: 4.9 vs. Northstar

02-07-07, 12:18 PM
Not sure if this conversation has been run into the ground or not, but whats everyone think?

02-07-07, 12:33 PM
I'm not an expert nor guru .From what I get , in general, 4.9lt seems more reliable to Northstar .It seems more reliable but let's not forget coolant tablets are mandatory for 4.9 unlike Northstar. I don't know what would happen if you didn't put those tablets in lower hos e .
Despite all quirks and problems ,I would still go with Northstar because if it were such a bad engine would it be default engine for Cadillac line up ?
May be by 5 years it would be the best engine made by Cadillac who knows ?

02-07-07, 02:27 PM
The 4.9 is a great engine and transmission combo that put out 200 HP, but it is a dinosaur compared to the 32 valve, 4.6 liter Northstar that puts out 275/300 HP. Both engines are reliable when maintained correctly. We have seen many NS's go over 200K miles. The Northstar platform has continued to evolve and improve and now the original Northstars are dinosaurs compared to the the current version. The Northstar has a +5600/6000 RPM red line and while I have heard that the 4.9 is stronger off the line, the Northstar eats the 4.9's lunch as the RPM's increase. I have owned both a 91 Seville 4.9 and now own a 96 Deville w/NS, love them both but the NS is freaking amazing...

That said, I would be reluctant to buy a NS not knowing its maintenance history, on-time coolant changes are imperative...

Understand that the 4.9 now is at least 12 model years old, we have been seeing internal leaks on the other board. The cylinder liners have o-rings that age/dry rot/shrink allowing coolant to leak into the crackcase, use the cooling supplement and change the coolant. The 4.9 can have a #1 main bearing knock that is just a nuisence and can be minimized by using Rotella 15W40.

02-07-07, 04:34 PM
coolant tablets are mandatory for 4.9 unlike Northstar. I don't know what would happen if you didn't put those tablets in lower hose.
Nothing. The 4.9 (unlike the Northstar) will readily mix coolant with the oil in the event of an intake manifold leak or a head gasket leak. The tabs are to prevent this as well as seal porous castings. They are preventative only so unless you have a leaky gasket, the engine will never know they weren't used.

02-07-07, 06:15 PM
Thank you Ranger for your explanations :)

02-07-07, 06:39 PM
I thought the Barsleaks GS/GM coolant tabs were manditory for the northstar as well.

that being said and put aside, with a few notable and expensive exceptions(Headgaskets) the northstar and 4.9 have a very similar track record with reguard to reliability. As far a longevity the northstar trumps the 4.9 hands down (again with the afore mentioned exception) The northstar can easily see 250k+ mi and still seem practically new where as things like the rocker arms (and mounts), cam shafts and cam driven gears start wearing well before this.

I own and drive both and they are both excellent engines.

02-07-07, 07:30 PM
I thought the Barsleaks GS/GM coolant tabs were mandatory for the northstar as well.
Technically mandatory in the 4.1, 4.5 & 4.9, but as mentioned above, not using them won't CAUSE any damage, though it won't prevent it either. Early Northstar FSMs and underhood stickers said to use them, but at some point GM changed lanes and does not use or recommend them any more on the Northstar.

02-07-07, 11:11 PM
hmm.. well that explains it, my 94 says it is required.