: Northstar Overheating!!! HELP



bigbuickgs
05-10-08, 02:11 AM
I just bought a 1998 STS. I knew a little about the northstar but not as much as I think I need to... Anyway when I got it is was a little low on coolant. I put about 1/2 a gallon in it, I drove it all week and no problems. I noticed it started getting hot. It was normally running in the middle, and it will go up to the notch before the red. It got to the red once but i shut it off right away and I don' think it caused any damage. When it got hot I noticed that there was no heat coming out of the vents. I thought this was odd, i checked the coolant again, and it was low again, i put another 1/2 gallon in it while it was running. it burped out a lot of air, and then sucked the coolant down. I added about another gallon, then the heat came back at the vents, and the gauge has not moved from the middle of the range. Then after about 20 miles it just started getting hotter again, and I lost my heat. I shut it off again towed it home and here is where it sits. So What now? Does anyone have any ideas. Thermostat? Air pocket? Plugged passage? Please help. Thank You

Ranger
05-10-08, 10:39 AM
I hate to say this, but it sounds like a classic head gasket gone south. Have the coolant tested for the presence of exhaust gases.

RickyHenry
05-10-08, 02:15 PM
Welcome to the 97-99 Northstar Head Gasket Replacement Club!!!!! it could be something other than a head gasket problem, but I strongly believe it is a blown head gasket issue because that is exactly what would happen with my car and I drove it off and on for months like that before succombing to the fact that it was a blown gasket.

Read my thread called replacing cylinder heads project...

Destroyer
05-10-08, 05:13 PM
Seems like a lot of owners are opting to sell their vechicles and do bandaid fixes just to get rid of them. Problem of course is that the new owners recieve an unexpected surprise. I could have done this when I sold my '98 with blown head gaskets but didn't. Of course I only got $1600 for it. Anyhow, sorry to hear of these problems. Some of these guys are a wee bit in denial over the headgasket issue but most are very knowledgeable on the subject and you will find great help here. We need to start a headgasket support group forum. :welcome5:

jeffrsmith
05-10-08, 06:41 PM
Seems like a lot of owners are opting to sell their vechicles and do bandaid fixes just to get rid of them. Problem of course is that the new owners recieve an unexpected surprise. I could have done this when I sold my '98 with blown head gaskets but didn't. Of course I only got $1600 for it. Anyhow, sorry to hear of these problems. Some of these guys are a wee bit in denial over the headgasket issue but most are very knowledgeable on the subject and you will find great help here. We need to start a headgasket support group forum. :welcome5:

I will second that - I think that that is exactly what I bought - a N* that had had a bandaid fix - not knowing about the HG probs with the N*. I fell in love with the car only to have it parked 6 weeks after paying too much for it - considering what I know now. I am getting ready to start the head gasket job myself.

Where shall we start the support group forum?

91parkave
05-10-08, 07:16 PM
what we should start is a cadillac Ls4 retrofit project, the northstar is a great motor but LS4's would be a great retrofit for durability and performance wise

Destroyer
05-10-08, 09:02 PM
what we should start is a cadillac Ls4 retrofit project, the northstar is a great motor but LS4's would be a great retrofit for durability and performance wise
Pure speculation but couldn't a 5.3 from a new Monte be installed?. Its a transverse mounted FWD GM V8. Maybe others familiar with both chassis's can chime in. Mayve even a 3.8 or 3.8 SC Buick?. I know there would be a loss in performace with either Buick V6 but the added reliability and better mileage might be a tradeoff that some would find worthwhile.

Submariner409
05-10-08, 10:15 PM
Commendable idea, but I think the loss of 50 or so cubic inches (to a 3.8) would ruin the torque curve and turn a 4,000 lb. car into a real slug. Now, if you could somehow swap in a 5.3, that's a horse of a different color.

CadillacSTS42005
05-10-08, 10:28 PM
5.3 would never mount instock form
and for the additional weight of a 5.3 we gain 3 yup 3 hp (comparing an L37 N* of course) ...
yea we gain more torque as well but from a speed standpoint itd be cheaper and easier to finally hack the N* and drop in an S/C

Destroyer
05-11-08, 06:48 PM
5.3 would never mount instock form
and for the additional weight of a 5.3 we gain 3 yup 3 hp (comparing an L37 N* of course) ...
yea we gain more torque as well but from a speed standpoint itd be cheaper and easier to finally hack the N* and drop in an S/CI'm talking more about making the car reliable than fast but the 5.3 LS motor would help on both fronts.

CadillacSTS42005
05-11-08, 07:03 PM
5.3 has only been around a few years (04?)
give it time before we say its a great reliable engine...
just as you say the 03+ N* may not be bulletproof give it time

Destroyer
05-11-08, 08:35 PM
5.3 has only been around a few years (04?)
give it time before we say its a great reliable engine...
just as you say the 03+ N* may not be bulletproof give it timeThe 5.3 is a smaller displacement LS motor which has been around since '98. These motors can take severe beatings and not flinch. They are used in full size trucks/vans/even the first SSR's. They are not known for H/G issues either.

CadillacSTS42005
05-11-08, 08:41 PM
and the 4.6 N* came from the bulletproof 4.9....

Destroyer
05-12-08, 12:51 AM
and the 4.6 N* came from the bulletproof 4.9....
Heh, there was a guy overheated at the parking lot at the local Walgreens today with a 4.9 Deville. Regardless, the Northstar is not just a bore and stroke from being a 4.9. There were many changes and nobody has ever called the 4.9 "bulletproof", better yeah but not bulletproof.

bigbuickgs
05-19-08, 10:25 PM
OK so back to the question at hand. I got the coolant tester today from my snap on guy. I did 4 tests two not running, engine warm both came back good. I did two running, on and off the throttle. one came back good, the other one the fluid turned green, the kit says it should turn yellow, for a gas engine, and green for a diesel. I put it to the tail pipe and sucked in exhaust, it instantly turned yellow(not green like in the test of the coolant). I dont know what to make of these results. Still no heat untill the gauge is at 12 o'clock, and it wil not over heat in the driveway, no matter how i play with the throttle if i am not driving it will not overheat. I am going to do some more research and then i think I am going to replace the HGs. unless anyone else has a better idea. Thank you for your help, and the great stories!!

krimson_cardnal
05-20-08, 02:33 PM
I believe that a positive test does not change the indicator color. You tested exhaust to check things out - trying to confirm what you were seeing at the radiator, correct. Check this SITE (http://www.arrowheadradiator.com/head_gasket_or_combustion_leak_test.htm). Interesting links at bottom of page as well. Looking like you're getting a positive - good luck, keep us posted. K_C