Increasing Mercury Marquis towing capacity

Car Talk
I have a 2004 Mercury Grand Marquis that only has 67,000 miles on it. The owner’s manual states that the maximum loaded trailer towing weight is 2000 pounds.
I would like to have a towing hitch installed and be able to safely tow a 3200 pound boat and trailer (fully loaded weight) combination. Are there any modifications ( transmission & oil coolers) that I could have added to enable me to increase the towing capacity. The trailer would have to have brakes due to exceeding the state limit of 3000 pounds for requiring brakes.

A Grand Marquis could probably pull a 3200 pound boat but it’s not the best tow vehicle available. A full size pickup with a towing package would be a better alternative. There is a good reason that the owner’s manual limits the towing weight to just 2000 pounds. I wouldn’t attempt it for safety reasons.

IMHO the only way to safely increase the towing capacity of any given vehicle is to replace it with one that has a higher capacity.

I’ve seen it done, but most of these had a special trailer towing package installed. This included HD transmission with HD radiator, HD springs and a performance axle.

I had such a package on my 1984 Chevy Impala which raised the towing to 5000 lbs I believe.

You could install a transmission cooler and make sure you have electric brakes on the trailer as well as a load distribution hitch. And keep the car out of overdrive.

If you can find a used Crown Victoria police cruiser it would have all this stuff already installed. They make good tow vehicles.

Your issue is not with the transmission cooler or oil cooler. The 1991-1997 CV/GM’s could tow around 5000 pounds IIRC. But what happened was that in 1998 Ford changed the rear suspension, adding Watt’s linkage, the rated towing capacity was noticeably reduced. The running gear (engine/transmission/rear axle) were all basically the same from 1991 until 2011 (there were ongoing upgrades, but the engine was always the SOHC 4.6L and the transmission was a AOD/AODE/4R7xx and the axle was always a Ford 8.8 inch).

Unfortunately short of reengineering the rear suspension, there’s not much you can do to increase the towing capacity.

The tow rating dropped with the watts linkage 4-link suspension design in '98.

There is nothing inherently worse with a watts-link design than there was with the splayed 4-link design of the cars. The roll center is lower with a watts-link but that would help, not hurt, towing. The watts-link would provide way better side-to-side stability than the splayed 4-link and that should do nothing but help towing as well.

Either Ford was concerned that big pivot stud on the 8.8 axle housing wasn’t strong enough to resist a trailer pushing the tail around or they were just being overly conservative. either way, I’m not sure I’d risk this.

Gee, what happened to tow ratings–is it structural or a liability concern? My grandparents toured all of North America, towing a camper with a 1966 Plymouth Fury III. Have to inagine it weighed more than 2000# loaded. The 8.8" diff (on the CV/MGM) is the same one from the F150, so…

I’m sure Ford would rather sell someone a more profitable Explorer/Expedition/F-150.

That 66 Fury had leaf springs. Structurally, they were very strong. The Fury’s unit body was pretty beefy, too. All those cars from that era had pretty high tow ratings even though their brakes were pitiful at best. Try stopping a 4000# car with 2500# trailer with 4 wheel drum brakes. Faaaaaaade! I sure don’t want to. Maybe we had fewer lawyers then. Don’t know.

The biggest addition would be the weight equalizing hitch.
Even thought my 79 Chevy pickup could easily handle the tounge weight of my 27’ camp trailer…The EQ hitch was a godsend to control the hiway bounce 'tween trailer and truck.
I would never expect the G/M to handle the tounge weight without an EQ hitch.

My thanks to all of you for your comments. I guess I will forget towing with this vehicle and just continue to use it as the sedan that it was intended to be.