This thread is in NO WAY meant to belittle the 1993 or any other Allante.

I believe it is a good thing to be aware of expected potential or ongoing issues on any car.
This thread is meant to do just that. Not the 1 issue in 1,000 cars, but the most very common
issues for this '93 model.

For those that dont know, every 1993 Allante had the 1st generation NorthStar 4600 engine
and this models are considered PHASE III.

I have tagged the thread .. " FAQ "

Please keep any issues in this thread to those strictly related to the 1993 Cadillac Allante.
Any issues common to all year models, including the '93, please post elsewhere.



ISSUE: Engine misfire, most probable causes: coils, primary wires, PCM



my 93 seems to be running on 7 cylinders, misfires, wants to stall. has 150k mi

what do I look for?

it was a coil
thanks




My 1993 Allante has an engine miss on a slight grade, high gear, but if it shifts down to the next gear the miss seems to go away.

I have changed the plugs, wires, EGR valve, PC valve. $$$$$$$$ +$$$$$$$ +$$$$$$$$ + $$$$$$$$$$

I have checked the diagnostics, no codes.

What else could I look for?







by Allantesource

the ignition coils if original are the most cause of a miss.

Spark plug wires are the second most common cause. The plugs are platinum and probably are fine. GM recommends a 100,000 mile change interval, but a Northstar powertrain engineer who used to post here said that change interval was arbitrary. They just didn't want to say anything would be good forever, for the life of the car. But the platinum plugs probably would be. I just replaced 4 originals on my '91, and they had about 180k miles on them. I had replaced the front 4 at about 100k miles and just had never gotten to the rear bank. The only reason I changed them was that I decided to replace the original spark plug wires. The rear plugs were still fine.

I really doubt that replacing your spark plugs will have any impact on your problem. You can isolate the problem cylinder through the on-board diagnostics, and then replace the coil. Or you can buy a coil and swap it through all 4 positions until you eliminate the problem one.


By Allantesource

In addition to the coils, '93 PCM's are also a real weak spot.

I have not seen an original still in place in years. Apparently most have needed replacement over the years.



to get to Dick, CLICK here:
ALLANTESOURCE (http://www.cadillacforum.com/showProfile.asp?memid=2895)

'93 unique topics

- engine misfire
- plenum failure
- flying soft tops
- flying boot covers
- headbolts
- struts
- transmission
- overheating
- ???

.. to come ...

.

Luckily the PCMs can easily be found - they were on a lot of Caddys, and I believe even the Aurora - and for not much - I think about $150, and that is from GM.

Heck, give me my old Northstar over the 4100 hook and tow any day - and even the 4500 has its share of problems.

I think one of the best parts of the Northstar is that a lot of the parts are still available - new - from GM - they put that power plant in so many cars.

It can't be such a bad engine - lots and lots of people race with the Northstar - very few with a 4100 or 4500.

Stealth -I think you are just itching for a fight - and this week, since my Allante is enjoying an extended stay at the Car Spa - there just isn't much bite in this Fox...

ORIGINAL: Stealth

'93 unique topics

- plenum failure
- flying soft tops
- flying boot covers
- headbolts
- struts
- transmission
- overheating
- oil leaks
- ???

.. to come ...


I have owned my 93 since 94 (79k miles)and I have had none of the above problems that you have so eloquently outlined. The N*'s in our caddies are nothing more then a detuned racing engine.

Hey Fox, this is he way I think of the older crowd with pre 93's.............If I have to explain they won't understand. Having said that, the pre 93's do have some good points too, and they are beautiful cars.

ISSUE: Northstar Plenum fire and explosion, most probable causes: leaky fuel regulator, original engine cover.

Conclussion; this ailment is only associated with the 1st generation NorthStars, not on subsequent generation Northstars of other Cadillacs.

FYI - for the purpose of this "engine" topic, the Phase II are the 1989 - 1992 Allante 4500 engines,
not to be confused with the hard/soft tops, Phase I, II, III. This topic does affect other Cadillacs but unsure as to what models and mfg dates are affected. I believe this was a GM recall.

by Allantesource

There is a definite reliability gap between the early Northstars and the 4.5's. Now that GM is not replacing '93 Northstars under warranty, that alone is a real good reason to opt for a Phase 2. The head bolt problem is expensive to fix, not to mention the oil leaks and the plenum issues.

by unk

on the cover for a 93, GM offered two designs intake mainifold cover...
- ORIGINAL design used bolts without grommets,
- second design is with grommets

newer design pn 17090937 costing around $210 if avail, shared with other models such as EldO '94

what do the grommets do?
by Allantesource


With grommets means that there are rubber grommets under the cover retaining bolts that will give if there is an explosion inside the plenum. Without the give of the rubber grommets, in the event of an internal explosion (such as from a leaky fuel pressure regulator) the plenum blows up and has to be replaced. I have no idea if the plenums will accept both covers or not. The only plenum I replaced personally was a later style, and it had been hit and cracked by a piston that went up through the valley. I sold an early plenum to someone who had the explosion in a very early '93 Allante'. But he would have used the cover that came with the one I sold him. You could always pick up a plenum off a '94 Concours, Seville, or Eldorado Northstar. Those are all the grommet style.
by jefft

Wait a minute, EXPLOSION? WHAT EXPLOSION. Every day is a new learning experience.

Just when you thought buying a 93 was a "safe" proposition ol Dick tells us all about the EXPLOSION in the valley! Jeezsch!
by Allantesource
The plenum issue is explosions in the plenum when the fuel pressure regulator malfunctions and leaks gas which can get ignited. The "fix" was to place rubber grommets under the cover bolts, so if/when there is an explosion, the cover lifts to vent the force generated and the plenum doesn't blow apart. That whole plenum system was redesigned for 1995. Early 1993 Allante's did not have the cover grommets. All were supposed to be modified, but as with every recall, some were missed.

by unk

An explosion can be caused by a faulty FPR


Cadillac plenum fire
local://upfiles/2893/A38287660C8A452AB5068ED2FD14D3C0.jpg

Hey, we all joined the same club when we bought any year Allante. I don't believe I have seen any one year or engine signaled out with "less" problems. I've only had "one" major problem with my "87" for instance. The "dreaded" head gasket problem which would have been alleveated if Cadillac had insisted on 24 mo coolant replacement from the go, go. Heck and all I had to do to correct this in my car was replace the engine!
The "brakes!",, heck, that's something all owners should expect and I feel sorry for the owners that don't know of sites "like this" and Allante source. I thought of "upgrading to a "93" because of the brake potential but when I weighed losing the seats and relative simpler systems all around vs getting a lot of power I really didn't have any use for, I decided the money for a hobby didn't warrant it. For a daily driver "maybe."
On the outside the cars are just as attractive. That "northstar" under the hood is pretty impressive but then you probably have all heard of the intake manifolds on the 4.1's and 4.5's being so attractive they've been usedfor "coffee tables."

When the ASA (Auto Inc) website has an article on rebuilding engines and the single Cadillac engine they quote.... "Cadillac's 4100 engine has suffered from a series of glitches including overheating, cracks and bottom-end knocking, most stemming from its somewhat unusual design and cooling system requirements." along with only 2 other brand name engines - Chrysler's 2.2-2.5 and Mitsu's 2.6 you know there has to be more then "legend" to the moniker "Hook and Tow"

Article quoted (the bad engines are listed about 1/2 down in the article...)

http://www.asashop.org/autoinc/june99/mech.htm

No Northstar on that list - and I have the late series Northstar - I hopefully won't burst into flames anytime soon...

ORIGINAL: foxpaws

When the ASA (Auto Inc) website has an article on rebuilding engines and the single Cadillac engine they quote.... "Cadillac's 4100 engine has suffered from a series of glitches including overheating, cracks and bottom-end knocking, most stemming from its somewhat unusual design and cooling system requirements." along with only 2 other brand name engines - Chrysler's 2.2-2.5 and Mitsu's 2.6 you know there has to be more then "legend" to the moniker "Hook and Tow"

Article quoted (the bad engines are listed about 1/2 down in the article...)

http://www.asashop.org/autoinc/june99/mech.htm

No Northstar on that list - and I have the late series Northstar - I hopefully won't burst into flames anytime soon...


The title of the article in the above link is:
" Repair, Rebuild or Replace? "
http://www.asashop.org/autoinc/june99/mech.htm

keeping THAT title in mind, read on ..
ohh, and BTW, what will the next high power '09 CTS-V and C7 Corvettes probably use ?

by the Engine Rebuilders Association (AERA)

In researching this engine, we discovered that few rebuilders are overhauling Northstar V8s - not because these engines are lasting forever (they're not) but because the Northstar V8s are such expensive and complex engines.

Cadillac has no reman program for Northstar V8s (if one fails, replace it with a new one).

None of the major production engine rebuilders are doing Northstar V8s, and some rebuilders told us certain critical internal parts are unavailable (such as oversize crankshaft bearings).

Add to this the fact that the cylinder liners can't be replaced or overbored and it doesn't leave much to rebuild.



for additional info ..
http://www.cadillacforum.com/m_17336/tm.htm


======================================

my only bubble bursting personal comment to all this Northstar chatter?

I dont believe the N* is an engine that can be economically overhauled and I do believe that
the use of salvage cars and the engines from "wrecked" cars" is an excellent and econo solution,
if you are willing to do your homework ...

IF the need is racing, overhauling/rebuilding the innards of a N* is probably not the answer,
adding accessories like blowers, NOS, and such, or exchanging cams, ignition system, exhaust systems,
filters, etc or changing the timing (performance chips) .. may be .. ask around .. do your homework as
it relates to your specific car and model and version of engine.

IF your need is to drive point A to point B, R&R is probably the viable economical answer for now.

Whether an Allante or any other Cadillac, no matter.

"B--U--T????? My neighbor in Texas bought a 93 Cad sedan for his wife for "economies" sake. He was impressed with the first car engine that you went 100,000 miles before even replacing the sparkplugs!!
Couldn't answer my question about how difficult it might be removing some spark plugs from an aluminum block engine after it had gone those 100,000 miles!

ORIGINAL: hyperion

"B--U--T????? My neighbor in Texas bought a 93 Cad sedan for his wife for "economies" sake. He was impressed with the first car engine that you went 100,000 miles before even replacing the sparkplugs!!
Couldn't answer my question about how difficult it might be removing some spark plugs from an aluminum block engine after it had gone those 100,000 miles!


zinzin,

i'm starting to believe that people are reading what they want and not what is written.

concerning the Northstars, my gut feeling is that a N* will go 250,000 to 300,000 miles without much
maintenance, including running the OEM plat plugs for that long, as long as:

1. change out the coolant at 24 month intervals,
2. change oil as required by oil monitors,
3. routinely replace all little things that fail, like coils, primary wires, etc ..,
4. run engine until it warms up well,
5. clean out the coke deposits on the intakes and make sure it doesnt build up on the piston rings.
6. dont race it every day.

I only change spark plugs ONCE on any car and that is only to the end of installing dual plat plugs for the
life of the engine. I have never every replaced OEM dual plat plugs and dont expect I ever will.
Whether GM or Lincoln/Ford, same practices.

the trani .. well, that is another subject.

Ah but you didn't read my post. I would almost defy anyone from "trying" to get out a set of plugs from an aluminum block after say five years and 100,000 miles. I asked the service manager when my 96 Voyager was in for service at 50,000 miles and three years about this same question. (The Voyager had 100,000 mile platinum installed plugs) He asked me how the car was running and suggested I go for another year and 15,000 miles more because so much of the engine had to be removed to get to the rear plugs (intake manifold and some injectors.) Said they werecausing more problems aftera plug change. But he did agree with me about "pulling" them at 65,000. Not because of the plug life but because of "plug freeze."
I know that you would make sure that a well lubed set of plugs would go in any work you do but not so sure this occurs in the factory asembling mass produced engines.
I've encountered just to many frozen plugs over the years of rebuilding engines.

I did read it. That being my point. Other than curiosity, why remove them, ever?
Unless the car ended up with cheap single electrode plats, installation was not done well
or is questionable, or car has problems like overheating.

Another reason to pull them? buyer demands a compression test. Now you possibly got a problem
if the factory didnt do the job OR over-torqued them.

If the engine has to come out, then it makes no difference.
Once the engine on a stand, we got ways to get plugs out, frozen or not.

Last year I had to deal with a 6-cyl import where someone "removed" the plugs cuz the manual
said 100,000 miles and an electrode broke off - he didnt bother to get it out. That plug change,
that was really not needed cost the owner the whole engine - $3,500 rem.

As you eluded to, a proper lube (I use anti-seize) of the threads is a must to avoid that.

Lastly, if it was a newly acquired car on my hands, I might be tempted to "inspect" or replace the plugs.

From my experience removing spark plugs from aluminum headed GM engines that were factory installed and undisturbed for 100k+ is not that big a deal. It's plugs that have been removed and re-installed or replaced without anti-sieze and/or improperly tightened that are. I know Ford 4.6 has some concerns. I have no info concerning Chrysler. To me replacing plugs on rear head of 4.1,4.5,or 4.9 especially the 86-92 E/K & V bodies that are most challenging. 4.5 pfi with its AIR pipes are the worst of all them.

ORIGINAL: slowroll

From my experience removing spark plugs from aluminum headed GM engines that were factory installed and undisturbed for 100k+ is not that big a deal. It's plugs that have been removed and re-installed or replaced without anti-sieze and/or improperly tightened that are. I know Ford 4.6 has some concerns. I have no info concerning Chrysler. To me replacing plugs on rear head of 4.1,4.5,or 4.9 especially the 86-92 E/K & V bodies that are most challenging. 4.5 pfi with its AIR pipes are the worst of all them.


May I assume that the challenge you experienced is due to access ?

Cut hands, fingers, wrist and forearms, doing them on the ground. Cuts and occasional burn from exhaust on a lift. Many times getting plug wire boot off plug is a challenge. Sticking boots lead Cadillac to come out with special coated spark plug, to help combat problem.

I believe "access" is the reason platinum plugs were designed. The first I remember were for a Pontiac??? that was designed for the new Wankle engine. The Wankle could not contain "seals" and a small V6 was subsituted. Wouldn't quite fit and engine had to be raised to get to the rear bank of plugs so platinum were installed in the rear. This was to far back for me to remember model of car but I'm sure these were the first long life platinum plugs.

ORIGINAL: hyperion

I believe "access" is the reason platinum plugs were designed. The first I remember were for a Pontiac??? that was designed for the new Wankle engine. The Wankle could not contain "seals" and a small V6 was subsituted. Wouldn't quite fit and engine had to be raised to get to the rear bank of plugs so platinum were installed in the rear. This was to far back for me to remember model of car but I'm sure these were the first long life platinum plugs.



zinzin,

here is a site that should keep you busy on them snowy nights.
http://rstreet.us/sparkplugs/index.htm

is this the 1st one ?

http://www.cadillacforum.com/upfiles/2893/19A495C5251E4F0AA76B16D965FBAE3E.jpg

Spark plugs are the most boring subject in the automotive world. A little like brands of oil. Someone will come up with the car name. It was sporty and produced for several years with the V6. My guess would be "mid seventies" when the "Wankle" was supposedly "revolutionary."
I used to have to pull over about every 700 miles with my XK 120M in the early fifties and remove and wire brush 6 plugs when the engine started "missing." No big deal, and well worth it. With a spin wrench on that engine, took less than five minutes. After a while I just purchased a spare set and the replacement time got down to three minutes. My wife got used to it! So much for the "leaded gas" at that time.
Was part of the "ritual" during pit stops at races then. Two outside tires and a set of plugs in less than a minute. (A simple operation with those "Offies.")