat towing, a pump like this is an absolute prerequisite regardless of which drivetrain you have. They work well, but they're also expensive. As of 2014, Remco sells pump kits for $1,100 to $1,400 -- and that's before the $300 to $500 in labor required to install it. Add another $300 to $500 for a tow bar installation. So, flat towing is a viable option if you don't want to pull a trailer or car dolly, but it's an expensive one.
If you have a front-wheel-drive Sienna, you can get around the transmission problem by putting the front end up on a car dolly. But, this presents potential a new problem in regard to the van's rear bumper. The Sienna has a respectable 6 to 8 inches of ground clearance, which is greatest under the rear bumper. That's good. But, the rear overhang is long, the Sienna is heavy and its suspension is soft. Lift the front end onto a dolly, and the Sienna's rear bumper may clear when the RV is sitting still, only to hit the ground every time you hit a bump. The cheapest and simplest solution here may be a set of supplemental rear airbags, which fit inside the stock springs and greatly stiffen them to keep your hindquarters from dropping. Not cheap at about $500 to $600 for the set; but, even after counting in the cost of a car dolly, still less than half the total cost of a pump and tow bar installation for flat towing.
Loading the entire minivan onto a trailer may be the best and simplest option for most, and the only option for people who don't want to modify their vans. That's especially true for owners of AWD Siennas, who don't have the option of using a car dolly. If you have AWD, keeping one set of wheels stationary while forcibly spinning the other is the quickest possibly way to fry your center differential. Loading a minivan onto and off of a trailer is a pain, and potentially dangerous if you have difficulty maneuvering your body into and out of the van while it's on the trailer. But, if you can deal with the aggravation, full trailering is the safest option as far as your van is concerned, it will reduce component wear on the van, it's quick, and it may be the cheapest option if you can find a used car trailer. The sky's the limit on what you can spend for a brand new car trailer, but used ones usually go for between $500 and $1,000 from private sellers.
Practically speaking, a full trailer is the best option if you can deal with it and have the room at your intended campsite. Experienced RV owners, though, know that last can be a deal breaker. Most RV parks don't allow anywhere near enough space to leave the trailer connected to the RV, let alone the extra 30 feet you'll need to load and unload something as long as the Sienna. This is where a car dolly really shows its value, especially since it's easily moved by hand once the vehicle is unloaded. Flat towing is even better in this regard, since you can easily disconnect before pulling your RV in -- a godsend if and when you have to back into a tight space. But, then again, you can do the same with a car dolly, if you don't mind pulling it by hand a short distance to your site. For most, then, a car dolly will offer a comfortable compromise when it comes to expense, modification, loading and parking in this application, assuming you don't have AWD. If you do, you're stuck with either a transmission pump modification or a full trailer.
Richard Rowe has been writing professionally since 2007, specializing in automotive topics. He has worked as a tractor-trailer driver and mechanic, a rigger at a fire engine factory and as a race-car driver and builder. Rowe studied engineering, philosophy and American literature at Central Florida Community College.