Cadillac Northstar Engine Problems

6 Common Cadillac Northstar Engine Problems

Jake Mayock

Meet Jake

Jake is a founder of 8020 Media and TuningPro. He has over a decade of experience in the automotive industry including parts sales, writing, DIY modifications & repairs, and more. Jake is currently converting his N54 to a single turbo and building a Miata track car. He’s an experienced, hands-on automotive enthusiast who delivers in-depth, well-researched content.

The Northstar engine is a family of GM engines produced from 1993 until 2011. From a technology standpoint the engine was extremely advanced and well ahead of its time. This lead it to winning a few “best engine” awards but the use of new technology resulted in quite a few problems and reliability issues. Furthermore, its transverse mounting and unique design make it very expensive to repair. Ultimately, the Northstar is not a very reliable nor is it cost friendly.

In this guide we’re going to discuss some of the most common engine problems that affect the Northstar. These include blown head gaskets, rear main seal leaks, valve cover issues, oil consumption, carbon buildup, and water pump failure. Additionally, we’ll discuss overall reliability in more depth below.

Northstar Engine Problems

  • Blown Head Gasket
  • Rear Main Seal Oil Leaks
  • Valve Cover Oil Leaks
  • Excessive Oil Consumption
  • Carbon Buildup
  • Water Pump Failure

1. Blown Head Gaskets

Head gasket failure is common for all Northstar engines. The engines head used torque-to-yield bolts, also known as TTY bolts. These are one-time bolts meaning they need to be replaced every time they are removed. Once TTY bolts are tightened they stretch. When the engine overheats the bolts stretch even further and don’t contract after cooling down like most metal does. When the bolts remain stretched and the head contracts, the head becomes loose on the block which causes the head gasket to blow.

While the Northstar engine was actually designed to be difficult to overheat, design flaws actually made it easy to overheat. As we’ll discuss further on, these engines burn a lot of oil which creates a lot of carbon buildup. This carbon buildup then causes increased engine temps which can blow the gasket too.

Lastly, the head gasket can also fail if the head bolts are removed and reused instead of being replaced.

Bad Head Gasket Symptoms

  • Rough idling
  • Poor performance
  • Lack of acceleration
  • Milky white residue in oil
  • White smoke coming from exhaust
  • Overheating
  • Bubbling radiator and coolant reservoir

Unfortunately, with the Northstar head gasket sealer and other tricks don’t work. The only way to repair the gasket is to replace it along with the TTY bolts. The best way to prevent this from happening is to prevent the engine from overheating. Turn it off immediately if it ever gets above normal operating temps. And make sure it is always topped off with coolant.

2. Rear Main Seal Oil Leaks

Northstar engines produced through 1999 commonly develop oil leaks at the rear main seal. The rear main seal is located at the back of the block where the the crankshaft exits the block. It’s responsible for preventing oil from leaking at the crankshaft exit.

While most rear main seals are pressed into the block, pre-2000 Northstar’s didn’t use pressed seals. This leads to the seal wearing down faster from the crankshaft spinning. Additionally, low engine oil levels or infrequent oil changes can also cause the seal to wear down and leak more frequently. Lastly, not driving your car for prolonged periods of time can cause the seal to dry out and crack causing it to leak.

In 2000 Cadillac redesigned the rear main seal by pressing it into the block which solved the premature wear issues.

Cadillac Rear Main Seal Leak Symptoms

  • Low engine oil
  • Oil dripping from back of the block

3. Valve Cover Oil Leaks

Northstar overheating can lead to cracked valve covers or bad valve cover gaskets. When the valve cover fails it is usually the cause of small hairline cracks within the cover. When these cracks form they let pressure and oil out and eventually increase in size causing more leakage. The gasket is also prone to failing from heat, but is also a common maintenance item. Gaskets go bad over time from normal wear and tear and as these engines get older the gaskets are more likely to fail.

Failure Symptoms

  • Oil leaking around the cover
  • Burning oil smell
  • Low oil levels
  • Rough idling
  • Cylinder misfires

4. Northstar Excessive Oil Consumption

Northstar engines are known to consume copious amounts of oil. While this is normal for a lot of high-performance V8’s it is mostly caused by the engine design. Northstar engines are known to consume up to 1 quart of oil every 500-1,000 miles. This is most common in 1993-1999 engines as the piston ring design was changed in 2000.

The oil consumption can be caused by leaks, but in this instance it is being burned off in the combustion chamber. The piston ring grooves are prone to carbon buildup, as discussed below. When this happens the rings get stuck in the ring lands and can’t clean the cylinder walls. This then causes blow-by to seep into the crankcase and oil to burn in the cylinder walls.

The result of blow-by getting into the crankcase is poor performance and bad fuel economy. What happens is this blow-by then gets recirculated into the combustion chamber through the PCV valve. This reduces the amount of oxygen in the combustion chamber which can cause misfires, rough idling, and overall poor performance.

Fortunately, this issue is remedied through cleaning the piston rings.

Piston Ring Cleaning

The excessive oil consumption is less of the issue here; the result of the excess carbon buildup in the piston rings is the issue. Since GM can’t solve the piston ring design issue the best remedy is to clean the piston rings.

The ring cleaning process includes filling the cylinders with a cleaning solvent, or seafoam, which dissolves the carbon and cleans the rings. The solvent is injected into the cylinders via the spark plug holes.

While cleaning the rings will fix the performance issues it won’t fix the underlying issues. This means cleaning the rings will need to be done again when the symptoms arise again.

5. Carbon Buildup Problems

We’ve talked a lot about carbon buildup and how it can cause a myriad of problems like head gasket failure and poor performance. While pre-2000 engines faced a carbon buildup issue that was caused by the piston rings, another carbon buildup issue arose for 2000-2002 engines.

These engines commonly buildup carbon within the cylinders. These carbon deposits are heated up during combustion which creates further heat within the cylinder, burning oil and causing the engine to knock or ping under acceleration.

This problem mostly occurs in early 2000’s models and can be fixed by using seafoam and some fuel system cleaner.

6. Premature Water Pump Failure

This is another common Northstar engine that isn’t at all unique to the Northstar. Water pumps tend to be a point of failure on quite a few modern engines, likely due to the fact that they are under high strain at all times. As the water pump is one of the most important components in an engine’s cooling system, a failing water pump on a Cadillac Northstar can be a significant issue if not addressed in a timely manner. While there is no way to predict a water pump failure, keep in mind that the 100,000-mile mark tends to be the point when you should think about replacing your Northstar’s water pump even if it hasn’t failed.

There have been reports of significant Northstar water pump leaks as early as the 40,000-mile mark, which is very early for a water pump to be failing. This leak can usually be spotted pretty early, as coolant will be leaking underneath the vehicle. A jump in engine temperature can also indicate that your Northstar has a water pump leak, so keep an eye on your temp gauge.

Northstar Engine Reliability

Are Northstar engines reliable? Yes and no. The technical advancements this engine made also led to a lot of problems that were created by poor engine design. When the Northstar is reliable it’s a great engine, when it’s not it’s a terribly painful engine to own.

While most of the problems we mentioned sound relatively easy to fix, they aren’t. The engine design makes a lot of what would be simple repairs into labor intensive and expensive repairs. Therefore, the biggest problem with the Northstar in my opinion is the cost of maintenance and repair.

Temperamental is the best way to describe this engine. While the service manual calls for 7,500 to 10,000 mile oil change intervals, don’t listen to it. Keeping the Northstar reliable requires proactive and tentative maintenance. Change the oil every 5,000 miles. Make sure it is always topped off on coolant. Always run high-quality synthetic oil and put a bottle of fuel cleaner in the gas tank every few fill-ups to help improve reliability.

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  1. Well, I don’t think that I will be purchasing the 2005 SRX that I was contemplating. Thank you for the info here.

      1. Im trying to find the cost of motor mounts for my 2001 cadi deville nirthstar. The car has been great to me. I need to k ow how many mounts they are an how to find them an tell if there bad before i take to shop

  2. Thank U….getting ready to pay too much for 2007 Cadillac DTS….with 40,000 miles….with the North Star Engine……..beautiful car….

    1. Smart move to walk away. I had a 2006 and it’s leaked oil…then the engine seized in 2013 because of the headbolt issue…after always being maintained. The engine is impossible to work on. For example, a water pump job is $1,500.

      1. I haven’t had one problem with my 2007 SRX North Star engine Bought it one year old it has 60000 miles on it now

  3. I purchased a 2009 STS Cadillac in 2009, I have 138,000 miles on it and never had a problem. THis definitely is the best car I ever owned. I still have it, the V8 Northstar englne amazing good gas mileage, took me all over the United States in comfort. I will own it until it falls apart or I fall apart.

    1. Because you don’t have a transverse model! if you had a FWD Northstar, seems like you might be singing a different tune. I’m happy for now with my LQ9 Escalade ESV, but I want something smaller for the better MPGs, been thinking about an STS.

  4. I have a 1996 DeVille it leaks water I am tired of it already I only had it a month so I am going to push it off a cliff so long deville

  5. I had an appointment tomorrow to look at a 1996 Cad Deville, 105k, for just under $3,000.00. It has had extensive work done to it. Headgaskets, water pump, hoses belts etc. After reading these comments from people that know more about this then I do I will pass on this. Being 70 and a 100% DAV from the Vietnam War,I have to watch my pennies. You folks are the bomb like the young kids say.

  6. 90% DAV here as well…. I spent too much on my 2011 DTS. I hope and pray this car endures for a long time….

  7. I have owned a 2011 DTS since 2013. I LOVE this Cadi. I will own it until I can no longer drive. Problems….yes. Mainly oil leaks (it seems every gasket on the engine leaks). Very irritating and messy. And a water pump that cost me $1000.00. Having said that I get over 27MPG on the highway if I keep it at 75mph or less. Super comfortable and fun to drive. AND I can do alot of (extra) repairs over the years compared to depreciation of a newer car plus higher insurance plus higher DMV fees plus sales tax on a new(er) purchase every 3-4 years. Overall it is a beautiful car spiral white zI’m happy, happy, happy!!

  8. Thank you for this! I’ve had a couple of older Cadillac’s (1964 & 1978) and absolutely love the way a Cadillac drives. The 2011 drives like a Cadillac! I love it so far, but started to panic when I started hearing about issues with the Northstar. I need to stop worrying and will start enjoying the experience… Greetings from Eastern North Carolina.

  9. I found a perfect looking 2001 Eldorado. It looks new, but has 160,000 miles. I can probably get it for about $1,000. because of the terrible reputation, but I have to be ready to junk it if the head gaskets blow. I’m torn. Buy it with no long term expectations, or run from it. Thoughts?

  10. Looking at the XLR, should I get it? Thinking about swapping in an LS3 after the Northstar dies, or should I replace swap it from the start.

  11. i have a 2011 cadillac dts premium 147000 miles runs like a charm if and when i need an engin i will buy another or car in love with it its like new in and out.

  12. I own a 1996 Cadillac Deville that I parke outside my house one evening and when I tried to use it the next day it turns over great but it just will not start it happened once before and I bought a used complete speedometer and replaced it it started after that until just about a year ago nothing comes on on the dash (speedometer) the car has less than 100,000 miles on it and I am sick of messing with it besides I am 73 now and not able to do alot of what I was able to do in earlier years. However if anyone has any suggestions I will try again I have checked that fuel pump is working I just don’t see having to replace the dash/speedometer unit every few years.

  13. Got a 2011 Buick Lucerne Super 4.6L V8 NorthStar L37. 4T80E Transmission. Reached 100k. Problems to expect for the later engines? All I read is early years. Please and thank you!

  14. Have access to a 97 DeVille with 34000 for 5K. About ready to flip a coin on buying it. Had one a while back. Still own special tool for water pump. Decisions decisions. I have to at least LOOK at it, right?

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