1998 Volvo S70

Article by on August 13, 2013, last modified on May 7, 2014

I'm a big fan of Volvo cars. Purchasing a pre-2000 Volvo was recommended to me since they are simpler and easier to work on. So far, this has been true. Getting repairs done at a shop is very expensive, so if you decide to get an old Volvo you either have to make working on cars a hobby or pay lots of money. I am choosing to make it a hobby and here are some notes that I hope to not forget.

DISCLAIMER: Any information on this page is for my own personal reference. If you choose to use it you do so at your own risk.

For beginners, I recommend getting a basic understanding of how an engine works. Visual.ly produced a great info graphic on this: "How A Car Engine Works".

Climate Control (Heating and Air Conditioning)

Diagnosing Issues

If you are new to issues with climate control, watch this video first: http://www.youtube.com/watch?v=2vmfxYg8LoY. In order to successfully diagnose issues with climate control you need to know the electrical system and how to test it and that video is an excellent overview.

From what I gather, you should diagnose is the following order:

  1. Fuse
  2. Climate Control Relay
  3. Heater Blower
  4. Heater Blower Resister

1. Check the Fuse

You can check the fuse by looking at it. If you can see the metal arch or bridge inside the plastic is broken it is a bad fuse. Alternatively, you can use a multimeter to test by setting the multimeter to ohms and ensuring it says zero (example). The fuse box is located under the hood by the hood's hinge on the driver's side.

2. Check the Climate Control Relay

The Climate Control Relay (the nobs on your dash) is easy to diagnose. The best way to check is to get access to the heater blower and check that you are getting voltage to the heater blower. If you are, then the issue is not the Climate Control Relay.

3. Check the Heater Blower

If you are getting voltage to the heater blower there is a good chance that the issue is the heater blower. To check it, simply turn the car on and put the air on full blast. Then, put the tips of the multimeter on the two power wires that feed the heater blower. If you get a Haynes manual and look at the wiring diagram in the back of the book it will show you what color they are; they should be a purple/yellow wire and a blue wire. If you are getting voltage at full blast and are getting a variant voltage based on turning the speed dial for the blower on the dash, then it is most likely the fan is bad. In my case, I found that the fan would keep on and off now and again. For $150 I bought a brand new one at Autozone and now it works!

4. Check the Heater Blower Resistor

If the fan is not getting voltage it is likely the issue is the resistor. Or, if the air works on full blast but not for some of the settings, say it works for 1, 2, and 5 but not 3 or 4, there is a good chance the issue is the resistor. The reason is that when you turn the air on full blast it bypasses the resistor, so if it works without the resistor in play that should be the cause.

Further Diagnostic Reading

These are mostly forums but you may find the conversations helpful.

Replacing the Heater Blower Resistor

Here is a how-to: http://volvospeed.com/vs_forum/index.php/topic/106427-blower-resistor-repair-guide-850sv70/.

Replacing the Heater Blower

Here is a great YouTube video: http://www.youtube.com/watch?v=frZl49p2quk. I found it to be very accurate even for my GLT.

Resetting the Service Light

I have yet to successfully do this. According to a video on YouTube, you:

  1. put key in position 1
  2. press the trip reset button and hold for 3 sec
  3. before the 3 sec is up, turn to the key to position 2
  4. count another 7 seconds for a total of 10 seconds and then service light should flash, and at that point release the trip reset button
  5. turn the car on and the service light should be off

Wiper Blades

In order to get the wiper blade inserts you have to ask for them at the counter at AutoZone. The reason they gave me was that people don't know there are different sizes. Which, I believe is meant to imply that people get fussy about buying wiper blades and not checking to ensure they are the correct size.

I bought some cheapo wiper blade frames and blades but the clips to hold the inserts in fell off. Which, means that the insert slips out. I did some searching and found that Rain-X's wiper blades are the best by a pretty good margin. Second are usually Bosch's. I wanted to be able to replace the inserts still so I went with Bosch Evolution wipers. I don't know if it's the quality of the wiper or its design, but it works well and is very quiet. I'll have to see how long they last and update again.


Oil Change

Changing oil is pretty easy. The oil pan bolt is within reach without having to crawl under the car, and where the bolt is the oil filter is just offset to the front left of the car facing down. I believe I used a 1/4 inch ratchet and a 17 mm socket to get the bolt off. I really like FRAM oil filters because of the rubber grip on them. You may need an oil filter removal tool to get the old one off, or if you are desperate you can hammer a screw driver into the old filter and then twist it off, but if you try it and break something you did not hear it from me.

If you've never changed oil, the easiest way I've found is to buy the big 6 quart jugs. Then, after draining the oil into an oil pan and pouring new oil in, pour the oil in the pan into the jug. Then, you can take the jug to AutoZone, place it on the counter, and they'll take it and recycle it for you. The old oil filter you'll just have to throw away.

Spark Plugs

Replacing Spark Plugs

Spark plugs are quite easy to change. The OEM version for mine was Bosch FR 7 DPP+ (link). I've heard the NGKs are just as good. Now, there is a bit of debate as to what the spark gap should be. I just plugged them in and they work great. But, where the gap is at can affect power and efficiency. According to the Haynes Manual a normal S70 gap is 0.9 mm (0.035") but the turbo is 0.7 mm (0.027"). A few different reviews said a tuned car or a turbo should have 0.028" down to 0.026". (Yes, no one is consistent about inches versus metric.). I've also read that the gap should be 0.03" for turbo. I think the point is: gap it at whatever works best. If you're like me and just want it to work then just buy them and plug them in since plugs are pre-gapped for you.

I always change the plug wires every time I change plugs, but I cannot confirm that is best practice or not.


Checking Spark Plugs

I've heard that you can tell a lot about the condition of your engine from how the spark plugs look when you take them out. Mine were covered with oil and here are some links, but I have no synthesis at the moment:

Fuel Filter

Changing the fuel filter takes about 20 min if you're quick, but budget for an hour. It's very simple to change. First, watch "Volvo 850, S70, V70 Fuel Filter Replacement - Auto Repair Series" or skim "Fuel filter replacement instructions on a 1998 Volvo S70 GLT". Then, here are the basic steps:

  • back the rear wheels onto car ramps
  • take off the pressure cap and let as much gas drain out as you can
    I used a small screw driver to open the valve, it works just like the valve on a tire. Wrap a rags around the screw driver to catch some of the gas and prevent the gas from spewing everywhere. Put a pan underneath to catch the extra gas. Don't worry, only the gas that was in the line between the fuel filter and the fuel pump will come out, maybe 20 oz or so.
  • remove the quick disconnect line on the "out" end of the filter and let any gas drain into the pan
  • remove the quick disconnect line on the "in" end of the filter
  • loosen the bolt for the strap that holds the filter in place (I believe a 12mm socket and the bolt is facing the ground right beneath the filter, you can't miss it.)
  • twist and wiggle the filter out
  • place the new filter in making sure the "out" and "in" sides of the filter are going the right way (the "in" side goes toward the gas tank and "out" side toward the engine)
  • connect the quick disconnects on both sides
  • tighten the bolt for the strap
  • start the engine while pumping the gas
  • check for leaks
  • drive around for a bit and check for leaks again, and you're done

Cruise Control

If you are having issues with the cruise control not working or not working properly, check out RSpi007's "Cruise Control Function and Trouble Shooting" video. It gives a good overview of possible issues, though the first half of the video is an explanation of how cruise control works (which, I suppose is good to not assume). However, my issue was different, so I'll list what all I checked:

  • cruise control brake switch: check to see that the switch is not on. If it is on, cruise control won't kick on and most likely your brake lights are on too. You can test this by pulling up on the brake pedal with the top of your foot and trying to set the cruise control, if it turns on then that's your issue.
  • cruise control relay: I wasn't able to find where this was at, but if it does come to it I found  this video on how to test a relay with a multimeter.
  • cruise control fuse: you can test this with a multimeter.
  • gas pedal cruise control arm (saw that in the video, but didn't see it on my GLT): check to see if it is loose.
  • bulb indicator warning light: this ended up being my issue. If the warning light is on on your dash then the cruise control won't work. I replaced one of the right rear brake lights and the cruise control started working. I happened to run across several good articles about this and about cruise control on "The Volvo Owners Club", here are some links:


If the ABS and TRACS OFF lights come on, from what I've read it is most likely the ABS control module which costs between $115-135 to be rebuilt. Many people link to www.modulemaster.com. According to one article you can have a mechanic remove the module, you send it off to Module Master to be rebuilt, and then put it back in when they are done. Allegedly you can still drive it in the mean time. I also found a pretty cool website where someone has resources on how to remove the ABS module yourself.



If you have a loud ticking noise coming from your engine it could be that you lack oil (example of ticking noise). I have noticed the ticking before and also noticed that it went away when I topped off the oil. But, I'm not certain this correlation tells any actual causation.

I've read that every 15,000 miles (2-3 oil changes) you should have the valve tappets checked and adjusted if needed, but I haven't found an opinion for this model. AutoZone says every 30,000 (link).

If the valves are loose you will hear a clicking sound and is a relatively benign condition. The valves are opening late and closing early which results in lower power and fuel efficiency. If the valves are tight there will be no noise. The valves are opening early and closing late which means that the valve could "burn" (i.e. it gets to hot and gets damaged in some fashion). (Reference bobistheoilguy.com)

It sounds pretty involved to check them. According to Mr. Haynes Manual you have to drain all the coolant and remove the timing belt for starters, not to mention having the special tools.

It doesn't sound extremely involved to check them. You just take the valve cover off, check a thing with a gauge, and adjust a screw. But, it does look like it might take you the better part of a day your first time (AutoZone's instructions). Note: the Haynes manual instructions are a little more involved, taking off the timing belt and draining the coolant.



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