Subaru EJ25 Coolant Crossover Pipe O-Ring

Made a quick trip to an Ace Hardware to get an o-ring for a coolant cross-over pipe on an EJ25 I was helping to put together. Turns out a #34 or #44 o-ring sits perfectly in the gland on the block and seals the crossover pipe perfectly as well.

You may also like


  1. Hi. Do you know if these o rings would also work on the coolant crossover pipe on an EJ205 engine? I have a 2002 WRX that has a coolant leak and this pipe might be the culprit. Ace Hardware is close by and I’m not trying to pay dealership prices for something I can get at a hardware store for a fraction of the price. I can’t find any info on the size o rings I need anywhere. This page is the only solid link that comes up. Thank you for your time.

    1. I am using all hardware store O-rings even though I have the ones supplied with gasket set. I am convinced this is the only way to get the correct sizes, gasket set suggestions be damned. They are wrong. Especially the orange one between the case halves.

  2. PS the seats for these O-rings at the crossover pipe ends is very corroded on my 2003 unit. Must use additive in coolant, methinks, this is a high evaporative area, being above the engine and all and really prone to corrosive action from oxidation. Can’t make a seal on crap, it’ll leak. I had to use an engraver to dig to the bottom of the pits, since they spanned the seat area. Had to polish the upper surface as well. Then I laid a bed of ultra grey and waited a bit, seated the new O-rings into it. Silicone upper surface, underside of crossover. Then put in the cleaned bolts, snugged down just to get the crossover pipe level and near the final position. then I waited an hour or more to withdraw the bolts, apply locktite and reinstall, finally torqueing to ten foot pounds. Man must torque, Mr. Torque. Not twerk. That’s when you strip out the threads or break the thing. Next time I will drill and install safety wire instead of or in addition to locktite. I just like how it works and looks.

  3. hi, how long does it take to replace the crossover pipe o-rings? I took my car to th edealer and they said it took nine hours to tear do it…

    1. @J shap,

      Stealership is pulling your leg, as usual. It’s a tedious, but simple task and certainly does not take 9 hours. It would, however, be good to pick up a Factory Service Manual (FSM) familiarize yourself with the layout of the EJ engine–exterior block design, where you’ll be working, has not changed over 30 years of production–but you’ll have to first drain your coolant (quickest but messiest way is to pull the thermostat housing located at the end of the lower radiator hose), remove the air intake from the throttle body, then disconnect all the engine harness plugs, coolant & fuel lines, and unbolt the intake manifold. The manifold along with the engine harness and fuel rail assembly will lift off the engine freely, exposing the coolant crossover pipe (the pipe running across the top of the block, says “subaru” on it) for easy access to remove and replace the seals. If you research, study, and work steady with no interruptions, shouldn’t take you more than an hour start to finish, maybe 2 if this is your first foray into engine repair.

Leave a Reply to Trueforger Cancel reply

Your email address will not be published. Required fields are marked *