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Discussion Starter #1
Hey all! I think I know the partial answer to these questions but I need consensus and advice. All responses will be greatly appreciated. Here goes. '98 DeVille with 106K. Starts right up. Alittle rough until warm. As it warms up, between about 90 and 150 coolant temp, the exhaust billows out steam. Once it is fully warmed up, the steam backs off. It could be worse because we have had alot of fog and humid weather(Southern WI). It did use up some coolant(1/2 gal in two weeks). I am thinking it's a head gasket leak that seals up when the block and heads warm up and expand. There is no oil on the resevior cap and the oil has no cream. Can I just add coolant as needed? Can I just have the head bolts tightened? Has anyone ever tried a leak sealant additive? If so can I just add it to the resevoir? One other unrelated issue, is the oil. I think I added too much oil. The dip stick is really hard to read. I checked it many times as I filled up. Then all of a sudden it was to the top of the orange level gauge. I figure the way N* supposedly go through oil, it'll come back down fairly qickly. I try to WOT every day. I only drive about 10-20 miles a day. I did have misfire code once before oil add and once after(reving it up cold). I also had an O2 code. Can I wait on changing the plugs and wires awhile? When it's hot, it runs like a champ. I love it and want to keep it a long time. Thanks again for any help/advice.:banghead:
 

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This is our......4th Dave with a DeVille? :)

Ah sorry.... its just pretty cool :)

About the problem... I dunno.... the steam and using coolant could be head gasket, but that alone really isn't enough for me to tell ya...
 

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93 Sedan Deville 4.9
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98 Deville Should Hold About 5 Quarts Of Oil . With A Filter Change. If The Dipstick Is Hard To Read. Clean It Off With A Piece Of Sand Paper. Add Some Solder Seal To The Resevoir. A Radiator Sealant. Comes In A Plastic Type Vial. Couple Cans Should Do Ya. It Looks Like Solder Flakes. Works Wonders Sometimes. Later. I Live In S.e. Wi To
 

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Discussion Starter #4
I thought I read somewhere that it holds 7.5 qts of oil? I have been reading posts for a couple of hours tonight regarding steam and head gaskets. If I have a leak, I don't think it's too bad yet. I'm thinking I'll get an oil change, coolant change(with tablets) and replace plugs and wires. I hope it makes a difference since that's about all I can afford right now. Thanks for advice! Keep it coming!
 

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93 Sedan Deville 4.9
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What Size Engine Is It? My 93 Sedan Deville Has A 4.9 Liter & Holds About 5 -5.5 Qts. It Might Be A Lil Different If You Have The Northstar Engine. Put In 5 Qts. With A Filter Change & Check It. Your Owners Manual Or Manual From The Auto Store Should Tell You. If It's Going Up Way Too High On The Dipstick You Probably Got Too Much In It. Good Luck
 

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2001 eldorado,2008 DTS,2005 XLR, '96 eldo,'95 eldo,' 89 eldo,'78 eldo,'11CTS-V
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A '98 Deville has the Northstar; takes 7 quarts of oil.
The only real way to check on a leaky headgasket, is with a leakdown test.
Tighening the headbolts probably won't help. If the headgasket is going south, nothing will help.
 

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Discussion Starter #7 (Edited)
My Cadillac dealer says they don't use tablets in coolant, but some type of additive. I wonder if it (like the tablets, supposedly) will fill very small leaks in the head gasket? Today, I let it warm up at an idle and had no noticeable extra steam. Just when I first took off. I had the oil changed with Valvoline Max and added STP fuel system cleaner to the gasoline. THEN, I drove round trip down to O'hare field in chicago. About 160 miles! Everything went fine. Mileage, temp and voltage remained in good ranges. I let the temp get up to 212 when standing, 197-201 while running. Volts down to 13.4 while standing, back up to the 14's while running. (The other day my battery and charging system checked out fine at AZ) I had to circle the terminal many times in an hour because they won't let you park. I am very happy with this "road test". I've had the DeVille for two weeks today. Tomorrow, I'll check the coolant and oil levels and report. Also! My trans fluid is dirty. I'll have to get it changed. Should I change the coolant or leave it awhile since I added a gallon the past two weeks(the low coolant warning came on after just a few days so it was probably pretty low when I go it)? I don't expect to add so much now if I'm patient letting it warm up slow. And, I think I can wait on the plugs and wires since "it ain't broke don't fix it".
 

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93 Sedan Deville 4.9
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If The Coolant Is A Clear Green Or Yellow, Like Prestone, Don't Mess With It. Change It When It Starts Getting The Brown & Dirty Look To It. If It Looks Good & Either Green Or Prestone Yellow Leave It Be. No Need To Fix An Unbroken Problem. Springtime Is Getting Nearer Every Day. If It's Not Missing Or Running Bad, Hold Off Until Warmer Weather To Change All Your Plugs, Wires & Such. Unless You Got A Heated Garage. Then Go To It & Have Fun.
 

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White Diamond '03 DHS (with DTS floor shift)
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The Northstar holds 7.5 qts. of oil.

Cooling system sealant tabs will not seal a bad headgasket nor where they ever intended to.

Drain and refill the trans. DO NOT flush it. Don't forget the drain plug under the side cover once the pan is off. Screens are reusable as is the gasket.

Find and fix the coolant leak before changing coolant. As mentioned, do a cylinder leakdown test to find out if the headgaskets are bad or not. The '98 has orange Dex-Cool. It should be changed at least every 5 years. The Northstar is an aluminum engine. Aluminum does not rust (it does corrode) so the coolant will look the same in 20 years as the day it was put in. Never rely on looks unless you are talking about a cast iron engine.
 
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