View Full Version : So I jumped into the Cadillac world with both feet

02-27-03, 02:49 AM
I'm a techie professional who is not too wealthy and "too young for a Cadillac" (I'm 33). I recently bought a Pearl White 94 STS to replace my old wreck. Not mint, but a stunning car. This is my first Caddy. First day I drove it, I fell in love with it. Power, luxury, handling & surprisingly good highway mileage - Wow! And the Northstar appealed to my techie side.

Then it overheated on a business trip. Blown head gasket 400km from home. I was quoted $2000 to fix it, providing nothing unusual was found. $400 rented a U-Haul and bought fuel to get home. It was a private sale, so I had no real recourse to the former owner (I briefly considered inviting him for a Molotov cocktail). I bought the car with my heart and not with my head. I know better. A LOT better.

I started fixing cars long before I could drive. I've done more repairs on the roadside than most people would do at home. I consider myself a "very serious DIYer". I should have looked the car over more thoroughly. Shame on me.

I decided to fix the STS myself & bought the factory service manual (it's great to have it, but it's not perfect). I didn't expect to have to remove the entire powertrain to ge the heads off, but it's a lot more accessible out of the car. And then I was able to put the powertrain in the garage. No room for the whole car & this isn't a fun sub-freezing winter driveway repair.

After I pulled the heads, it got worse. 6 head bolt holes had damaged threads. Pulled head bolt hole threads in the block are a common reason headgaskets blow on early Northstars (ref: Caddyinfo.com). Later blocks have steel inserts to eliminate this problem. The TIME-SERT thread repair kit is expensive, but there's no alternative & it's way cool for tool geeks like me. It came this morning, so that's Saturday's job.

After all this, would I buy the car again? YES! Not this one maybe, but an STS for sure. The powertrain is an amazing package. I've never before owned anything high performance, but I've been interested in the hardware for years. The Northstar boasts lots of great stuff from the factory. The more I look at it, the more impressive it is. I'm hooked.

This forum has tremendous potential. I've already read numerous threads in the performance/technical/modifications areas & I like what I see. DIY Cadillac owners are quite rare, but it's nice to know there are some out there & how to contact them.

I've certainly learned about the Northstar a whole lot faster than I expected to. I'm willing to share what I have learned with anyone who wants to know more.

Glad to be aboard.

Allante North *
02-27-03, 07:16 AM
Hello eehoepp,

Welcome! Sorry to hear about your problem. Sounds like you are well on your way to fixing ot right. While you heve her torn down, why not port and polish the heads and exhaust. You might squeeze some more ponies out of her that way. I hope it all comes together for you and your Caddy is back on the road very soon.

02-27-03, 08:58 AM
First let me say HI! Welcome to our very cool site! Second let me say that 33 is not too young for a Cadillac I've been a Cadillac owner since I was 17 ( My First car ) Have fun, We've got some great stuff going on here! I'm sorry to hear about your problems But....Isn't it cool to dig into a machine like this and work on it? I find that to be a lot of fun! You might consider some minor porting of your heads while they're off. I've never looked at a set of Northstar heads off the engine but I ported my 4.9 heads and the car runs much stronger now! I also milled my heads to raise the compression a bit! That isn't neccesary on a Northstar as they already have good compression! Let us know what you wind up doing...

02-27-03, 09:15 AM
when did they start using steel inserts in the north* engine?

My car overheated into the reds so many times i can seem to remember how many(dealer couldn't figure what was wrong). I was wondering what kind of damage that can do to my aluminum block.

02-27-03, 11:06 AM
I'm not sure exactly when the transition date was. Before I got over the sticker shock of the Time-Sert repair kit (I finagled a fair bit to get it for $670 CDN (normally it would be around $850), I checked the local Cadillac dealer to see if they had the kit & would do the inserts for me. They farmed all the warrantee thread repairs to a local automotive machine shop. This shop made their own inserts and tooling & quoted me $1000 just to fix the block. I found out about the cast-in steel inserts while talking to the guy (owner?) of the shop. I think he said the cast-in inserts stared in 1996, but I was also reeling from his quote, so I don't trust my memory.

The overheating only happened under load. It would idle all day long and run fine. As soon as I started driving, the temperature skyrocketed.

When I pulled the heads, one head bolt had almost zero torque. Closer inspection of the gasket confirmed it to be the bad cylinder.

I considered doing some porting and polishing, but I don't want to take apart more stuff than I have to and time is somewhat critical. My wife and I have been juggling one vehicle for too long. And the casting quality is very good to begin with. GM used a very fine mold sand for these heads. I have read that the biggest bang-for-the-buck improvement in flow you can get is from port matching. I haven't checked the fit-up, but I will. This is not a slopp-tolerance small block Chevy engine by far.

Trouble is, I wasn't able to drvie the car long enough to baseline/calibrate my SOTP.

Yeah, I'm enjoying working on this engine. But my garage is losing the battle with the maple tree that is vying for the same space (garage lists to port) & as a result it's drafty and unheated. It's out of the snow, though.


02-27-03, 12:57 PM
I've had Northstars apart and I've NEVER seen steel inserts from the factory. I'm not sure what you've been told but, I think it's wrong. Maybe the GenII engines do, I've never had a '00 apart.

02-27-03, 04:37 PM
Welcome aboard, Eric. Thanks for signing up! It's good to have another person here who doesn't mind getting their hands dirty...

Okay. Now back to the discussion...

02-27-03, 09:49 PM
Originally posted by Katshot
I've had Northstars apart and I've NEVER seen steel inserts from the factory. I'm not sure what you've been told but, I think it's wrong. Maybe the GenII engines do, I've never had a '00 apart.

well i asked the service man what kind of damamge my north* can receive from numerous overheating into the reds and all he said was the steel wall cylinders (he told me there is no way i can do anything to the block)

02-27-03, 10:42 PM
Welcome abroad!
I'd rather have the 4.9 anyday over the Northstar...but that's just me! :) Keep us posted on how it goes..

02-28-03, 07:47 AM
Originally posted by Devil_concours
well i asked the service man what kind of damamge my north* can receive from numerous overheating into the reds and all he said was the steel wall cylinders (he told me there is no way i can do anything to the block)
That's a semi-correct statement. But to be honest, the BLOCK is the LAST thing you need to worry about after an over-heat.

02-28-03, 08:12 AM
Originally posted by Katshot
That's a semi-correct statement. But to be honest, the BLOCK is the LAST thing you need to worry about after an over-heat.
what things should i worry about after overheating into the reds numerous times from coolant leak other than headgasket?

03-01-03, 09:43 PM
Sounds great, I jumped into the Cadillac World many years ago and in it stronger than ever now!

03-02-03, 09:45 AM
Originally posted by Devil_concours
what things should i worry about after overheating into the reds numerous times from coolant leak other than headgasket?
You will seldom experience any problems with the block due to over-heating. That's not to say that you can't cause some excessive bearing wear and even piston and ring damage, it's just not anywhere near as common. Generally speaking, the damage tends to be greatest at the top-end of the engine. The heads DEFINATELY take the bulk of the damage. It's not uncommon to virtually destroy aluminum heads.

03-02-03, 02:12 PM
Yeah, I'm a little concerned about damaged heads. I know all the usual horrors - warps, cracks, etc. So far I've cleaned the heads almost to the point of looking new. I did a VERY close visual examination of the combustion chambers & I don't see any cracks. Actually, they look really good. I will check them for warpage and leak test them before they go back on. I don't even want to THINK about what a replacement Northstar head is worth.

I just finished installing the inserts in the front bank. I had to take a warm-up break (brrrrrrr). The Time-Sert kit is a dream to work with. It's not idiot-proof, but it is idiot-resistant. Anyone who understands the difference between number, letter and fractional drills, and has a healthy measure of patience and good attention to detail is capable of doing this repair. It takes about 15-20 minutes per insert.

The only downside to this job is dealing with the chips. Blowing the chips out of the holes & degreasing the holes means there's finely atomized cutting fluids and solvents (brake cleaner) floating around the garage (Koff, Koff). And I ended up sacrificing a T-shirt to control where the chips land. I split it up the back so it opened wider and cut a slit in the middle of the front so it just nicely stretches tight over the alignment plate. The T-shirt work really well, and it makes it seem like I'm doing surgery. It keeps about 99.5% of the chips out of the innards. I'm still worried about that other 0.5%, though.

Still havin' fun, which is the most important part.

03-02-03, 02:44 PM
Hello Eric. :) I, too, am new here to this forum. A few buddies of mine let me on to it. :)

I bought my first, and current, Cadillac at age 25. :) So you're not alone in being a younger guy.

Sorry to hear about your misfortune, but you must be having fun. Sounds like you are. :)

It is good to see another "hands on" Caddy guy too. I'm learning a lot as I go. I will be doing a T56 (6 speed standard from a 97 Z28) tranny swap in my car the end of this month. Or, I should say, will be assisting others in the install of my T56. ;) But it's still fun. Yesterday I was there helping Jeff (94badasscad) install a set of headers on his 94 Fleetwood. :)

Being a "techie" I assume you are taking lots of pics to share with us here? I am very curious to see the internals of the Northstar engine.

...and don't even start with the cold, uninsulated garage stories... I totally understand. :)

*with no heat or insulation in my garage, which doesn't matter because I can't even shut the door with my FW in it...* ;)

03-02-03, 03:05 PM
Yeah, pictures. That's right - lot's of 'em. Post 'em any time now...

Ok, I haven't taken any yet, but I will. I knew someone would call me on this sooner or later. I've been a bit reluctant to take the camera out there due to the general oiliness of everything.

I dropped the whole powertrain out the bottom of the car - struts, hubs & all. I built a custom-fit dolly to roll the powertrain into the garage. I had originally intended to put the engine on the stand, but it was easy enough to work on sitting assembled to the trans, etc. And there really isn't room in the garage to have everything separated.

There's already a great site out there that shows how this repair is done:

My engine isn't nearly so clean as that one, but I intend to wash off the worst of the crud. I've owned vehicles from all of the big three & they all leaked oil in some quantity, so the leaky Northstar doesn't bother me too much.

I have the heads off, but the oil pan is still on (it may come off yet). Any requests for specific photos while it's apart?

03-02-03, 03:29 PM
I know that this is probably not what you want to hear right now but....Have you looked at the lower case half to see if it's leaking? If it is....THIS is the time to do the repair on it with everything being out of the car and all it 's right there! It might be worth a look...

03-02-03, 07:26 PM
I've got one word for you, MAGNA-FLUX
Visual inspection DOES NOT CUT IT!!!! Spend the money and get them checked right before you go through the trouble of reinstalling them. I ALWAYS send heads out to the shop once I have them off. I've been bitten too many times.

03-06-03, 05:53 PM
All the insert work is done. Anybody need a slightly used repair kit?I ordered 10 more inserts than I need to be on the safe side & didn't mess any of them up, so it's still a complete kit. Glad to be done with it.

Yes, the case half seals are leaking/seeping oil. Since the car is new to me, I don't know how fast it leaks. And from what I've heard so far, it almost seems to be an endemic problem. I am debating whether or not to tackle the case seals or not. I know this is the time, but my garage is not friendly to open bearings. Squirrels and mice and cats seem to like scurrying around in there. This is the same reason I'm reluctant to tear down the heads to have them professionally tested for cracks.

I picked up a precision straight-edge & feeler gauges yesterday and quickly checked the heads last night. They do not appear to be warped. :banana: I will check them again tonight more thoroughly. I will also leak-test them tomorrow. In a former lifetime I was a foreman in a QA department. I learned a LOT from those guys. I feel confident that I'll be able to vet the heads myself.

I also stopped in at the local dealer to order in the parts I need. The parts are actually pretty reasonbly priced. 2 head gaskets with head bolts, 2 exhaust manifold gaskets, 4 head-block dowel pins (had to come out to put the inserts in), camshaft seal & both coolant pipes around the back of the engine (they were rusty & started leaking when I pulled the hoses off) for $500 CDN taxes included. Not bad.

I hope it looks more like an engine than a pile of parts by the time the weekend's over.