I used to tow my 7000 lb sailboat with a 351H.O., and c-6 trans at 70 MPH with no problems. But I had to get rid of it, because everything underneath was rusting out.
I'm looking for a used E-150 van, 2000 or newer, with a 5.4 to tow the sailboat to florida this winter. But I have heard of the 5.4 blowing plugs, and having head gasket problems. Is this a major problem, or just a few engines. What years would be more reliable, between 1998, and 2003. I try to avoid a new engine, the first few production years.
I currently have a 95, E-150, with a 302, but it doesn't have the power to pull the sailboat. I miss my 351!
The 2v 5.4 is a stout motor with a few flaws that got worked out as the design aged. I'm not too keen on the 3v version, but as we can see here... not too many people are reporting problems on an engine that is now 2 1/2 years old.
My only issue with the towing aspect is the GCWR... I see too many people towing too heavy a load for their trucks and wondering why they blow transmissions and run through brakes. Vans are heavier than trucks so the towing capacity drops. A fully loaded E150 with the 5.4 will not tow 7000# and be "cool" about it. It's not the engine that I'd be worried about, but the rest of the drivetrain, suspension, and brakes...
The no trouble one-to-get is the 3 valve that has the later head and 100 k plugs, plus if you can get the 4R75 trans (don't know how they are spec'd) there is a thread stating the 75 has beefier internals.
Many people on there are complaining about the plug blow out issue. On the other hand, if someone has a solid van with the blow out issue I bet you can buy it for short money...the repair does not require head removal, it just takes some mechanical aptitude. There is a really good series of posts in there on how to deal with it. I would think the main issue with a van is accessing the plug hole. Posts in the forum seem to indicate that #3 on the right side is the most common blow out. Before the blow out people think the have a lifter noise or manifold leak but it's actually the plug hole "breathing"
I have a 98 e250 work van with the 5.4 and we have been pulling an enclosed trailer with it for 50,000 miles at least and it has held up fine. It now has about 150,000 on it and we still are pulling hard.
I was 100% pleased with my 2000 F150 5.4 until it blew a head gasket at around 77000 miles. Way to young IMO.
My two pennies is get the V10 in an E250. You won't have that much worse mileage. Towing anything drops my mileage to around 10-13 MPG. That's with a 16x5.5 tailer, 600lb mower, weed eater, backpack blower, and 2 guys. In short, not that much weight.