Generally this is a Very Bad Thing:

That’s water/coolant boiling away off your engine. Usually this is due to a busted hose… or you didn’t put the cap back on your radiator… or your radiator is 16 years old and finally sprung a leak! In the last case, the steam will be much less dramatic, and you should be able to drive home by just pulling over every 5 miles or so and re-filling your radiator. Straight water is fine here… don’t worry about the ideal 50-50 coolant-water mix.

So I didn’t document this whole process as well as I would have liked. But here’s the start. One Acura Integra 91′ GS 1.8L 5MT:

Before you start replacing your radiator, verify the leaking fluid is really coming from your radiator. This can be done by wiping everything down, filling your radiator back up, starting the engine and letting it idle, and figuring out where the drips/spurts/gushing rapids is/are coming from.

Next step… take your old radiator out to get a good look at it. Here’s where you start:

Here’s where you finish:

Most everything you need to un-fasten to get the radiator out is right there in front of you on top. To get the radiator out, here is what worked for me:

1. Undo everything you can see that obviously attaches to or holds the radiator in place (two hoses, some electrical on the left fan, mounting braces on each side or the radiator and one mounting/pipe brace)
2. Struggle clumsily with radiator trying to pull it out. Grunt. Wipe grease on pants, forehead. Realize you need to remove the fans first.
3. Remove the left fan. This involves removing two more mounting bolts, and squeezing the fan out past the pipes & tubing.
4. Remove the right fan. This has two more mounting bolts, then some electrical deep down the right hand corner. This is the crux of the whole operation. You need to remove some wiring from it’s bracing clamp thinger. Here’s a shot of the evil wire clamps all opened up.

   

   The small black clamp opens by sticking a flathead or knife in that little slot and then prying up. The bigger white clamp can be opened with some finger prying. If you don’t have small hands and thin arms here you’re going to have recruit your local preteen to help you out here. It’s a tight squeeze.

5. There’s one more hose at the bottom of the radiator you can get to now (this one goes radiator -> engine block). Undo it. If you have an automatic transmission, I think there’ll be two more small hoses down here to undo, but with your 5MT, that’s it.
6. Physically lift your leaky radiator out of the engine compartment. Who’s your daddy now??

Now, if you want to fix your leaky radiator rather than buy a new one, keep in mind that whatever patch you implement will have to withstand high temperatures and pressures. And potholes. Basically, it’s generally not worth it, especially since if (and by ‘if’ I mean ‘when’) you mess it up you’ll have to spend another day doing this all over again. Sooooo…. take your old radiator:

And throw it in the landfill, where it will sit and slowly decompose over the next couple hundred years. And buy a new one! I searched all around and found one as cheap as $102.48, but shipping was going to take a few days and cost another $20 bucks. I need my car now, not in a few days! To the rescue: radiator.com! These guys rock. Call them. They not only matched the lowest price I had found elsewhere, they had my radiator ready for local pickup within the hour. When I picked it up, the price tag said $179.99. I was out the door with tax for $111. Yee haa. My new baby:

Before you throw the new radiator in, realize that they make one radiator for both manual and automatic transmissions. If you have a manual, you don’t need the little intake/outflow nipples for the transmission cooling system at the bottom of the radiator. Go to Kragen and get a hose and some clamps, and connect the two nipples. While you’re there pick up some more coolant.

Installing the new radiator is pretty much exactly removal in reverse, except harder. But you’ve already had one practice time. Don’t get frustrated, be one with your radiator. Love thy radiator, and thy radiator thou lovest back.

Now that your new radiator’s all in and connected, add in 50-50 coolant-water mix until the radiator is full. Leave the cap off, start the engine. There should be some bulbing. Some coolant may spill over, don’t worry, your dog and/or baby will clean that up for you. Anyway, the level should drop as air that was trapped in the engine and radiator finds it’s way up to the top. Add more coolant and water. After a few minutes of this, the bubbles will stop. Keep an eye on the engine temperature as you do this…. it should be fine, but still.

And that’s it! Pop the radiator cap back on, take it for a spin around the block, make sure everything’s cool, then take it for a little jaunt out on the freeway. Bask in the glory that is a well-cooled 1.8L 5MT running silky smooth.