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Discussion Starter #1
Hello,
I'm going to be looking at a '91 Deville as a prospective purchase tomorrow. This is my first time with this generation Cadillac, and I was wondering if there's anything in particular I should look out for / pay attention to? It has 176K on it, claimed to have excellent body and interior. Asking price is $1000, seems like I can't go wrong for that. It has 4.9L V8.

I also already checked out an 89 Eldorado/ 4.5L. I am curious about the reliabilty/maintance comparison between those two engines. The Eldorado has 144K on it, and is in pretty good shape overall, other than a REALLY stiff gas pedal (odd thing to have). But it's $1,500, so a little more coin.

Just curious about your guys' opinions. Any suggestions would be greatly appreciated.

Thanks!
 

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1991 Deville / 1989 BMW 635csi
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896 Posts
You have nothing to worry about, the 4.1 4.5 and 4.9 are all same design engines. Be sure to read ALL of the stickers on the rad support under the hood and follow them. The Port Fuel Injection (PFI) engine requires premium fuel. Coolant MUST be changed every 2 years and coolant seal tabs MUST be used. If you purchase any of these cars, change coolant RIGHT AWAY!! Change oil a little earlier for the first couple months just to make sure its clean inside and enjoy. These cars are generally not terrible on fuel if maintained. If the 4.9 engine makes a knock, it is most likely the common harmless #1 main bearing thump, it is just annoying. In the summer, run Rotella 15W 40 oil to make thump go away, this oil is too thick for winter, so just use the reccomnded oil. If you want to make the thump go away completely, change all mains, i mean might as well if you are in there. Purchase which ever you like best, these cars are flawless and have lots of pep and go. You have nothing to worry about. Just don't beat it and it will go forever.

4.1 V8 = 1982-1985 = (aka HT4100) 125hp @ 4400rpm 190ft/lbs torque @ 2200rpm
4.1 V8 = 1985-1986 = 130hp @ 4400rpm 190ft/lbs torque @ 2200rpm
4.1 V8 = 1987 = 135hp @4400rpm 200ft/lbs torque @ 2200rpm
4.5 V8 = 1988-1989 = 160hp @ 4400rpm 210ft/lbs torque @ 2000rpm
4.5 V8 PFI = 1990 = 185hp @ 4200rpm 225ft/lbs torque @ 2000rpm
4.9 V8 PFI = 1991-1995 = 200hp @ 4200rpm 270ft/lbs torque @ 2000rpm
 

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'12 White Diamond CTS-V Sedan, '10 Cyber Gray ZR1
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265 Posts
Any links on how to flush the coolant and what the tabs are exactly? See my post on getting a '92 Deville. I'm going to change the oil this weekend and check tire pressures, etc, but wasn't aware that coolant needs to be changed so frequently. I guess they didn't use Dexcool back in '92. :)
 

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'87 SDV
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The coolant change schedule and sealer tablets have been common to Cadillac engines for over 20 years. The reason is that the aluminum block and cast iron heads have different rates of expansion and contraction during normal heating and cooling cycles. Without the sealer/conditioner, leaks eventually form and allow coolant to get into the oil, creating an acid brew that resembles cream of mushroom soup. When this happens, main and crank bearings are toast in a very short time. The aluminum block is highly susceptible to corrosion as well.

The procedure for changing coolant is listed on a sticker on the radiator support. Simply drain the rad either with the petcock or by removing the lower hose at the rad. Close whichever drain you used, refill the rad with distilled water. LEAVING THE RADIATOR CAP OFF, run the engine for about 10 minutes at a high idle to allow the water to circulate into the engine. NEVER USE A FLUSH PRODUCT on an aluminum Cadillac engine. Drain the flush water and refill the rad with 50/50 of any good green anti-freeze. The coolant supplement (GM part #3634621) comes in a blister pack of 6 'pills' which are crushed and added to the radiator. Do not put it in the overflow tank. You can also use Bars Leak Gold Powder, which is the same product in a different form. The factory service manual suggests that the rad be topped off by having a companion run the engine up to 1500 rpm, watch for the coolant level to drop in the rad, then top it off, intall the cap and fully tighten it before allowing the engine to return to idle. Take the car out and drive it for 10-20 minutes to circulate the sealer - and viola! You're good to go!

A word of caution: These Cadillac cooling systems build pressure very rapidly.. If the engine has run for more than 10 seconds with the rad cap installed, do not remove the cap until the engine has completely cooled.

Good luck - enjoy your Cad! :thumbsup:
 

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'12 White Diamond CTS-V Sedan, '10 Cyber Gray ZR1
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265 Posts
Wow, thanks for the great information, Noahsdad. This car seems to run good, but does need a little TLC. While the car was rarely driven in the past few years, the oil is over a year old and I'm sure the coolant hasn't been flushed in 3-4 years. Is the coolant change a miles/heat cycle thing or is it an age thing? The coolant is 3-4 years old, but probably has 5-6k miles on it.

I guess I'll do the coolant flush, oil change, and tinker with the trunk latch over the Christmas holiday. :thumbsup:
 

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Discussion Starter #6
Thanks for all the info guys!
I'm going to check out the Deville later today, when the owner gets home from work. I'm curious, how many of the coolant pills are you supposed to put in per change, all 6?

-Jon
 

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White Diamond '03 DHS (with DTS floor shift)
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Our old guru said 6 tabs. The manual for my '97 said 3. I went with 4.
 

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If this car has ever seen salt, you may want to check out the body mounts. It is a common rust-out point even if the car looks fantastic elsewhere.


Regards,

Chris
 

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1992 Town Car Cartier & 2014 Accord LX MTX
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Look for coolant leaking through the block, mine has it due to the previous owners' neglect. Mine leaks coolant on the front (transverse) of the engine, by the belt, about halfway down, on the side near the passenger compartment.

Also, listen for the main bearing thump. It is a trait inherit to the 4.9's, its harmless, just annoying. My '92 Deville has this too.
 

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Discussion Starter #10
Hello,
Well I checked out the Deville today. It was too rough for me. Body DID have some rust- around the insides of doors, both front doors didn't open right, passenger door didn't close at all! Claims it freezes "whenever it sits outside in the cold" well I don't have a garage, so that's no good.

Then, I started it up, and was greeted by a barage of idiot lights that stayed on throughout the test drive: "Service Engine Soon", "Service Vehicle Soon", "Anti-Lock", and "Service A/C". In other words, service the whole damn car. Combine that with 4 worn out tires, and I have almost no control on the snow. Brakes were very hard/heavy to push. All problems that the Eldo doesn't have. Engine and trans sounded/drove alright, but the mere presence of all those lights definetly indicates a larger undertaking than I'm ready for. That combined with broken door handles/latches indicates a severe lack of maintance.

So, it seems that all signs point --> Eldorado. It's definetly worth $500 more than the Deville. The Eldo also comes with a spare set of wheels- the original wire wheels. The owner added snowflakes! New Factory radio, new a/c compressor and climate control unit, brakes, rotors, should be a solid car for $1500. Triple Black!
 
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