98 deville cooling fans not working!!!

[drew51074]

i just got a 98 deville from a buy here pay here for 500 bucks!! yes i know, something must be wrong with it. my cooling fans dont work. they only come on when i turn the a/c on. is there a groundable temp sensor plug somewhere i can just ground to make the fans come on when the car is running?? even when i have the a/c on, they are not blowing at full blast. do these caddy's have 2 speed fans like my mark viii??? from what i've been reading in the caddy forums these cars like to blow headgaskets. i drove it 60 miles in stop and go traffic and she got up tp about 240* at the stoplights. im sure thats not good. how hot is too hot in these cars? do really have to drop the entire front end with suspension, engine, and tranny to change the head gaskets?

[Ranger]

do these caddy's have 2 speed fans like my mark viii???

Yes.

how hot is too hot in these cars?

Well, cooling fans come on low speed at 224 and high speed at 229. 240 is not a good sign. That may be why you got it for $500.

do really have to drop the entire front end with suspension, engine, and tranny to change the head gaskets?

Yes, that is why it costs so much.

[JohnnyG]

Mine on my '99 don't even come on when I turn on the air, they only come on when the temp gauge goes one tick above the middle mark. I wouldn't worry too much unless it's overheating....then you have some work to do.

[Ranger]

They should be on whenever the A/C is on.

[drew51074]

so is it just physically impossible to do the head gaskets with the engine in the car, or is it just a pain in the but to do so?? the reason why im askin is,i am a mechanic but i have most of my experience with imports and a few FWD domestics, but never done a northstar engine. i have the mechanical no how, just not the experience with these motors. i here a lot of shops charging ridiculous prices based on how long its supposed to take to a particular job, say 3-4 hrs to change a timing belt on a honda civic, when i've done the same job a million times in less than an hour! so has anyone tried changing the headgaskets in the car and got to a point where it was physically impossible to continue? or is it the cadillac dealerships that say so? the one up front dosent look to hard to get to, but the one towards the firewall looks like it might be a problem.

[Ranger]

It has been done in the car, but almost everyone who has done it says they would never do it again. Everyone says that it is easier to drop the drivetrain. One hard part is drilling out the head bolt holes to Timesert it. You would need a 90 angle drill for that.

[zonie77]

It can be done in the car but it's MUCH harder. Even a Caddy engr said he wouldn't do it that way again.

You can pull the engine out the top but that is still harder than dropping the cradle. The cradle is made to drop out "easily" LOL.

[drew51074]

One hard part is drilling out the head bolt holes to Timesert it. You would need a 90 angle drill for that.

ok, that's foreign to me. Timesert?? what the hell is that?? is that manditory, or just a mod to make them not so prone to blow a gasket again??

[drew51074]

also, while im on the subject of dropping the craddle, can anyone steer me to the link for the FSM's for these cars??

[drew51074]

ok. im confused. maybe this common for these cars but, i just had the car idling in my driveway for over an hour with the a/c on so the fans would stay on and the temp never went over 199*. i just drove it about 20 miles round trip to walmart and back and the temp never went past 215*!! is this normal for this car with blown headgaskets?? no steam from the exhaust, no hesitation, no O2 sensor codes being kicked up, plugs are clean, no white residue on them, no bubbling from the cooling system, all the signs i've seen from other cars im not seeing here. are these cars just that ellusive when it comes to the headgasket being blown?? whats a sure way to check for blown headaskets on this motor? compression test? i'd really like to just find out where the temp sendor switch is on these cars so i can get the fans running properly. anyone want to steer me towards its location?? or even the FSM's would be great!!

[Ranger]

Timeserts are thread inserts to prevent thread failure in the future, You should Timesert ALL 20 bolt holes regardless of how they look and DO NOT even think of using Helicoils.

http://www.timsert.com

you can get a new FSM from http://www.helminc.com for $135, but Ebay is your friend.

[Ranger]

Northstars tend to run with a blown head gasket for quite some time. Overheating slowly gets worse. I may be wrong, but I think the temperature sensor is on the rear bank head on the drivers side. Someone will correct me if I am wrong. The sure way to check for a bad head gasket is a cylinder pressure test (not a compression test). Testing the coolant for exhaust gases will usually prove one way or the other but can give a false negative under certain conditions.

[Logan]

One quick tip. Have seen this on Z28's...

Some cars, have rather large plastic air dams to force air up into the radiator while moving.

Z28's have a huge one. These can get damaged or knocked off from curbs or steep driveways.

The car will idle all day ok. But get overwhelmed if the car is moving.

[drew51074]

One quick tip. Have seen this on Z28's...

Some cars, have rather large plastic air dams to force air up into the radiator while moving.

Z28's have a huge one. These can get damaged or knocked off from curbs or steep driveways.

The car will idle all day ok. But get overwhelmed if the car is moving.

funny you mentioned that air dam problem. mine is totally missing! it looked like it was zip tied up at one point but it didnt stay. i'll have to get something in there for now to redirect the airflow when im moving.

[drew51074]

Northstars tend to run with a blown head gasket for quite some time. Overheating slowly gets worse. I may be wrong, but I think the temperature sensor is on the rear bank head on the drivers side. Someone will correct me if I am wrong. The sure way to check for a bad head gasket is a cylinder pressure test (not a compression test). Testing the coolant for exhaust gases will usually prove one way or the other but can give a false negative under certain conditions.

its been my experience with other cars if there is compression getting into the cooling system it tends to gurgle or blow bubbles out of the cap when it is removed. its only overheated on me that one time sitting at the light on the way home when i got it. it hasnt overheated since and it has never lost any coolant or anything. like i said before, these motors might have totally different signs when it comes to bad headgaskets, but im still hoping its just a bad sending unit and the guys at the dealership just wrote it off as a bad head gasket. i might just do the gaskets for the sake of sayin i did it and make a lil extra cash on all those caddy's out there that no one wants to fix. they seem to be all over the place!!!

[zonie77]

The FSM is not online (at least to my knowledge) so you have to purchase of use alldata if your local library has it.

Ranger's 9:55pm post is right on.

Drive it and see how it acts.

N*'s don't lose total seal initially. The threads pull and they lose some tension. Imagine an engine with maybe 20 or 30 lbs torque on some of the head bolts. Eventually they lose all seal but the beginning stages can be real foolers.

Drive it and see how it acts. Also look at this thread. You don't want to do the HG's for giggles.

http://www.cadillacforums.com/forums/north...air-part-i.html

[Cadillac Jim]

Your problem doesn't sound like a head gasket to me. It sounds more either nothing is wrong, or you have a minor problem like poor coolant, partially blocked radiator air flow, or a partially clogged radiator.

My 1997 FSM gives this sequence of checks for engine overheating (pages 6-178 and 6-179):

1. Cooling system not holding pressure.
2. Coolant not 50% to 60% antifreeze (protection to at least -34 F).
3. Loose water pump belt. Note that this is a dedicated belt on between the cam and water pump on the driver's side, front head.
4. Bad thermostat bypass.
5. Bad water pump.
6. Obstructions in the radiator fins. Check for leaves or road debris between the A/C condenser and the radiator, not just debris in the condenser or bent over fins on the condenser.
7. Clogged cooling system passages.
8. Damaged water pump belt.
9. Inoperative cooling fans.
10. Restricted coolant flow through the throttle body (!!!).
11. Sticking thermostat.
12. Leaking radiator.
13. Leaking surge tank or hose.
14. Loose or damaged radiator hoses and connections.
15. Water pump gasket leak.
16. Water pump seal leak.
17. Damaged surge tank cap.
18. Cylinder head gasket leaks (at last!).
19. Loose cylinder head bolts.
20. Cracks in cylinder head and cylinder block.
21. Leaking heater core.

I can't find the temperatures for the fans to go to low and high speed but I think I remember that the temperatures are fairly high, like 240 F for low speed and 260 F for high speed, unless the A/C is on. The A/C will run them at low speed all the time. Thus some variation in engine temperature in traffic in hot weather is normal with the A/C off, but the needle movement will be gradual, and the temperature should not go past about 3/4, where the fans come on low speed.

[Ranger]

The fans go on low at 224 and high at 229.

[drew51074]

i think im going to start with number 9 and 19 and that list. i know for a fact the fans are not working as they should, and it would hurt to check the head bolts just to make sure they are torqued down to the proper specs. as far as doing the headgaskets for fun, thats not the case. i just want the experience getting one done. as a mechanic i want to know how its done and all that it entails so the next time i find a northstar with supposide blown HG's i know what im getting into worst case senario. it will an learning experience and another skill i will have aquired as a mechanic. i've done engine and tranny swaps in Pontiac Transport minivans, and its the same deal almost. just with the 3.8l V-6. you have to drop the entire front end out to do anything major. it will just be the first time for me with an northstar. now that i've noticed, i see alot of these northstar power cars in the back of dealers ships with "major engine problems". buicks, oldsmobiles, caddys, etc. i buy and sell dealer trade ins for a living so it might become profitable for me to learn to do these headgaskets because it seems like a common problem with these cars and no one wants to fix them. i just hoping i lucked out with this one i got and its the cooling fans, but i wouldnt mind buyin a couple of these cars cheap and fixing and flipping them on EVILbay.

so the temp switch for the fans are on the cyclinder head it self?? thats not common is it?? usually its near the t-stat housing or on the bottom of the radiator. maybe thats just maybe my experience with imports kicking in. thats probably why i cant find it. im looking in the wrong places. im goin to try to find it today and go and buy a FSM form my local parts store. its a GM so they should have one with at least this northstar motor in it. everything else on this cars works. oh, and i saw some of you guys telling me the temp gauge should be near half way and such, but i've been blessed with a digital dash so i wouldnt be able to tell if its at a half way point or not. as a matter of fact, when the temp got to 240*, the dash indicator told me to shut the car and then it wouldnt start for another 3 mins. showed me a count down and everything.

[Ranger]

i think im going to start with number 9 and 19 and that list. i know for a fact the fans are not working as they should, and it would hurt to check the head bolts just to make sure they are torqued down to the proper specs.

Never do that. The head bolts are coated with a Loctite sealer and you do not want to disturb that.

im goin to try to find it today and go and buy a FSM form my local parts store.

I don't think you will find a FSM there. Forget Haynes & Chiltons. They are useless for anything but the most basic DIY'er. Get a FSM from Ebay or http://www.helminc.com

i saw some of you guys telling me the temp gauge should be near half way and such, but i've been blessed with a digital dash so i wouldnt be able to tell if its at a half way point or not.

On the digidash, I ran 206 (summer) and 213 (winter) as normal temps.

[Cadillac Jim]

You really don't want to get into an Easter egg hunt in a Northstar, unless you are just itching to pull it down to the smallest pieces and put it together, which some DIY types have stated is a three month project. If you have more than nights and weekends and have a professional mechanic's facilities, infrastructure, equipment and helpers, you can probably do it in a week, full time.

The order of the things to check on the FSM list is determined to minimize the average time to repair, so it's not casual or random. I would suggest that you begin with an inspection for obvious leaks and then use a pressure test to eliminate most of them, including the dreaded heater core leak. The next thing I would do is check the coolant for protection to -34 F or better, then test it for anticorrosion capacity remaining and for combustion products. This can be done quickly in a few minutes, and will find or eliminate all the cooling system problems except clogged radiator or cooling system passages and bad water pump. A flush and change of coolant will eliminate everything except a bad water pump, which should have become obvious by that time anyway. You will be done, without dropping the cradle or spending more than a half day of DIY time and using no professional facilities except some coolant test strips or solution. If you do need to do the head gaskets, you will know it by then and can plan the job.

The head bolts on the Northstar are torque-and-twist head bolts. From the factory they are installed with a sophisticated technique that ensures accurate and uniform clamping force on the heads that cannot be matched in accuracy by any manual procedure. You can be sure that factory engines have the proper torque, and that you can't come as close as they were originally if you disturb them. The head bolts don't lose their torque setting. They are sealed at the factory with Locktite as Ranger says, for that very reason.

I've had the dreaded head gasket problem. My symptoms were typical. The procedure:

• Let the coolant go more than 5 years (2 years with green coolant). This will exhaust the corrosion resistance and traces of bad coolant will find its way into the head bolt wells and one or more of the head bolts will start to pull out. This accounts for the "loose head bolts" in item 19. This is a sure way for expensive repairs for any engine with major aluminum parts such as intake manifold, head(s), block, etc. I've seen it cause problems on a 1960's Chrysler 440 because the thermostat housing was aluminum; a hole popped right out of the top of it; I fixed that one for a friend to get his wife out of a jam while he was out of town.
• Gradual increase in loss of coolant from none to occasional adding to a quart a week or more with no other symptoms.
• A temperature spike to 3/4 (or 240 degrees or so) about a minute after pulling a hill or similar engine stress at highway speeds.
• Gradual increase in sensitivity to starting the temperature spike.
• Worsening temperature spikes, including boil-offs and DIC messages that the A/C has been turned off, etc.

That's not what I am seeing in your original posts. What I see is what seems like normal temperature variations in traffic with the A/C off, and good cooling system performance with the A/C on and the fans running on low. I'm not sure that you need anything more than a flush and a coolant change, with possible change of worn belts and hoses.

[drew51074]

good info. i was going to get the generic FSM just as a road map to where everything is, like this ellusive temp switch for the cooling fans. that is my first order of business before anything else. get these fans goin. my mitsubishi has a habit of turning my a/c off when i get the temps up there. i take it these n* do the same thing right? at what temp does that happen?? me turning on the A/C is the only way i can get my fans on so maybe when i get to that cut of temp for the A/C its cutting off my fans too.

[Logan]

There is a GM factory online service manual.

http://service.gm.com/index_en-US.html

It is what the GM dealers use. If you are a GM employee you can get free access. Just use your GMID login. You can also subscribe for daily rates at about $20 per day.

If your lower underbody closeout panel is missing, this would be creating the issue.

I also attached a picture from a 1998. #7 is where the coolant sensor is.

[drew51074]

There is a GM factory online service manual.

http://service.gm.com/index_en-US.html

It is what the GM dealers use. If you are a GM employee you can get free access. Just use your GMID login. You can also subscribe for daily rates at about $20 per day.

If your lower underbody closeout panel is missing, this would be creating the issue.

I also attached a picture from a 1998. #7 is where the coolant sensor is.

found it!!! finally. i would have never found it by myself. even with the pic you sent printed out, it still took me a good 15 mins. to locate it. it was a PITA to get to. thanks Logan!!! fans are up and running full time now. the funny thing is the sensor looks brand spanking new!! bad sensor?? wrong sensor?? i jumped the connections on the plug and they came right on. full blast. i've been driving it now around town for about 4 hours and put about 80 miles on her and the temp doesnt go above 194*. i flushed the radiator and engine block out. and installed a 180* t-stat. i'll just have to keep my eyes on it to see what happens. my check engine light came on again. some transmission code came up along with my mas air code. something about the converter not lockin up? does this have something to do with the low temps its running now?? i know you guys were sayin 224* to 230* was normal. my overdrive in my Mitsubishi Starion doesnt engage til the temp goes above 150*. is this the same type of warm up feature on the deville? it didnt throw out that tranny code til i installed that 180* t-stat, and i got a "service air ride suspension" message on my DIC for the first time since i've started driving it. whats that about. are these air rides systems as tempermental as the lincoln mark viii air ride suspension?? that thing is a by-polar piece of equipement if i've ever seen one. some times it works fine and other times im 6 feet in the air in the rear and the front end is plowing the darn road!! are these devilles full air ride in all 4 corners ?? or just the rears??

[winterset]

There is a GM factory online service manual.

http://service.gm.com/index_en-US.html

It is what the GM dealers use. If you are a GM employee you can get free access. Just use your GMID login. You can also subscribe for daily rates at about $20 per day.

If your lower underbody closeout panel is missing, this would be creating the issue.

I also attached a picture from a 1998. #7 is where the coolant sensor is.

found it!!! finally. i would have never found it by myself. even with the pic you sent printed out, it still took me a good 15 mins. to locate it. it was a PITA to get to. thanks Logan!!! fans are up and running full time now. the funny thing is the sensor looks brand spanking new!! bad sensor?? wrong sensor?? i jumped the connections on the plug and they came right on. full blast. i've been driving it now around town for about 4 hours and put about 80 miles on her and the temp doesnt go above 194*. i flushed the radiator and engine block out. and installed a 180* t-stat. i'll just have to keep my eyes on it to see what happens. my check engine light came on again. some transmission code came up along with my mas air code. something about the converter not lockin up? does this have something to do with the low temps its running now?? i know you guys were sayin 224* to 230* was normal. my overdrive in my Mitsubishi Starion doesnt engage til the temp goes above 150*. is this the same type of warm up feature on the deville? it didnt throw out that tranny code til i installed that 180* t-stat, and i got a "service air ride suspension" message on my DIC for the first time since i've started driving it. whats that about. are these air rides systems as tempermental as the lincoln mark viii air ride suspension?? that thing is a by-polar piece of equipement if i've ever seen one. some times it works fine and other times im 6 feet in the air in the rear and the front end is plowing the darn road!! are these devilles full air ride in all 4 corners ?? or just the rears??