Protect Your 4R100 Transmission with a Bypass Delete
The Dangers of Overheating
Heat kills. It’s just a fact of life. Get anything too hot and it dies, often spectacularly. If you leave a tomato seedling out in the noonday sun, that might be what you’d call an annoyance. Fry the 4R100 transmission in your 2004.5-2010 Ford truck, and that might be what you’d call a real bad day.
Naturally, nobody goes out of their way to overheat their transmission, but sometimes it just happens. Say that you have a heavy load to move on a hot day. It’s not something you can put off until the middle of the night, when everything cools off a bit. Your truck simply has to do its job, no matter what. This is what you bought it for in the first place. If you have to baby it, you made the wrong choice at the dealership.
The Impact of Wear and Tear
Yet everything slowly changes as your truck gets older. Lubricated parts wear down a bit. That opens up the tolerances and means you get less oil in the places it needs to be. This in turn, means that the heat dissipation that comes when everything is tight and new starts to tail off just a bit. Add in some extra tough abuse, and you have a recipe for severe damage if everything isn’t working right.
The Problem with the Original Design
As bad as this might be, the real wild card is found in the original FoMoCo transmission cooling system design. This included a temperature-controlled bypass valve that deliberately restricted flow into the external transmission cooler. This was done so the fluid would heat up to its normal operating temperature much faster.
While Ford had its reasons for doing this, it sets up a potentially life-ending problem for your 4R100. Should the little check valve, which shuttles fluid in one direction or the other, decide to go on vacation, you end up with a transmission that sends a very reduced, or even zero, amount of fluid out through the external tranny cooler. Instead, it simply comes out of the transmission and cycles right back into the pan directly.
The Solution: Bypass Delete
Moving hot transmission fluid around and around inside a hot automatic transmission obviously has its disadvantages. This is why you should cure this problem with an automatic transmission cooling system bypass delete. This is a big way of saying that you need to eliminate the problematic check valve before it eliminates your transmission for you.
Protect Your Investment
Modern automatic transmissions are amazing pieces of complex machinery that do their jobs well. If you don’t keep them cool, however, they will die early. In addition to being complex and effective, they are also extremely expensive to replace. It makes very little sense to risk wiping out your valuable transmission because you don’t want to mess with a cheap and easy-to-swap part on the outside of the transmission itself. Do yourself a favor and trade out that old valve for a new non-bypass one that will ensure your transmission gets fed every drop of cool ATF it can handle.