Mishimoto  |  SKU: MISMMTS-RAM-89H

Mishimoto 89-93 Dodge 5.9L Cummins 87.5C High-Temperature Thermostat

Regular price $ 7402

Can I pick up my order or have it installed at your shop?

Absolutely. We offer local pickup on most products and full professional installation at our shop in Washington, MO. Whether you just want to grab your parts or have our techs handle the install, we’ve got you covered. Give us a quick call at 636-429-7020 or message us to schedule a visit — we’ll make sure the parts are ready when you arrive.

How do I know if this part fits my vehicle?

Unsure if it’ll fit? No problem — that’s what we’re here for. Send us your vehicle’s year, make, and model, and we’ll verify fitment before you order. We can also point you toward compatible upgrades or supporting parts if needed.

What if I need to return a product or it’s defective?

Most unused items can be returned within 30 days in their original packaging. Some products are covered by a manufacturer’s warranty as well. If something arrives damaged or doesn’t meet your expectations, just let us know — we’ll help you get it replaced, refunded, or repaired. (Tracking updates are also emailed automatically once your order ships.)

What's the lead time on custom or fabricated parts?

Many of our parts are built to order — especially fabricated or performance components. These can take additional time to produce before shipping. Lead times vary by manufacturer and demand, but we’ll always keep you updated along the way. If you’re working on a tight schedule, reach out before ordering at 636-429-7020 and we’ll confirm current availability or estimated ship dates.

Description

The 12-valve first-gen Cummins in your Ram is considered one of the best diesel engines ever produced, and for good reason. Fuel efficiency, torque, and simplicity are just a few characteristics that give the Cummins its stellar reputation. We're huge fans of the Cummins engine, which is why we’ve developed a high-temperature thermostat for the 1989-1993 5.9L 12v Cummins. This Mishimoto thermostat activates at a higher temperature (189.5°F) compared to the factory thermostat (180°F). By raising the activation temperature, coolant flows through the system later, promoting quicker engine warmup. The Mishimoto high-temperature thermostat is ideal for vehicles in cold climates, where rapid warmup and quicker in-cabin heat is vital. This thermostat includes a high-quality replacement gasket and our signature Mishimoto Lifetime Warranty.

This Part Fits:

Year Make Model Submodel
1989-1993 Dodge D250 Base
1989-1993 Dodge D350 Base
1989-1993 Dodge W250 Base
1989-1993 Dodge W350 Base