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How to Repair Bottom End Oil Leak Cadillac Northstar Engine

by Contributor

Hey there it is time for, Why is My Luxury Car My Cadillac STS leaking OIL! WOW! It's $2800.00 to fix! What did I do wrong? or as I say "OH NO MR. BILL" its "Sluggo". Cadillac from 1994 and 2000 + even some newer one leak oil from bottom end. I wrote as a Service Adviser for 20 years with Cadillac, and GM along with Mercedes-Benz. Yes I have seen a lot of factory problems with Cadillac through the years, and yes all the manufactures have some kind of problem, but nothing made me more angry than the Northstars lower end oil leak and the fact that they had head gasket problems on top of it, but that's another e-How, How to article. I also recommend you "DO NOT" try to fix this oil leak problem yourself go to a trusted GM Cadillac dealership and or if you have a non GM/Cadillac repair shop you know of that is good and can trust, but be careful my friends, a lot say they can and really can not correctly fix this problem. This is just a guide what you might go through to fix this leak if you were brave enough to fix it yourself.

Step 1

This is what you need really a car hoist, mabe not this one, but a car hoist

Like I said take your Cadillac Northstar to your local repair garage and bite the bullet and if not here ya go. First read your repair manual you bought from Cadillac, oh ya first BEER, pop it and enjoy you'll need it. To remove your Cadillac engine though the top you need to push you hood back full tap that helps you open your hood to max position for easy access and pulling engine not all years had this and you need to pull hood. You need to unhook battery positive cable, some are under hood on older models and some on newer are under rear back seat. Then all wires under hood that are connected to engine, there are wire looms that are easier to disconnect when doing this, but that need to be disconnect have to be, and first before you start this take a picture it could help you, and pop another BEER. You will have to be on top engine compartment area and under car for disconnecting various components. Like exhaust and various other bolts, remember repair manual read it will help you. Top end disconnection. Take loose and or remove cooling system hoses, drain coolant into recovery pale, do not and I repeat myself do not! drain coolant into driveway of street, nor drain in ground soil, protect your habitat at all times, pull radiator which at that time check side cooling tank fins if they are cracked take to radiator shop and either replace tanks and or replace radiator, also drain engine oil out into container and do not be cheap and put old oil and or coolant back into engine, replace and there are a number of recycle place that take your old oil and coolant to like the part stores where you got your oil and coolant from a lot offer that service. Oh and pop another BEER! Again checking your Cadillac repair manual look for all bolts needed to be removed heading for engine removal. Have your cherry picker ready and finding the engine pull straps top side engine right and left side go a head and attach your chain in readiness of the big pull. Make sure you have removed torque converter bolts and all bell housing bolts, and get ready to pull engine out. Like I said in the beginning get help from a friend. One to shake engine uncouple and the other to pull cherry picker to right to help uncouple engine from trans and lift out of engine compartment. Oh you and your friend deserve to pop several BEERS, NECTOR of the GODS.

Step 2

This is where you really need to go, to the service drive.

Now you have engine out you will need tranny bolts you pulled out of bell housing and if to short you will need to get at least 4 and mount and bolt engine to engine stand and make sure it is attached correctly by spacing out mounts as even as possible for balance and make sure engine stand is a heavy duty one. If your engine falls to the ground and breaks, its junk and New Cadillac engines for Northstars are around $6500.00 or so and use I wouldn't go there you don't know what you will get. Pop another BEER!!! You will need to flip your engine over so back side is exposed for easy access. I would suggest cleaning up before you start by buying Engine Gunk and spraying down and washing off, this is a very or can be a dirty job, Hens forth the name GREESE MONKEY, for your knowledge base. Again looking at Cadillac repair manual see replacement of gaskets and I highly recommend resealing complete bottom end of engine so you will not have to pull out engine for long time, be smart not cheap!! Install new gaskets and seals also some GM sealant will help. When doing oil pan use the special GM sealant you got at your Cadillac dealer and don't be real cheap its expensive but very good when it comes to plugging a leak as in oil pan, make sure rear main seal replaced and front timing cover seal and finish under engine and flip back over on top side again. Ok time to pop another BEER, ok 2 then and call it a day.

Yes now you know this is where you needed to go first the dealer instead of pissing wife off. That is me

The next day and another beer after breakfast, juice, and coffee your ready to start engine back in installation and again get your friend to help reinstall engine back into engine compartment, same way but reverse of what you had done yesterday to pull engine in first place. Make sure you put all bolts back in engine you pulled out, remember pictures you took, good idea to look at them, POP a Beer. after all bolts reinstalled time to hook wires back up and into position just as they came out from yesterday, remember Cadillac repair manual. Reinstall radiator, all hoses and clamps, forgot put new motor mounts in, Cadillac motor mounts break like crazy, one reason the transfers sitting engine is hard on them so replace them. Hook up exhaust and anything you have removed and or loosened under the car. Install fresh oil, also you replaced the oil filter, and install new coolant, note 96 and new used Dexcool and 95 down used the green [engine coolant]( don't mix them up not good. With all fluids in, hook up battery, one last inspection and fire engine up. if you did the job right and I hope you did your engine will start and run and will have no leaks, sit back and you know what POP A BEER!!! You deserve it.


  • The Cadillac dealer a lot of times the Tech being having an engine hoist will pull trans and leave engine in car and charge full pop for engine removal and will charge extra for motor mount removal when you have paid for it already, watch the double labor charges they will try to pull on you.
  • Like I said I would not try doing this repair myself, and thank god I was in the service sales end not the actual hard wrenching side.


  • Remember take your time when doing anything like this, and if your not sure read the repair manual and once you start the dealer is no help and if you have to tow to the shop because you could not answer the bell fixing this monster, they will charge you more money, can you blame them, no, YOU TOOK THIS APART!
  • OH and about the BEER do not over due it be safe I just through that in about the BEER to lighten things up, good luck to all who try this you will need it!!! Maybe you should lay off the beer and go straight for the JACK, just kidding, LOL, NO DRINKING!!!!

Items you will need

  • You will need various metric sockets, ratchets, air tools, floor jack and stands if you can get, or barrow from your best pal down the street.
  • Screw drivers Phlips/straight
  • Metric wrenches
  • Metric Sockets
  • Ratchet wrench
  • air tools would be great!
  • Cherry picker
  • an extra body or 2 like someone who knows what they are doing.
  • Service manual
  • various gaskets and seals, buy all the bottom end seals and gaskets, from either parts store and or Cadillac dealer, which is what I recommend several tubes of sealer high temp also from Cadillac deal
  • a lot of luck remember I said take to dealer, you should!
  • and a lot of BEER, yes BEER the nectar of the Gods, you'll need it.

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