Jeep 2.5L I-4 Engine Plastic Valve Cover FixPosted in How To: Engine on January 3, 2017 0) (
It’s well known that, years ago, some genius at AMC decided it would be a good idea to put plastic valve covers on Jeep 4.2L (258ci) engines. Unfortunately, it didn’t take long for them to start leaking. What’s less known is that the genius decided to do the same thing with the AMC 2.5L four-cylinder. While the aftermarket long ago addressed the needs of inline-sixes with nice aluminum valve covers to replace the leaky plastic, the four-banger owners were left out in the cold with perpetual puddles in the driveway. While quite a few of those 2.5Ls were long ago replaced with small-block Chevys, AMC V-8s, and other popular engine conversions, there are still quite a few four-popper–powered CJs, Cherokees, Comanches, and early YJ Wranglers running around and marking their territory wherever they go. Luckily, there’s a cheap and easy junkyard fix.
We already knew that an engine swap was coming sometime in the near future when we acquired our new-to-us ’84 Jeep CJ-7 with a 2.5L, but having the less desirable engine led to a more desirable price tag. We wanted to enjoy the Jeep while we were gathering parts for the engine swap, but the oil slick it left in every parking space was both annoying and expensive due to constantly topping it off. One day, a friend wondered aloud if the aluminum valve cover from a later 2.5L would bolt in and replace the plastic one, so we decided to find out. For $10—or less than the cost of the two quarts of oil we were dumping into the engine every other week—we acquired a junkyard-fresh aluminum cover, and 45 minutes later, we had an engine that leaked a whole lot less. The total cost was just under $35 only because we went all-out with a new gasket, bolts, fill cap, breather, and a bit of breather hose. Had we stuck with just a gasket and the valve cover, the whole shebang would have been less than $20. The swap didn’t stop all of the engine oil leaks, but it did fix all of the leaks coming from the top of the engine and reduced overall leakage by more than half. Keep in mind this swap works with only the AMC 2.5L and not the earlier GM 2.5L Iron Duke engines, which have tin valve covers anyway. Here’s how we did it.