By on October 4, 2010


SQ writes:

Hello, I am a young female looking to buy a car in a few weeks. I’m in love with Cadillacs & was wondering which years of Cadillac Eldorados have aluminum around the engine? I have been researching this for weeks and have not found any information. Could you please help me out with this?

I would greatly appreciate it. Thank You!

Sajeev Answers:

Ludacris once said, “Cadillac grills. Cadillac mills. Check out the oil on my Cadillac spills.” And I feel he described America’s love-hate relationship with Aluminum Eldorados quite well.

Just to clarify, the aluminum Eldorado motors are from the HT-4100 family and the Northstar family. Both motors have aluminum engine blocks with iron sleeves: the place where pistons live. They are all nightmares to fix for various reasons, but some are worse than others. I researched the forums regarding the legendary crappiness of the Northstar Cadillac engine, coming to a conclusion. Which might be so harsh that I’m proactively begging for the Best and Brightest’s mercy.

Here goes: if you have a Northstar-powered Cadillac older than the 2002 model year, it will (more often than not) have cylinder heads that will not seal, needing threaded inserts to fix stripped threads. (These threads are where the head bolts go into the block, so that’s pretty labor intensive.) It shall be expensive and difficult to repair, and there’s no guarantee it’s a permanent fix. Unless you believe in the magic potion known as “Heal A Seal.”

SQ, since you are a young lady, buy a car you don’t like, get over it, and buy an Eldorado later. You know, when you have the time and space for a second car. And then make it a 1979 or 1980 Biarritz with that awesome stainless steel roof and a distinct lack of aluminum under the hood.

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37 Comments on “Piston Slap: Aluminum is not one of El Dorado’s Lost Treasures...”

  • avatar
    Educator(of teachers)Dan

    I have heard that the 4.5 and 4.9 of the mid 80s to early 90s is not a bad engine.  Although all that evidence is anecdotal.
    I agree with Sajeev, go buy an 1979-80 Eldo with the V8-6-4 engine, it was a 6.0 big block with a crude cylinder management system.  Disable the system and yes it becomes a 14mpg car but damn fun!  Besides you weren’t really worried about fuel economy buy a Caddy, were you?

    • 0 avatar

      The only Eldorado with the variable displacement technology was the 1981 model. It used the same V-8 as the 1980 model, but fitted with the variable displacement technology. This system is easily deactivated by disconnecting the computer that controlled the number of cylinders that were in use at any time.  

      I agree with Sajeev…stay far away from any Eldorado equipped with the Northstar V-8. Or any other Cadillac with the Northstar V-8, for that matter.

    • 0 avatar
      Educator(of teachers)Dan

      Thank you for the clarification.  I’ve been toying with the idea of one of those late 70s early 80s Cadillacs with the big honking engine.  I also know that there is apparently a wire that can be accessed and have a switch installed on it so that the V8-4-6 system can be turned on and off.

    • 0 avatar

      I don’t have time to look for the link but there’s a nice website out there that some V4-6-8 owner put together. It explains all about that early cylinder deactivation system. It turns out it’s not nearly the big deal everyone made it out to be back in ’81. Big deal as far as either making it (sort of ) work or just disabling it, as has already been pointed out.

    • 0 avatar
      bumpy ii

      The 4100 was straight crap, the 4500 was not so hot, and the 4900 was okay but rather weak for its size.

  • avatar

    Woah Sajeev, thanks for treating us all to that Heal A Seal website. You need to put some time aside to study up on that disappointment waiting to happen.

  • avatar

    “Both motors have aluminum engine blocks with iron sleeves”
    The “Iron Duke” syndrome?
    Didn’t we learn anything from Vietnam?
    “Nation building” is apparently akin to aluminum engine building…. or is that “stretching” things.
    I adore analogies.
    They make me giggle akin to a little girl.
    When it happens at the Wal-Mart folks tend to stare, though… unless I pick up a Tickle Me, Elmo before I commence giggling.
    Back to the shanty.

    • 0 avatar

      Not that I know every motor’s specs, but iron sleeves in an aluminum block is very commonplace.  Everywhere, and it works.  The Northstar’s problems lie elsewhere, and while the HT4100 was an aluminum block with iron (!) heads, that wasn’t a big problem either.

    • 0 avatar
      bumpy ii

      GM tried building an aluminum-block engine without the sleeve. They put it in the Vega.

      The Northstar was almost literally two Quad4’s on a common crankshaft, and it inherited all the flaws of the Q4.

    • 0 avatar
      John Horner

      The HT4100 engine was a massive pile of trouble which the Northstar was supposed to be the Big Fix for. Young Northstars are very nice engines, but they do not age gracefully.
      If you want an older used luxury car, the Infinity Q45s and early Lexus LS series are the ones to go after.

    • 0 avatar

      The Quad4 was a pretty good engine for its time, but like all GM engines of the era it seems, it had gasket issues. My father bought a ’92 Olds Achieva with the 150 horse Q4. We never had an issue with it but right after we sold it the new owner suffered the gasket failure. Still feel kinda bad about that one. This was pre-interwebs so the information wasn’t as readily available.

    • 0 avatar

      Actually the first Q45s (the good looking ones) were absolute junk…I lost count of how many ones had vario-cam failures at 100,000 miles in this town.  The only ones I ever saw for sale had less than 95,000 miles on them, and all the others seemed to be in the junkyard.

  • avatar

    My dad bought a ’93 STS with the Northstar back in 1998, and traded it in a few months ago (100K on the clock) for a new Taurus SHO.  Never had any head gasket issues, so he dodged the big bullet.  In order to properly fix the leaky heads, you have to drop the entire subframe, in order to get the proper angle at which to drill out the head bolt holes in the rear (firewall side) cylinder bank.  You have to drill out seventeen holes per side, tap them, and then screw in steel thread inserts to the proper depth, using permanent locktite.  Special kits for this available, one from GM, and (a better) one from an aftermarket supplier.

    While you have the engine out, it’s a perfect time to change the starter, alternator (water-cooled, $500), other hard-to-get-to coolant hoses, re-seal the lower block (to stop those oil leaks), and heck, might as well rebuild the auto tranny while it’s out of the car.  Hence the north of $5K repair bill just for a single leaky head gasket.

    If you must have a Northstar (I fought off the temptation after looking into the head repair mentioned above), look for one which has a newer engine, and/or one which is cheap enough that if you get a few years out of it before major repairs are required, you’re money ahead.  So if you can find a decent one for $3-4K and drive it into the ground, getting 4-5 years (hopefully) out of it, there you go!

    As for that magic engine sealant – it’s activated by heat.  My friend used it on his pre-Northstar early 90s Cadillac in a failed attempt to fix a leaky head gasket – he sealed it alright – it completely plugged the catalytic converter!!!

    • 0 avatar
      bumpy ii

      “While you have the engine out…”

      There is no way that phrase can end well.

    • 0 avatar

      “...alternator (water-cooled, $500)…”

      OK, change the starter, alternator, hoses. Yup, good ide-ah-wait a minute. Did you say the alternator is cooled by the engine’s cooling system?! What engineer on crack thought that was a good idea? I’ve seen plenty of oil-cooled alternators (Delco units on transit buses and coaches) but I’ve never heard of this one. What pray tell is the purpose of not air-cooling the unit? Was it because of placement? Kickback to some production VP at GM from the vendor who got this alternator spec’d in? Drumming up future business for Mr. Goodwrench?

  • avatar

    Why not get a warranty that covers the engine?

  • avatar

    There are (at least) three different flavors of FWD NorthStar engines
    The Good: starting in with MY 2004 GM finally switch to longer stronger, and most important Coarser head bolts that seem to have enough grip in the block to last the life of the engine.
    The Bad: From MY 2000-2003 GM used long fine threaded bolts that hold better, but still pull out of the block… When the bolts fail, not amount of heat-a-seal will solve the problem and
    The Ugly: From MY1993-1999 GM used the same short fine threaded head bolts as are used on the Quad4 engine with similar results.  You can expect that almost all of these engines will fail.

    As was posted above the only thing that any miracle in a can will seal up is your heater core… or worse.  It will not fix a head-bolt failure…

    For all NorthStar engines service the coolant soon and often.  This is rumored to help the blocks hold on the head bolts a little longer… But there are no guarantees with this motor…

    If you buy one of these pre 2004 cars… Yes DEFINITELY get an extended warranty if one is available.

  • avatar

    The early Northstars should be avoided like the plague — numerous issues that will make you more suicidal than a Hells Kitchen contestant.  The 4.9 (iron heads on an aluminum block) was not so bad in terms of reliability.  The problem with the 4.9 is that it’s a relatively primitive mill — 2 values per cylinder, push-rod engine that looks like something out of 1957.  Max HP on the 4.9 is 200, max torque is 275.  The engine launches alright, but runs out of steam fast.  I know, I used to own a 92 Seville.  Around town the 4.9 also gets abysmally bad gas mileage.

    • 0 avatar
      Educator(of teachers)Dan

      Actually I like the 4.9 cause its fairly torquey and feels like an old school small block. I’m sorry but I don’t expect a 4.9ltr engine coupled to a 4-speed automatic (an engine that was developed during the 80s) to rev to 8000RPM.

    • 0 avatar

      The 4.9 is an “old school small block”.  That was a big part of GM’s problems.  While every other car maker had moved on to modern V8 designs, GM was still churning out old school small blocks.

    • 0 avatar
      Sam P

      Ten years before GM introduced the 4.1/4.5/4.9 liter pushrod V8 engine family, Mercedes-Benz was putting smooth overhead cam V8s in the 280SEL 4.5 and 450SL. Hell, Jaguar had an overhead cam V12 that went into the XJ12 and XJS. They weren’t reliable, but then again, neither were the 4.1 liter GM engines.
      GM was so backwards in the 1980s it was almost sadly hilarious.

  • avatar

    Internet car forums are a good research tool, but they also tend to over-exaggerate failure rates by about 200%. And GM failure rates by about 400%
    I’ve known many, many people with Northstar-family engines, of all years, with mileage up to 210K, and I only know of one person that suffered a major failure and that was at 115K.
    That being said, the engine’s internet reputation has done enough to stop me from buying one several times.  And it’s a fussy motor just in general.
    However, if you have your heart set on a Northstar Eldorado, I’ll disagree with Sajeev and say go for it. Just as long as your financial situation allows you to pay $5500 if something major fails.  Otherwise look elsewhere.
    Be sure you get it inspected too.

  • avatar

    The Northstar engine was porported to be able to be driven up to 50 miles with no coolant as a “limp home feature”.  In the case of my 1999 Deville, this was NOT TRUE.  It did not kick in.  If you ever get a Northstar powered Cadillac DO NOT let the engine overheat EVER.  If the engine starts to get hot, pull over immediately.  There is a setting in the drivers information center that tells you the exact temperature of the engine – USE IT.  Overheating that engine WILL cause it to blow its head gasket.   A simple blown hose or a bad radiator can TOTAL your car.  Other than that, I loved my Deville.  It gave me 155K trouble free miles.  And the trans on that car was bulletproof – and comes with a trans cooler from the factory (I assume to accomadate the “limp home” feature that does not work)

  • avatar

    I used to drive a 1999 Olds Intrigue with the so-called “Shortstar” V6 (i.e. a Northstar with two cylinders lopped off). Any ideas on how that engine does over time?
    I sold my Intrigue to my sister at about 95K miles, not because it was becoming a problem, but because I wanted something else. The car now has almost 170K miles and the engine has been trouble free. Well, the CEL is on, but I think that’s related to the gas tank or some other pressure issue outside of the engine itself. The engine continues to work and still feels strong, though with maybe a few less horses than before, but strong, nonetheless.

    • 0 avatar
      Educator(of teachers)Dan

      I’ve wondered that one aloud too, and never been properly answered on here.  I guess one advantage if you could pick up an Intrigue cheap is that if all else fails a 3800 will swap in there no problem.

  • avatar

    I know many people who have had Northstar engines over the past decade.  Of all those people, I only know 1 who had any major engine problems –> the engine overheated it was toast. Tons of people run these to 200k miles with no problem.
    I have 3 Northstar-based engines right now. My 01 Oldsmobile Intrigue has the 3.5 “Shortstar” with 150k miles on it. One of the best V6’s ever made! Decent low end power, but amazing top end.  And I’ve never had any engine problems with it. Like most N*’s, it does burn a quart of oil every 5k miles. But that’s not bad at all.
    I also have an 03 Aurora with the 4.0 V8. One of the smoothest engines ever made. No Joke. It has a slight valve cover gasket leak, but that’s nothing major and it burns oil at about the same rate as the Intrigue.
    Finally, I have an 07 DTS with the 4.6L V8. I love the sound of that thing when you push it. Not had a problem yet, nor do I expect any to pop up for 200k miles.
    Too bad GM didn’t keep the Northstar’s power ratings competitve. They did do the 05 update for the longitudinal versions, but only 320hp isn’t all that impressive compared to the competition. If they had put some $$ into it (Direct injection, some internal redesign,etc.), they easily could’ve topped 400 hp in naturally aspirated form.

    • 0 avatar

      Interesting…amongst my friends, acquaintances and coworks an Olds Aurora with the 4.0 V8 is one of the top 3 mileage champs.  Last time I checked by boss’ car, it had crested 400,000km without any major failures.
      Numbers 2 and 3 are equally unlikely culprits.  Feel free to guess.

    • 0 avatar

      For the record, the original Olds Aurora I test drove for TTAC a looooong time ago was a high mile unit. These motors (at least the Olds 4.0)  seem to do okay with a lot of highway usage and proper servicing.  Otherwise, they tend to not live for very long.

  • avatar

    Another day, another anti-Northstar rant.

    I can’t speak for the earlier engines, but I’m with phewop118. The Northstar does exactly what I expect of it: provide smooth, seamless power and a sense of effortless acceleration in my STS. I, too, love the sound. There’s a winding, uphill road that we drive each week. I use the manumatic mode to keep the revs up and the STS just powers up the hill with authority making a great noise all the way.

    Best of all, the “bad” reputation of the STS meant that I got the car for an absolute steal of a deal. With a full warranty.

  • avatar

    So long as the coolants been serviced and the car has been driven hard you should be fine.

    I bought a 2006 DTS and it has 60k hard miles on it and the N*/4T80E hasn’t missed a beat. Like phewop118 the motor makes serene noises when asked to move.

    If by chance the N* motor does happen to give you CHECK COOLANT messages then head on over to the cadillac forums and look up Northstar Performance. That shop has developed a stud kit to replace the headbolts and its what I’m going to do when I get the my 1996 Eldorado on the road. Don’t Timesert if you do to much of a gamble like Sajeev said. Go with Norms inserts or the studkit.


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