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1990 Borugham
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7 Posts
Discussion Starter #1
Hi fellow Cadillac fans!

First time post here. 2.5 years ago I bought a 1990 Brougham w/ the 5.7, then with 82k on it. I drove it regularly for about a year, and then quite sporadically after I went off to college and the car stayed home.Today the mileage is about 89k. Throughout all this time, the car has been quite reliable, with only one unexpected and minor repair. The car has been mostly driven around town, with a little highway driving and one or two long highway stints to open it up and let it stretch its legs.

However, there is one issue that has been ongoing since I bought the car, and that has been the slow but steady loss of coolant. I always check the coolant when the engine is cold, and noticed that there would slowly be less and less and coolant in the reservoir. I would say that on average I have had to add coolant about every 500-750 miles. I do not wait for the reservoir to run dry, but I usually fill it after I see it drop an inch or two from the "add" line. I have been adding prestone 50/50 mix, and have gone through one gallon of the stuff since I bought the car. Im now starting to break into the 2nd gallon.

So what Im asking is, what do you guys think is the cause for the mysterious disappearing coolant? Is it something I should worry about and try to pinpoint, or can I continue enjoying the car and adding the coolant when needed? I dont want to ignore the problem if its serious, but I dont want to throw away money trying to find and fix it either, as I just dont have that kind of money as a college kid.

Thanks for any feedback!

Oh, and heres two pictures of the car. Its my baby!
 

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chevy 350 powered 86 FWB, 00 safari h.t. 66 toro, 83 lesabre
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6,397 Posts
Hi fellow Cadillac fans!

First time post here. 2.5 years ago I bought a 1990 Brougham w/ the 5.7, then with 82k on it. I drove it regularly for about a year, and then quite sporadically after I went off to college and the car stayed home.Today the mileage is about 89k. Throughout all this time, the car has been quite reliable, with only one unexpected and minor repair. The car has been mostly driven around town, with a little highway driving and one or two long highway stints to open it up and let it stretch its legs.

However, there is one issue that has been ongoing since I bought the car, and that has been the slow but steady loss of coolant. I always check the coolant when the engine is cold, and noticed that there would slowly be less and less and coolant in the reservoir. I would say that on average I have had to add coolant about every 500-750 miles. I do not wait for the reservoir to run dry, but I usually fill it after I see it drop an inch or two from the "add" line. I have been adding prestone 50/50 mix, and have gone through one gallon of the stuff since I bought the car. Im now starting to break into the 2nd gallon.

So what Im asking is, what do you guys think is the cause for the mysterious disappearing coolant? Is it something I should worry about and try to pinpoint, or can I continue enjoying the car and adding the coolant when needed? I dont want to ignore the problem if its serious, but I dont want to throw away money trying to find and fix it either, as I just dont have that kind of money as a college kid.

Thanks for any feedback!m

Oh, and heres two pictures of the car. Its my baby!
If I was a betting man, I would bet on either a seeping radiator hose or failing clamp or a freeze plug that is just starting to go. If you know anyone with a lift, put it up in the air, and look around with a light.
 

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2014 ELR
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9,740 Posts
I'd bet on water pump leaking out the weep hole. A leak that doesn't really drip on the ground. With the engine off and cold, reach under the water pump. Wet?
 

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1979 Coupe deVille, 1995 Sedan DeVille (sold)
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1,846 Posts
1 gallon in 2 1/2 years isn't too bad. :)
I wouldn't worry about it too much as long as the rate of loss doesn't increase.

If you really want to correct it, though, I would pressure test the system. You can borrow or rent a pressure tester at most auto parts stores.
You just screw it in in place of your radiator cap, pump it up to pressurize the system, then look to see where the coolant is coming out.
 

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RWD 90DL350
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13 Posts
All are good suggestions. I'm changing a 350 intake manifold gasket at present time. It finally showed a leak on right front corner of manifold. No visible leak until now. The oil was not contaminated. Keep close eye on the dipstick and if oil looks milky ( homogenized) then you are getting coolant into crankcase and bearing damage is to be expected. Best to you and your Brougham looks nice.
 

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84 Coupe w/500
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5,665 Posts
I think a leak that slow would be impossible to find but I'm going with hoses then water pump. Probably see some staining on a hose or two.
 

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1991 Cadillac Brougham D'Elegance 5.7 Litre, 1994 DeVille
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6,796 Posts
CHeck the hoses and if the rad has been replaced and is a plastic tank kind have a close look at it too. They can leak from the tanks enough to cause the coolant level to lower over time but not leave drips on the ground. Wherever it is the best time to look is after the car has just been driven, if you're lucky can you see a wet spot somewhere or a bit of steam if you look carefully.

I've had that intake leak at the right side before too.
 

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1990 Borugham
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7 Posts
Discussion Starter #9
Thanks everybody for the advice! I'll be sure to try some of your suggestions. Its a relief to know its probably nothing too serious/critical.
 

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300 SRT8, 392 cubic inches of tire smoking power!
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8,189 Posts
If there's no oil in coolant and no coolant in the oil I'd put some Alumaseal in it and call it a day. Put it directly in the radiator, not the overflow tank.
 
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