GM Cadillac Northstar engine features and issues
#1
01-04-2008, 10:20 AM
GM Cadillac Northstar engine features and issues
FEATURES
ISSUES
by By Larry Carley
Engine Features
The Northstar V8 has a die-cast aluminum block with a bottom end girdle that splits along the midline of the crankshaft bearings. This takes the place of the main bearing caps. In model year 2000, GM began using a new high pressure "squeeze" casting process for the lower crankcase to reduce porosity in the aluminum, which may allow oil to seep through and leak (this has been a problem on some engines).
The cylinders have cast-in-place iron cylinder liners that are not replaceable. Compression up to model year 2000 was a relatively high 10.3:1. It was lowered to 10:1 in 2000. Each head has two camshafts (one intake, one exhaust) and four valves per cylinder (33mm intakes and 29mm exhausts). Direct-acting hydraulic lash adjusters are positioned over each valve. The overhead cams are all chain-driven, and use an intermediate chain sprocket under the front cover to connect to the crankshaft. Three separate hydraulic tensioners are used to keep the cam chains tight.
The Northstar V8 is an interference engine, which means if a chain fails or is disconnected when the engine is cranked over, the valves will hit the pistons. That's something you don't want to happen with an expensive engine like this!
The intake manifold is Nylon 66 thermoplastic, which helps cool intake air by conducting less heat from the engine. Fuel delivery is by sequential fuel injection with separate injectors mounted under the engine's top cover. Under the top cover you'll also find the MAP sensor, intake air temperature sensor and fuel pressure regulator. If the fuel pump relay fails on a Northstar V8, the engine should still run because the fuel pump also can be energized through the oil pressure sending unit.
A four-coil distributorless ignition with a waste spark set up provides spark to the plugs. Two crankshaft position sensors are used (A and B) plus a camshaft position sensor to provide timing inputs. Both crank sensors are mounted in the block and the cam sensor is located on the rear head in front of the exhaust cam. There's also a knock sensor on the rear head between cylinders 1 and 3 to retard timing if detonation becomes a problem under load.
The ignition system has two modes of operation: "module mode" and "ignition control mode." In ignition control mode, the PCM controls ignition timing using sensor inputs. If there's a problem in the PCM or with its sensor inputs, the module mode takes over and runs the engine with a fixed 10 degrees of advance. The engine continues to run (essentially a limp-in mode) but with reduced performance.
In model year 2000, the DIS ignition system was changed to a coil-on-plug design, which eliminates the spark plug wires and waste spark. Each head has its own ignition module that fits in the middle of the valve cover.
Another feature of the Northstar engines is a "limp home" mode that allows the engine to continue running if all the coolant is lost. If the PCM senses an overheating condition, it temporarily disables up to half of the cylinders. This pumps enough air though the engine to keep temperatures from getting hot enough to cause any damage. Even so, GM says the vehicle should not be driven more than 50 miles in the limp-home mode.
Another unusual feature you may see is a liquid-cooled alternator on the DeVille and Seville. Cadillacs are crammed with electrical accessories that put quite a load on the charging system, so using liquid cooling helps prolong the life of the alternator. In 2001, GM went back to an air-cooled alternator to "eliminate the coolant tubes and potential leak points."
Engine Features
The Northstar V8 has a die-cast aluminum block with a bottom end girdle that splits along the midline of the crankshaft bearings. This takes the place of the main bearing caps. In model year 2000, GM began using a new high pressure "squeeze" casting process for the lower crankcase to reduce porosity in the aluminum, which may allow oil to seep through and leak (this has been a problem on some engines).
The cylinders have cast-in-place iron cylinder liners that are not replaceable. Compression up to model year 2000 was a relatively high 10.3:1. It was lowered to 10:1 in 2000. Each head has two camshafts (one intake, one exhaust) and four valves per cylinder (33mm intakes and 29mm exhausts). Direct-acting hydraulic lash adjusters are positioned over each valve. The overhead cams are all chain-driven, and use an intermediate chain sprocket under the front cover to connect to the crankshaft. Three separate hydraulic tensioners are used to keep the cam chains tight.
The Northstar V8 is an interference engine, which means if a chain fails or is disconnected when the engine is cranked over, the valves will hit the pistons. That's something you don't want to happen with an expensive engine like this!
The intake manifold is Nylon 66 thermoplastic, which helps cool intake air by conducting less heat from the engine. Fuel delivery is by sequential fuel injection with separate injectors mounted under the engine's top cover. Under the top cover you'll also find the MAP sensor, intake air temperature sensor and fuel pressure regulator. If the fuel pump relay fails on a Northstar V8, the engine should still run because the fuel pump also can be energized through the oil pressure sending unit.
A four-coil distributorless ignition with a waste spark set up provides spark to the plugs. Two crankshaft position sensors are used (A and B) plus a camshaft position sensor to provide timing inputs. Both crank sensors are mounted in the block and the cam sensor is located on the rear head in front of the exhaust cam. There's also a knock sensor on the rear head between cylinders 1 and 3 to retard timing if detonation becomes a problem under load.
The ignition system has two modes of operation: "module mode" and "ignition control mode." In ignition control mode, the PCM controls ignition timing using sensor inputs. If there's a problem in the PCM or with its sensor inputs, the module mode takes over and runs the engine with a fixed 10 degrees of advance. The engine continues to run (essentially a limp-in mode) but with reduced performance.
In model year 2000, the DIS ignition system was changed to a coil-on-plug design, which eliminates the spark plug wires and waste spark. Each head has its own ignition module that fits in the middle of the valve cover.
Another feature of the Northstar engines is a "limp home" mode that allows the engine to continue running if all the coolant is lost. If the PCM senses an overheating condition, it temporarily disables up to half of the cylinders. This pumps enough air though the engine to keep temperatures from getting hot enough to cause any damage. Even so, GM says the vehicle should not be driven more than 50 miles in the limp-home mode.
Another unusual feature you may see is a liquid-cooled alternator on the DeVille and Seville. Cadillacs are crammed with electrical accessories that put quite a load on the charging system, so using liquid cooling helps prolong the life of the alternator. In 2001, GM went back to an air-cooled alternator to "eliminate the coolant tubes and potential leak points."
ISSUES
by
By Larry Carley
Northstar V8s are, like other engines they've had some problems. According to various sources, head gasket failures are not uncommon. Nor is oil burning or oil leaks.
Cadillac service bulletin 01-06-01-011 deals with oil burning on 1996-'99 Northstar V8s. The cure, says Cadillac, is to do a ring cleaning procedure (seems those long oil change intervals weren't such a good idea after all). Cadillac recommends using GM cleaning kit (P/N 12378545) and Kent-Moore J-45076 induction/evacuation tool to do the job. The cleaner is added into the cylinders through the spark plug holes and allowed to soak the rings for two hours. The cleaner and dissolved crud is then vacuumed out of the cylinders through the spark plug holes, followed by an oil change. Cleaning the throttle body and EGR valve is also recommended.
On 2000-'01 Northstar V8s, a buildup of carbon deposits in the combustion chamber can cause a cold knock condition. Bulletin 99-06-01-101A says to use top cleaner to remove the combustion chamber deposits. If an engine has failed and is being rebuilt or replaced, the Engine Rebuilders
Association (AERA) says the plastic intake manifold also should be replaced. The reason? Because of the complex shape of the manifold, it's impossible to tell if any engine debris has been blown back inside it. If the debris works loose and is ingested into the new engine, it will cause a repeat failure. That you don't want.
No oil pressure on a 1993-'94 engine? Debris between the oil pressure relief valve and its seat will prevent oil pressure buildup. The cure here is to clean or replace the pump (P/N 3543258), which is located on the front of the engine.
Oil leaks around the rear main crank seal have been a problem on some 1996-'99 engines, so GM has developed a new rear main oil seal (P/N 12556107) that should cure this problem. It's a press fit seal that takes a special tool (J-42482) to remove and install.
In 1995, GM revised the original crankshaft balancer to provide smoother operation and longer durability. If the balancer is removed from the crankshaft for any reason, GM recommends installing the newer, improved balancer (P/N 12552437 or 12552436, depending on the engine).
If you have to pull a cylinder head on a 1993-'99 4.0L or 4.6L Northstar V8 to replace a gasket or do a valve job, do not reuse the old 11mm head bolts. Also,
GM has revised the head bolt torque values and tightening procedure as follows:
[ol][*]In sequence, torque all bolts to 30 ft.-lbs.[*][*]In sequence, rotate all bolts an additional 70°.[*][*]In sequence, rotate all bolts an additional 60°.[*][*]In sequence, rotate all bolts another 60°.[*][*]Torque the front three M6 head bolts to 106 in.-lbs.[*]
[/ol] Because the Northstar V8s are aluminum, thread damage is not unusual. GM's recommended thread repair kit is J42385-500 for main and head bolts, and J42385-2000 for other fasteners.
Northstar V8s are, like other engines they've had some problems. According to various sources, head gasket failures are not uncommon. Nor is oil burning or oil leaks.
Cadillac service bulletin 01-06-01-011 deals with oil burning on 1996-'99 Northstar V8s. The cure, says Cadillac, is to do a ring cleaning procedure (seems those long oil change intervals weren't such a good idea after all). Cadillac recommends using GM cleaning kit (P/N 12378545) and Kent-Moore J-45076 induction/evacuation tool to do the job. The cleaner is added into the cylinders through the spark plug holes and allowed to soak the rings for two hours. The cleaner and dissolved crud is then vacuumed out of the cylinders through the spark plug holes, followed by an oil change. Cleaning the throttle body and EGR valve is also recommended.
On 2000-'01 Northstar V8s, a buildup of carbon deposits in the combustion chamber can cause a cold knock condition. Bulletin 99-06-01-101A says to use top cleaner to remove the combustion chamber deposits. If an engine has failed and is being rebuilt or replaced, the Engine Rebuilders
Association (AERA) says the plastic intake manifold also should be replaced. The reason? Because of the complex shape of the manifold, it's impossible to tell if any engine debris has been blown back inside it. If the debris works loose and is ingested into the new engine, it will cause a repeat failure. That you don't want.
No oil pressure on a 1993-'94 engine? Debris between the oil pressure relief valve and its seat will prevent oil pressure buildup. The cure here is to clean or replace the pump (P/N 3543258), which is located on the front of the engine.
Oil leaks around the rear main crank seal have been a problem on some 1996-'99 engines, so GM has developed a new rear main oil seal (P/N 12556107) that should cure this problem. It's a press fit seal that takes a special tool (J-42482) to remove and install.
In 1995, GM revised the original crankshaft balancer to provide smoother operation and longer durability. If the balancer is removed from the crankshaft for any reason, GM recommends installing the newer, improved balancer (P/N 12552437 or 12552436, depending on the engine).
If you have to pull a cylinder head on a 1993-'99 4.0L or 4.6L Northstar V8 to replace a gasket or do a valve job, do not reuse the old 11mm head bolts. Also,
GM has revised the head bolt torque values and tightening procedure as follows:
[ol][*]In sequence, torque all bolts to 30 ft.-lbs.[*][*]In sequence, rotate all bolts an additional 70°.[*][*]In sequence, rotate all bolts an additional 60°.[*][*]In sequence, rotate all bolts another 60°.[*][*]Torque the front three M6 head bolts to 106 in.-lbs.[*]
[/ol] Because the Northstar V8s are aluminum, thread damage is not unusual. GM's recommended thread repair kit is J42385-500 for main and head bolts, and J42385-2000 for other fasteners.
#2
03-15-2010, 09:10 PM
The Northstar V8 has a die-cast aluminum block with a bottom end girdle that splits along the midline of the crankshaft bearings. This takes the place of the main bearing caps. In model year 2000, GM began using a new high pressure "squeeze" casting process for the lower crankcase to reduce porosity in the aluminum, which may allow oil to seep through and leak
does anyone know when the next casting process change was made?
.
#3
03-15-2010, 09:32 PM
also, dont miss this thread ...
https://www.cadillacforum.com/forum/...ead.php?t=9611
Aluminum engine coolant system protection - Seville STS 2000
.
https://www.cadillacforum.com/forum/...ead.php?t=9611
Aluminum engine coolant system protection - Seville STS 2000
.
#5
03-21-2010, 07:28 PM
my 96 sts northstar make me very sick........... when i part motor out,,,,,,piston oil ring bad.....main bolt threat bad . and i try to use stud on main bearing........spend allnight to find down . and i fuond this web site ,it so good to me.to know more about my sts
#6
06-18-2010, 02:50 AM
my 96 sts northstar make me very sick........... when i part motor out,,,,,,piston oil ring bad.....main bolt threat bad,, Cylinder Head Gasket Set is also defective.. and i try to use stud on main bearing........spend allnight to find down . and i fuond this web site ,it so good to me.to know more about my sts
I aslo have a GM Cadillac Northstar engine..luckily im having no problems with it till now,..
Last edited by kurtdaniel; 06-21-2010 at 11:44 PM.
#7
12-04-2010, 12:11 PM
North star head gasket solution in Toronto
As talked about at the top of this thread the mention of known head gasket failure.
I have one of those cars ang GM thought the time sert was the fix but later found it does not last not even to get the engine through the original GM warranty. My engine was one of those as well.
I finally found a an engine rebuilder who created a fix for the GM extended warranty company that he has great sucess with for over 12 years.
his information and contact information is at www.cadillacexperts.com.
He has guarded his fix as a trade secret and will discuss the fix with a cadillac owner who needs a fix. No it does not use studs or interst he created a proven fix.
The Northstar engine is a great power plant but GM has not created a good way to hold the heads down to prevent head gasket failure.
I have one of those cars ang GM thought the time sert was the fix but later found it does not last not even to get the engine through the original GM warranty. My engine was one of those as well.
I finally found a an engine rebuilder who created a fix for the GM extended warranty company that he has great sucess with for over 12 years.
his information and contact information is at www.cadillacexperts.com.
He has guarded his fix as a trade secret and will discuss the fix with a cadillac owner who needs a fix. No it does not use studs or interst he created a proven fix.
The Northstar engine is a great power plant but GM has not created a good way to hold the heads down to prevent head gasket failure.
#9
04-02-2011, 10:47 PM
It allowes for burning a few.
I love the power mine gives me though and my head gasket repair is holding great.
#10
04-10-2011, 12:09 PM
ALL Northstars from induction day in early 90's to present have cooling I/E head bolt probs..even the newest crap/caddies sporting any' v-8 sideways mounted engine.v-8's were never ment to be mounted sideways like a v-6 in anything! i have a new caddie 2010 i am selling it for a mere $8,000 as it sports a v-8 northstar..sideways mounted crap..even that torpedo-type trannie they sport has it's probs even the new ones..caddie hasn't made a totally reliable nrthstar engine/married to that god awful torpedo trannie that lasts a full 150 thou mls w/o major probs and yes even the 2010's are junk..