- 5,062
- Panama City, FL
I posted this in the Show-off-your-latest-purchase thread, and someone said "Start a thread with this!" So here:
I bought my ex-mother-in-law's 1998 Aurora.
Ex-mother-in-law??? See, the thing is, my family and my ex-wife's family have been close for years and years. I grew up friends with their son, my sisters grew up friends with their daughter. The daughter went through a marriage or two and then I married her. After about 10 years she found another guy to marry and left me, but the family, and her kids, are still friendly and supportive. When my ex-father-in-law passed away a few months ago, this car became excess inventory and the M-I-L offered it to me at a crazy price.
Mechanically the car is near-perfect. Cold A/C, tons of gadgetry, like 10-way power seats, memorized seat positions for two drivers, Bose stereo, electronically controlled transmission with two driver-selectable modes (basically sedate and smooth, or quick and punchy.) 250-HP 4.0-liter 32-valve V8, a member of the GM Northstar family. The engine is externally identical to the Cadillac 4.6-liter Northstar, and dimensionally interchangeable. All the power stuff works, windows, locks, keyless entry, seat position memory, heated seats, etc. The leather is perfect, as is the carpet. No sagging headliner. She never used the sunroof, and I hate sunroofs so I'll not be using it, either, but that means it doesn't leak! 👍
Exterior, the car is sad..... It lived its whole life under southern Live Oaks, and the paint is cracked and large areas are simply not there. No rust, though, as the hood and trunk lid are aluminum, and elsewhere the primer is still intact where the paint is gone. Two minor exceptions on the roof in front of the rear window, a bit of surface rust that needs to be cleaned and primed.
Interior is in MUCH better condition!!!!
Things I am discovering about the car.... it leaks oil. This is apparently very common with the Northstar family. Valve cover gaskets, oil pan gasket, and the block splits at the crankshaft.... all potential leak sites. I made one trip under the car, and the whole engine is filthy and greasy! 👎 I will probably replace the valve cover gaskets soon, as they are accessible. The oil pan cannot be removed with the transmission or exhaust in place, as the transmission blocks access to several bolts, and the exhaust has a crossover pipe under the pan. If that's a leak source, I will be adding oil between changes. Forever.
All that switchgear in the doors..... windows and locks, the seat position switches, seat heat, and the driver's seat memory selection, plus the passenger's own temperature control. All of those wires pass to the door through a boot over the hinge. Remove the boot and you see this (from the passenger side): What could possibly go wrong?????
Here's the driver's side, showing the most common electrical issue with these cars..... broken wires to the door switches. These have been fixed now....
While troubleshooting the failure of the right-side mirror to go up and down I removed the door panel to get at the connectors for testing. There are 3 16-pin connectors, a 6-pin connector, and two 4-pin connectors in the passenger door! The mirror by itself needs TEN wires!!! (A pair for the up/dn motor, a pair for the lt/rt motor, then a pair for the position sensor for up/dn and for lt/rt, as the mirror positions are included in the seat memory, and then there's a pair of wires for the mirror heaters....) Turns out that broken yellow wire at the LEFT door was the mirror issue!
As for the source of all these electrons being pumped around this thing, here's what's under the back seat! Pretty much what's back there on any well-equipped GM car these days. Note to self for hurricane season: Don't drive it into salt water!!! (Those fuse boxes have covers which I've removed for the picture.)
She sold me this car for a measly 1,000 dollars! That's about half the blue-book retail even counting the poor paint condition, I think. I am needing tires for my old car, and that was going to cost me over half that! Tires, car. Tires, car. Lemme think....... The sticker was in the car, and new it was just above $35,000. I've had to do a couple of fixes, and some more are coming up. It needs a drive axle on the right side, it clatters up there in right turns. The cruise control doesn't work, and all the wiring and switch tests in the service manual pass (oh, yeah.... I got a set of factory shop manuals on eBay for 25 bucks!) so it looks like it's the module itself. I've found salvage yard prices anywhere from 25 to 55 dollars for that. My best improvement is that I moved my Bluetooth capable radio from my old car to this one so I have the phone interface and tunes from the phone. That required a third-party adapter to feed the radio into the Bose amp, as the Bose system uses balanced low-level inputs from the head unit to the amp.
OK, from here down is not in the other thread, this is just over here......
Things I have gleaned from the Aurora forum I found, and from perusing a Cadillac Northstar forum. First off, people argue that the Aurora 4.0 is NOT a Northstar, because Northstar means Cadillac. That's incorrect. The Aurora 4.0 is not just developed from the Northstar, it is a Northstar! Same 84-mm stroke, but bore reduced from 93 to 87 mm. All exterior dimensions and fittings are identical, and they are completely interchangeable. On that forum there are several guys who have swapped the 4.0 out for a Cadillac 4.6, sometimes even using the Aurora valve cover gasket which has the 4.0 cast on its face. I don't know that it's worth the effort, but OTOH if you used one of the L37 motors you got at least 30, maybe 50 more horsepower. Even the 3.5-liter V6 available in 2001+ Auroras is a Northstar, although missing two cyclinders. It's nicknamed the Shortstar.
In the other thread the question came up, aren't those Northstars hard to maintain? I don't think they're hard to maintain, but proper maintenance is apparently critical. They're VERY hard to work on for even the simplest repairs, as everything is packed very tightly indeed in the engine room. It's important that oil change and coolant change intervals are followed, as the aluminum is said to be porous enough that some have been known to seep oil through the metal! That leads to problems if overheated to any degree. Head bolts can pull loose leading to head gasket issues, with water in the oil, air in the radiator, both fluids escaping the car, etc. etc. Head gasket repair requires new head bolts, which is not always done, resulting in an even weaker head/block clamping force. the best head gasket repair involves drilling the bolt threads and replacing with permanent studs in the block. So, coolant change. CHECK!
I'm not a fan of Dex-Cool at all, and that's what GM used in these. You absolutely cannot mix Dex-Cool with the traditional green coolants, and if you want to change, you have to flush the system thoroughly! The new coolants on the shelves seem to be OK with either Dex-Cool or the green stuff, but whatever you do, you have to keep the coolant fresh enough to have its corrosion inhibitors active. (That's what goes "bad" in old coolant; it still cools just fine, but its chemistry gets used up and you start getting icky stuff in the system.)
I'm told not to use full synthetic or even synthetic blend, as that stuff just leaks worse. I really don't know if that's just an old wives' tale or if it's really true. I do have some significant oil containment issues, though, so when I changed it this weekend I stayed with true dyno fluid. A lot of it, though! It takes 7.5 quarts!
It also takes premium fuel, and fuel mileage is not....... stellar. In town I'm seeing 14, maybe 15 if I can stay out of stop-n-go. I saw one stretch of days down around 12..... I took it out on the road a couple of weekends ago and saw mid-20s, so that's a significant improvement over my previous car. (That was my dad's 1988 Crown Vic, purchased from his "estate.") By comparison, the Crown Vic barely gets 20 on the highway, and is about the same as the Aurora in town, maybe a tiny bit less. But the Aurora's gas is 40 cents a gallon higher.
I'm not sure why the premium is required. Everyone I ask says "high compression." Well, the Aurora has 10.3:1 compression. My FJR, a rev-happy DOHC, has 10.8:1 and runs on regular. Not just "runs because I've tried it," the owner's manual specifies regular.
OK, other Northstar "issues." Like any DOHC engine, the valvetrain needs a LOT of oil, and the valve covers have to contain it. As the car ages, those gaskets get brittle and the seal gets not-so-good. Good news is both covers are reasonably accessible, so I'll probably give those some TLC. Other potential leaks include the oil pan gasket and the seam between the upper and lower block. The oil pan is complicated by the fact that there are actually two surface matings there, as there is a baffle plate between the pan and the engine. No big deal, right? Just remove the pan and reseal!!!!
Um.......... no.
Remember the statement earlier about packaging? I have another saying I like to use, which is that GM designs cars to be assembled on the line, and they could give a rat's ass about what effort is required to service them. Case in point: the transmission sits alongside the engine as there is no room to keep it in line with the crankshaft. It nestles against the block under the right-side (rear of the car) exhaust manifold, and it obscures many of the oil pan bolts. Furthermore, there is an exhaust crossover from the left (front) bank under the engine to the pipe at the back. That crossover must be removed to drop the pan, and I'm not sure its bolts are accessible with the engine in the car. Even if they are, you can't get the pipe out from between the engine and the transmission. So any work on sealing up the oil pan's seams involves MAJOR work! In the shop manual, in the process for removing the oil pan, step ONE in simply, "Remove the transmission." Removing the transmission involves draining the coolant and removing some coolant pipes across the back of the engine, and the things required to do in any one step keep backing up into other removals seemingly ad infinitum. Here's a view of someone's work on a Cadillac.. they've removed the transmission pan. You can see how the transmission is in the way of getting to the engine oil pan, and the exhaust crossover is also visible, under that black skid plate..
So as far as THAT goes, if that's maintenance, then yes, maintenance is quite difficult. To me, that's mechanical work. "Maintenance" is stuff like oil changes, keeping coolant good, new spark plugs once in a while. That's easy. But the motor seems to be extra sensitive to it.
I mentioned the seam between upper and lower block a while ago. instead of the traditional iron-block skirt, with the crankshaft retained by bearing caps down inside the block and the oil pan attaching to the bottom of the skirt, this engine splits at the cranshaft. The crank goes in to an inverted upper block, and then the lower block is mated and bolted on. The lower block contains the bottom half of the crank bearings. Of course, that leaves a seam all the way around the block at crankshaft level, a seam that is supposed to keep oil inside the block. There's no gasket, just a sealing compound, but again, that ages and may lose its seal, allowing oil out into the otherwise pristine environment. This of course, is not even remotely repairable with the engine in the car. Here's a view of yet another someone else's motor, with the joins clearly visible, and then a pic of still another guy's engine with the lower block removed:
So if the block join or the oil pan are sources of oil leaks, that shall remain to be the case for as long as I have the car, and I shall pour the occasional quart (or two) into the engine as needed, driveway be damned.
Other than the scary stuff about the engine possibilities, I am quite happy with the car. It's extremely comfortable, loaded with "luxury" features, drives and rides very nicely, and is dang quick if you don't mind hearing cash register bells along with the V8 intake noise. The M-I-L didn't have a working keyless entry remote but I found an eBay vendor with 2 for 35 bucks so that's done. It's got fairly new tires and the battery was new last year, so expensive stuff is not expected soon. As I stated above I need to replace a drive axle, and I would like to get the adapter to allow the steering wheel buttons to control my radio as they did with the factory radio. My radio is compatible, has a jack for that, so it's only about the money. Like anything.
I would be interested in hearing anyone's [informed] opinions and experiences with these, or with other Northstar-engined cars. Do you or did you have one, or do you know someone who does/did? Anyone old enough to have been a racing fan in the late '90s early 2000s will remember the Aurora Indycar engine, which was basically the stock block, different cams, probably different pistons to accommodate boost, and of course turbocharging. 650 HP! Also, the Cadillac LMP car they took to France (with limited success) was actually the 4.0-liter Aurora engine, again turbocharged and running around 600 hp.
I bought my ex-mother-in-law's 1998 Aurora.
Ex-mother-in-law??? See, the thing is, my family and my ex-wife's family have been close for years and years. I grew up friends with their son, my sisters grew up friends with their daughter. The daughter went through a marriage or two and then I married her. After about 10 years she found another guy to marry and left me, but the family, and her kids, are still friendly and supportive. When my ex-father-in-law passed away a few months ago, this car became excess inventory and the M-I-L offered it to me at a crazy price.
Mechanically the car is near-perfect. Cold A/C, tons of gadgetry, like 10-way power seats, memorized seat positions for two drivers, Bose stereo, electronically controlled transmission with two driver-selectable modes (basically sedate and smooth, or quick and punchy.) 250-HP 4.0-liter 32-valve V8, a member of the GM Northstar family. The engine is externally identical to the Cadillac 4.6-liter Northstar, and dimensionally interchangeable. All the power stuff works, windows, locks, keyless entry, seat position memory, heated seats, etc. The leather is perfect, as is the carpet. No sagging headliner. She never used the sunroof, and I hate sunroofs so I'll not be using it, either, but that means it doesn't leak! 👍
Exterior, the car is sad..... It lived its whole life under southern Live Oaks, and the paint is cracked and large areas are simply not there. No rust, though, as the hood and trunk lid are aluminum, and elsewhere the primer is still intact where the paint is gone. Two minor exceptions on the roof in front of the rear window, a bit of surface rust that needs to be cleaned and primed.
Interior is in MUCH better condition!!!!
Things I am discovering about the car.... it leaks oil. This is apparently very common with the Northstar family. Valve cover gaskets, oil pan gasket, and the block splits at the crankshaft.... all potential leak sites. I made one trip under the car, and the whole engine is filthy and greasy! 👎 I will probably replace the valve cover gaskets soon, as they are accessible. The oil pan cannot be removed with the transmission or exhaust in place, as the transmission blocks access to several bolts, and the exhaust has a crossover pipe under the pan. If that's a leak source, I will be adding oil between changes. Forever.
All that switchgear in the doors..... windows and locks, the seat position switches, seat heat, and the driver's seat memory selection, plus the passenger's own temperature control. All of those wires pass to the door through a boot over the hinge. Remove the boot and you see this (from the passenger side): What could possibly go wrong?????
Here's the driver's side, showing the most common electrical issue with these cars..... broken wires to the door switches. These have been fixed now....
While troubleshooting the failure of the right-side mirror to go up and down I removed the door panel to get at the connectors for testing. There are 3 16-pin connectors, a 6-pin connector, and two 4-pin connectors in the passenger door! The mirror by itself needs TEN wires!!! (A pair for the up/dn motor, a pair for the lt/rt motor, then a pair for the position sensor for up/dn and for lt/rt, as the mirror positions are included in the seat memory, and then there's a pair of wires for the mirror heaters....) Turns out that broken yellow wire at the LEFT door was the mirror issue!
As for the source of all these electrons being pumped around this thing, here's what's under the back seat! Pretty much what's back there on any well-equipped GM car these days. Note to self for hurricane season: Don't drive it into salt water!!! (Those fuse boxes have covers which I've removed for the picture.)
She sold me this car for a measly 1,000 dollars! That's about half the blue-book retail even counting the poor paint condition, I think. I am needing tires for my old car, and that was going to cost me over half that! Tires, car. Tires, car. Lemme think....... The sticker was in the car, and new it was just above $35,000. I've had to do a couple of fixes, and some more are coming up. It needs a drive axle on the right side, it clatters up there in right turns. The cruise control doesn't work, and all the wiring and switch tests in the service manual pass (oh, yeah.... I got a set of factory shop manuals on eBay for 25 bucks!) so it looks like it's the module itself. I've found salvage yard prices anywhere from 25 to 55 dollars for that. My best improvement is that I moved my Bluetooth capable radio from my old car to this one so I have the phone interface and tunes from the phone. That required a third-party adapter to feed the radio into the Bose amp, as the Bose system uses balanced low-level inputs from the head unit to the amp.
OK, from here down is not in the other thread, this is just over here......
Things I have gleaned from the Aurora forum I found, and from perusing a Cadillac Northstar forum. First off, people argue that the Aurora 4.0 is NOT a Northstar, because Northstar means Cadillac. That's incorrect. The Aurora 4.0 is not just developed from the Northstar, it is a Northstar! Same 84-mm stroke, but bore reduced from 93 to 87 mm. All exterior dimensions and fittings are identical, and they are completely interchangeable. On that forum there are several guys who have swapped the 4.0 out for a Cadillac 4.6, sometimes even using the Aurora valve cover gasket which has the 4.0 cast on its face. I don't know that it's worth the effort, but OTOH if you used one of the L37 motors you got at least 30, maybe 50 more horsepower. Even the 3.5-liter V6 available in 2001+ Auroras is a Northstar, although missing two cyclinders. It's nicknamed the Shortstar.
In the other thread the question came up, aren't those Northstars hard to maintain? I don't think they're hard to maintain, but proper maintenance is apparently critical. They're VERY hard to work on for even the simplest repairs, as everything is packed very tightly indeed in the engine room. It's important that oil change and coolant change intervals are followed, as the aluminum is said to be porous enough that some have been known to seep oil through the metal! That leads to problems if overheated to any degree. Head bolts can pull loose leading to head gasket issues, with water in the oil, air in the radiator, both fluids escaping the car, etc. etc. Head gasket repair requires new head bolts, which is not always done, resulting in an even weaker head/block clamping force. the best head gasket repair involves drilling the bolt threads and replacing with permanent studs in the block. So, coolant change. CHECK!
I'm not a fan of Dex-Cool at all, and that's what GM used in these. You absolutely cannot mix Dex-Cool with the traditional green coolants, and if you want to change, you have to flush the system thoroughly! The new coolants on the shelves seem to be OK with either Dex-Cool or the green stuff, but whatever you do, you have to keep the coolant fresh enough to have its corrosion inhibitors active. (That's what goes "bad" in old coolant; it still cools just fine, but its chemistry gets used up and you start getting icky stuff in the system.)
I'm told not to use full synthetic or even synthetic blend, as that stuff just leaks worse. I really don't know if that's just an old wives' tale or if it's really true. I do have some significant oil containment issues, though, so when I changed it this weekend I stayed with true dyno fluid. A lot of it, though! It takes 7.5 quarts!
It also takes premium fuel, and fuel mileage is not....... stellar. In town I'm seeing 14, maybe 15 if I can stay out of stop-n-go. I saw one stretch of days down around 12..... I took it out on the road a couple of weekends ago and saw mid-20s, so that's a significant improvement over my previous car. (That was my dad's 1988 Crown Vic, purchased from his "estate.") By comparison, the Crown Vic barely gets 20 on the highway, and is about the same as the Aurora in town, maybe a tiny bit less. But the Aurora's gas is 40 cents a gallon higher.
I'm not sure why the premium is required. Everyone I ask says "high compression." Well, the Aurora has 10.3:1 compression. My FJR, a rev-happy DOHC, has 10.8:1 and runs on regular. Not just "runs because I've tried it," the owner's manual specifies regular.
OK, other Northstar "issues." Like any DOHC engine, the valvetrain needs a LOT of oil, and the valve covers have to contain it. As the car ages, those gaskets get brittle and the seal gets not-so-good. Good news is both covers are reasonably accessible, so I'll probably give those some TLC. Other potential leaks include the oil pan gasket and the seam between the upper and lower block. The oil pan is complicated by the fact that there are actually two surface matings there, as there is a baffle plate between the pan and the engine. No big deal, right? Just remove the pan and reseal!!!!
Um.......... no.
Remember the statement earlier about packaging? I have another saying I like to use, which is that GM designs cars to be assembled on the line, and they could give a rat's ass about what effort is required to service them. Case in point: the transmission sits alongside the engine as there is no room to keep it in line with the crankshaft. It nestles against the block under the right-side (rear of the car) exhaust manifold, and it obscures many of the oil pan bolts. Furthermore, there is an exhaust crossover from the left (front) bank under the engine to the pipe at the back. That crossover must be removed to drop the pan, and I'm not sure its bolts are accessible with the engine in the car. Even if they are, you can't get the pipe out from between the engine and the transmission. So any work on sealing up the oil pan's seams involves MAJOR work! In the shop manual, in the process for removing the oil pan, step ONE in simply, "Remove the transmission." Removing the transmission involves draining the coolant and removing some coolant pipes across the back of the engine, and the things required to do in any one step keep backing up into other removals seemingly ad infinitum. Here's a view of someone's work on a Cadillac.. they've removed the transmission pan. You can see how the transmission is in the way of getting to the engine oil pan, and the exhaust crossover is also visible, under that black skid plate..
So as far as THAT goes, if that's maintenance, then yes, maintenance is quite difficult. To me, that's mechanical work. "Maintenance" is stuff like oil changes, keeping coolant good, new spark plugs once in a while. That's easy. But the motor seems to be extra sensitive to it.
I mentioned the seam between upper and lower block a while ago. instead of the traditional iron-block skirt, with the crankshaft retained by bearing caps down inside the block and the oil pan attaching to the bottom of the skirt, this engine splits at the cranshaft. The crank goes in to an inverted upper block, and then the lower block is mated and bolted on. The lower block contains the bottom half of the crank bearings. Of course, that leaves a seam all the way around the block at crankshaft level, a seam that is supposed to keep oil inside the block. There's no gasket, just a sealing compound, but again, that ages and may lose its seal, allowing oil out into the otherwise pristine environment. This of course, is not even remotely repairable with the engine in the car. Here's a view of yet another someone else's motor, with the joins clearly visible, and then a pic of still another guy's engine with the lower block removed:
So if the block join or the oil pan are sources of oil leaks, that shall remain to be the case for as long as I have the car, and I shall pour the occasional quart (or two) into the engine as needed, driveway be damned.
Other than the scary stuff about the engine possibilities, I am quite happy with the car. It's extremely comfortable, loaded with "luxury" features, drives and rides very nicely, and is dang quick if you don't mind hearing cash register bells along with the V8 intake noise. The M-I-L didn't have a working keyless entry remote but I found an eBay vendor with 2 for 35 bucks so that's done. It's got fairly new tires and the battery was new last year, so expensive stuff is not expected soon. As I stated above I need to replace a drive axle, and I would like to get the adapter to allow the steering wheel buttons to control my radio as they did with the factory radio. My radio is compatible, has a jack for that, so it's only about the money. Like anything.
I would be interested in hearing anyone's [informed] opinions and experiences with these, or with other Northstar-engined cars. Do you or did you have one, or do you know someone who does/did? Anyone old enough to have been a racing fan in the late '90s early 2000s will remember the Aurora Indycar engine, which was basically the stock block, different cams, probably different pistons to accommodate boost, and of course turbocharging. 650 HP! Also, the Cadillac LMP car they took to France (with limited success) was actually the 4.0-liter Aurora engine, again turbocharged and running around 600 hp.
