98 deville cooling fans not working!!!

[winterset]

Could it be P0741 and P1860? - if so, you may get the experience of pulling the tranny out to replace a $45 sensor. The car will run for thousands of miles with this fault, just a little loss of MPG. I recommend driving the car a while with this code, and get an understanding of all the cars 'issues' and plan to tackle each when convenient.

[drew51074]

Could it be P0741 and P1860? - if so, you may get the experience of pulling the tranny out to replace a $45 sensor. The car will run for thousands of miles with this fault, just a little loss of MPG. I recommend driving the car a while with this code, and get an understanding of all the cars 'issues' and plan to tackle each when convenient.

bad sensor huh? in the tranny?? great. i dont remember the actual numerics on that tranny code. i will have to check it out again 2mrw. its been my experience with certain sensors on certain cars that you can fool the sensors by unplugging them and installing certian resistors to give a normal reading to the ECU's, therefore elliminating the trouble code. anyone know where the plug is located for this particular sensor?? is it a variable resistance sensor? or a non variable? what is its purpose actually?? right now im showing a 28 mpg avg. is this lower than average?? thats darn good for a V-8 as far as im concerned. then again i have been babying it around for now til im sure the HG's arent blown. no A/C either. its been pretty nice out lately and i've had the windows open keeping an ear out for any strange noises. so far so good beside the service engine soon light and th air ride message on the DIC.

[Ranger]

I think a 180 stat is too low. I believe they are supposed to use a 190. Normal temp is 205-215. Cooler than that will have an effect on emissions, computer & mileage.

Devilles were standard with an ELC (Electronic Level Control) system. That's air shocks in the rear. Unless your car was optioned with CVRSS (Continuous Variable Road Sensing Suspension), the message is talking about the rears. Check the front struts for any electrical connectors.

If the DTC is P0741 you can live with it. BBF just had a lengthy thread on replacing his TCC solenoid. Do a search for more info on P0741.

[drew51074]

yeah, i've been driving it all day today. stop and go trafffic, highway, the works. 120 miles in all. never went above 194*, and that was with the a/c on the whole time. i guess its safe to put a 190* t-stat. thats what the factory t-stat was calling for. i just opted for the lower aftermarket one. i know i posted a 28 mpg avg earlier. its more like 18-20 mpg. i dont know where i got 28 mpg from. must have been on instant mpg when i saw that. is 18-20 mpg's about average for these cars?? i still think thats pretty darn got for a V-8 in this road yacht.

[Ranger]

i know i posted a 28 mpg avg earlier. its more like 18-20 mpg.

You'll do better on the road. I just made a 320 mile trip to northern Wisc. and got 27 on the way up and 27.5 on the way back.

[BodybyFisher]

On the road you should get 22 to 25 or more. Run your tires hard (35 to 36 PSI). The suspension is not as tempermental as the Lincoln air bladder system. There are air shocks in the rear hooked up to a compressor with one or more level sensors that detect level.

I don't know where you live but your heat will be lousy with a 180 degree stat. There is no reason not to use the 190 stat, the PCM expects to see certain temps, it will take longer for the system to go into closed loop, you will burn more fuel as a result, etc

[drew51074]

I don't know where you live but your heat will be lousy with a 180 degree stat. There is no reason not to use the 190 stat, the PCM expects to see certain temps, it will take longer for the system to go into closed loop, you will burn more fuel as a result, etc

i live in south florida, i wont be using the heat at all down here, but i think your right about the t-stat. im going to change it out tomorrow.

[Cadillac Jim]

I had a problem with the 180 degree thermostat too and double-checked. The FSM and the dealer both say it's a 180 F thermostat. The 15 F difference comes because the thermostat is at the coolest point in the engine, where the water comes back from the radiator, and the ECT is at the rear of the front left (rear, driver's side) corner of a head, which is the hottest point in the engine. Leave the 180 F thermostat.

[JimD]

Without regard to the possible impact on engine operation as a result of 10 degree difference in the cooling system thermostat, there is another case where it is important to use OEM parts based on your VIN. And part of that is because the thermostat is controling how much "cooled" coolant is allowed into the engine while the coolant temperature data going to the PCM is derived from coolant that is circulating in the engine.

And due to the thermostat being placed to control the volume of "cooled" (inlet) coolant, the thermostat is a unique design. The Northstar cooling system operation is contrary to traditional system design where the thermostat was positioned to control the volume of coolant leaving the engine (outlet) to pass through the radiator.

Regarding thermostat specifications, my '98 FSM is silent. The '04 FSM says the thermostat should be fully open at 185 degrees F.

[BodybyFisher]

Its interesting I just looked at Rockauto and they stated that it takes a 180 degree stat, very surprising.

[Cadillac Jim]

I couldn't find the thermostat nominal temperature in my FSM quickly, but it does state in Thermostat Testing that if it doesn't open by 188 F, it is bad. The one I got at the dealer based on my VIN was labeled as a 180 F thermostat, and it's a California car. ADAP lists my car as having a 180 degree thermostat. Rock Auto lists my car as having a 180 F thermostat.

[BodybyFisher]

I couldn't find the thermostat nominal temperature in my FSM quickly, but it does state in Thermostat Testing that if it doesn't open by 188 F, it is bad. The one I got at the dealer based on my VIN was labeled as a 180 F thermostat, and it's a California car. ADAP lists my car as having a 180 degree thermostat. Rock Auto lists my car as having a 180 F thermostat.

This is news to me, I would have bet my booty that it was 195. Its funny that GM has done things like this, they did this with spark plugs also, some are spec'd for .050 some .060.. Weird stuff

[Ranger]

We had this discussion not too long ago, but I forget what the outcome was and I even posted numbers from the FSM. Looks like I stand corrected.

[Cadillac Jim]

I would have sworn mine was a 190 F or 195 F too, being a California car and the well-known standard operating temperature of about 200 F. But as I understand the reverse-flow cooling pioneered on the Northstar, the cooled radiator water comes into the thermostat and then to the water pump, then to the heads; thus the thermostat is at the coolest point in the engine, not the hottest as in older systems where the hot water came out of the thermostat into the radiator. A 180 F thermostat in a reverse-flow cooling system is a lot like a 195 F thermostat in an older engine, except that it keeps the engine temperature more stable under varying conditions. The engine temperature will run about 195 F while cruising at 45 mph into a headwind in -20 F temperatures in Canada, 215 F idling in NYC in July, and 205 F cruising at 120 mph on the Autobahn in August.

[drew51074]

i figured that the 190* t-stat was OEM standards because it said it was a OEM direct replacement t-stat on the computer at the parts store. i opted for the aftermarket which was rated at 180*. maybe the fact that my fans are now running at full blast all the time now, its keeping the temp pinned at 197* no matter what i do. i have a new temp switch on the way because i dont want to burn out my fans. we'll see where the temps go from there. i had her up to 120 mph today and the temps did move from 197*.

[jordan]

Yes,It can be done in the car but it's MUCH harder.

[Logan]

I think..maybe..this guy is missing the lower close out panel. This certainly would create a problem while driving along. It would idle ok all day long..

"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. "

I've mentioned it. Noboby sees it. If that lower panel is missing..it will run hot in drive mode.

[TDK]

Drew,

Do a hydrocarbon test on the coolant. That will tell for sure - if cylinder pressure products/exhaust got into the coolant. It is a real good sign that no coolant is lost or much routine overheating, (as you well understand already).

If not any leak, then I think you got lucky on that $500 deal my friend.

Even if a bad head gasket, its somewhat manageable and cost-effective to repair - if you like the rest of it OK.

And by the way - welcome!

Many come sniffing around this site looking for fixes to problems - and stay for the fine company

Good Luck and glad to know ya

[Cadillac Jim]

The air dam is very important in keeping road debris out of the A/C evaporator, too. You can just about guarantee that you will lose the evaporator to pinhole leaks if you drive on the highway without it.

[drew51074]

The air dam is very important in keeping road debris out of the A/C evaporator, too. You can just about guarantee that you will lose the evaporator to pinhole leaks if you drive on the highway without it.

yeah, i've already made a visit to my local newspaper printing press and scavanged one of their used alunimun sheets that they use on their printing machines. the are thin but real sturdy. im going to fab one up and paint it and replace it with that. it will be better than another OEM plastic piece.

[drew51074]

Drew,

Do a hydrocarbon test on the coolant. That will tell for sure - if cylinder pressure products/exhaust got into the coolant. It is a real good sign that no coolant is lost or much routine overheating, (as you well understand already).

If not any leak, then I think you got lucky on that $500 deal my friend.

Even if a bad head gasket, its somewhat manageable and cost-effective to repair - if you like the rest of it OK.

And by the way - welcome!

Many come sniffing around this site looking for fixes to problems - and stay for the fine company

Good Luck and glad to know ya

iv've done the carbon test already and it passed, but i've heard that that test can be missleading. im goin to install the OEM t-stat and temp switch today and see what happens from there.

[drew51074]

UPDATE>>>>

ok, i got the new t-stat and MAS today, and decided to check to see if any new codes popped up and wouldnt you know, i got two new ones. along with the P0102 mas code, and the P0741 torque converter code, i now have a P1660 cooling fan code, which im sure has something to do with me hot wiring the fans to run all the time, and a P0117 air temp sensor code. does that have something to do with the cooling fans running none stop? or is this a new problem? i guess im going to have to replace the cooling fan high speed switch to get that annoying check engine light off, but wondering if the P0117 code is another problem rearing its ugly head. is the air temp sensor that little sensor in the airbox with the filter? or is it located somewhere on the throttle body or intake. i've learned not to assume anything with this car as far as where certain parts and sensors are on other cars i've worked on. other than that, the cars been running awesome. i've put another 200 miles on it after filling her up for the first time ($65!!!!!) and she says she's getting 19.9 mpg. i still have 10 gallons lift and 197 miles til im empty. when i filled her up it said 450 miles til empty. that would have worked out to be 22 mpg, but i havent been on the highway since i filled her up so i wasnt expecting that good of a mpg, but its not that far off.

[drew51074]

ok, correction, before some calls me on it. the P0117 code is actually a low coolant temp voltage code. not a air temp code. im thinking its because of my 180* t-stat and my fans running all the time. someone correct me if im wrong.

[Cadillac Jim]

The P0117 means that the ECT sensor or wire is shorted to ground.

[drew51074]

The P0117 means that the ECT sensor or wire is shorted to ground.

im taking it that the ECT you are reffering to is the sensor on the rear head which wasnt working on my car, so i unplugged it and jumped the connections in the plug. so i guess everything i've done so far to keep the temps down is causing all these new codes. i'll see what happens after this week end when i put everything back to stock parimeters. the only code im guessing wont go away is the P0741 code. where does the wiring for this sensor come into the tranny? if i can find out what the proper resistance needed for this sensor to read ok, i can just put a resistor in line before bad sensor in the tranny. i've done this plenty of times with normally aspirated cars with intake pressure and temp sensors that i have boosted.