: Northstar Swap Question

02-06-14, 08:06 PM
Hi all,

I recently got my mitts on a 2001 Deville DHS. It has 88k miles on the engine. I am getting about 18 MPG highway and burning oil like crazy.

I have a 2000 Deville with 185k miles in storage. The engine was replaced in 2006 by the dealership when they could not figure out what was wrong with the original 2000 engine (bought used; was still under warranty). My understanding is that a 2006 engine was placed in the car, as well as a new computer (at least, that's what my mom told me, and she is who I bought the car from .. don't have service records -- could I obtain this from the dealership where it was serviced?). Although the 2000 Deville has 185k miles, the original engine was replaced at about 100k -- so the new, 2006 engine only has about 85k miles on it.

The 2001 Northstar and the 2006 Northstar have just about the same mileage.

I got about 22 MPG highway on the 2006 Northstar and burned virtually no oil, so before I sell the 2001, I was wondering if I could swap the engines out. Seems like a good idea to me -- newer engine, better mileage, and makes my DHS even hotter. :)

What do you guys think? Is this interchange possible? I read through the first few pages of the Northstar swap thread (sticky) but didn't get anything out of there that said it was a definite yes.

Thank you :)

02-06-14, 08:15 PM
It's not a direct swap. Several differences, including a completely different ignition system. The engine may be from '06, but it's not a 2006 Northstar.

A Northstar with 85K is barely in adolescence. Lots of work to swap, Really no point.

Do some reading in the Technical Archives about oil consumption.

02-06-14, 08:39 PM

And check the FPR. If it is leaking internally it can cause your fuel mileage to drop. Likewise if you have a slipping TCC. Pull the DTC's and see if you have a P0741 code.

02-10-14, 12:19 PM
My DTS has an intermittent P0741 code.

02-10-14, 12:48 PM
The OP's 2001 DHS should easily get 24 - 27 mpg highway (long term) on 87 octane fuel.

The 2000 should have the exact same engine - and get the same mileage.

Both engines are the VIN Y 275 hp / 3.11:1 economy final drive package.

Take a look at your engines - if they both have the 4-coil ignition cassettes then neither engine is newer than late 2003. (The "2004" SLS used all 2003 and earlier parts) In 08/03 (the start of the 2004 MY) Deville engines went to a separate 4-coil 4-boot 4-connector COP system.

This is what the cassettes look like - and my guess is the engines are identical.

02-10-14, 12:58 PM
........... and here's the 2004 Deville COP arrangement.