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Cadillac 1993 Deville 4.9, 1991 Eldorado Touring Coupe
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370 Posts
Discussion Starter #1
Trying to diagnose a coolant loss. My overflow bottle will empty out in about a months time if i let it go and then the radiator starts to lose coolant.

I see no leaks in the Radiator or coolant recovery bottle at all. No puddles on the ground either. No hoses leaking including the heater hoses and T valve.

When i am driving for a little length of time (car running at least a half hour) Will smell burnt coolant.

Wondering if the water pump is passing coolant and it is hitting the exhaust and burning off, Hence no puddles.

What indications are there that the water pump may be getting ready to quit? I hear no bearing noise. Car has 71 k

Thanks!
 

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1995 FWB 128,*** miles
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2,255 Posts
Bring the car to operatioal temperature, open up the hood and increase RPM to some 4000 manually. Watch carefully for leaks. Suspected areas are the water pump, the heater valve (the plastic T may develop tiny cracks), the both radiator side tanks are known to crack too, all hose connections. Increased RPM will increase the pressure and some leaks you would never see under normal idle RPM will become visible.
 

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93 Sedan Deville 4.9L
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Similar to the above you can get a pressure test done, You can rent the tool from most autoparts stores and do it yourself.

The benefits to the pressure test is that you can do it with the engine off so you can safely poke around some while looking. I had a similar issue, their was a leak in my side tank that would only leak under pressure, it sprayed toward the front of the car and hit the fans so their was never any easily visible signs of a leak.
 

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Cadillac 1993 Deville 4.9, 1991 Eldorado Touring Coupe
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370 Posts
Discussion Starter #5
Thanks! good idea. I noticed that after running just a minute or so, The passenger side of the radiator gets wet. One might think , Problem identified...The radiator side is cracked seeing as how they are plastic.

HOWEVER, It looks more like the water pump or serpentine is "whipping" the leaking coolant onto the radiator as its a uniform streak and the lower radiator hose has the uniform streak of coolant on it as well. Cant quite reach down there to feel and see if the spray is actually whipping off the belt (its slight and not visible) with the engine running for fear of a false move and getting snagged in the serpentine. But it really looks like thats the issue.

Water pump makes no unusual noise as though the bearing is grinding or wearing, There is a slight whining but that seems to be normal operating noise and was like that if i recall for a long time.

I just dont want to replace a water pump for nothing. But even with pressuer test, what else could it be with the coolant being whipped off from that area.
 

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1995 FWB 128,*** miles
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2,255 Posts
Can you shield the radiator tank with a piece of something to isolate the problem. Again be careful, do not get hurt.
 

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Cadillac 1993 Deville 4.9, 1991 Eldorado Touring Coupe
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370 Posts
Discussion Starter #7
Yes good idea!....I`ll cut a piece of cardboard and make sure its buttoned down and run the car, If it does not get wet from the engine side....Then it IS in fact the radiator!
 

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Cadillac 1993 Deville 4.9, 1991 Eldorado Touring Coupe
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370 Posts
Discussion Starter #8
Test results: Wet piece of cardboard facing the engine and for the first time while running that test heard some clunking in the area of the pump. Conclusion: Looks like "Great White" Needs a new water pump. Was hoping to avoid that.
 

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1995 FWB 128,*** miles
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Test results: Wet piece of cardboard facing the engine and for the first time while running that test heard some clunking in the area of the pump. Conclusion: Looks like "Great White" Needs a new water pump. Was hoping to avoid that.
Well, at least you know what to do. There are a couple of quite difficult nuts and bolts on the pump, so be prepared.
 

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Cadillac 1993 Deville 4.9, 1991 Eldorado Touring Coupe
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Discussion Starter #10
Yes dont remind me lol....Attacking it tomorrow..wish me luck im going in!
 

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93 Sedan Deville 4.9L
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Good Luck, If you have done it before it shouldn't be too bad a job. I struggled the first time i did it, but think I could do it pretty easy if I had to do it again. Hopefully that solves it for you
 

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Cadillac 1993 Deville 4.9, 1991 Eldorado Touring Coupe
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370 Posts
Discussion Starter #12
Thanks all! Mission accomplished. Definitely not smooth as silk easy to replace, But not as bad as i imagined it might be.

Not the end of the head scratching though. Everything is buttoned up, No leaks, Did the trick ....But it was weird when i got the old pump out, Virtually no play at all with the impeller. But most certainly was leaking.

The pump that came off was also dated Jan 2003. I bought the car with 64k miles and has 71k now (dont drive much) and i bought it Dec 2006. Hmmmmm.

Been replaced once...Guessing somewhere around 50k ish by the date and approximate average mileage. I have to wonder whats up there.
 

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1995 FWB 128,*** miles
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Thanks all! Mission accomplished. Definitely not smooth as silk easy to replace, But not as bad as i imagined it might be.

Not the end of the head scratching though. Everything is buttoned up, No leaks, Did the trick ....But it was weird when i got the old pump out, Virtually no play at all with the impeller. But most certainly was leaking.

The pump that came off was also dated Jan 2003. I bought the car with 64k miles and has 71k now (dont drive much) and i bought it Dec 2006. Hmmmmm.

Been replaced once...Guessing somewhere around 50k ish by the date and approximate average mileage. I have to wonder whats up there.
I have noticed as soon as one replaces the original water pump, one keeps replacing them...
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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759 Posts
I was trained in Foreign Car mechanics class that the key to successful water pump replacement is to make sure the old gasket is completely removed from the engine housing. That means drill with wire brush to hone that surface down to shiny metal with no burrs. If there is even a small trace of old gasket dirt or gunk of any kind, the new gasket may not seal 100.00000 percent perfect and could start leaking again sooner than bargained for. That was 40 years ago but it's probably still true today even for the highly exalted Cadillac. Many notches later on my wrench "guns" I still follow that rule of thumb. Haven't yet had the joy of doing it to my 92 Deville yet (Thank-you Lord!). There was probably nothing wrong with your water pump itself, so now you have a spare. Just a thought.
 

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93 Sedan Deville 4.9L
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I never looked for a date on the one I took off, but their was alot of play in the impeller so it was trash. Judging by the bolt tightness it wasnt original either. I've had the car less then one year so I dont know when last it was done. I spent a full hour or two cleaning gasket off when I did it so hopefully that helped. The other 93 has been in the family for about 6 or 7 years and we haven't touched its pump yet. It has 104k while mine went last at 118k so we may have a few years left on it.
 

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1995 FWB 128,*** miles
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2,255 Posts
I bought my Seville nine years ago with 77.000 miles. I have made 93.000 miles since and have not touched the water pump. I believe adding coolant supplement (bar's leaks golden seal powder) every year with coolant change helps to keep the pump in good shape too.
 

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Cadillac 1993 Deville 4.9, 1991 Eldorado Touring Coupe
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Discussion Starter #17
I think what happened in my case was the original was replaced by someone and yes......bad cleanup up the old gasket, because now that thats been mentioned here, It did seem shoddy, So my pump leaked by a bad gasket job.....But i replaced it anyway while in there ...and by habit i did do a good gasket replace...Not that i change a lot of water pumps....Hoping not to :) last one i did was 15 years or so ago...Chevy 350.. But thats one anyone could do with blindfold and one hand tied :)
 

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'87 SDV
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Don't want to sound like a GM parts ad, but one of the keys to replacing a water pump ONCE on a 4.x engine is to use only a new(not rebuilt) Delco pump from a GM or AC/Delco dealer. The remans just use cheap internals to keep the costs down. The initial outlay is greater, but the payoff is not being back into it 2 or 3 years down the road.
 

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93 Sedan Deville 4.9L
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Don't want to sound like a GM parts ad, but one of the keys to replacing a water pump ONCE on a 4.x engine is to use only a new(not rebuilt) Delco pump from a GM or AC/Delco dealer. The remans just use cheap internals to keep the costs down. The initial outlay is greater, but the payoff is not being back into it 2 or 3 years down the road.
Heh, Hopefully Bosch is good enough (Probably not lol) I would have liked to go delco, but the way mine went I had no choice but to go with what was localy available. Might could have gotten delco at a deler, but if I had the choice would prefer rockauto. Luckily mine has not leaked at all since I replaced it
 
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