Hi everyone. i know, another overheating problem. please bare with me. had a problem where car would start getting to 2nd mark past 12. didnt matter if it was uphill, down hill, flat surface....it would just happen. if i reved the engine up to 2500-3000rpm, the gauge would come back to 12. then my upper radiator hose went right near the engine. i replaced it and let the car idle with cap off of resivoir to try bleed air out of system giving it spurts up to 2500rpm every now and then. i tried to fill the hose when i put it back on but went right through the radiator and back out of the engine where it gets hooked to. the next day car overheated badly.....reving didnt even help. I limped it home after it cooled down and checked the overflow. coolant was coming out of the overflow hose. when i could finally get cap off, i topped off the tank and did a repeat of the previous day. at that point i turned on the ac while hot and the car stayed at dead on 12 oclock for 45 minutes. today, same thing. car overheating and coming out of the overflow. I checked the oil, no water in oil. NO white smoke from tailpipes. The top radiator hose was very hot and tight. the lower radiator hose where it hits the thermostat was cool, not tight. i touched the metal on the other side of the thermostat where it meets the 'y' and burned my finger....could this just be a sticking then stuck thermostat?? or possible water pump failure? radiator is only 5 months old as the old one had cracked the plastic on the passenger side. did i not purge the air out properly?? i go back to work on the 5th and have time to play with it right now. the water pump belt looks good and is turning, so i have no clue. any input would be appreciated. thanks.

 

Heres an update. I changed the thermostat. the old one was shot. rubber diaphram on both sides wrinkled and ripped. car was great for awhile then started getting i mark to the red. had heat on high to try purge any air as it will blow hot as you bring up the rpms, then run warm to cold at idle. purge line does have a flow from it at the serge tank. the upper radiator hose gets hot as does the one side of the radiator. lower hose just warm and so is that side of radiator. do i possibly have a bad 5 month old radiator? all fans come on as they are supposed to. thing that bothers me is you only get heat when bringing up the rpms. possible bad water pump? gonna get a flush and fill this weekend.

 

sounds like low coolant issue or stuck thermostat. See what happens after you do the flush.

 

what model are we talking about?
different models and years have different systems.

Some models are self purging; some have a burp valve atop engine, etc…

sounds like a serious air in the coolant problem, water pump cavitation, stat in reverse, any or a combo of any, etc ..

screw on caps have a vents built in; old style caps have overflow tubes; purge lines flow to the surge tank; etc.....


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Thanks Daddylac and Stompers. This is the older style with the vent tube at the overflow and no purge nut near the water pump. finally broke down and had my mechanic friend take a quick look. he thinks either the water pump is shot or a plugged radiator as i did find old leak seal material in the top hose when i replaced it. Thermostat went spring in, the same way the old one came out. hes gonna do a whole system flush and a flow test on the radiator. he doesnt feel its a head gasket issue either. its a 2000 DHS with the northstar. thinking back, the water pump was replaced about 5 yrs ago or more as i remember it was still under warranty as a certified preowned. besides the failling windows (thats just stupid engineering..they could have made metal instead of plastic!) this car is still in great shape with 159,000 miles. still getting the top hose pressurised and hot, bottom hose warm only and just past thermostat, very, very hot. also heat comes and goes. almost seems like there is a BIG air bubble that wont go away. im gonna pull the purge line again at the overflow and make sure the pipe going into the overflow isnt clogged. ill keep this updated so hopefully it helps someone else having the same/similar problems. Is there a way to effectively purge the air? or do you have to just let it do its job. i was told that if theres air at the thermostat, it wont open. unsure of how to try purge THAT air, if that is what is really happening. right now the temp goes right up to the last white line and never seems to cross it. takes a couple of miles of driving to get it there. drove 6-10 miles in stop and go traffic and never went into the red. are these systems just slow purgers? Thanks again!

 

Not sure about the 90's but I think the therm should be spring up should it not??

 

Hi. the spring end is up into the y, while the thermostat end is toward the hose. thats how the other one came out. Jiggle valve is toward the bottom the same as when i pulled the old out.

 

Just wanted to give everyone an update. Main problem was a PLUGGED radiator core. Wich in turn, ruined the water pump and the thermostat. So, IF you DO NOT have water in the oil, have NO white smoke out the tail pipe, passenger side of radiator very HOT, Drivers side of radiator WARM, seems like no coolant flowing and coolant boiling out the vent on the overflow......get it checked ASAP.....my radiator was only 6 months old and now shot. Previous friend mechanic never flushed system OR replaced thermostat when replacing the radiator. My NEW mechanic says in his opinion, ALWAYS flush system AND replace thermostat on a radiator change. i guess at least it wasnt the heads.....gotta kiss that car when i get it back! lol! hope this at least points other people in the right direction. After hearing the horror stories about the heads, if your temp gauge EVEN hits 3/4 of the way.....STOP and let it cool and get it checked! dont fool around with it and risk ruining that engine. Im now out $500, but would have been alot worse if i damaged those heads. Thanks to all who commented on this thread, it was much appreciated!

 

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.