98 Olds Aurora- cooling issue

[DemonElf]

Hello fellow gear head idiots. I have a 1998 Olds Aurora, 4.0L DHOC V8 Northstar engine. Just had my coolant change and thermostat. Before it would sit at 250° according to my temp gauge on the dash, when i drive it drops to 200. Now its the same but when i start the engine after driving it would jump to 270°.

 

Advice on if my temperature sensor is bad or do i have overheating issue? One guy said that my head gasket is leaking but my fluid level never changes, no coolant out the exhaust, none in the oil, no oil in the coolant tank.

 

Thanks

[codpiece]

@@ldoz might be able to help you. He is a mechanic.

[Damage_inc-]

your coolant fans should be comming on around 200-220 to kool engine.id look into that-maybe 2 fans .relay and sensor .check if fans working .if not fix that first-id guess a dead high speed fan

 

love this guy  this is a basic .may or maynot pertain to your car-

Edited April 26, 2016 by Damage_inc-

[Slackernet]

The coolant system is all about flow. The fans only help at idle when there is no air flow from driving down the road. Yes the northstar design is prone to head gaskets going bad. The head bolt threads pull out of the alum. block from expansion and contraction over the years. To verify the coolant temp sensor CTS is reading right, you will need a meter and a way to check temp. 

 

to check temp this is the cheapest way to do so.....

Non-contact Infrared Thermometer Temperature Gun with Laser Sight

http://www.amazon.com/Nubee-Non-contact-Infrared-Thermometer-Temperature/dp/B00JA3BMDW/ref=sr_1_10?ie=UTF8&qid=1461672264&sr=8-10&keywords=pyrometer

Here is the resistance table for the CTS. you need a digital meter set to ohms to check this. ohms can only be checked with no power to the sensor. it has to be unplugged. it will set a code while testing as the circuit will be open. not to worry once you plug it back in an run the car a few times the code you created from testing will clear itself

 

 

 

PS: If you would rather roll the dice on a new CTS they are only 15.00 and are easy to install.Its literally one plug and if you are quick you will not loose to much coolant at all

 

Here is an OEM AC Delco sensor on amazon

http://www.amazon.com/ACDelco-213-928-Equipment-Multi-Purpose-Temperature/dp/B000C9I038/ref=au_as_r?_encoding=UTF8&Make=Oldsmobile%7C51&Model=Aurora%7C567&Year=1998%7C1998&ie=UTF8&n=15684181&newVehicle=1&s=automotive&vehicleId=1&vehicleType=automotive

Edited April 26, 2016 by Slackernet

[7Toes]

if your head gasket is leaking then exhaust is blowing into your coolant making the high temp

[JohnnyNashville]

Sounds like you have some sort of blockage....flush your system and refill with new antifreeze, go ahead and toss on a new thermostat...let us know if that works

 

aj

[BUDMAN]

If it cools down as you drive, it is an air flow concern. (electric fans)

 

note .. engine always gets hotter after being shut off !!

Edited April 27, 2016 by BUDMAN

[DemonElf]

The mechanic ive been talking to said to try taking a pressure nozzle to the radiator to clean the exterior of it. If still overheating, then need to get a new radiator due to possible blockage. He ran through step by step things to fix that are the lowest cost. Already replaced the thermostat with a fail safe thermostat that will fail in the open position if it overheats. He told me off the bat my water pump is a bitch to get to since it is cam driven and not belt. Oh and learned about the GM pills for my radiator and engine. GM knew about the warping of the heads and just made a solution to the heads leaking by a sealant that is constantly running through the system. Thanks all for the suggestions. Will keep you posted. @@Slackernet the mechanic tested my cts and read the temp of the bottom of the heads of the engine. Temp gauge is reading right.

[bds1961]

Warm the car up. Then run your hand up the radiator. If there is any blockage the bottom section of it will be cool and it will get warmer as you slide your hand up. Most cars use a cross flow radiator with the tanks on the sides. Sediment as it builds up plugs the tubes that run from side to side on the bottom first. If that turns out to be the case it is usually best just to changes it out. A lot of manufactures went to plastic tanks on the ends that are hard to remove and replace for cleaning them out. The cost to have it rodded out is close to the same price to change it out if you do it yourself.

[Damage_inc-]

If it cools down as you drive, it is an air flow concern. (electric fans)

 

note .. engine always gets hotter after being shut off !!

correct-check the fans

 

 

he said he already changed the fluid and tstat and he did not say if overheated boiled over yet so id make sure the hi speed fans kiks in-if fans not comming on to cool then fix them.first

 

yes northstars have headgasket problems sometimes but it would boil over and if it does boil over then  get a sample of coolant  when it boils over and test it for hydrocarbons.to see if infact it is a headgasket issue

like this

Edited April 27, 2016 by Damage_inc-

[DemonElf]

The fans do kick on at idle. Possibly a blockage in the radiator. Thats where I'll start and hope it fixes it. Now have to find one, the mechanic found one on ebay but i camt locate it on my searches. Least mine is easy to search for since there is only one engine made for it.

[loaderXI]

@@DemonElf

 

The water pump on these are known for taking a shit and wiping out the pulley and belt...They are not that hard to do your self but you do need a special tool

to R+R as they turn in and out

 

 

http://www.ebay.com/itm/RADIATOR-FOR-CADILLAC-OLDSMOBILE-FITS-DEVILLE-FWD-AURORA-4-0-4-6-V8-8CYL-/271458079864?fits=Make%3AOldsmobile%7CModel%3AAurora&hash=item3f34299478:g:8GAAAOSw9mFWL5So&vxp=mtr

 

Short clip

[KaptCrunch]

other is your timing chian is stretched, check  TDC to marks  

 

other  is spark timing running  to late

[KaptCrunch]

forgot to say the rad fins are solid to tubes and not crunchy

[CW4]

So right after starting it up after driving a while does the temp drop from 270 back to the normal range?  Had a RV with a Ford 460 it it that would almost be pegged out on the gauge if I cranked up 5 minuted after driving for a bit.  Always dropped back down in a minute or so to where she normally ran at.

[Logan]

Your new thermostat is it the correct temp. unit? The older engines ran around 180 to 195. The newer engines run a hotter thermostat due to EGR and emission controls. Also, does your thermostat sit flat horizontal or does it sit in the engine vertical to the block, if so, check to make sure the vent hole in the thermostat is to the top of the block, so air doesn't get trapped. To check if it is a flow problem try a radiator pressure pump. It pumps air into your (full) cooling system to check for leaks (pressure drop)blown head gaskets (pressure build) plugged rads (rev engine and see if it builds slight pressure, then let it idle and the pressure should drop fast, if not, then your rad is restricting flow) These pumps are not that expensive or your garage could do it. Should give you an answer. Hope it helps.