SIXXDOGG Posted October 27, 2009 Report Share Posted October 27, 2009 Well I am back again with ANOTHER issue......2nd motor...and now THIS one is overheating. Today.....I was driving.....temp went to about 2 oclock.....pulled over and it was leaking out coolant of of the cap... I slowly opened it........then closed it back up again thinking that I didn't put it on right when I last checked my level a couple days ago... This issue happened another 3 times.......within 5 min intervels...... Took it to the shop.....he was 90% sure its a head gasket......Here I am using top oil....change coolant every 12 months.....I baby this car and it looks MINT.... I have another appt tomorrow to have it looked at again by someone else..... What can this be? I sure hope its not another head gasket issue........ Thanx in advance Link to comment Share on other sites More sharing options...
bigmoparjeff Posted October 27, 2009 Report Share Posted October 27, 2009 On a Northstar (and most other modern engines) there aren't too many possible causes of overheating: low coolant level stuck thermostat clogged radiator inopperative cooling fans - hot when car not moving, and would cool down as speed increased missing/slipping water pump belt failed water pump - unlikely on a Northstar bad head gaskets slipping transmission - extreme case, again unlikely Since you have been good with changing your coolant, your radiator should be fine, you know it's full. I'm sure you would notice if the trans was slipping real bad. The belt and fans are easy to check yourself. The Northstar uses a steel impeller on the pump, so it's very unlikely that there's a problem with the pump, though it's very easy to inspect it. Thermostats can be hard to diagnose, since bad headgaskets will give similar symptoms. The best thing to do is check the cooling system for hydrocarbons. That will tell without a doubt if the gaskets are bad. This can be done with the emissions machine sniffer, or by using a kit available from Napa. Was the replacement engine new, used, or rebuilt? Is it 150KM on the car or on the new engine? Jeff Link to comment Share on other sites More sharing options...
Cadillac Jim Posted October 27, 2009 Report Share Posted October 27, 2009 A clogged bypass can give symptoms identical to a failing head gasket or sticking thermostat too. It's easy to check also. It's a 3/8" hose that goes from the water pump over to the bottom of the surge tank. Just pull it off and watch it when someone starts the car and see if a stream of water erupts -- or not. There is one more symptom, coolant leakage, but this isn't likely the cause for this car. Also, on most troubleshooting charts for overheating, including the Northstar, I've see low oil level. With three extra quarts and an oil level sensor, that's hard to do on a Northstar, but I didn't want to leave it out. -- 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...
BodybyFisher Posted October 27, 2009 Report Share Posted October 27, 2009 Let me contradict the prior post, on a Northstar there are a LOT of things that will cause you to over heat. 1) a pressure leak, from radiator end tanks, hoses, clamps, heater pipes, crossover seals, water pump body gasket, water pump, the coolant tank 2) a clogged radiator 3) a slipping water pump belt or weak tensioner 4) an improper coolant concentration allowing the coolant to boil at a lower temp 5) a bad thermostat 6) a clogged air purge line 7) cooling fan problems 8) a collapsing hose First check to make sure that the system can hold pressure, then check the thermostat. Mechanics should NEVER jump to conclusions, without proper diagnostics. 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...
Ranger Posted October 27, 2009 Report Share Posted October 27, 2009 Second motor? Where did it come from? Link to comment Share on other sites More sharing options...
SIXXDOGG Posted October 28, 2009 Author Report Share Posted October 28, 2009 Good evening everyone! Well I took it to to places.....and it is the head gasket. I watched them perform the test......fumes in the coolant..... This is the 2nd motor.....had 80 000 on it when I got it.....now its @ 150. Dumped in 6 gm pellets....took it for a ride tonite...drove it for 40 min and it didn't over heat.... This car is MINT and I am really gonna miss it..... Is it worth anything to sell it? Link to comment Share on other sites More sharing options...
Cadillac Jim Posted October 28, 2009 Report Share Posted October 28, 2009 Perhaps you need to understand your problem before you panic and start talking selling the car. For one thing, an unfixed overheating problem with your car makes it unsellable except as a parts car or scrap. With everything in running order and typical condition, a 1998 STS is worth about $4500, more or less depending on condition and how the car is equipped. You can check it yourself on www.kbb.com I once bought a car for scrap prices because it was burning oil. It was only 4 years old but the owner wanted nothing to do with it, even when I offered to fix it for free and let her keep it. The problem was the PCV valve, a $2 item that is easily replaced in a few seconds. I drove that car for four years and never had a problem with it and it never burned a drop of oil. Except a bypass hose that burst because my mechanic thought that we didn't need to change it. The first thing I would do is run the codes. Here's how: http://www.caddyinfo.com/readingcodes.html Since you are spooked by a previous head gasket problem and this engine is used without its early maintenance history known, and it now has 140,000 miles on it, you should have the coolant checked for combustion products to clear that up right now. If the test is positive, you know where you are. If not, then you can find the problem and fix it. This sounds like it might be a blocked bypass hose to me. The same radiator shop where you take it for testing the coolant can check out that. -- 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...
SIXXDOGG Posted October 28, 2009 Author Report Share Posted October 28, 2009 Hello! Thanx for reading my posts..... (you should have the coolant checked for combustion products to clear that up right now. If the test is positive, you know where you are.) ..... I had it checked.....and there was combustion products in it..( ...The car is misfiring....Cyl 2 had 230 000 of them.....just had new wires and plugs installed last year.... Drove it today....lasted 30 min...then started to overheat again.......its blowing steam/collant out the cap.... ( Link to comment Share on other sites More sharing options...
SIXXDOGG Posted October 28, 2009 Author Report Share Posted October 28, 2009 This sounds like it might be a blocked bypass hose to me. The same radiator shop where you take it for testing the coolant can check out that. Where is this hose located? Thank you Link to comment Share on other sites More sharing options...
bigmoparjeff Posted October 29, 2009 Report Share Posted October 29, 2009 The bypass hose is the small diameter hose that goes into the tank that the rad cap is on. Since it's been confirmed that you have combustion gasses in the coolant, it's certain that you have bad head gaskets. There are only two other causes of hydrocarbons in the coolant: a cracked cylinder head, or a cracked engine block, and I've never heard of these on a Northstar. Unfortunately you'll have to decide whether it's best to fix the STS or sell it/trade it, as-is. Jeff Link to comment Share on other sites More sharing options...
SIXXDOGG Posted October 30, 2009 Author Report Share Posted October 30, 2009 Good evening everyone! Well....since my wonderful sts has the head gasket issue....I was wondering if this issue is the same with the 2006 sts v6? Anyone here know of any issues I should be concerned with if I go this route? Lets say 50 000km on the car..... Do they drive as nice? Bose system as good? Link to comment Share on other sites More sharing options...
Texas Jim Posted October 30, 2009 Report Share Posted October 30, 2009 I have heard of very few engine problems with the 3.6. Link to comment Share on other sites More sharing options...
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