Polaris Posted August 21, 2014 Report Share Posted August 21, 2014 I just bought a 99 STS with the Northstar engine. I love the car but immediately started having problems with the cooling system. So far I have had it flushed and new Dex coolant installed. The cap is new, purge line is flowing and there are no hyddrocarbons in the system. There are no obvious leaks only a little weeping around the cap. And yet, it will lose 1/2 gallon after less than 200 miles. Link to comment Share on other sites More sharing options...
barczy01 Posted August 21, 2014 Report Share Posted August 21, 2014 Do you see any white smoke when you start it? After you park the car at night, how does the car start in the morning, smooth or bucks and jerks and will smooth out? When the car is cool, see what the surge tank smells like and hopefully its not a gas smell. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted August 21, 2014 Report Share Posted August 21, 2014 Even if there is head gasket leakage, the coolant will test good for about a week after it is changed. If you can smell exhaust in the overflow tank, or smell coolant in the exhaust, then you have head leakage. If not, look for a sticking thermostat, the wrong thermostat for your car, or a thermostat installed backwards. A new radiator cap can be the problem if it is not the right one for your car (15 psi rated and intended for overflow tank systems, not surge tanks), the seating surface is dirty or scarred, or isn't screwed all the way down. You are best off getting real AC/Delco thermostats and radiator caps crossed over to your car by model or VIN. Then, there's always leaks. Look for cracked radiator tanks and leaky hoses, particularly at the hose clamps. -- 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...
Polaris Posted August 22, 2014 Author Report Share Posted August 22, 2014 Thank you, both for the responses. In the morning it does run rough then smooth out. Also, I have seen a white plume behind me once but not consistent. I will sniff the overflow this morning and will try the thermostat next. Also, is the WOT process legit, I know it's fun but, is it real? Link to comment Share on other sites More sharing options...
airmike Posted August 22, 2014 Report Share Posted August 22, 2014 Curious, did you buy that car from an individual or dealer? That sounds like the head gasket problems I had. Where are you located? Link to comment Share on other sites More sharing options...
winterset Posted August 22, 2014 Report Share Posted August 22, 2014 Also take a whiff of the exhaust (of course not a deep breath, rather just stand near the back of the car) in the morning. If you smell a sweet smell, you are leaking coolant into the cylinders from a bad hg. This explains the rough idle at startup. The plugs cannot fire properly of they are covered in coolant. Link to comment Share on other sites More sharing options...
Polaris Posted August 24, 2014 Author Report Share Posted August 24, 2014 Thank you all I appreciate the help. Here is the latest; I cannot smell antifreeze in the exhaust or exhaust in the overflow tank. I just replaced the thermostat nothing to report yet. Immediately after I bought the car I replaced the plugs and wires as it was misfiring on cyl 1. It no longer misfires and I think it is smooth running but, my brother who has owned Caddies thinks it is rougher than it should be. Very subjective call. Link to comment Share on other sites More sharing options...
Polaris Posted August 24, 2014 Author Report Share Posted August 24, 2014 I bought from an individual and live in the Seattle area. I know it is buyer beware but the prior owner had to know and said nothing. Link to comment Share on other sites More sharing options...
barczy01 Posted August 24, 2014 Report Share Posted August 24, 2014 The back bank 1,3,5,7 is usually the bank to go first, especially #1. Link to comment Share on other sites More sharing options...
KHE Posted August 24, 2014 Report Share Posted August 24, 2014 Rent or borrow a cooling system pressure tester and pressurize the system when i's cold. Then look for leaks. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Polaris Posted August 25, 2014 Author Report Share Posted August 25, 2014 Thanks, I will pressure test next. By the way, the thermostat is not the problem. Link to comment Share on other sites More sharing options...
princess Posted August 25, 2014 Report Share Posted August 25, 2014 I have the exact same weird issues with my 1996 93K on it it would require coolant every week or 300-500miles or so about a half a gallon however the car externally would be bone dry. Idle rough in the mornings and then smooth out.... after 4-6 minutes. (finally got it to through a misfire 0300 code after i ran hot in traffic and restarted next day)Ive come to the conclusion (loose based one thou) that my Headgasket on bank #1 is in the processes of going You indicated you replaced the plug on Cylinder 1? what did the old plug look like when you removed it? or do you still have it?I also noticed that my O2 sensor on that bank would through fault codes because i believe it is picking up the coolant burning off in my exhaust on that particular bank. Link to comment Share on other sites More sharing options...
KHE Posted August 25, 2014 Report Share Posted August 25, 2014 Make sure to not overfill the surge tank - the correct cold level is 2-1/2" down from the neck. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Polaris Posted August 27, 2014 Author Report Share Posted August 27, 2014 I have found a replacement engine and want to confirm it is the right one for this car. Again it is a 99 STS with the Northstar 4.6L engine. The VIN # is 9. The engine I found has a ID tag of T10L, is this the right unit? Link to comment Share on other sites More sharing options...
KHE Posted August 27, 2014 Report Share Posted August 27, 2014 I have found a replacement engine and want to confirm it is the right one for this car. Again it is a 99 STS with the Northstar 4.6L engine. The VIN # is 9. The engine I found has a ID tag of T10L, is this the right unit? The T10L doesn't mean anything to me. There is a 1/2" flat pad on the back part of the engine near the harmonic balancer that has the last ten digits of the VIN or it may be the complete VIN (I can't remember). If it is just the last ten digits of the VIN, then the first digit should be a 9 on the replacement engine. If it is the complete VIN, the eighth digit should be 9. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
airmike Posted August 27, 2014 Report Share Posted August 27, 2014 I have been told only 1998 & 1999 work. I also don't know about T10L. I know it is entirely too much work to take it out and then discover you don't have the correct one. Do you know what it is out of? Link to comment Share on other sites More sharing options...
Polaris Posted September 9, 2014 Author Report Share Posted September 9, 2014 Replacing engine now, anyone want a used Northstar? Link to comment Share on other sites More sharing options...
barczy01 Posted September 9, 2014 Report Share Posted September 9, 2014 If you were closer I would take it. I have been building quite a few motors and fixing engines shipped to me this Summer. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted September 10, 2014 Report Share Posted September 10, 2014 If I had a place to work, the time, and an engine stand, a Northstar and 4T80E would be a nice project for my wife's 99 Pontiac Grand Am GT when she moves on to another car. But the only way for that to happen would be for the Grand Am to go away and leave its space in the garage, which is a Catch 22. It would be great to double the horsepower of that nice little car, if I could get the front wheelbase to work out. But, sadly, no thank you. Mabe Cody could use a spare or parts engine - but I think he's using a 2002, so he probably would want a post-1999 engine that has the same parts as his. -- 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...
Polaris Posted September 27, 2014 Author Report Share Posted September 27, 2014 Just finished putting the "Y" block in my "9" car; it is running great. I'm happy again. Now want to rebuild the old engine to sell. I need the stud set to replace the head bolts, any reccs as to where to get it? Link to comment Share on other sites More sharing options...
tj95eldorado Posted October 11, 2014 Report Share Posted October 11, 2014 I would use the Carrolls Custom Caddy stud set... Link to comment Share on other sites More sharing options...
winterset Posted October 11, 2014 Report Share Posted October 11, 2014 I didn't know you can interchange the 9 and Y. Isn't the ecm and transmission gear ratio different? How did this work? Link to comment Share on other sites More sharing options...
Cadillac Jim Posted October 11, 2014 Report Share Posted October 11, 2014 You can change the differential and final drive ration on the 4T80E. It comes out the right axle shaft. The VIN 9 cars used a 3.71 final drive ratio while the VIN cars use a 3.11 final drive ratio. The PCM will throw a code if it isn't the right one. The differences between the VIN 9 and VIN Y engine (1993-1999) and transmission are the intake cams, the final drive ratio, and the PCM. I suspect that the PCM can adjust to the "wrong" intake cams but I don't know because I've never heard from someone who has tried that and has real data on the car, such as exhaust emissions, OBD data, and/or dyno data. -- 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...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.