cthier Posted August 7, 2006 Report Share Posted August 7, 2006 Hello all, I have a 98 STS with the North Star V8 that drives great. The problem is is seems to overheat if I put any load on it. That is under normal driving its seems ok but if I want to use any of that North Star power it overheats. I replaced the Radiator and the Water pump but no luck. Any ideas? Thanks Charlie Link to comment Share on other sites More sharing options...
Cadillac Jim Posted August 7, 2006 Report Share Posted August 7, 2006 Ask a radiatory shop to test the coolant for cumbustion by-products (head gasket leakage). Then, if there is no head gasket leakage, a pressure check is in order, to see if there is an air leak or coolant leak somewhere in the system. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
jhall Posted August 7, 2006 Report Share Posted August 7, 2006 Charlie, I assume you changed the water pump belt, but did you also check the belt tensioner? These loose spring strength over time and this can result in a slipping belt at higher RPM - where it counts. Link to comment Share on other sites More sharing options...
Ranger Posted August 8, 2006 Report Share Posted August 8, 2006 Check the purge line to be sure it is not pluged. Link to comment Share on other sites More sharing options...
cthier Posted August 9, 2006 Author Report Share Posted August 9, 2006 Thanks for the info so far. I am taking it to a Shop tomorrow that can test for combustion byproduct in the cooling system. I suspect it is a blown head gasket but the issue is I just had the head gaskets replaced at the local shop. It started this behavior the day I pick it up. The Dealer assured me the head gasket was fine so I replaced everything else and still no luck. While doing some research I found lots of articles saying it was mandatory to replace the head bolts when you do a head gasket job on the North Star V8 do to how much torque is applied to the bolt causing them to stretch and not being able to reuse them. Do any of you know if there is an official Cadillac or GM technical paper stating this? Thanks Again Link to comment Share on other sites More sharing options...
KHE Posted August 9, 2006 Report Share Posted August 9, 2006 Thanks for the info so far. I am taking it to a Shop tomorrow that can test for combustion byproduct in the cooling system. I suspect it is a blown head gasket but the issue is I just had the head gaskets replaced at the local shop. It started this behavior the day I pick it up. The Dealer assured me the head gasket was fine so I replaced everything else and still no luck. While doing some research I found lots of articles saying it was mandatory to replace the head bolts when you do a head gasket job on the North Star V8 do to how much torque is applied to the bolt causing them to stretch and not being able to reuse them. Do any of you know if there is an official Cadillac or GM technical paper stating this? Thanks Again It is mandatory to replace the head bolts not because they stretch but because the factory bolts have an aggressive threadlocking compound applied to them that cannot be re-applied practically in the field. The factory headgaskets come with new headbolts so I wouldn't suspect that the head bolts themselves are the cause. The shop that replaced the headgaskets may not have installed the Timeserts in the block or improperly installed them and the head bolts have lost their retention power. A pressure test of the cylinder will quickly verify head gasket integrity. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
cthier Posted August 9, 2006 Author Report Share Posted August 9, 2006 Thanks for the info so far. I am taking it to a Shop tomorrow that can test for combustion byproduct in the cooling system. I suspect it is a blown head gasket but the issue is I just had the head gaskets replaced at the local shop. It started this behavior the day I pick it up. The Dealer assured me the head gasket was fine so I replaced everything else and still no luck. While doing some research I found lots of articles saying it was mandatory to replace the head bolts when you do a head gasket job on the North Star V8 do to how much torque is applied to the bolt causing them to stretch and not being able to reuse them. Do any of you know if there is an official Cadillac or GM technical paper stating this? Thanks Again It is mandatory to replace the head bolts not because they stretch but because the factory bolts have an aggressive threadlocking compound applied to them that cannot be re-applied practically in the field. The factory headgaskets come with new headbolts so I wouldn't suspect that the head bolts themselves are the cause. The shop that replaced the headgaskets may not have installed the Timeserts in the block or improperly installed them and the head bolts have lost their retention power. A pressure test of the cylinder will quickly verify head gasket integrity. I read a littlie about the TimeSerts but are they only install if the block strips out or should they be used every time? Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted August 9, 2006 Report Share Posted August 9, 2006 Time-serting is a thread repair procedure. However, the risk is if the threadholes are not timeserted while the heads are off, the threads may pull after the heads are torqued down, sometimes up to 10-14 months later, even if they do appear to torque down properly during assembly. So I recommend any time the heads come off the engine, time sert all the headbolt threads. I would rather pay the extra charge up front and know I had a good fix than risk needing to replace the head gasket again in a year. Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
BodybyFisher Posted August 9, 2006 Report Share Posted August 9, 2006 PLEASE confirm that you replaced the water pump belt and checked the water pump belt tensioner... 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...
cthier Posted August 10, 2006 Author Report Share Posted August 10, 2006 PLEASE confirm that you replaced the water pump belt and checked the water pump belt tensioner... Yep, Replaced the belt and checked the tensioner. I tried to do all the simple things first. Link to comment Share on other sites More sharing options...
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