Knock Sensor Replacement

1998 Volvo V70 GLT

1. Disconnect Neg. Battery Terminal

2. Disconnect fuel feed and return lines at rear of the engine

The Haynes manual shows a fitting for both the feed and return lines, but I only had onefor the feed line. I disconnected the return line at the hose union next to the firewall. Theview on the right shows both lines disconnected. Be ready for a small amount ofleakage with a few shop rags.

3. Disconnect fuel line clamps at the rear and top of the engine

Removing these clamps is fairly straightforward.

4. Disconnect Fuel Injector Feed Line

Use a 17mm open end wrench.

5. Disconnect Accelerator CableFirst, remove the cover from the accelerator cable bracket, remove the cable clamp, pull back on the cable cover to lift the cable through the cable bracket slot, then slowly release the cable. Note the position of the cable end in both pictures.

5. Disconnect Accelerator Cable (cont.)

Finally, disconnect the cable from the cable drum. I saw no transmission dropdown cable. Note the cable cover off to the side.

6. Disconnect the Injector Electrical Connectors

Remove the electrical connector from each injector on the fuel rail. Remove the

fuel rail cover for more room. The wire loom is in bad shape, I’m going to order a new one. I wrapped some electrical tape as a temp fix.

7. Remove the Fuel Rail

Remove the fuel rail mounting bolts and carefully wiggle the fuel rail loose from the intake manifold. When you order the knock sensor, order a new intake manifold gasket and new o-rings for the 5 injectors. After replacing the o-rings, smear them

with silicone grease before reinstalling the fuel rail. Check the Haynes manual for

mounting bolt torque and position tightening info.

7. Remove the Fuel Rail (cont.)

This view shows the intake manifold without the fuel rail. There was a lot of dirt and debris around the fuel ports. I used a vacuum cleaner to get rid of it. The spark plug cover has to come off to route the crankcase ventilation hose through

Ports 2 and 3 when lifting the manifold off the head.

8. Disconnect Turbo Inlet Hose

Loosen the hose clamp and remove the turbo inlet hose from the throttle body.

While there, disconnect the idle air control valve connector (shown removed), and the throttle body connector on the bottom of the throttle body.

9. Disconnect MAP Sensor Hose and Idle Air Control(IAC) valve lower hose

Disconnect the Manifold Air Pressure sensor hose from the hose union, and disconnect the IAC lower hose.

9. Disconnect MAP Hose and Idle Air Control Valve (IAC) Lower Hose (cont.)

This view shows the manifold hose union without the MAP sensor hose with the IAC lower hose disconnected. I numbered the hose and hose union with a piece of masking tape to remember where it went. Once the IAC lower hose is removed, you can tie the turbo inlet hose back out of the way.

10. Throttle Body View

This view shows the turbo inlet hose and throttle cable removed from the drum, with the IAC valve and throttle body connectors disconnected.

11. Manifold Vacuum HosesThis view shows three of four vacuum connections connected to the intake manifold. The Haynes manual describes them as the as A. Inlet Air Temperature Control Valve, B. MAP sensor, C. Brake ServoI don’t think the manual is correct, but I removed and numbered only A and B. The brake servo hose connector (C.) was very difficult to reach, but was long enough that I could remove the manifold without disconnecting the hose. Disregard the X’d out connection. You removed it already in Step 9.

A B

C

A

B

C

12. Disconnect Transmission Dipstick Standoff and Intake Manifold Lower Support

For me, this was one of the hardest things for me to do. There is not a lot of room to work in this area• There are two bolts under the manifold that have to come off. One secures

the dipstick to the manifold. It installs vertically and easy to get to from under the car. The other is a vertical bolt which connects the manifold to a support fitting. This one is nearly impossible to reach with regular hand tools.

• However, the support bracket connects to the engine block with a horizontal bolt. Use a long extension from the front of the car to reach it. Leave the fitting attached to the bottom of the manifold. There is also a wire support bolted to the block through the fitting. Remove it too. I started the reinstallation of both bolts from the top of the car, then tightened them from under the car.

• These bolts are a PITA, but once you get them off, you almost have the manifold off.

13. Remove Intake Manifold

Follow the instructions in the Haynes manual for loosening the intake manifold mounting

bolts, then lift the manifold off the head. You have to feed the crankcase ventilation hose

through ports 2 and 3. Remove the oil separator vacuum hose from the fitting on the right

side of the manifold as you lift it off the head. I saved the hose clip. The circled area is

the manifold support that bolts to the block. I just propped the manifold up inside the

engine compartment out of the way. Be careful not to bend or damage any components.

14. Replacing Knock Sensors

Time to finally replace the sensors. With the manifold in the upper right corner, this view

shows the front of the block with the 10 intake valves, the oil separator (A), and associated

hoses. The rear knock sensor is also visible (B). Remove the forward hose from the oil separator

to reach the forward knock sensor (C).

A

B

C

14. Replacing Knock Sensors (cont.) This view shows the end of the oil separator hose that connects to the right

side of the intake manifold. Try to save the hose clip

14. Replacing Knock Sensors (cont.) Remove old front and rear sensors. Install the new front sensor with the

connector in the 3:00 position. Install the new rear sensor with the connector in

the 5:00 position. Follow the Haynes manual for their torque settings.

(Interesting location for the starter – behind the intake manifold…wow!)

FrontRear

14. Replacing Knock Sensors (cont.)

When installing the new sensors, route the new harness as with the old sensors.

This view shows the sensors’ connector on the subframe, forward of the starter.

Conclusion

• The Haynes manual is invaluable, use it. It rates the job as “fairly difficult.” I’d

agree. I’m no expert, I would rate my skill as Level 2 as per the IPD catalog.

What a feeling of accomplishment when the car started and ran perfectly on that first key turn, and the CE light went out!

• Keep track of your parts and use a torque wrench during reassembly in reverse order.

• Take your time - work safely.

• I saved each hose clamp I cut off and took them to the store to size new screw

type clamps to make sure I had the exact number I needed.

• The job took me about 9 hours because I wasn’t familiar with it, but I could probably do it a lot faster a second time.

• I kept $650 in my pocket, not in the Volvo service department’s bank account.