Over This

S70 maintenance - Thermostat and ECT

My check engine light was on for a while, but since the car seemed to run OK, it didn’t bother me much. However, one day after shutting off the engine, the radiator fan kept spinning for several minutes. That surely was eating up my battery power, so it started to worry me.

Thanks to volvoforums.com, I was told that the probably was likely my electronic coolant temperature sensor (ECT). My research showed that it was a pretty easy job and also best accompanies by a replacement of the thermostat. So, I bought all the parts and tried my hand.

Many sites warned that the two T40 bolts were going to be difficult. In preparation for this, I looked around for some PB’laster as suggested. My web searches couldn’t locate it at the usual hardware stores, but for some reason a single Walgreens location in town had it. Amazon sold it, but I didn’t want to pay $9 for a large can or wait the extra days. So, I went to the Walgreens. Argh, they didn’t have it! Their computer said it was in the store somewhere, but it was nowhere to be found. It definitely not next to the WD40 …

Disappointed, I went home and borrowed my roommates WD40 and sprayed the bolts. As a test, I tried to unscrew the bolt, and I heard it crack and saw some powder come up. That worried me a little, because in the forum someone showed a picture of a broken low quality torx bit. None of my tools are high quality, so I was worried this could happen to me, but luckily I was still OK. I sprayed some more WD40 and called it a night to let the WD40 do its work.

Oh, back to my low quality tools. Not only are they low quality, but in some cases they aren’t even the best for the job. I was using a T40 bit that fits into driver. Real mechanics have T40 bits that fit onto socket wrenches. Here’s how lame my setup was … a T40 bit sitting in a 1/4″ hex socket with an extension connected to my 98 cent ratchet from Lowe’s. I had to tape the T40 bit to the socket so that it wouldn’t fall out when I lowered the tool into place. It did the job in loosening the back bolt, but my tape method totally failed, and the T40 bit fell somewhere into the dark depths of the engine =( Not learning my lesson, I opted for a cheap $6 toolset from HomeDepot that had the T40 bit. I thought I’d be better off this time since I found a proper sized extension with a magnet, and I used duct tape this time!

So, finally, I had courage and I got out my trusty copper pipe to act as a breaker bar. I held the tools firmly in place to minimize the chance of stripping the head, and I was able to break it loose. When I took it out, I could see some white area, which was probably the powder I saw earlier. I guess it was loc-tite or something …

OK, so here’s where the next surprise came … before I removed the bolts, I had pinched off the radiator hose as best I could. What I didn’t realize was that there was a lot of coolant sitting on top of the thermostat. I opted not to drain my coolant first, and this was probably a bad idea. Well, not a whole lot of coolant was lost, but it could have been mitigated. All the coolant started to splash out because the 2 bolts mentioned earlier helped form a seal around the thermostat. Once loosened,  …

Moving on … so I changed out the thermostat in 5 seconds. It just sits in place and the pressure of the bolts keeps it there. So, I turned my attention toward the ECT. I was a little puzzled because the “ECT” in my hand was so not the same as what I saw in the guides. It mentioned a 19mm nut, and I thought that maybe that was part of the car and that it would screw over the new ECT. So, I kept going … Much to my chagrin, I realized that my 19mm open wrench was missing from my bag of wrenches. Neither of my roommates had one, so I was stuck! I was not in the mood to put everything back just so I could drive to the hardware store, so I called my dad. Luckily he had one, so we planned for him to bring it by the next morning.

With the 19mm wrench in hand, I was able to loosen the nut. There’s not a lot of room to turn a wrench, but there’s enough to get the job done. So, I took out the ECT, and it looked just like the ones in the guide, Sadly, it was not remotely close to what I had bought. Going back online to see what I bought, I realized that I had bought a “electronic coolant level” sensor! Dang it! So, once again, I was stuck …

I remembered that someone in the forum mentioned buying their ECT from Napa, so we went there after having lunch. They didn’t have it. After trying two other auto parts stores, we were able to reserve one at a PepBoys across town. It didn’t have a crush washer in the box, but I guess I wasn’t too bothered by having to reuse the old one at this point.

So, I installed the new ECT, and put everything else back in place. I also refilled my coolant tank and started the car. It started, but the Check Engine Light was still there. Oh well, I thought … maybe it’ll go away after I drive it. I drove the long way to church, and it still didn’t go out. Argh. Then, upon my roommate’s suggestion, I used my OBD reader and erased the codes, and that did the trick. The Check Engine Light went away and hasn’t come back.

Yay.