| HT4100 4.1, 4.5, 4.9 This forum is to discuss the newer aluminum block Cadillac engines. | Cadillac Forums: For those of you with coolant loss issues. 
01-08-08, 10:59 AM
|  | Cadillac Owners Fanatic Cadillac(s): 93 SDV / 94 Z28 Conv. 355 | | Join Date: Feb 2005 Location: Bradenton, FL Age: 37 | | | For those of you with coolant loss issues. If you are having coolant loss issues and can't find the source like I was having, you may want to check the plastic heater 'T' next to the firewall, passenger side. Every time I turned on the heater I would loss coolant with no avail to the where abouts of the source. It turned out to be the 'T', it was so small I didn't notice any collant pooling, until the T broke in half going down the interstate. two hours and 27$ later it was fixed. So check your T, it could save you being stranded on the highway. | 
01-08-08, 10:54 PM
|  | Cadillac Owners Connoisseur Cadillac(s): 1995 FWB 87,*** 1991 Seville 175,000 SOLD | | Join Date: Dec 2005 Location: MA Age: 50 | | | Re: For those of you with coolant loss issues. The T is a known source of coolant leak. Plastic develops tiny cracks and you can see the coolant only when you increase (manually) RPMs till say 3000. That's how I found out my T was bad.
Thanks for bringing it up. | 
01-09-08, 10:09 AM
|  | Cadillac Owners Enthusiast Cadillac(s): 1995 Cadillac Sedan Deville 4.9, 1992 Cadillac Brougham 305 | | Join Date: Aug 2007 Location: West Palm Beach, FL Age: 20 | | | Re: For those of you with coolant loss issues. yep ive had the same problems.... went threw 3 Ts in 6 months. im still losing coolant somehow and my coolant resivour doesnt pull any coolant in the radiator, i dont know why... | 
01-09-08, 04:45 PM
|  | Cadillac Owners Enthusiast Cadillac(s): 93 & 88 Allante, 88 Eldorado | | | | | Re: For those of you with coolant loss issues. They must have cheapened the T on the newer models. My 88 Eldorado has a T made of steel and it's still fine. | 
01-09-08, 05:17 PM
|  | Cadillac Owners Fanatic | | | | | Re: For those of you with coolant loss issues. The "T" on my 4.5 was fine. It was the water control valve that kept leaking. | 
01-09-08, 05:35 PM
|  | Cadillac Owners Connoisseur Cadillac(s): 1995 FWB 87,*** 1991 Seville 175,000 SOLD | | Join Date: Dec 2005 Location: MA Age: 50 | | | Re: For those of you with coolant loss issues. Quote:
Originally Posted by Brizzal yep ive had the same problems.... went threw 3 Ts in 6 months. im still losing coolant somehow and my coolant resivour doesnt pull any coolant in the radiator, i dont know why... | The hose running from the reservoire to the radiator neck is likely plugged with coolant supplement or something. Check it out. You may have halempty radiator and will not even know that. The radiator cap may need replacement as well. | 
01-10-08, 10:34 AM
|  | Cadillac Owners Fanatic Cadillac(s): 93 SDV / 94 Z28 Conv. 355 | | Join Date: Feb 2005 Location: Bradenton, FL Age: 37 | | | Re: For those of you with coolant loss issues. When it rains it pours! Now that my T is fixed I found a tiny crack in the front of the rad.. I guess it's to be epected with a 15 y/o car. | 
01-10-08, 03:53 PM
|  | Cadillac Owners Connoisseur Cadillac(s): 1995 FWB 87,*** 1991 Seville 175,000 SOLD | | Join Date: Dec 2005 Location: MA Age: 50 | | | Re: For those of you with coolant loss issues. Quote:
Originally Posted by medicz28 When it rains it pours! Now that my T is fixed I found a tiny crack in the front of the rad.. I guess it's to be epected with a 15 y/o car. | You probably mean a plastic side end tank. Yep, they fail. Get an aftermarket all metall radiator for some $150 and replace. Not a big deal, really. | 
01-10-08, 08:48 PM
|  | Cadillac Owners Fanatic Cadillac(s): 93 SDV / 94 Z28 Conv. 355 | | Join Date: Feb 2005 Location: Bradenton, FL Age: 37 | | | Re: For those of you with coolant loss issues. Thanks for the reply, not really worried about it, it's just one thing after another. | 
01-17-08, 11:44 AM
| | Cadillac Owners Member Cadillac(s): '93 Sedan DeVille | | Join Date: Jun 2007 Location: Moneta, VA | | | Re: For those of you with coolant loss issues. Appreciate the info. I was losing coolant too and mine was from loose small bolts on the front of the engine. Not really sure what the bolts are for, looks like some kind of plate or cover, but after tightening the coolant loss has almost stopped. Couldn't find the leak, but like HUF has mentioned, high steady revs while watching under the hood found it.
Anybody else out there ever have this kind of problem?
I'm going to double check the T also.
Bill
Last edited by General_Motors_Fan; 01-17-08 at 11:49 AM.
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01-18-08, 09:00 AM
|  | Cadillac Owners Connoisseur Cadillac(s): '87 SDV | | Join Date: Jun 2005 Location: Michigan Age: 50 | | | Re: For those of you with coolant loss issues. Quote:
Originally Posted by General_Motors_Fan Appreciate the info. I was losing coolant too and mine was from loose small bolts on the front of the engine. Not really sure what the bolts are for, looks like some kind of plate or cover, but after tightening the coolant loss has almost stopped. Couldn't find the leak, but like HUF has mentioned, high steady revs while watching under the hood found it.
Anybody else out there ever have this kind of problem?
I'm going to double check the T also.
Bill | The water pump on the 4.X series engines is a wafer thin plate held on by 18 fasteners of various sizes. Most are small (10mm as I recall) bolts and nut/stud combinations. They are very sensitive to correct torque. If someone replaced the pump and tightened the bolts by 'feel,' some of them are bound to vibrate loose and leak. | 
01-20-08, 01:23 AM
| | Cadillac Owners Enthusiast Cadillac(s): 93 Sedan Deville 4.9L | | Join Date: Sep 2005 Location: Texas | | | Re: For those of you with coolant loss issues. Quote:
Originally Posted by General_Motors_Fan I'm going to double check the T also.
Bill | Dont just double check it, Replace the POS lol.
I did a full coolant flush including heater core just before it got cold (about 5 weeks ago) I spent the other night in the 30 degree rain working by the light from the headlights replacing my T in the middle of a parking lot cause it snapped in half and blew coolant all over the engine bay.
When i did the flush i checked the T and it had no signs or cracks or weakness, the other night it fell apart in my hands.
I have had the T go in both my 93 devilles, both times i wasnt at home either lol. | 
01-20-08, 01:49 PM
|  | Cadillac Owners Connoisseur Cadillac(s): 1995 FWB 87,*** 1991 Seville 175,000 SOLD | | Join Date: Dec 2005 Location: MA Age: 50 | | | Re: For those of you with coolant loss issues. Quote:
Originally Posted by behind-bars Dont just double check it, Replace the POS lol.
I did a full coolant flush including heater core just before it got cold (about 5 weeks ago) I spent the other night in the 30 degree rain working by the light from the headlights replacing my T in the middle of a parking lot cause it snapped in half and blew coolant all over the engine bay.
When i did the flush i checked the T and it had no signs or cracks or weakness, the other night it fell apart in my hands.
I have had the T go in both my 93 devilles, both times i wasnt at home either lol. | Wow. Never heard of thermostats falling apart... | 
01-20-08, 02:40 PM
| | Cadillac Owners Enthusiast Cadillac(s): 1985 Sedan DeVille | | Join Date: Aug 2007 Location: Southern Maryland | | | Re: For those of you with coolant loss issues. he's referring to the T-shaped pipe by the heater control valve | 
01-20-08, 09:42 PM
|  | Cadillac Owners Connoisseur Cadillac(s): 1995 FWB 87,*** 1991 Seville 175,000 SOLD | | Join Date: Dec 2005 Location: MA Age: 50 | | | Re: For those of you with coolant loss issues. Quote:
Originally Posted by ehall he's referring to the T-shaped pipe by the heater control valve | Oh, I see. Thanks. | | Cadillac Discussion Tools | | |
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