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Now that the vehicles are approaching 20 years old, the AWD Volvos we love are starting to get a bit long in the tooth. A frustrating fault that is occuring more and more involves the rear subframe, and the fuel equipment snaked through it.

Rear Subframe Removal

The P80 chassis was comprised of a slew of FWD and AWD models, some turbo, some non. The AWD versions of these vehicles utilized an all-aluminum rear subframe to house the suspension and rear differential. Entwined in this subframe is the gas tank, braking system, evaporative emissions system, and more.

A lot of AWD Volvos are starting to hit the market with unrepairable evaporative emission system leaks, and part of the problem is due to the mass of fuel pipes that are snaked above the fuel tank. After dropping my subframe, I realized that most of these pipes were rusted out, requiring me to fab up some replacement hoses in order to get the system sealed back up again.

Not only is it difficult to do this job on jackstands without a lift, but the corrosion I've found is horrendous from the aluminum subframe fusing itself to the vehicle's steel body. It's only held on to the car with six bolts, two of which broke off in the body and the rest were covered in corrosion.

If you're looking to buy an old '98-00 V70R, it may be wise to restrict your search to somewhere below the rust-belt. While EVAP leaks are repairable, it's a high cost involving a lot of time, so another vehicle is almost always needed during this procedure.

Diagnosis

The easiest way to know there is an evaporative emissions system problem is by an illuminated Check Engine Light. Any code from P0440-P0456 indicates an emissions system fault, the common ones being P0455/P0456 for large or small leaks, respectively.

If it is difficult to fill the fuel tank because the nozzle clicks off frequently, that's a good way of knowing there is an EVAP system issue in the rear of the vehicle around or on top of the fuel tank. After removing my rear subframe and sealing up all of the rusted hoses and cracked rubber lines, my S70 AWD could be filled with fuel non-stop. Prior to this, I had to readjust the nozzle multiple times or even pump at half-speed just to get the tank full.

Also, there is an EVAP purge solenoid located on the radiator shroud that controls the flow of evaporative emissions into the engine. If this is clogged or stuck open, a code can set. Apply 12v to the pins of this solenoid to listen for a click. Blow into the solenoid and repeat this process - the air should stop and start in conjunction with the power application. If there is a small leak when the valve is in its sealed position, replace the purge solenoid. If the solenoid doesn't respond to electricity, replace it.

If all else fails and you cannot find the source of the leak, get the system smoke tested at a shop, or borrow a friend's. If smoke pours out from above the gas tank, you're in for a rear subframe job. It's the only way to properly fix the mess of pipes, tubes, and wires above the tank, and is a great time to overhaul the system for another 100,000 miles.


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Written by :
Alex Fiehl


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