Radiator Fan Problem
 

I have a 92 Bonne SSE... 160k miles, most of them trouble free. It's been developing a engine overheating problem, due to (in part, I think) the radiator fans not coming on, when they should. With the air condition on, the fans come on (this is normal and good), and they also come on with the defroster on (again, this is normal and good). But with neither the air or defroster on, the fans never come on. The dealer recently replaced the radiator fan relay (an expensive little item), but no joy there. I suspect the water temperature sensor... but the temp guage acts normal, so it may not be that. The radiator itself is in good shape... clean outside, flushed, fresh antifreeze. I'm still using the factory recommended 195 degree thermostat... haven't switched to 180 degree yet... Anyone have any idea about the fans not coming on as they should?

BTW, this bonne also has the feared "stalling when hot" syndrom, discussed elsewhere in the bonne club postings. Seems like it's either running out of gas, or maybe it's too much gas.... anyway, when it gets hot, it will only idle. Won't accelerate at all. Cool it down, and it runs fine again. Other postings on the net have got me thinking about the fuel pump, or maybe even the catalytic convertor blocking when it's hot. The crankshaft sensor is a new possibility, that I've read about here. I guess that could be it, but I'm not sure.

Anyway, first things first. I'd like to fix the radiator fans....

Thanks

-Roger

Welcome to the club.

So how hot does the engine get? From what I understand, the secondary fan won't kick on until it's atleast 220^ or hotter. I recently put in the 180^ themostat and I rarely get over 210^ except for when I have been running it hard then just stop for a bit. It sounds like your fans are working but without knowing the temps it has been running at it's hard to say. Is it that the main fan never runs until the high temps?

My catilytic converter recently was blocked but it just blew out the exhaust and didn't actually hinder perfomacne much at all when it was.

For the stalling issue, what about O2 sensors or filters? It seems that you have already done some homework on this but the obvious sometimes get over looked, just a thought.

I agree with 95.....my fan hardly ever comes on with the 180° Stat. You should also add a tranny cooler. That sucker has to get blistering to have the fan come on. Normally, when it does kick on, one fan is at half speed and the other is at high speed. The AC causes BOTH to come on full speed.

The stalling problem is a new one on me, but for your car, the O2 sensor is only a $20 part (you're lucky like me.....they got expensive in 94) and you only have one. It's probably due, anyway.

You're naturally going to have more heat problems than any other year, as the 92 is EGR-less. The Rat can give you more info on this.

Good luck!

Welcome!
BTW: Is your engine NA or SC?
:?

How hot does it get? Well, if I can assume that the temp guage calibration is accurate, it gets up to between 235 and 240. It wants to go higher than that, too, but by that time, I'm well into evasive maneuvers... getting out of traffic, and/or turning the heater on full blast to disipate heat. A blown head gasket or cracked head is about the last thing I need... Normally, the temp is rock steady at 195 degrees. But when it decides to go above 195, it does so quickly... it can be at 240 within a minute or two. Where I get into trouble is in stop-n-go traffic, and also when cruising with a tail wind that equals my forward speed (hey, I live in Kansas... that happens alot!). So, bottom line, it only happens when there's minimal air movement through the radiator. Back when the fans were working properly, I remember the temp would edge up to maybe 220, then I would hear the fans kick on, and the temp would immediately edge downward to 195 again. That doesn't happen anymore... no fans.

On the stalling issue, I will check the O2 sensor... for $20, I'll probably just replace it, and see what happens. I guess I'll quit worrying about the catalytic convertor. It's good to hear that exhaust will blow through any blockage. I really didn't want to replace one of those $$$ things.

I'm interested in this ERG-less feature of the '92... Being without EGR sounds like a good thing, but you say it makes the engine run hotter? Is that because the mixture must be leaner, to meet emission standards, without EGR? I used to have a '91 bonne, also.. I think it had EGR (I remember replacing the EGR valve on it). Why did they change the design?

Thanks for the advise, guys... you've obviously been around these pontiacs alot.

-Roger

Trust me The EGRless Engine is NOT better! I've got one & so far one exhaust valve has been burnt & one exhaust manifold is cracked due to the excessive heat! :x The only reason I still run the Stock 195 Stat is because Winter up here gets to be -40 (& that's -40 to you Yanks too) :shock: As to why GM changed it this way, it was because the 92 NA 3800 met Emisions Standards w/o it! :shock: GM will NOT put on anything they (GM) have to! :evil: By 93, GM realized their mistake & put the EGR Valve back on it's 3800's! :)

JR,

Thanks for your reply, too. No, there are no check engine lights and no codes when I get the stall condition. It seems to idle fine, but when you push the accelerator, it just "coughs"... like it's not getting any gas. If the car had been 20 years older, I would have called it vapor lock... that's what it feels like. But that's not supposed to happen with high pressure fuel pumps mounted next to the gas tank.... pressure in the lines is too high to allow vapor lock. That's what got me to thinking about the catalytic convertor. If it were blocked when it gets hot (stalled in traffic, remember), then the engine wouldn't be able to breath enough to run very fast. But then... that's only one theory. :?

-Roger

A plugged Cat will stall out the engine, yes! But this has nothing to do with the fans not coming on though! :roll: You could always disconnect the battery for about 20 min, then reconnect the cables. This will cause the ECM to RELEARN! This may solve the problem with the fans. If this doesn't work I would first try jumping the fan relays to see if the fans will come on! Also check the Coolant SENSOR (Not Coolant SENDER) to see if functioning properly. :wink:

You need to a flush, thermostat, check the lines and all the sensors! Those temps sound crazy ! Sounds like your not that far from hell with those temps!!!

DeathRat -

I think you asked earlier if the engine is NA or SC? I haven't a clue... how do I tell?
What are the differences?

I can reset the PCM by disconnecting the battery... no problem. Good idea.

Question on the Coolant Sender vs. the Coolant Sensor. I assume the sender is the one that feeds the temp guage (that seems OK). That one is probably located on the block, on a water passage, near the thermostat, no? The Coolant Sensor... is that one on the radiator itself? Is its purpose to check (low) coolant level and not temperature?

Thanks for all the info... I'm getting an education this evening!

-Roger