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Replacing coolant reservoir?


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I have to pull my old reservoir out of my '98 Eldo, as I finally found the nagging leak today. It is coming from the hose connection at the bottom. I initially thought it might be a bad cap, as I was reading in another post. I replaced that and it almost seemed like it was getting worse. Every time I drove it it was leaking coolant all over. Then I noted it was primarily dripping from the frame, not out the overflow hose...

Anyway, I removed the two 8mm hex head bolts holding it in, as well as the clamp surrounding the A/C line along side it. Then when I moved it some I noticed the connection at the bottom hose there was leaking. The stub the hose is clamped to is cracked. However I cannot seem to get enough movement to pull it up to disconnect that hose that goes back to a T-fittiing there. Cant get at the clamp the way it is. Has anyone done this that can give me any pointers? Is there a trick to getting this in/out? Do I need to pull the battery out as well? Didn't look like that would help...

I ordered a re[placement reservoir on Ebay so I hope it works out. Didn't want to risk putting an old used one in the and OEM from dealer would be way overpriced… Thanks for any help that you could give me here!

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

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When I started taking on my own maintenance, I could feel a break in the fitting on the bottom of the surge tank where the heater hose T fitting comes in. This is the main route for water back into the cooling system that comes in through the bypass. There was a persistent leak there and had been for years so I bought a new surge tank. Turns out that a dealer tech broke it off trying to twist off the hose for some reason when the car was new. He just pushed the broken fitting into the hose and clamped the hose on what was left. I recall the problem quite clearly; the car was about a year old at the time.

The hardest part was getting the old fitting out of the hose. The surge tank fitting has a copper insert to allow the hose clamp to tighten well, and it was very difficult to get needle-nose pliers to grip on it well enough to work it out.

To answer your question about tips in getting it out, mine was easy because the fitting was broken off and it pulled out easily. It was originally broken off by some tech that didn't have the necessary patience. As for tips, I would hold the hose with my hand and rotate the surge tank back and forth as much as I could and work the hose off the fitting. There's no space to rotate much, but take your time, rest and go back if you have to, and it will eventually work out of the hose.

Don't cut the hose. It's a special neoprene hose that never goes bad, and the dealer can't help you get another one.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Thanks for the info Cadillac Jim! Yes, I will definitely be cautious taking that hose off, and will not cut it. But I have a feeling I'll be up against pulling a broken off stub out afterwards like you had to. It is almost completely cracked off and the clamp that's on there is one of those squeeze type. I cannot even get a pliers on it, much less squeeze it!

I did find a youtube video on removing the tank just now. It is pretty helpful and does show removing the battery first. Will start there tomorrow...

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

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Yes, you need to remove the fender brace and battery to get room to access the surge tank.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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So I gto this reservoir replaced this week, but not to happy with aftermarket part... :( First the dang thing had wrong size fasteners clipped to the top rim, so I had to use larger bolts... Now the "check coolant level" message is coming up every time I use the vehicle, and the level is actually fine. I contacted EBay seller and theyre shipping me a replacement, but still have the hassle of taking it all apart again... :angry2:

Edited by sprucegoose

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

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The surge tank has a coolant level sensor in it. The connector is on the bottom. See if the aftermarket product has such a sensor; if not, you will need a new surge tank that *does* have the sensor to get the message to go away.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Sorry Jim, I forgot to mention that part!

I did plug in the sensor on the bottom of the reservoir when I put the new one in. Unfortunately I could not test it until I filled up the reservoir and put the battery back in place...

When I get the new one I will fill it with water and plug in the sensor to test before I replace the defective one. I think this should work!

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

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  • 2 weeks later...

Replaced this reservoir with the replacement I was sent today. Same problem, check coolant level message coming up. Could not test prior to install as I couldn't get at plug to swap to new one till I pulled it all out anyway...

I think the sensor or the socket that it is pressed into is bad on these things though... I went to pull the plug off the first unit in car and the whole sensor pulled out! I expected coolant to start leaking out, but it didn't! Maybe that sensor tip doesn't need to contact the coolant, but thought it would...

Took my chances that the second one would be good, but same darn issue. I think ill just live with it as I sure don't feel like pulling it out again. At least for now...

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

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Are these some kind iof aftermarket tanks? If so, you might want to get a OE tank and be done with it.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Yup, aftermarket. OEM was over 3x the price, but I guess u get what you pay for though...

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

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