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Hello to all.
I want to make a general inquiry about the 4.5 engine. I found an absolutely beautiful 1990 coupe deville with 81k. What kind of issues or concerns did the 4.5 have. I am aware that it is a decendant of the pos 4.1. Were there significant improvements to the 4.5 ? Thank you in advance.

Mike
 

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1993 Cadillac sedan deville
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281 Posts
The 4.5 was an okay engine still had some of it's problems they were still working out some of the bugs that the 4.1 engine really had the 4.5 is okay but not major improvements were done like i said they stll had some quirks but if you wanna buy a cadillac buy an 90-95 with a 4.9 that's the best engine cadillac ever made in my opinion they can last 300k easily if well maintained for!
 

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1990 Cadillac sedan devile
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616 Posts
my 90 just hit 136000 on the body and 150000 on the engine and still purs right along . the only problem ive had with the engine is the the watter pump inlet stripped out where the bolts thread in . im from what ive heard it a fairly common problem with 4.9s and 4.5s alike theother commom problem being the intake manafold gaskets blowing
 

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1990 Cadillac Eldorado 4.5 PFI
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63 Posts
The '90 4.5 and the '91-95 4.9 are virtually indentical. Only major differences being a stroke increase, deletion of A.I.R. system, and new design oil pump on '91 and up 4.9's. The '90 4.5 has all of the same reinforcements on the block, PFI fuel injection system, heads, cam, etc. Very reliable engine if maintained. Problem areas are the same as the 4.9. Water pumps, intake gaskes, fuel injectors, valve cover gaskets, etc. Do a search and you will find that most of the issues these engines have are common between the two. Make SURE that the previous owner has maintenance records. Coolant flushes with seal tabs are VITAL to long engine life and reliability. Also make sure that the transmission fluid and filter have been serviced regularly. Even if they have, these tranny's are subjected to plenty of torque and can fail around the 100-120K mark. Mine made it to 103K before reverse went out. However, some on here have over 150K on their stock tranny with no issues. Make sure that you inspect the suspension carefully. From the factory they are pretty solid, but wheel bearings and ball joints will wear from time. The ball joints are riveted in from the factory(great idea, GM:thepan:) and can be a PITA to replace. Also, make sure that the rear air ride is working correctly. The rear end should be level with the front and not sagging. You should hear the pump kick on intermittantly. If it is constantly running or turning on every 5 minutes then suspect an air leak somewhere. I guess that this seems like alot of stuff to look for, but no more that any used car. Do your due diligence and you will be rewarded with a classy ride that will give you many years of enjoyment.:cool:
 

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2011 Crown Vic LX, 2009 Chevy Malibu 2LT
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From the factory they are pretty solid, but wheel bearings and ball joints will wear from time. The ball joints are riveted in from the factory(great idea, GM:thepan:) and can be a PITA to replace.
:thehand:

That's why GM was nice enough to include grease fittings on all front end joints, including ball joints, tie-rod ends, and even the stabilizer links. My '95 has 171,000 on the original front end joints and transmission. A little tlc goes a long way...

Lube the front end with every oil change and I guarantee you will never have to remove one of those riveted ball joints (unless you hit something/go curb hopping and break one :bonkers: )
 

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93 & 88 Allante, 88 Eldorado
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778 Posts
My 88 Eldorado with the 4.5 engine has 240,000 miles and the engine has never been touched. Not even the injectors or intake manifold gaskets. The trick with these engines is to change the coolant every year and make sure to add bars leak. Also, I run diesel Shell Rotella 15w40 engine oil that is high in anti wear ZDDP. The newer gas engine oils have been reformulated and no longer provide the lubrication that our older engines require. However, the transmission on these cars are a bit weak. Mine failed at 150,000 miles. The sprag gears are weak, and the shift points are not crisp enough to allow extreme longivity.
 

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2011 Crown Vic LX, 2009 Chevy Malibu 2LT
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My 88 Eldorado with the 4.5 engine has 240,000 miles and the engine has never been touched. Not even the injectors or intake manifold gaskets. The trick with these engines is to change the coolant every year and make sure to add bars leak. Also, I run diesel Shell Rotella 15w40 engine oil that is high in anti wear ZDDP. The newer gas engine oils have been reformulated and no longer provide the lubrication that our older engines require. However, the transmission on these cars are a bit weak. Mine failed at 150,000 miles. The sprag gears are weak, and the shift points are not crisp enough to allow extreme longivity.
Although it seems most of this board considers teh 4.9 to be the most reliable caddy engine made, I'd have to say from my own experiences and others here that the earlier TBI equipped motors were much more reliable than their PFI brothers. Not that the later motors were problematic, but it seems that any problems encountered with any of the 4.X motors are fuel injection related on the later PFI's. I experienced no engine problems on my 190,000 mile Eldo with the TBI 4.5 except for a faulty ISC motor. Even the water pump was original (not that this is related to any differences, probably just luck). However,I replaced the FPR and injectors on both the 90 and 95 PFI's. If you search for injector and FPR replacement for the 4.9 on this board, you'll probably get quite a few pages worth of results...

In my opinion, the TBI 4.5 was the most reliable engine cadillac made, not the 4.9 . I must say though, the extra kick in the PFI motors is well worth the minor extra potential problem areas. Hopping in my TBI Eldo after driving the '90 around is almost agonizing when puttin the hammer down :) Seems like the PFI's have a lot more than the little they are rated for over the TBI's
 

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93 & 88 Allante, 88 Eldorado
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778 Posts
Yup, I strongly agree that overall, the 88/89 4.5 is extremely reliable if maintained (cooling, oil high in ZDDP). The TBI system is much less finicky than the newer PFI system. Rarely do I ever hear of injector problems. This engine also didn’t have the classic engine thump that some 4.9’s exhibited.

I also drive an Allante with the Northstar so yes, when I get into my Eldorado, it feels pretty anemic 155 hp vs. 300hp. However, the 4.5 does maintain speeds up hills very well but if falls on its face if trying to pass and accelerate say from 50-100 mph.
 

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1990 Cadillac Eldorado 4.5 PFI
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63 Posts
Drewsdeville, most people do not own these older Caddy's since new. I agree that if you own the car since new, and lube all of the joints since new, you will not have to replace front end parts as frequently as those who don't. However, :nono: I have been a service manager for over 10+ years. Ball joints, sway bar links, tie rods, etc., all wear out eventually, even with routine maintenance. Their very design dictates that they will wear out with time. I am happy that you have 171K on your factory ball joints, but that is not the rule, it is the exception. Ask anyone in the know, and they will tell you that after 15 years and 100K miles the front end will more than likely be worn out. Let alone 20 years.
 

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2011 Crown Vic LX, 2009 Chevy Malibu 2LT
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Drewsdeville, most people do not own these older Caddy's since new. I agree that if you own the car since new, and lube all of the joints since new, you will not have to replace front end parts as frequently as those who don't. However, :nono: I have been a service manager for over 10+ years. Ball joints, sway bar links, tie rods, etc., all wear out eventually, even with routine maintenance. Their very design dictates that they will wear out with time. I am happy that you have 171K on your factory ball joints, but that is not the rule, it is the exception. Ask anyone in the know, and they will tell you that after 15 years and 100K miles the front end will more than likely be worn out. Let alone 20 years.
I completely disagree from witnessing not only my own but others experiences as well. Just oo much to call it luck or the exception... but to each man his own, right?

Even my buddy has a Corolla with 147k on it, NON GREASABLE joints, all original. Dads Cutlass Supreme with 140k? Gramps Silverado with 165k? All original front end joints. Cars drive tight and they hold their alignments perfectly. Either I'm living in some kind of virtual reality or... :hmm:

I've seen it both ways. Sometimes you get some bad luck and front end joints wear out (of course, you see more of this than not as a tech...that's why you have a job). It's just as realistic as them lasting the life of the vehicle. Fine. However, I find your claim that 100k is the average life of front end parts to be incredibly low...
 

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1990 DeVille
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181 Posts
The local Caddy dealership's oldest mechanic thinks the 4.5 is the best of all. 2nd best might be the newer 3.6, but there's not enough experience with them to really know.

For now, in his 30 years of Caddyfixing, the 4.5 is #1.
 

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1990 Cadillac Eldorado 4.5 PFI
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Drewsdeville, the point you are trying to make is valid, as is mine. Cars are built by people on earth, not angels is heaven. Parts wear out, the public needs people with the know-how and tools to fix them. Such is the circle.
 

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How reliable is it? My 1990 seville just turned 160k today. The previous owners had majorly abused this car from a maintenanace standpoint (they had NO idea what an oil change was). After cleaning the crud out of the lubrication system it runs better than i had expected.
 
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