Stop in for a cup of coffee
that 3.0 was a low power engine. Other then that not bad.
Chrysler Mitsubishi 3.0L V6 Engine
The Engine's Weaknesses
Over the years, the MMC 3.0L V6 has proven itself to be a real workhorse capable of racking up lots of miles. Some of these engines have gone 200,000 to 300,000 miles in aging minivans! But the years and miles also have revealed the engine's major weaknesses. The main ones are oil leaks, oil consumption and valve guide/seal problems. The bottom end has proven to be rock solid but the valve guides and seals (especially in the earlier motors) have been troublesome.
In the back of each of the OHC heads is a black round rubber cam plug. If this plug pops out, the engine will quickly dump its oil supply and self-destruct. The cam plugs tend to loosen up during extremely cold weather so it is important to make sure they are leak-free and tight. If you replace these plugs, make sure you use the later "improved" versions, which are wider than the original narrow plugs.
The Positive Crankcase Ventilation (PCV) system on the 3.0L V6 sucks blowby vapors from the crankcase through the baffles that are built into the valve covers. There is also a drain hole in the covers so excess oil can drain back into the engine. If the drain hole becomes plugged, oil can be drawn into the PCV system causing a huge increase in the engine's appetite for oil. Likewise, if the baffles are clogged with sludge, pressure can build up in the crankcase forcing oil to leak past other gaskets and seals in the engine. There is no way to clean the baffles because they are located between the inner and outer liners in the valve covers. So if the valve covers are dirty and caked with varnish and sludge, they should be replaced with new ones.
To prevent sludge from returning, change the oil and filter regularly. Short-trip, stop-and-go driving especially during cold weather accelerates the buildup of moisture in the crankcase making 3,000-mile or three-month oil changes a must.
The 3.0L V6 uses pressed-in valve guides, which may work loose as the engine ages. The problem occurs mostly with the exhaust guides and allows oil to leak past the guide seal into the exhaust port. Chrysler says oil consumption is excessive if the engine uses more than one quart in 1,000 miles on vehicles with less than 50,000 miles on the odometer, or more than one quart in 750 miles on higher mileage engines. On engines built since 11/15/91 (build code BDL7.067), snap rings have been
installed on the exhaust guides at the factory to prevent them from slipping, and on engines built since 10/2/92 (build code BDL7.416) the intake and exhaust valve stem seals were revised to improve oil control. The build code label can be found on the intake plenum.
Chrysler Technical Service Bulletin 09-18-92 describes the oil consumption problem and offers the following repair advice. If a 3.0L V6 is burning too much oil and/or blue smoke is visible in the exhaust, check compression and verify the correct operation of the PCV system to rule out these as possible causes of the oil usage. If both are okay, remove the intake plenum and manifold, then the valve cover, rocker shaft and cam bearing cap assembly on the front head. Remove one of the cam journal caps from the assembly and reinstall it on the head to hold the cam in place so the cam does not come out of the journals when the engine is rotated later.
Examine the valve guides. If any can be moved with finger pressure or appear to be higher or lower than the others, the head will have to be removed so the guides can be replaced. Chrysler says the guides must be replaced if the distance from the top of the exhaust guide to the valve guide boss on the head is 0.335" (8.5 mm) or less.
If the guides are not loose and have not slipped, a special tool (MD998790) can be used to cut grooves in the exhaust guides so clips can be installed to prevent them from coming loose. Use a magnet and a shop towel to remove the cuttings. Then install new positive valve seals on the guides, reassemble the valvetrain and valve cover and repeat the same procedure on the rear head.
that 3.0 was a low power engine. Other then that not bad.
Chrysler Mitsubishi 3.0L V6 Engine
The Engine's Weaknesses
Over the years, the MMC 3.0L V6 has proven itself to be a real workhorse capable of racking up lots of miles. Some of these engines have gone 200,000 to 300,000 miles in aging minivans! But the years and miles also have revealed the engine's major weaknesses. The main ones are oil leaks, oil consumption and valve guide/seal problems. The bottom end has proven to be rock solid but the valve guides and seals (especially in the earlier motors) have been troublesome.
In the back of each of the OHC heads is a black round rubber cam plug. If this plug pops out, the engine will quickly dump its oil supply and self-destruct. The cam plugs tend to loosen up during extremely cold weather so it is important to make sure they are leak-free and tight. If you replace these plugs, make sure you use the later "improved" versions, which are wider than the original narrow plugs.
The Positive Crankcase Ventilation (PCV) system on the 3.0L V6 sucks blowby vapors from the crankcase through the baffles that are built into the valve covers. There is also a drain hole in the covers so excess oil can drain back into the engine. If the drain hole becomes plugged, oil can be drawn into the PCV system causing a huge increase in the engine's appetite for oil. Likewise, if the baffles are clogged with sludge, pressure can build up in the crankcase forcing oil to leak past other gaskets and seals in the engine. There is no way to clean the baffles because they are located between the inner and outer liners in the valve covers. So if the valve covers are dirty and caked with varnish and sludge, they should be replaced with new ones.
To prevent sludge from returning, change the oil and filter regularly. Short-trip, stop-and-go driving especially during cold weather accelerates the buildup of moisture in the crankcase making 3,000-mile or three-month oil changes a must.
The 3.0L V6 uses pressed-in valve guides, which may work loose as the engine ages. The problem occurs mostly with the exhaust guides and allows oil to leak past the guide seal into the exhaust port. Chrysler says oil consumption is excessive if the engine uses more than one quart in 1,000 miles on vehicles with less than 50,000 miles on the odometer, or more than one quart in 750 miles on higher mileage engines. On engines built since 11/15/91 (build code BDL7.067), snap rings have been
installed on the exhaust guides at the factory to prevent them from slipping, and on engines built since 10/2/92 (build code BDL7.416) the intake and exhaust valve stem seals were revised to improve oil control. The build code label can be found on the intake plenum.
Chrysler Technical Service Bulletin 09-18-92 describes the oil consumption problem and offers the following repair advice. If a 3.0L V6 is burning too much oil and/or blue smoke is visible in the exhaust, check compression and verify the correct operation of the PCV system to rule out these as possible causes of the oil usage. If both are okay, remove the intake plenum and manifold, then the valve cover, rocker shaft and cam bearing cap assembly on the front head. Remove one of the cam journal caps from the assembly and reinstall it on the head to hold the cam in place so the cam does not come out of the journals when the engine is rotated later.
Examine the valve guides. If any can be moved with finger pressure or appear to be higher or lower than the others, the head will have to be removed so the guides can be replaced. Chrysler says the guides must be replaced if the distance from the top of the exhaust guide to the valve guide boss on the head is 0.335" (8.5 mm) or less.
If the guides are not loose and have not slipped, a special tool (MD998790) can be used to cut grooves in the exhaust guides so clips can be installed to prevent them from coming loose. Use a magnet and a shop towel to remove the cuttings. Then install new positive valve seals on the guides, reassemble the valvetrain and valve cover and repeat the same procedure on the rear head.