: New motor to replace the northstar

09-23-13, 01:07 AM
Hi, I've seen post on replacing the northstar with another northstar but not one for replacing the northstar with a completely new and different engine. I figure if you replace a northstar with another northstar, you will probably end up with same issues. I had a 1999 D'elegance which blew the head gaskets because the dealer did something wrong. I love the ride and the car. I would like to purchase another 1999 and just replace the northstar engine with a new and different engine. I realize that the transmission may need to be change too. I would like the new engine to get least the same MPG I rec'd with the northstar - 25-26 MPG on the high way. My question is: what engine would that be?
Thank you for you assistance,

09-23-13, 09:02 AM
Simple answer: No other engine will fit/work/adapt to the Northstar System.

Read through the sticky thread ^^^ for Northstar engine compatibility by model/year/type (VIN 9 or VIN Y).

09-23-13, 10:18 AM

Fix it the right way and it will outlast the rest of the car. By that I mean drill and retap all 20 head bolt holes and then insert or stud them. THAT is what the dealer SHOULD have done.

09-24-13, 02:18 AM
Thank you for the quick reply. I didn't realize that there were other NS systems in the vehicle, thus replacing the motor and transmission there would be no NS system left to fit/work/adapt with. What are the other NS systems and if those we're replaced too would it work?


Thank you also for the quick reply. The dealer broke the Mas Airflow Sensor, which in turn made the engine run away and accelerate. This shortly made the engine overheat. The dealership states it was broken when it came and was going inform me in 2 weeks when I came back with something I had made an appt to get done. According to a GM certified mechanic, this is a critical part of the motor and is very dangerous and his belief was that the service person had no idea that it was cracked. Anyway, some of the issues with the engine is the oil pan - it leaks. I am told that the entire motor needs to be pulled to replace a rather inexpensive part. Other than the motor being destroyed by the dealership and the oil pan issues the vehicle was excellent. It rode great and there was room for 6 people to sit semi-comfortable. Bottom line it sounds like if the motor is not screwed with, the only true issue is the oil pan issue (the gasket), which is apparently very expensive. All others are pretty much normal repairs. I'm informed that all the NS engines have the oil pan issues, is that true?


09-24-13, 05:30 AM
"Northstar system" is just GM terminology. you can replace your engine with another Northstar (of certain years), and that's it. Many of the cars electronics are designed to work with the Northstar, there is no orher engine that will bolt in without modification, there is no other transmission that will bolt in without modification, the....

Northstars don't have "oil pan issues". If the oil pan seal is leaking, yes, the engine does have to be removed (or the engine supported from above, and the cradle removed). But how much is it leaking? The $2,500 or donot would cost to repair the leak can buy a LOT of oil.

I still don't understand why it needs to be replaced. It overheated because there was a problem with the MAF, and...?

09-24-13, 09:56 AM
No, all Northstars do not have oil pan/oil leak issues and the reason that the seal replacement (no gasket) is so expensive is that the entire engine has to come out of the car and the oil pan taken off, the seal groove cleaned and replaced with a special RTV bead.

The engine is in 3 parts - the upper cylinder block, the halfcase/main bearing lower halves/stud girdle, and the oil pan - all of which are machined as an assembly, torqued together and form one solid structure.

Bottom line: You cannot replace a Northstar engine with any other type.