EngINtel: A Stack of Gifts Almost as Satisfying as Chestnuts Roasting on an Open Fire

At this time of year, let me be the first one to to give you a gift – and it’s one you’ll likely use again and again. Many of you may have not seen this issue, but once it bites you, you will always remember the Nissan KA24 engine series in the SOHC configuration.

figure 1 ka24 nissan sohc block may have timing chain wear that looks like a machined surface. the black square area is a hole into the coolant passage. The engine is actually a pretty darn good engine (which compounds the problem) yet if it has a weak link it is the big long timing chain and tensioner system in the front of the block. When the timing chain, guides and tensioner get high miles and wear the chain can actually start rubbing against the front of the block (Figure 1).

The wear actually looks as though it is a machined area and you may over look the big grooved area. But when the chain cut/rubs into block long enough it may actually break into the water passage (Figure 1).

More often than not when this situation occurs the chain has trashed the front cover as well and if there was coolant in the oil the cover gets the blame.

figure 2 the use of a screened gasket between the intake and injector manifold would stop any previous failure debris from entering a newly installed engine. So take heed when you encounter the KA24, 2.4L SOHC Nissan engine for remanufacturing: there may be a hidden problem that can easily get over looked. Make certain that you inspect the front of the block and if there is any chain rub groove you better make certain that enough casting thickness remains not to end up with a coolant breach.

Back in September, I wrote an article titled “Nightmare on Ford Street” that talked about the 1.9L and 2.0L Ford Escort and 2.0 Ford Focus engines. I described the extremely high rate of instantaneous failures due to debris in the manifold from the original failure, thus contaminating the new install.

Figure 3
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When it comes to the Chrysler Hemi-based engines used in Top Fuel dragsters and Funny Cars, you’ve likely heard the commonly referred to 11,000 horsepower those engines can make. That’s 1,375 horsepower per cylinder! That level of performance is pretty insane, but did you also know these drag cars are knocking on the door of 340 mph, and are getting very close to 300 mph in the eighth mile? Or how about the fact that they burn roughly 15 gallons of fuel in a single run, and at maximum pull down around 6,800 rpm, they flow 90 gpm of fuel?! These engines also create so much horsepower that many engine components are only good for one to five runs, and in the case of pistons, the amount of force can even reduce the dome to some degree!