Coolant Bypass Valve

The first signs of coolant bypass failure usually go like this:



***This job will be about a thousand times more fun if you let the engine cool over night before digging in.

1). The valve is crammed in pretty well against the firewall. Remove the plastic cover over the engine wire harness by grabbing it from the bottom and pulling straight up.

2). This plastic cover also has to be removed. It just snaps on. I got my fingernails under the top and bottom and pulled it right off.


3). With the covers removed it should look like this. Beer break?


4). Use a screw driver to slide the harness lock to the right. I had to go in on the other side too from the top.

5). There are two 10mm hex nuts and a hanger holding this bracket to the firewall. Remove the nuts, lift up the weather seal a little, and unclip the hanger.


6). *This step was removed because it turned out to be unnecessary.


7). Unplug the harness. Mine had a lot of sand in it so I blew it out.


8). Once you bend up the bracket you can see the turbo bypass valve control solenoid mounted under it. Unplug the three vacuum lines from it, taking note which ones go where. The next picture will be helpful if you lose track though. If your vac lines are original they're probably hard and brittle. This is an excellent opportunity to replace them with some beautiful silicone hoses like mine!



9). Once you have all this stuff out of the way you can finally get a good view of the coolant bypass valve. It's tight back there. I used a combination of Vice Grips and a hose clamp tool to get the hose clamps off. Getting a hose clamp tool with an extension cable sort of like this might make the job a hell of a lot easier. It's hard to get long-handled tools in there. Don't mix up the hoses that go to the valve or you won't get any heat! I prominently marked with a Sharpie the top left hose so I knew where it went. The valve is held to the wall with a zip tie around the upper left hose. Clipping it gives the valve more wiggle room so you can maneuver tools in there. If you look at your new valve you'll notice on the back there's a little clip-like thing. There's a metal bracket that slides into there that holds on the solenoid valve that opens and closes the coolant bypass valve. I didn't get a good picture of it, but the old valve just slides straight up and off.


10). Once the the old valve is out of the car, be sure you let it know how you feel about it.

11). When I did this job on my last 9-5 (2001 V6) I lost a LOT of coolant out these hoses, even with nothing left in the reservoir! This time I hardly lost any. Just in case, be prepared with a pan under the general area, and have new coolant ready to top off. Earlier 9-5's use green stuff, later ones use orangey/red DexCool.


12). Reassembly is the easy part, thank goodness. Everything goes back in reverse order. When you're putting the new valve in, take EXTREME CARE not to break the little vacuum hose nipple off the top of it. It's fragile, and without it the $100 valve is pretty useless. Top off the coolant reservoir with an approximate 50/50 mix of the coolant that applies to your car and DISTILLED WATER. I didn't have to add much so I didn't take great care in measuring out an exact 50/50. I backed the car out and let it run for a while to make sure there weren't any leaks. So far, so good!

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