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DIY: 1998 Volvo S70 GLT Heater Core, Heater Hoses

heater core heater hoses - DIY on 1998 Volvo S70

We have several heater core / hoses documented repairs, but this guide by CN90 is so good there’s no sense in not including it. It’s really good. Here’s a few related posts:

In the thread below, songzunhuang discussed replacing the two (2) heater hoses etc., only to realize that it is much better to get rid of the whole thing (O-rings, firewall coupler etc. etc.) and simplified the system by using this approach: Heater Core —> Cut Pipes —> Generic Heater Hoses —> Gutted Coupler —> Re-used the barb fittings —> Generic Heater Hoses —> Engine: … hp?t=67217

Make sure you read through the entire thread above.

Another good thread by rspi … hp?t=58733

  • Anyway, this is my experience with ebay Heater Core ($40 incl. shipping), and used standard heater hoses to simplify this whole convoluted Volvo setup.
  • This is strictly preventive maintenance at 167K. The cabin once in while has this very faint sweet smell. The car consumes two (2) cups of coolant every 5K or so (going from Max to Min). Since others have reported the heater hoses can burst, dumping coolant in a matter of seconds and since the heater hoses are 18 years/167K old, it is time to replace them on a preventive basis. This is one job you do NOT want to do in the middle of nowhere, trust me.
  • Budget 4-6h for this whole project.
  • Heater Core, Heater Hoses Parts:

    • Ebay Heater Core ($40) Do NOT use the two (2) O-rings that come with the ebay heater core: when cold they are OK but when you drive the car, the system is pressurized, they will seep a bit. Best is to buy two (2) Volvo OEM O-ring (PN 3545586), about $3-$4/each.
    • Others mentioned the ebay heater core can smell. So I boiled some water, added some DW detergent, then dipped the HC in there to clean all the grease (I removed the foam for this process, maybe unnecessary step), then rinse with water. You can put the HC in the DW but it takes a long time for the whole 2-3h cycle.
    • Standard 5/8-inch heater hose. I used Gates brand (someone told me Gates is better than Thermoid brand), 6 feet is bare bone minimum. I bought 8 feet just in case, it is about $1.50-$2.00/ft at Napa auto parts. In contrast, if you buy Volvo OEM heater hoses, they are about $60/each!
    • Six (6) clamps for the project: 2 inside the cabin, and 4 at the firewall area.
    • Prestone coolant and distilled water.

    Heater Core, Heater Hoses Tools:

    • Torx keys
    • Screwdrivers
    • Pair of pliers
    • Angle Grinder or Dremel tool to remove factory crimp in order to re-use the barb fittings.
      Wear goggles when operating Angle Grinder or Dremel tool!!!
    • Butyl Rope (stuff used seal vapor berrier or older windshield glass, buy it at local auto glass store), this stuff is used to seal the firewall coupler/generic heater hose space. Or you can use your favorite caulking stuff, as long as it can handle engine heat.
    • Latex gloves: there are a lot of sharp edges to deal with!

    VRD: DIY: 1998 Volvo S70 GLT Heater Core, Heater Hoses Rebuild!

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