jje1953 Posted March 31, 2012 Report Share Posted March 31, 2012 Thanks to some sage advice from people here at the forum, I know where to look when I have a temperature spike on my '98 Deville. The problem is, the "bolt with a hole in it" continues to re-clog with small, gritty chips, that are white in color. The chips will mush in your fingers, but they will definitely clog the bolt. A few have suggested that the chips are remnants of the radiator tablets that were frequently put in Northstar coolant systems. I have not put any in, but the previous owner probably did. Whatever the gunk is, there seems to be an endless supply of it in my coolant systems. Two thorough coolant flushes have not expelled the little nasties, and clearing the bolt has become an ongoing process. At the same time, the heater core seems to be plugged (heater only works after long warm up period), even though it was flushed both ways on the last system flush. It appears that wherever the major concentration of the gunk is, it continues to break off in tiny pieces that invariably clog the bolt. It's pretty much a dog chasing it's tail by this point. You can have a flush done, but you never get rid of the residual gunk and the beat goes on. I have actually thought of having the bolt opening drilled out to a larger opening so the small chips would pass through. I'm sure the gunk may be clogging the system elsewhere, but that never results in the problem a clogged bolt causes. Enlarging the hole size may have other implications. Wouldn't know on that. Any thoughts on that, or what it might take to end this problem and get the system cleaned out? Link to comment Share on other sites More sharing options...
BodybyFisher Posted March 31, 2012 Report Share Posted March 31, 2012 First, the GM cooling supplement tablets are BROWN, not WHITE so its not the tablets What is the history of the car, could someone have tried to SEAL it before you bought the car?, and this is the evidence? I have seen silicone clog it on more than one occasion and rubber in another. It seems that you have done about all you can do, reverse flushing the cooling system, it has to be something breaking loose. I would clean the tank and pull the heater core and see what I find, but I don't think that will solve your problem. I would NOT make that hole bigger, it may negatively impact your heating Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
Texas Jim Posted March 31, 2012 Report Share Posted March 31, 2012 If I was going to the trouble of pulling the heater core to check it... for 37 bucks I would replace it while I had it out... http://www.amazon.com/Delphi-HC0172-HVAC-Heater-Core/dp/B000CGI5O0/ref=au_pf_ss_1?ie=UTF8&Model=DeVille|406&n=15684181&s=automotive&Make=Cadillac|46&Year=1998|1998&carId=003 Link to comment Share on other sites More sharing options...
Ranger Posted April 1, 2012 Report Share Posted April 1, 2012 First, the GM cooling supplement tablets are BROWN, not WHITE so its not the tablets What is the history of the car, could someone have tried to SEAL it before you bought the car?, and this is the evidence? My thoughts exactly. I don't think that enlarging the bolt hole would do any harm, buy that's just my $0.02. Link to comment Share on other sites More sharing options...
KHE Posted April 3, 2012 Report Share Posted April 3, 2012 I would not enlarge the hole in the bolt. You need to keep flushing the system until all the crud is out if the system. If you are flushing with a garden hose, I would suggest taking the car to a radiator shop and have the entire system power flushed. The radiator shop can get higher pressures and should be able to flush out the crud in the system. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
rockfangd Posted April 5, 2012 Report Share Posted April 5, 2012 I second the replacement of the heatercore. If you are going to go through the hassle of removing it, replace it. Most aftermarket cores dont have the plastic tanks (thank god. the oems did and they like to crack) depending on what is in there you may have to replace the radiator. When you are getting the system flushed is the thermostat being removed? GM FAN FOREVER Nice, clean, luxury= fine automobile Link to comment Share on other sites More sharing options...
donandmax Posted April 28, 2012 Report Share Posted April 28, 2012 Does the 98 Deville have this "bolt with a hole in it" ?? Link to comment Share on other sites More sharing options...
rockfangd Posted April 28, 2012 Report Share Posted April 28, 2012 It should. I know the 99 has it. just not sure about 00up GM FAN FOREVER Nice, clean, luxury= fine automobile Link to comment Share on other sites More sharing options...
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