I've had the same overheating experiences for the last two years. My 98 Cad Deville only had 75k on it when I experienced the first overheating issues, flushed out system, replace rad cap 20lb, thermostat, water pump, etc. First problem I had with overheating issues, I replaced the 2 lower coolant pipes with rubber hoses and re-routed them from under to around front of engine after my mechanic discovered one of them had rusted out and was leaking.
Then 2 months later I began getting check coolant levels messages and overheating again. After taking to a garage they told me the head gastet was going bad. Eventhough, I did not experience white smoke, or water or coolant in the oil, no white milky subtstance on the dip stick. But anyway my research brought me to a product, called Thermogasket via www.rxauto.com
, which was the only product out there with specifically with success with the aluminum block and bolts on the northstar engine, the company also engineered a part to eliminate the air bubble issues that is common with the Northstar engine which now I think may be related to the corrosion that occurrs throughout the metal coolant pipes in the Caddys preventing coolant to completely flow thru the coolant system. After Thermogasket usage I found it to be an amazing product, I was able to save the car and drive another 30k miles and then much to my dismay the over heating issues returned. The engineer with rxauto (Thermagasket company) has been really helpful as well and told me how to get the air pockets out that should not be their with their part installed.
This time I removed the purge line and found major corrosion, radiator hot on one side and cooler on other side, cleaned the line, purged the air bubbles. Then I purchased No-Rosion Coolant system flush (a serious bad - *** coolant flush) from www.No-Rosion.com
, ( $7.95) Man the crap in the pipes and radiator, I could not believe that I could have even driven it period, awesome product. I followed with their No-Rosion Inhibitor ( $9.95) to prevent future corrosion. I was tempted to buy another radiator first or at least replace the core, but I thought for a $8 I'll give it a shot, hardest part was waiting for it to come in the mail 3 days.
There are no words to describe how I feel about having my baby back. To think I was ready to sell for a $1000 listing it for parts, noting head gasket shot. Connected to the diagnostic computer tool and reset, so the service engine light turmed off. Cruises at 195 degrees, purrs like a kitten.
Boys this is the way to go - no more overheating problems. I hope this helps everyone. I love my Caddy, but out of desperation I bought a 2000 Saturn LS1 to drive while the baby was down. My back is killing me getting in and out of that low to the ground s--t-box Saturn.
By the way, while detailing the Saturn so I can sell it, I forgot I left the Caddy idling for 20 minutes, when I realized it, I saw the temp was running at 203. Not bad considering just a short four weeks ago, after driving less than 2 miles I broke down and the temp rose to 252 degrees. I rolled into the mechanics shop and he diagnosed it with a blown head gasket.
By the way a big shout to you all on the forum, you helped this crazy chick repair all the problems too, my friends thought I was crazy and told me to just get rid of it - what do they know they never owned a Caddy before.
Now Im riding high and comfortable in my Caddy with a big *** grin on my face and no more back pain.