Tech Blogs

Dyno Day

Published in the February 2009 Issue February 2009 Column, Cummins, Duramax, PowerStroke

Dmax Tech

PUSHED INJECTOR CUPS

Out of the four Duramax motor types (LB7, LLY, LBZ and LMM), the LB7 was the only model that came equipped with injector nozzle sleeves commonly referred to as injector cups. The injector cups are seated tightly into the cylinder head and held in by the injector via the injector hold down. The problem that is associated with these sleeves is that they can lift up out of the head slightly and begin to leak compression, causing pressurization of the cooling system. This is commonly mistaken for blown head gaskets, and results in costly and unnecessary repairs.

The largest symptom of a "pushed" injector cup is coolant system pressurization, usually resulting in coolant puking from the coolant reservoir after hard acceleration runs. This is usually an early symptom and is the first thing that will get your attention. If not taken care of, the leak can progress until the coolant will puke from the reservoir even at idle and can even allow coolant to start entering the cylinders after the motor has been shut down causing much more potential damage to a motor through hydro locking, cylinder wall rust and pitting. Signs of a blown head gasket are coolant in the oil or excessive crank case pressure, and that will require removal of the heads and replacement of the gaskets.

Injector cups can be repaired in most cases by resealing the injector nozzle with red hi-temp 271 Loctite. In some cases the injector cup will have excessive heat damage and will need to be replaced and resealed with red Loctite.

You can contact us at dteditor@dieseltechmag.com for more information about this procedure.

PSD Tech

7.3L Rod differences

How much horsepower your 7.3L Power Stroke motor can handle really depends on what connecting rods are in it. The 7.3L Power Stroke offered in the 1994-2003 Ford trucks was built with two different styles of connecting rods. The earlier trucks came with a much stronger, more reliable forged rod while the later models were built with a weaker powdered metal rod (PMR).

The forged rod motors can handle upwards of 500 rear wheel horsepower plus/minus without major issues. Granted, what the motor can withstand depends greatly on what aftermarket parts are being used, such as turbo, injectors and tuning. The powdered metal rods have been known to break and send pieces through the block around the 400 hp range. Again, a lot of variables go into how much the rods will actually hold up to.

Ford made the swap from forged rods to PMR rods around the 2000-01 model year, but to find out for sure what rods are inside your model, try this. First off, there is an inspection port on the driver's side rear of the block, directly behind the oil filter base. It is a 5/16-inch pipe plug, right at the lower edge of the block. You can remove this plug and see inside the crankcase. By rotating the engine by hand you'll be able to position that cylinder so you can see the rod end and the end bolts. If it looks to have a nut threaded onto a bolt, you've got forged rods. If it looks like the head of a bolt, it is a powder metal rod.

Second, you can check the motor serial number, found on the valve cover build sticker or on the block where the oil cooler is mounted. Using these numbers below you can determine which rods are inside. From the start of production of the 7.3L Power Stroke in 1994 thru engine number 1425746 and 1446713 thru 1498318 will have forged rods. Serial numbers 1425747 thru 1440712 and 1498319 to final production have powdered metal rods.

CUMMINS Tech

1994-2002 dodge 2500/3500 track bar upgrade

If you've got a 1994-2002 Dodge 3/4 or 1 ton truck, you may have noticed that as you rack up the miles, it has more of a tendency to wander all over the road. This can be caused by a number of reasons, such as worn tie-rod ends, worn upper or lower control arm bushings, worn steering gear, worn ball joints, and/or a worn track bar. Obviously, steering and suspension components wear over time and need to be replaced. An inspection of these components will usually tell you which is the most to blame and which needs to be replaced first to begin to correct the problem. However, when looking for the problem, the first place to look should be the track bar.

During these years, Dodge used a track bar with a rubber bushing at one end (the lower side that connects the axle) and a ball joint type connection at the other end (where it connects to the frame). The ball joint is the weak link in this chain. Because of the location and stress on the joint, it wears and gets loose quickly compared to the other steering components. We've seen these joints wear out in as little as 25,000 miles. This "slop" allows the axle to move from side to side as the truck moves down the road and especially when steering force is applied to the wheels, causing the truck to wander. Sooner or later, you look like Jed in the opening credits of "Beverly Hillbillies" as he uses 180 degrees of the steering wheel to the pilot the old Buick truck down the straight road.

In 2003, Dodge changed the design of the track bar to have rubber bushings on both ends of the track bar, eliminating the premature failure of the joint. Windecker Machine in Canada fabricates a bolt-on bracket that allows 1994-2002 trucks to use the greatly improved 2003 track bar. We have over 90,000 miles on this set up and it's still working well. The track bar bracket can be purchased from Windecker Machine for $159. The 2003 track bar must be purchased from a Dodge dealer for $260 MSRP. However we have been able to get Mopar parts at shop rates offered to the public from a website called www.moparpartz.com in the past. They offer the track bar for $182.

Sources:

Windecker Machine Ltd.
306-842-3790
www.solidsteel.ca/Trackbar.htm

Mopar Partz
www.moparpartz.com

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