Cooling Problem with 3.0 V6

I have just recently purchased a 1999 3.0 V6 Super 166. Beautiful car and a real pleasure to own.

I have 2 problems with my cooling system that I hope that there is some experience on out there that I can draw on.

The first problem is that I seem to have an intermittent problem with the cooling fan. About every 7-8th time I step out of the vehicle the radiator fan does not switch off. At the moment I have to manually disconnect the lead to the fan motor to prevent the battery running flat. I assume this is a relay problem as it is unrelated to the temp of the vehicle. Has anyone else had a similar problem and if so have you found a solution?

The second problem is that when I am stationary in traffic for any period of time the temperature increases right up to the upper end of the gauge. These two problems seem to be unrelated as I have listened and the radiator fan is definitely on. I have however noticed when I am moving very slowly in traffic the temp is fine. As I have been moving very slowly the air movement created would not be enough to cause a significant cooling effect.

Through many hours thought and a little luck I have found that if I rev the engine just over 1000rpm when stationary then the problem is solved, thus I have deduced that the water pump is not effectively pumping at idle. I was hoping to find out if this is a known problem and if I should replace the pump?

My current line of thinking is to get a power flush performed on the cooling system to clean out the gunk that builds up and then if that doesn't work replace the pump.

Any advice or ideas?

What condition is the radiator in? Are both stages of the fan working? What do you call "the upper end"? Fan should kick in at 92-ish degrees and stop the temp going higher. If it does your rad is US.

Water pump IS a known problem as they have a plastic impellor which cracks and slips on it's mounting. But, it usually affects the car at speed, not idle, where it can cope with the engine soeeds/load.

Re. the fan, some cars are fitted with fans that continue to cool the car after the engine has been shut down....I don't know if this applies ot the 166 though.

wrinx

Ooops, sorry, just realised you're a newbie Welcome and don't forget to post pics of your car

wrinx

Hi there and welcome to AO.

I would check your radiator. It seems your cooling system is performing well below par and the rads on the 166 are a known weak spot (Well thats a little harsh, but on cars the age of ours, it's a problem to look for)

Mine was not leaking but the matrix was shot! How the car didn't boil I will never know but I had noticed the temp getting hotter and the fans running often.

I can't guarantee it but I am 99% sure Wrinx is right and the fan is supposed to carry on running when you stop the car (Dependant on engine temp of course!)

Thanks for your posts

When I say hot I mean near to the red which I think is at 130, I have been swtiching the engine off before it reachs that which for memory is around 120 but certainly alot higher than the 90 that it seems to run at under normal driving conditions.

Understand the fan can continue running for some period but when the problem first occured it was still running an hour later! Also at times when I do disconnect it it will start up when I reconnect (before restarting the engine) hours later...

When you say your heater matrix was shot I assume you could visually seen the problem? As much as you can seen when it is fitted it looks like it is very good condition...

Thank you for your knowledge on the water pump as well, does that mean you can just repace the impellor or is a complete unit?

Siper the little concertine metal wafer in the rad corrodes. It might LOOK fine but if you give it a prod you may find that in areas it just falls away or crumbles.
Also check your thermostat. If faulty it should default to open but of course it could fail when jammed shut!
Water pump impellor could still be faulty. It could slip as easily at idle and be fine at speed as the other way round.

Water pump is a new unit, get the GTV(?) metal impellor upgrade. Unfortunately this will be expensive as you may as well replace the belts and tensioners whilst the belt is off.

Check the rad first....

wrinx

It seems highly unlikely that the impellor would slip when rotating slowly & then work when under higher load - unless the belt is loose & not turning the pump properly (don't know if it is the aux belt or the cam belt without checking).

I have never known the fan to continue when engine off (does on wifey's punto, but not on my 166).

Temp gauge should only go high when there is a real problem - the dash gauge has some sort of anti-scare device & reads 90 all the time when running unless major variation.

Rad & thermostat check & full flush might help to diagnose the fault.

Simple check for the thermostat - start engine from cold, hold top rad pipe & it should get hot suddenly, rather than gradually - this is a sign the thermostat has just opened.

Originally Posted by CrispDust

Siper the little concertine metal wafer in the rad corrodes. It might LOOK fine but if you give it a prod you may find that in areas it just falls away or crumbles.
.

Yep thats spot on. Mine just disintegrated when touched. Didn't look too bad visually.

Thank you eveyone for your input.

I will take a closer look at the radiator, and then check the thermostat as HowardA descibed. I will also take a look at the belts to make sure they are of proper tension.

A power flush and replacing the coolent is only going to be positive so I will do that and fingers crossed my problem will be solved.

Failing that I will have to take a look into the relay and temp switch for the fan and then the water pump.

I will keep you all posted with progress.

Originally Posted by HowardA

I have never known the fan to continue when engine off (does on wifey's punto, but not on my 166).

Admittedly, I'm running a 164, but when the rad temp sensor failed last time the fan continued to run once it kicked in.

Regardless of whether it had got the temp down, including with the engine stopped but the ignition on.

Also started to run the fan on startup from cold .

Not certain wether this is applicable or not but on a Capri I used to own a dodgy engine earth strap used to give a sky high reading on the temperature gauge it scared the life out of me the first time it happened it could cause both problems you descibe if the 166 works the same way something else to look into anyway & a much cheaper thing to repair if it is the problem

Almost definitely a new temp senor for the radiator fan.

Powerflush has not helped. Still hoping for a sticky thermostat but I suspect it is the water pump.

I use the car to get around for work so I have to be able to rely on it and I haven't the time to do any more work myself so it is going into Alfaman on Thursday to see what they can do.

Will report back when we find the problem.

I had exactly the same problem, and it was my water pump impeller that had cracked. You can check the water temp at each end of the cooling system using a digital thermometer, the difference on mine was 30 degrees!!!
I think Wrinx got his deduction the wrong way round, the engine is more prone to overheat at low speeds/idle and less so when at spped as the airflow aids the cooling. Mine used to begin to overheat only when in town, but was fine on the motorway.
I had the GTV pump fitted and all the belts done at the same time as they were only 10,000 miles from being done anyway.

S.

Hi

I had a similar problem. The cooling fins on the radiator were corroded an crumbling away. I have just replaced the radiator and it seems OK at the moment. I havn't been out on a hot day yet so hold your breath.

If you want to do the work yourself , you need to;
Remove the Bumper, The panels in front and above the radiator
YOu then have easy access to the bolts.
You remove the Fan.
Then disconnect the bottom hose, then the top.
Leave the plastic elbo connector on the radiator till you get it out,

The elbow connector has two metal bits that you squeeze and then prise the elbow connector off.

Mine was on pretty solid so I used a small G Clamp to sqeeze while I wiggled it off.

Good Luck

Originally Posted by The Stefmeister

I had exactly the same problem, and it was my water pump impeller that had cracked. You can check the water temp at each end of the cooling system using a digital thermometer, the difference on mine was 30 degrees!!!
I think Wrinx got his deduction the wrong way round, the engine is more prone to overheat at low speeds/idle and less so when at spped as the airflow aids the cooling. Mine used to begin to overheat only when in town, but was fine on the motorway.
I had the GTV pump fitted and all the belts done at the same time as they were only 10,000 miles from being done anyway.

S.

Whoa Stef, Think Wrinx was correct, at slower speeds the slipping/cracked impeller can pass enough water through to cope, at higher speeds it slips and coolant flow is not enough.

Hi, I had the same problem with my 1999 Super, I replaced the Radiator, thermostat and temperature sensor on the thermostat housing and still the needle would rise alarmingly to 120+degrees. The fan cut in as it should and the engine didn't seem overly hot, i discovered that when the temp gauge rose to 120 and then i switched the engine off and restarted it, then the guage would stay at 90 for exactly 2 minutes before rising to 120 again. I took it to Alfaman and they confirmed my suspicions that it was an electrical problem with the guage in the dash and the cooling system itself was working fine. Hope that helps a little bit!

i wouldnt drive it too much it it overheats, that can cause a lot of damage..if you are stuck in traffic and it overheats you can turn the heater to the max and the fan max too , it will get very warm in the car but at least it will save yor engine. most likely its a bad radiator