1989-1993 Dodge 5.9L Cummins Grid Heaters

Grid heaters on the 1989-1993 Ram 5.9L Cummins

The 5.9L Cummins is a direct-injection engine, which is why it gets by without glow plugs. Cold-start help comes from one resistive grid mounted between the cast air horn and the intake manifold. It works on a schedule set by intake air temperature. Above 59°F it does not pre-heat at all. From 59 down to 15°F it pre-heats for about 10 seconds, from 15 down to 0°F for about 15 seconds, and below zero for about 30 seconds, with post-heat cycles after the engine fires. In practice that means a grid problem stays hidden in warm weather and shows up when the temperature drops.

What fails and why

Two things go wrong, and both come with age. First, the gaskets. The grid is sandwiched between the horn and the manifold on its own gasket set, so it adds sealing surfaces to the boost path. When they leak you hear a hiss at the horn under boost and find oily residue around the horn flange. Second, the element. A worn element shows up as slower cold starts. On trucks that are now more than 30 years old, both are age items rather than design defects.

Stock replacement vs. upgrade

There is no performance version of a gasket. The goal is a dry, tight seal that holds boost. If an aftermarket air horn is in your future, keep in mind that it replaces the cast horn that feeds the grid, so doing the horn and the grid gaskets in one job saves opening the same joint twice.

What we carry

This collection carries the MAHLE G32749 intake heater grid gasket. MAHLE lists it for 1989-2007 5.9L Cummins engines, a range that takes in every first-gen year. It is the seal at the grid heater, and it is the part to have on the bench whenever the air horn comes off. For the rest of the air path, see our intakes category.

Fitment notes

Because this gasket is listed across a wide span of 5.9L years, confirm on the listing that it matches your engine. If the truck has had its engine or intake changed at some point in its life, match the part to what is actually on the truck, not to the title. When in doubt, verify by VIN or call us.

Frequently asked questions

Does the 1989-1993 Cummins use glow plugs?

No. The 5.9L is direct injected, so it relies on a single intake air grid heater between the air horn and the intake manifold. That grid warms incoming air for cold starts instead of heating each cylinder.

When does the grid heater actually turn on?

Only when intake air is below 59°F. Pre-heat runs about 10 seconds between 59 and 15°F, about 15 seconds between 15 and 0°F, and about 30 seconds below zero, followed by post-heat cycles once the engine is running.

How can I tell if my grid heater gasket is leaking?

Listen for a hiss at the air horn under boost and look for oily residue around the horn flange. Either one points at the gasket stack between the horn, grid and manifold. Slower cold starts, on the other hand, can mean the element itself is wearing.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.