MAHLE GS33757 Valve Cover Gasket & Injector Seal Kit (2001-2004 6.6L Duramax)

Fitment

Fits the LB7 6.6L Duramax only, 2001-2004, in the Chevrolet Silverado 2500HD and 3500 and the GMC Sierra 2500HD and 3500, single or dual rear wheel on the 3500. The LB7 was never offered in a 1500 or 1500HD.

Watch the 2004 split. LB7 and LLY parts are not interchangeable, and valve covers and injectors are on that list. Check the 8th digit of your VIN: a 1 is the LB7, a 2 is the LLY. LB7 injectors, lines and return hardware are LB7-only, and the LLY's injectors are a different length and mount outside the valve covers. If your VIN says LLY, this kit is not for your truck.

The 2003-2004 Kodiak and TopKick C4500/C5500 also used the LB7, under the LRY medium-duty power option. This page is written for the pickups, so check a medium-duty truck with us first. Verify fitment by VIN or call us.

Why this part

The LB7's defining weak spot is its original Bosch injectors, and they sit under the valve covers. Original injector life is commonly given as 60,000-150,000 miles depending on the source: Bostech puts failures at 60,000-120,000 miles, and Diesel Power Products says 100,000-150,000. The signs include white or gray smoke at warm idle, rough idle, hard starts, a rising oil level or diesel smell on the dipstick, falling fuel economy and low power.

That rising oil level is fuel. When the under-cover injectors leak, fuel runs past the injector cup seal into the head oil drains and the crankcase. Injector cup seal leaks can also let coolant or combustion into the wrong place. The injector harness lives under the covers too, and its insulation can rub through and mimic a dead injector.

Every one of those jobs starts with the valve covers off. Gaskets that have been on an LB7 since the factory are tired by now. The GS33757 replaces them with MAHLE's OE-quality kit so the top end goes back together sealed and keeps its factory performance.

What you get

One MAHLE GS33757 Valve Cover Gasket & Injector Seal Kit for the 2001-2004 LB7. The listing does not give a piece count, so call us if you want the contents confirmed before the covers come off. MAHLE lists these features:

• OE Quality
• Maintains a Factory Performance

About MAHLE

MAHLE began in 1920 as a small engine shop in Stuttgart, Germany. Pistons made the name, but the company also makes the sealing parts shops use to close an engine back up: valve cover and timing cover gaskets, complete engine gasket sets and fuel injector seal kits. Browse the MAHLE line for the rest of the Duramax parts we stock.

Frequently asked questions

Will this fit my 2004 Duramax?

Only if it has the LB7. 2004 was a split year. Check the 8th digit of the VIN: a 1 means LB7 and this kit fits; a 2 means LLY and it does not.

Is this everything I need for an LB7 injector job?

No. The recommended LB7 injector job replaces all eight injectors as a set with updated Bosch-design units, plus new cups, copper washers, banjo seals, seal kits and, past 150,000 miles, the eight high-pressure lines. This kit covers the valve cover gasket and injector seal side. Call us and we will build out the rest of the parts list with you.

Why is my oil level going up?

On an LB7, a rising oil level with a diesel smell on the dipstick is the classic sign of fuel getting into the crankcase from leaking under-cover injectors. Oil analysis showing more than 5% fuel backs it up. Fix the injectors first; this kit is part of closing the top end back up afterward.

Questions on fitment? Call the shop at the number in the header. We install everything we sell.