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Dave Nova
Dave Nova, Cadillac Technician
Category: Cadillac
Satisfied Customers: 19452
Experience:  ASE Master Certification. GM World Class Certification
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2001 Cadillac El Dorado, ETC, V8 4.6 L, 279 C.I; 300 HP, VIN

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2001 Cadillac El Dorado, ETC,
V8 4.6 L, 279 C.I; 300 HP, VIN: 1G6ET129881B105733 Engine “9”

May 2009. Coolant leaking from reservoir tank, deteriorated plastic at outlet: Replaced reservoir tank with new OEM tank and new Dexcool 50/50 mixture.

July 2009. Radiator tank gasket leakage: Replaced radiator OEM replacement type and coolant Dexcool 50/50 mixture.

Sept. 2009. Noticed cooling system level down approximately 2 qts. every 4 weeks, temperature needle would deflect ¼ “ to the right of normal on a 5 miles long grade approx. 500 feet in elevation, ambient air temp 58 degrees. Also smell anti-freeze when pulled vehicle into garage. Normal temp past 8 years: 1 needle width to the right of center. Cooled engine to ambient temp 8 to 10 hours in garage to 65 – 75 degrees, service coolant Dexcool 50/50 mixture.

Jan. 2010. On going re-servicing intervals narrowed to every few days. Loosing coolant out of reservoir overflow hose.

Jan. 2010. Purchased Stant Pressure Checker: Found pressure cap, 18 psi. rated, leaking pressure not holding but 5 – 8 psi. Purchased new OEM pressure cap. Pressure tested to 18 psi held at 16 psi. Pressure tested system and cap, no leaks.

Feb. 2010. Thermostat reflected opening at 195 degrees, normal on OBDII scan tool. Replaced thermostat with OEM unit serviced coolant Dexcool 50/50 mixture. Checked water pump drive belt and tension good. On going re-servicing for the next two months, narrowed to every day 1½ quarts coming out of over flow at reservoir tank. After driving approx. 70 miles mostly level or down grade ok, temp approx. 197 to 204 degrees per OBDII scan tool until the last part of trip. A 5 miles long grade approx. 500 feet in elevation last leg of trip 58 degrees ambient air temperature. Then system reflects a temperature approx. ½ “ to the right of normal but not into red approx. 234 degrees per OBDII scan tool topping the grade at 75 mph daily.

Mar. 2010. Replaced both right and left cooling fan relays and series parallel cooling fan relay, total 3 relays.

April 2010. Took car to Cadillac dealer, Dealer checked cooling fans with A/C on, both fans run, with A/C off cooling fan comes on at spec. 221 degrees. High speed fan comes on at spec. 234 degrees. Pressure checked system no leaks. Checked cooling sym for engine gasses passed chemical test no combustion chamber leaks into cooling system. Found pressure cap bad, warrantee cap topped off sym.

May 2010. Re-checked pressure cap found OEM leaking down to 10 psi. Replaced pressure cap with Stant brand cap pressure holds at 16 psi. pressurized to 18 psi.

May 2010. Replaced radiator with warrantee OEM style radiator service coolant Dexcool 50/50 mixture. Cooling sym runs normal until going up grade then depending on grade it can pull temp up to 244 high speed fan comes on with air on.

May 2010. Extended hose from coolant reservoir to 2 qt. plastic container to catch over flow when going up grade.

May 2010. Checked for discoloration of exhaust pipe forward of Catalytic converter also aft. found normal. No swooshing noise from exhaust when accelerating, engine revs up fast normal. Transmission serviced normal fluid bright red no burnt smell no slippage noted. Gas mileage normal 20.2 to 21.6 daily highway. Climate control operates normal cycles on and off as needed maintaining desired temp. Engine oil and filter is changed between 3 and 5 K miles 5 – 30 W. Gasoline used 91 octane.

Items not verified or replaced: visual of water pump and rpm of cooling fans.
If I understand correctly, you are concerned about the vehicle running hot and the loss of coolant. Correct?
Customer: replied 7 years ago.
Yes. As long as I don't drive up a grade the coolant stays in the system with or without the climate control on.

Do you ever notice any steam from the exhaust on startup or a rough idle for a short time on startup?
Customer: replied 7 years ago.
No steam or white smoke. Hot or Cold with a pressure tester pumped up to 18 psi. I now recover my overflow via an extended hose from the reservoir to a two qt plastic bottle I've fastened to the side of the radiator. When I get to work the vehicle sits all night and cools. In the AM I refill the reservoir with the expelled coolant and return home. The last 5 miles is a grade 500 feet above sea level. I then pull temp and expels coolant into my 2 qt container. No lost fluid to the engine oil or combustion chamber. Passed the chemical color change for gasses in the coolant system.
Please read my original quote of my problem I believe all this has been stated.


Your problem is still most likely a leaking head gasket. This is very common on the 4.6 Northstar engine. The head bolts actually pull the threads out of the block. The problem may not be evident on the chemical test, but you aren't performing the chemical test while under load pulling a grade. If this is the problem, it will worsen and become more evident.

Customer: replied 7 years ago.
Why not a drivability problem and lack of white smoke? Will a re-torque of the heads be a possible fix?
Will chucking 200 psi of shop air into the combustion chamber at TDC via the spark plug hole also find a leak?
Shop air will likely not help to find the leak. Combustion pressures are well above 200 psi. Retorquing the heads is not a viable solution because of the situation with the threads in the aluminum block. Most of the time when head gaskets are replaced, it is necessary to install helicoils in all of the head bolt holes. The only possible driveability concern that would cause an engine to run hot is a lean fuel mixture. If the mixture was this lean, you would get a check engine light and some related trouble codes.
Customer: replied 7 years ago.
What check would verify your theory which is viable? How can this be proven without a tear down?
Possibly running the engine at increased rpm while performing chemical test to simulate running under load.
Customer: replied 7 years ago.
As a run on a smog dyno? Any other ways to verify other than a costly hope and a poke tear down?
Ball park what is the average two heads off on cost at a dealer? Can it be done in chassis on this vehicle? Regards
Running on a smog dyno would be a good test. The engine must come out of the car to service the heads. This is very labor intensive. This calls for 20 hours labor. Adding helicoils to the block for reassembly will add another 3-4 hours to this. Labor costs alone will be over $2000.
Dave Nova and 2 other Cadillac Specialists are ready to help you
Customer: replied 7 years ago.
I accept your answer as a route to pin point the problem.
Thank you.
You are welcome. Thanks for using Just Answer.

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