Print

Email

Rebuilding The Chrysler 2.7L

Page 2 of 3

Other Things To Know

That's about all there is to know about the major components for the 2.7L motor. The castings aren't all that complicated, but they can throw you a curve if you're not watching for the differences. However, there are a few more things you should know before building one of these engines.

Rod Bearing Failures

These engines usually fail because they lose a rod bearing, but no one is sure why the rod bearings are failing. Some people think that the coolant from the water pump gets inside the engine if the seal starts leaking, but there are two weep holes that vent to the outside, so that's probably not the reason for the bearing problems.

A lot of the cores are really sludged-up, so some believe that most of the failures are caused by neglect. However, we know of one car that had the oil changed every 3,000 miles at the dealership and still lost a rod bearing at 60,000 miles, so that's obviously not the only reason they fail.

Others have suggested that the bearing material that was used for the rod bearings wasn't right for the application, but no bearing material can stand up to constant abuse, so it probably isn't fair to blame the bearings themselves for the problem. It may well be that some or all of these factors are contributing to the rod bearing failures, but the bottom line is that no one really knows why they're failing, so the jury is still out.

However, the service manager at a local Dodge dealer shared an interesting theory that seems to make some sense. He agrees that  neglect will definitely cause the problem, and he's definitely seen some engines that have been neglected, but he says that even if you use the right oil and change it faithfully, the engine still won't go the miles because the coolant temperatures are pretty high (the high speed fan comes on at 230º) and the engine only holds four and a half quarts of oil, so the oil gets too hot and it begins to break down.

Multi-viscosity oils revert back to their base viscosity if they're subjected to too much heat and pressure, so a 5W-20 may well revert back to a 10W or even a 5W viscosity if it's "abused," and that's just not good enough for these engines.

Running the oil too hot would explain the brown stain we see on the inside of the engines and may even help explain the heavy, thick, greasy sludge that we see on some of the heads. In any case, no matter what causes the bearing failure, it means that about 25 percent of the rods and a lot of the cranks are junk when they come in, so rebuilders should plan on buying plenty of core float.

Computers and Cam Gears

Then there's the problem with the computers and the cam gears. Chrysler has used two different computers and two different cam gears, depending on the model year and the platform.

• The '98-'01 Intrepid and Concorde (LH platform) and '01-'04 Sebring and Stratus (JR platform) used the "current generation engine controller," so the gear for the left intake cam was p/n 4792305.

• The '02-'04 Intrepid and Concorde (LH platform) came with the "next generation controller" or "NGC," so these engines had a different gear for the left intake cam that's listed as p/n 4792305AB in the Chrysler microfiche. All the windows for the sensor were relocated to correspond to the updated program in the new engine controller, so you must use the cam gear that matches the computer in the car so it can sequence the fuel injection correctly or the car won't start and run.

• There's been some confusion over which computer and cam gear were used for the 2.7L engines in the Stratus and Sebring in '03 and '04. It seems logical that Chrysler would have switched over to the "next generation computer" in everything in '03, but that's not the case according to the parts book. It shows the 4792305 cam gear that goes with the "current generation computer" is still used for the JR cars up through '04, so apparently Chrysler hasn't updated this platform yet. It's probably a good idea to check the cam gear on the core before you sell the engine, just to be sure, though.