I'm posting this in a couple of places because I know people only pay attention to certain forums. Anyway, does anyone know the specs (specifically the flow rates) of the Motorcraft PW423 water pump and the Motorcraft PW494 water pump ? The reason I ask...I have a 99 Expedition Eddie Bauer, 5.4L, 4x4 with the heavy duty tow package. This past weekend it overheated 2 hrs from home, and resulted in an expensive tow home. I discovered the radiator was clogged, AND the water pump was shot. I replaced the radiator, and water pump with the appropriate PW423. Everything seems fine, BUT someone on another forum told me I should have replaced it with the PW494 which is a water pump from a 2000 Excursion 6.8L. He said it fits the 5.4L and flows more coolant than the 423. I'm curious if anyone has done this, or knows the difference in flow rates between the 423 and 494.

Thanks.

 

 

I'm not an engineer, but I've been around enough cooling and hydraulic systems to know you are 100 % correct. That's why I was trying to figure out the flow rates. This "Bubba" claims to be a Ford mechanic (yeah, yeah, I know), so I was hoping he might know something the average person doesn't. He claims he ran an Excursion 6.8 pump on his 01 5.4 and it made a noticeable difference in cooling, especially when towing.

 

Looking at the pictures on RockAuto for the water pumps for the 5.4 and 6.8, it looks like the 6.8 version would actually flow more water, and the bolt pattern looks close enough to bolt up.

I'm with Pirate though, that this "mod" may do more to hurt than help. Ask this "bubba" if he has any real sources to back up the claims... I've not seen any cooling issues on the 5.4 excursion (mine) or 5.4 expedition (my brother's) that I've driven.

 

 

Yeah, I tend to agree with both you guys, but just wondered if it was a viable option. I hope I got all the crap out this time. I flushed, and back flushed the system, which got a TON of rusty looking crap out of it..

I have a trans temp gauge installed in the line before it goes into the radiator AND an aftermarket trans cooler (thought the stock one was too small). I'm only pulling about 5,500 lbs, but the temps haven't been bad. BUT, this is the first time I've installed one in line, usually I put them in the test port on the case. I'm still deciding whether I'm gonna move it or not to the test port.

It's supposed to be over 100 F (including humidity) here this weekend, so I'm going to load up the trailer and run it around town to see how she does. At least if it runs hot again, I'm close to home. lol.

 

 

Already had. Back story on this thing. I bought the Expedition in June 2017 from a friend's parents, with 168,000 miles. They bought it new in 99 and everything ever done to it was done at the dealer (or so I thought). It had the factory tow package, was in very good shape, they had all the maintenance records, and thought i was fairly safe. When I bought it, I knew it needed a speed sensor and both heater cores. I replaced the heater cores and heater hoses and back flushed the lines. The coolant was a redish/ orange, but I thought that was the coolant color.

No problems with it since. Flash to the past weekend. About 90 miles from home, while pulling my 18' trailer with an ATV and side by side, it suddenly overheated. Pulled over and it almost instantly started to cool down. After a bit got back on the road, and about 5 miles later it overheated again. Luckily, there was an exit, and I stopped at an Auto Zone to pull the thermostat (thinking I had a sticking thermostat). Got back on the road, about 10 miles later, it overheated. Pulled over, it cooled down, and I babied it 2 miles to an exit with a repair shop. The repair shop said the radiator was clogged, and the fan clutch was weak. Claimed the water pump was flowing fine. After the radiator was pulled, the mechanic showed me the rad and coolant. The coolant was almost mud colored with pieces of rust floating in it. The radiator was thin, maybe 1 or 2 core, and the mechanic said it was the wrong one. The replacement radiator was twice as thick, maybe 3 or 4 core. Rode it around the town for a while before getting back on the road, and it seemed fine.

Got about 30 miles farther, and it overheats again. Baby it to an exit, but of course there is nothing around. After a couple of useless hours of trying to find either a shop to get towed to, or a parts place that had a water pump, I gave up and just found a tow company to pull me home. After checking it over, I don't think it blew a head gasket, so I figured I'd replace the water pump. When I pulled it, I could not believe what it looked like (pic below), and the coolant was still nasty. Flushed and back flushed the entire system twice, and put a new pump on it. Driving around town it seems fine, but I'm hopefully going to put the trailer and ATV's behind it today and test it out. Temp is supposed to be 96 with a heat index of 104. Should know one way or the other with that temp.

 

Well, put almost 90 loaded miles on the old girl today. Ambient temp about 95 with the heat index at 101. She performed flawlessly. She ran center of the gauge, which is cooler than it has ran loaded since I got it. Normally it runs about 3/4 way up the gauge when loaded. Sill within "normal" but definitely on the hot side of it. I like it back down in the center, lol. Trans temp never got above 140...as opposed to 175 normally. AND as a bonus, my AC was a little colder. I could definitely feel the fan clutch engaging like it hasn't before. So I guess, all in all, the system overhaul and new parts definitely made the difference. I'm still curious about the difference in flow rates between the 5.4 and 6.8 water pumps, though.