What Wears Out on the MX-13
This engine runs hot and runs a lot of miles, so the charge-air and coolant hoses take a beating first — heat cycling cracks the silicone at the bends, and the hump hoses at the turbo connections are usually the first thing to weep. After that it's the air filter housing, the fuel filters (MX-13 goes through a lot of fuel, so filtration matters), and NOx sensors once the aftertreatment system has some age on it.
We carry straight and formed silicone coolant hose, CAC hump hose, air filters built for the D371061 housing, NOx sensors, fuel filters, and fuel tank caps — the stuff that actually fails on this engine in the real world, not a parts-store catalog of everything ever bolted to a MX-13.
How to Order the Right Part
Don't order off the truck year alone — get us the VIN or pull the number off the part you're replacing. Two 579s built six months apart can have different hose routing or a different water pump depending on when PACCAR changed suppliers.
Specifics matter here: charge-air hoses need to match ID and length, not just 'about 3 inch' — measure the stub ends. Water pumps come in variable-speed and fixed versions and they are not interchangeable. NOx sensors are thread-specific and connector-specific, so a part number match beats a description match every time. If you're not sure, read us the number off the old sensor or filter housing and we'll cross it.
Belts are rib-count and length — count the ribs on the old one before you call, saves us both a return.
Why Get It From Us Instead of the Dealer
Dealer parts counter is going to quote you OE pricing and OE lead time. Our aftermarket parts cross-reference to the same PACCAR/Detroit/Freightliner numbers and cost less, usually a lot less on the sensors and fuel filters.
Everything we sell carries a 6+ month warranty, and if something's wrong with it, we deal with it — no runaround.
We've been doing this at a Tacoma counter long enough to know which hose fits which chassis and which sensor throws a fault code if you get the connector wrong. Call with the number off the old part and we'll get you the right one the first time.
Frequently asked questions
Will this fit my Peterbilt 579 with the MX-13?
Likely, but 579s span several build years with running changes on hoses and water pumps. Give us the VIN or the number off the part you're pulling and we'll confirm before it ships.
Is the aftermarket part as good as the dealer part?
Honestly, it depends on the part. For hoses, filters, and sensors, the aftermarket cross-reference parts we sell do the same job at a lower price and carry a 6+ month warranty. We're not selling you genuine PACCAR-branded parts — we're selling the direct-replacement version, and for wear items like these that's what most fleets run anyway.
How do I know if I need the variable-speed or fixed water pump?
Check the number cast or stamped on your old pump, or give us the engine serial number off the dataplate. Guessing here gets expensive — the two aren't interchangeable and swapping wrong can affect coolant flow.
My CAC hump hose looks fine but it's leaking boost — what's going on?
Silicone hose can look okay on the outside and still have a pinhole crack from heat cycling on the inside layer, or the clamp's just lost tension. Pull it and check the ID and length against what we've got listed before you order — measure, don't eyeball it.
Not sure which one your engine takes?
Run your VIN and we’ll match parts to your exact truck and engine serial, or call the counter — a person who knows these engines verifies fitment by the number on your old unit before the order ships. No wrong-box returns.