Did you know that you could technically drain every drop of coolant from a Cadillac Northstar engine and still drive home without causing ANY damage?
Despite the black eye on Cadillac’s Northstar engine that was its head bolt design leading to head gasket issues, the Northstar V8 is an engineering tour de force of its time. One particularly interesting feature (or rather, fail-safe) worth nothing was the Northstar’s unique limp home mode which, when the engine’s computer detected an overheating condition, turned the Northstar engine into an air-cooled engine. That meant, if a miscreant decided to foil your night out and stab your radiator, draining every drop of coolant out of your Allante, STS, Eldorado, what have you, you could technically still drive home.
If the power control module on a Northstar equipped car detected an overheating condition which could be caused by a number of issues, most notably low or no coolant, fuel, and spark is shut off on up to four of the eight cylinders at a time. With no combustion happening in up to half of the cylinders, fresh air is pumped through those cylinders effectively cooling the engine.
Thanks to Cadillac’s all-aluminum construction and it’s larger than average oil reserves, a whopping 7.5 quarts of oil, the Northstar is able to shed heat a lot better compared to a traditional cast iron engine block. To put that oil capacity in perspective, even the modern LS2’s in Corvettes only need 5.5 quarts.
With the cooling properties of oil pushed to its limits and the Northstar not actually an air-cooled engine, Cadillac recommends running in limp mode for up to 50 miles although there is some anecdotal evidence on some Cadillac forums of going much further. Top speed was limited to around 65 MPH depending on road conditions and exterior temps. Additionally, oil degradation at such high temps meant an oil change was in order once repairs were wrapped up.
Someone on Youtube uploaded what their Northstar sounds like as it makes its way home on the aforementioned limp-home mode. Keen ears will notice that since the car is firing in an uneven manner, it doesn’t sound the prettiest.
And here’s Cadillac advertising this unique Northstar feature via this informational video you’d probably see running at an Auto Show or dealership.
For 1993, the Northstar V8 brought class-leading performance, even in front-wheel drive configuration, to Cadillac’s lineup. Power for the 1993 Allante was a generous 295 HP and 290 lb-ft, all to the front wheels.
Cadillac did flip the engine 90 degrees and run power to the rear wheels in 2004 for SRX, XLR, and STS. Power bumps to 320 HP and 315 lb-ft made up for the power losses going through a driveshaft.
Cadillac even threw a roots supercharger on for 2006 STS-V and XLR-V which, in its most powerful configuration, made an enormous 469 HP and 439 lb-ft.
But, what about limp-home mode and how much power you made then? According to Cadillac Jim on Caddyinfo, apparently Car and Driver, upon finding out about limp home mode in 1997, drained a Northstar of its coolant and beat the living piss out of the V8 in a torture test of sorts. a 0-60 MPH time of 18 seconds and a quarter mile time of 25 seconds was recorded. Extrapolating from those numbers, C&D estimates that in limp mode, a Northstar only makes 50 HP. If anyone comes across that article, let me know in the comments below.
The Northstar engine remains one of Cadillac’s best engines and features like limp-home mode are proof of that. I’d be remiss not to mention that if you’re in the used market for one of these gems, it’s the 2004.5 and newer engines you’ll want. Headbolts from GM’s LS6 remedied the dreaded headgasket issue.
Did you own a ‘lac with a Northstar or know someone that does? How was it to drive or ride in one? Let me know your thoughts in the comments below.