Tips for replacing the Coolant Temp Sensor - Volvo Forums

johnysmith · #1 09-18-2011, 07:23 PM

I need to replace the coolant temp sensor, but realized the sensor is under the intake manifold. Are there any tips on an easy way to reach it without having to remove the intake manifold?

swiftjustice44 · #2 09-18-2011, 08:39 PM

It is possible to remove and exchange the sensor w/o pulling the intake. Small hands and an inspection mirror a definite plus. I've tried it both ways and honestly, it is faster and less frustrating by far...to just pull the intake. You will need a new intake gasket before you reassemble which in and of itself often cures a few minor headaches.

Leaving the intake in place means you'll be fumbling around the flame trap hoses as well as the injector plug wires and grounds. As I recall, I can pull the intake without removing the fuel rail...just disconnect the ground wire from the two main rail bolts. After removing the intake nuts, the entire manifold w/ throttle spool and throttle body still attached, can be gently lifted back towards the driver's corner of the firewall.

johnysmith · #3 09-18-2011, 09:28 PM

Thanks for info. Removing the intake manifold with the fuel rail on sounds like a much simpler task than completely dissembling all of it.

swiftjustice44 · #4 09-19-2011, 09:57 AM

Well, pulling the fuel rail isn't really that big of a deal...the only real issue is you may be disturbing old seals that will leak upon the reinstallation. Probably the easiest fuel rail removal in the world. Still, why disturb anything you don't have to. The real PITA is if you remove the throttle spool assembly and unhook the cable(s). As I said though, all that can be left alone.

zloetakoe · #5 09-19-2011, 09:13 PM

I replaced it with the manifold in place. Bad idea jeans.

My hands/wrists when I got done looked like I had done a bad job of committing suicide. Will definitely be pulling the manifold if I do it again.

swiftjustice44 · #6 09-19-2011, 09:58 PM

LOL! Did you notice my mentioning "small hands" in post #2? It's impossible to swap it out w/ intake in place w/o some bloodshed!!

mightyjak · #7 09-20-2011, 01:56 PM

I've been going through the exact same thing! Couple of notes:

1. Be sure you get the right sensor. I ordered one from AutoZone and it was blue instead of black. I didn't think anything of it until I found out that black can replace blue, but blue can't replace black. There is a difference!

2. Due to the above, I've had the sensor in and out about 3 times in as many days. Definitely easier removing the manifold. You can leave the fuel rail on, but I also found that disconnecting both fuel lines at the rail helped considerably. You can fish the flame trap tubes through the fuel rail and clear the intake manifold away.

Titan Joe · #8 09-20-2011, 07:15 PM

I did it with the intake in place in about five minutes. I didn't even need to top off the coolant. You'll need a 3/4" 12 point deep socket if I remember correctly. Also an extension of perfect size helps. If you are missing one of those (especially small hands), then removing the intake is a good choice. However that's when my car started hunting at idle, and no one can figure it out. I would recommend a new gasket and torque to 13-ish lbs on a torque wrench for the 13mm nuts on the manifold.

pcarnut · #9 09-20-2011, 09:55 PM

Perfect timing for this thread. My temp gauge is not moving at all so I'm thinking I will need to replace the sensor. The inlet and outlet hoses are hot so I'm pretty sure the thermostat is working. Would this sensor being out give me a check engine light, in other words, besides giving a signal to the gauge, does it also feed something to the ECU?

swiftjustice44 · #10 09-20-2011, 10:07 PM

Quote:

Originally Posted by pcarnut

Perfect timing for this thread. My temp gauge is not moving at all so I'm thinking I will need to replace the sensor. The inlet and outlet hoses are hot so I'm pretty sure the thermostat is working. Would this sensor being out give me a check engine light, in other words, besides giving a signal to the gauge, does it also feed something to the ECU?

No. Volvo used 2 different senders; one for the gauge located under the intake by cylinder 2 and another, referred to as the ecs, located by cylinder 3. The gauge sender is further forward and easier to access than the ecs. The gauge sender being out in no way affects fuel mixture; it merely drives the gauge. It's possible the connector is merely loose.