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what to check when buying a northstar?

9K views 53 replies 8 participants last post by  westman995 
#1 ·
I'm looking to go pick up a 2002 dts tomorrow and I'm wondering if there's anything specific to check. I'm buying it just for the engine. Its going into s 2000 dts. Is there a way to be sure its a vin 9 engine while its still in the car? I'd hate to buy it only to find out its been replaced with a y engine. Car has 180k so who knows if its been repaired/replaced
 
#2 ·
The only difference on that engine will be all four camshafts. You could look at the side of the block, and you wouldn't even know for sure without checking the camshaft casting numbers by taking the valve covers off (if someone has ever done a head or cam swap).

If you can get underneath the car, there is a VIN pad with the last 8 of the vehicle VIN stamped into the engine, and also the letters either "LD8" or "L37". L37 is the VIN 9. This VIN pad is right near the RH transmission output shaft/tailstock.

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Out of curiosity, is there a reason you don't just fix the engine that's in your DTS? Is it blown?
 
#5 ·
I am studding the engine before I put it in. I plan to fix any common problems on it before it goes in. I already have the studs I bought a while back. I still need to figure out what I'm all going to need like gaskets and what not.

Right now I need to know if there's anything special to check out on the engine before I buy it. I don't want it to end up being junk
 
#9 ·
Thread title: The same things you would check when buying any other car/engine on earth. The Northstar is not alone in its quirks, faults, care, feeding, and maintenance. ANY internal combustion engine has its problems. It's a power producing, highly stressed mechanical marvel and it will not, can not, should not run forever, regardless of the fact that the body it's in cost $65,000 out the door.

hell - even your Waring Blender craps out once in a while. A used car is a used car and the chances are 99 - 1 the reason it's on the lot is because the original owner was tired of sinking money into it. Now it's your turn.

Homework for anyone: The entire Cadillac Technical Archive way up ^^^ in the top black bar. The sticky posts in any forum of interest. Cadillac Tech Tips. all of Engines; Northstar. "................ but, that's a lot to read !!!" Tuff muffins. Get off your butts and learn something.
 
#10 ·
Well I bought the car. Has more miles than I was hoping but I hear other than the head gasket problem they're pretty reliable so hopefully its worth it. Its got 195k on it.

I've already started taking stuff off to remove it. I notice the alternator and everything around it is caked with oil. Could this be a valve cover gasket or is it likely something else?

Should I be trying to reveal the bottom end? Replace any other parts while its out since it's got higher miles?
 
#12 ·
I have everything but money haha. The cost is what's going to slow me down but I do plan on fixing everything before it goes in. No sense in having to drop the emgine again.

I've got the cradle out of the car. Now I have to figure out how to get the engine off of the cradle/trans. I should have removed all the brackets on bottom of engine and the flywheel bolts while it was in the car
 
#13 ·
You can either pull your torque converter with your engine then remove it later, or remove the starter and access the bolts from there. Offset box wrench time.

The brace on the bottom (4 bolts) needs to be removed though, but it would be easily accessible unless the cradle is sitting on the ground.
 
#14 ·
It turned out to be easier than I was thinking. I've got everything seperated. Engine is ready to be taken apart. After that I need to see what I all need to buy for it. Mostly gaskets/seals. I want this engine to last. I don't want it to leak a drop of anything anytime soon.

I've been pricing parts on rockauto.. and as far as I can tell, its going to cost A LOT to get everything resealed on this engine.

Should I go with fel pro head gaskets? They're $18 each on rockauto.

I also need valve cover gaskets at the least. I would like to just replace almost everything: intake, throttle body, etc... crossover if necessary..

One of my main questions is about resealing the lower end. I understand there is some sort of plate/gasket that goes in there. Its at least $60 if I recall..

Prices are adding up real quick. Good thing I bought my studs a while back
 
#15 ·
You must replace the oil distribution manifold when you separate the halfcase (lower main bearing halves, main bolt girdle). There's a Service Bulletin on how to use the new GM RTV gray instead of the oil pan and halfcase seals. Use a pair of MLS head gaskets - $120 each. No grinding on the crank (rolled radius throws and mains), no honing the cylinders. No deck milling allowed - deck out of spec by .004"+, replace the block. Heads can take a .008" cut MAX. #2 piston ring is one-way - dot up. Use an Edelbrock, CompCams, Mondello, Engle assembly lube on the new bearing shells and cam followers. Special procedures for oil pump overhaul and installation - mess up that torque sequence and you have 0 oil pressure. Yes, without question, remove, clean and replace the water crossover and gaskets (new style). 5W-30 synthetic oil and a WIX 51522 filter. AC Delco #41-987 Platinum professional plugs. A Q-Tip dab of silicone dielectric ignition grease in each plug boot tip.

Got a GM/Helm service manual set ???? You're gonna need it every step of the way.
 
#18 ·
There are several threads in here and in Tech Tips that contain MANY pictures on Northstar top overhaul and total overhaul, as well as pictures and videos of the stud installation process.

Better yet, get a multi-year subscription for your particular car - www.alldatadiy.com - or find a real GM/Helm service manual on eBay. Used pricing has inflated due to the new prices at helm - www.helminc.com
 
#19 ·
I've pulled about half the head bolts out. None of them have pulled any threads with them. What is the chance that this engine has already been repaired with inserts? Will I be able to tell easily if it has inserts once the heads are off?

And if it already has inserts, can I still stud it?
 
#22 ·
I am just about ready to pull the heads. I think I just need to remove the timing chains now. Front cover and oil pump are off.

I am having a hard time deciding if I should reseal the bottom end or not, since it has higher miles and I have no idea what the previous owners did or did not do to it. Thoughts?

I'm also wondering about the rear main seal. It is the one with the green lip or whatever. However it almost looks like It Isn't seated all the way or something. I'm gonna try and get a pic up soon
 
#24 ·
Starting to think I may as well just completely disassemble it and check everything over since its already this far apart. Maybe put new rings in it? Also would obviously reseal bottom end if I go that route.

Guess ill also need a seal installer. Which installer to use for a fel pro seal? Require sealant?
 
#26 ·
Don't use the Fel-Pro seal. Use the GM seal P/N 12568025. Definitely use the correct installer tool. And if you do re-ring the Northstar; talk to us. We've found the right hone/ring set to reduce oil consumption tremendously. We sell the rings as well.

Here's a small list of part numbers I've compiled (and adding to regularly) to make it a bit easier for people to order parts. If you knew the difference between the Fel-Pro and the GM rear main seal, you'd gladly pay the extra $20 or so it costs.

http://www.northstarperformance.com/partnumbers.php
 
#27 ·
The cylinders look good, still shows the cross hatch patterns in it. If the rings don't wear either I'd rather not take the pistons out of the block.

I bought a full gasket set so I've already got the fel pro seal. I will look into the gm seal. I have been using your page for a couple part numbers. I couldn't find the sealant at first, but I realized it was cuz you use the canadian part numbers.

So I'm thinking ill just basically reseal the whole engine up for the most part like I had originally wanted to do. Any other parts I should pay close attention to?

I finally got the heads off it yesterday. Is it ok to turn the crank? I want to clean the carbon off the pistons. I think I have it in the right position to time it when it goes back together

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Nevermind it didn't come with the rear main seal. Just the front. Are all the other fel pro gaskets good to use? Ill definitely get the gm rear main seal. Is a oil manifold off rock auto ok to use? Its a Victor reinz I believe
 
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