Hello,
Im not entirely happy with the original thermo fan on my Alfa 75 v6. I was looking at upgrading with an aftermarket SPAL brand 16 inch one. Im hearing good things about them...just wondering if anybody has ugraded their thermo fan on their Alfa 75 v6? Any advice would be really appreciated guys as its the only thing holding my 75 back from being pefect!!! :) Thanks very much
I believe the best improvement will be had from making a shroud around the fan rather then just replacing it. So that way the air if funnelled to the fan... If that doesn't make sense, look at the picture. Air is then sucked through the whole radiator rather than where the fan sits... Upgrading the fan alone might help, but I reckon a shroud will out do a fan by itself.
(http://www.mahaffeymotorsports.com/images/fan-shrouds/fanshroudshow.jpg)
What is it about the fan that makes you think it's not performing?
It is just not good enough...not sure how the other 75's are, but when stuck in traffic the fan just cant keep up with the heat, anyway I'd like to know other peoples experiences with v6 75's temperatures
On a really hot day, 40 plus, then my fan comes on and off every minute or so if I'm in town traffic. Any other day it operates just as much as any other car? But I wouldn't say it doesn't keep up, it works. Still, if you can improve it, then why not?
Alfamania, yes ofcourse you can always improve on the current setup and indeed a few of us have done these improvements, but simply on a standard 75, although the stock rad esp on a v6 does struggle to maintain temps, at the end of the day aslong as you arnt overheating, which if the fan wasnt adequate you wouldve done by now, i wouldnt be too concerned about the fan cycling on and off. In simple terms even if you were to improve the fan, a better fan would still be cycling on and off to maintain any temps higher then the thermostat temp, which brings me back to my radiater issue and the fact that it isnt good enough in my opinion to maintain thermostat temp.
I could go on, i also believe the waterpumps on idle dont push enough volume but were opening a can of worms here. My point being, dont bother lol
It is what it is i guess, maybe I just leave it then and do some more driving :)
Exactly :)))
This scan is from the Alfa Romeo V6 High-Performance Manual
Check out the 164 radiator. They tend to be a bit thicker and use wider spaced cooling fins. This way more air can flow thru the radiator and the actual air passages are less likely to get blocked with crap.
They can also be bought new off of eBay for quite a reasonable price.
If that doesn't fix your woes, then it is either an expensive drop in replacement aluminium radiator or you go about making something from another car fit.
I'm going down the 'something from another car' path, but it's been a bit of a pain in the ass and only the sort of thing I'd suggest if you like making and modifying things................ :o
VL-VS V8 Commodore Aluminium radiator:
Another option, which is drop in and needs no modification, is a 3Lt radiator. They are about 10mm thicker than 2.5Lt and twinspark radiators. Running a 2.5lt rad in a 3lt makes a difference for how fast the car heats up and switches on the fan [I ran one while had my 3lt rad' cleaned].
You could even think about a Davies Craig electric water pump that pushes water through at a constant speed, they fit into the radiator hose, but sometimes flow is not the answer, as if the coolant flows too quick, then it can't absorb the engine heat and deposit all the heat to the radiator, also try a higher pressure radiator cap to increase boiling point and shrouding of the radiator can increase airflow by 10%, instead of it leaking airflow around the sides, Colin.
I have a 3 litre guys. Is the 164 radiator straight fit? Jazie.k I dont understand what youre trying to say? do you mean drop in a 2.5 radiator in a 3 litre engine? Isnt it the same radiator for 2.5 and 3.0? I was just looking at puting in a high performance Spal 16 inch fan? the Spal fan amp rating is 17 to 21 amps. Would my 3 litre 75 handle that? or do i need an auto electrician to modify relays? Thank you :)
Hi
I've had great results with a SPAL fan recently - the fans with the curved blades, and the support ring connecting the outer tips of the blades tend to have the highest CFM. Tend to be quieter too.
I'm sure you've checked it already, but sticky thermostats are often the cause of cooling system woes... (I've had two dodgy twinspark thermostats cause issues with my car - one didn't close fully so the car took ages to heat up, and the next one didn't open fully - causing the car to eventually run out of cooling overhead in summer traffic gridlock...)
It's worth checking the condition of the wiring in the car - possibly that will restrict the current more than anything, the fan will run slower if the wiring (which has a little age on it now too) can't pass that much current (or was designed with a lower current in mind for the stock fan)
You might even find the stock fan runs much faster when you connect it directly to the battery, as opposed to running via the normal wiring loom - meaning you could get additional stock fan performance with some wiring modifications. his made a big difference to the cooling in my old GTV6. ( Another way to check is to check (with the fan running) the voltage across the fan connector and the voltage at the battery - see how much drop there is. )
I guess if you're going to need wiring mods to run the SPAL fan anyway - you could try running the stock fan that way first to perhaps save the cost of a new fan.
I don't know if any of that helps... but good luck !
Are you sure the rest of the cooling system is perfect? No amount of extra airflow across the heat exchanger will help if the waterpump is slow at idle, or if there are other reasons the heat transfer is inefficient (clogged radiator, scale in the passages, wrong coolant mix, T-stat). Most systems are designed with very little in the way of excess efficiency, so it only takes a small change in the overall efficiency and your temps quickly spiral uncontrollably to boil point.
Having had a bit to do with engine conversions in 4WDs, and mucking about with changing fans, rads etc, I can tell you the shroud is a critical component of getting max flow from your fan. Tip losses and air recirculation are huge with an unshrouded fan. The shroud also helps pull air across the full surface area of the radiator.
My 75 doesnt have a plastic type shroud cowling like how all newer cars have....does it mean mine is missing? It just has a steel round ring frame and 4 mount tips for the fan? Is the 164 the same? Was thinking maybe using something from the 164 for upgrade but I reckon same?
Quote from: Alfamania on October 23, 2013, 08:07:39 AM
I have a 3 litre guys. Is the 164 radiator straight fit?
I was told about the 164 radiator into TA Alfa's by For90s. Maybe send him a PM to confirm.
From memory 164 rad hose outlets/inlets are the opposite to 75, cant rember as it was awhile ago but i think it was abit thicker which meant with a fan om the back it fouled the cross member. All these issues can be addressd easily if your handy with the tools, but brings me back to my point of not worth it on a standard car.
I have a 147 gta also and youd just love the hoovecraft thermo cycling on and off on a hot summers day then lolll alot of newer cars seem to address these issues with variable speed fans and such, but i just dont think a standard car is at that level of need.
To put things into perspective for you, my 75 is mildly modified and runs a xr6 turbo radiator, fan with shroud, ducting and falcon 75 degree thermostat, and temp can still creep up slowly idling in traffic with the fan cycling on and off. And i can control my fan via the ecu, so can do what i like with it!
Brings me back to my point about water pump flow, maybe even possibly coolant passages compared to modern cars, as a friend of mine had the same setup in his factory xr6 turbo and idling on a hot day the fan didnt have to cycle on half as much.
In regards to higher pressure caps, im currently inti a volvo 850 resovoir with a 21psi cap, but my setup is obviously not stock, when i was trying to improve my standard setup i tried, 164 1bar cap and gta 17 psi cap, both of which cracked my original, and later replacement original resovoirs.
The only thing i can say made a difference was the lower temp fan sensor, which i think held the fan running longer before cycling off. I actually stil got this and you can probly have it for next to nothing like 20$ as i dont need this anymore.
Apart from that, make sure the obvious basics are all in check and enjoy driving your 75 :)
By running a higher pressure cap, you don't really guarantee anything.
Unless you measure it, how d you know the pump can actually pump to the higher pressures?
And while the boiling temperature goes up with higher pressure, I doubt coolant can actually absorb and dissipate more heat energy as a result.
However, you may get advantages by running a higher system pressure AND running the pump faster, because the higher operating pressure should delay the effects of cavitation in the coolant as the pump starts to run too fast.
Basically, if you run the pump faster, the point at which cavitation of the coolant occurs will happen at a lower engine speed. But because the coolant is under more pressure (because of the higher pressure cap), the point at which the coolant starts to cavitate should be pushed a bit further up the rev range.
A properly shrouded radiator fan would still be a good thing as it will increase air flow thru the radiator when the fan is doing most/all of the work. But the fan and shroud will be a bit of a flow restriction at speed.
I have seen fan shrouds with little hinged flaps around them, so that when the fan is trying to suck air thru the radiator (and so cause a pressure slightly below atmospheric pressure), these flaps are sucked closed. But when the car is moving and the air flow thru the radiator is higher, these flaps get pushed open by the air flow and allow more air to flow thru the radiator.
Hi duk, yes i agree with all youve said, esp about the caps and measurements, basically these are like a bandaid solution which would require measurements, but i guess sometimes we just need to bite the bullet and suck it, as time may well be spent doin something else then doing a thorough engineering test. At the end of the day takes 2 secs to unscrew and swap a cap and read the gauge back to back driving. You are correct though scientifically.
In regards to the fan shrouds i have seen those flaps i think on a corolla or some other toyota and on some audis, fact is though unless you are quite familiar with the frontal aero of our cars, or for any matter any specific car, whos to say it wouldnt be detrimental, as in theory and practice some times things just dont work, as in the extreme you could create any effect but like you say without testing who knows and infact why bother. Standard car, standard fan=drive and just dont pay any attention to the fan cycling lolll time would be more well spent cleaning the car for concorso or something rather then opening a can of worms on an issue thats not there. I agree with all youve said duk, but alfamania just trying to save you some time/coin bud, if it aint boiling and overheating, you dont have an issue.
Cooling system is clean as I have recently recoed the top end of motor with new top end gasket sets and whole system flushed. Its just the fan....it comes on at 90deg and I can just see it be on for a long time until it turns of...and thats in cold weather let alone in hot summer day. Anyone know the amp rating for the factory set up? Im looking at getting a high performance 16 inch Spal fan apparently rating at 17 to 21 amps. I just need a stronger more efficient fan that doesnt need to stay on forever until it brings the temp down. I hope Im making sense. Thank you
Quote from: david sammartino on October 23, 2013, 04:20:31 PM
The only thing i can say made a difference was the lower temp fan sensor, which i think held the fan running longer before cycling off. I actually stil got this and you can probly have it for next to nothing like 20$ as i dont need this anymore.
Hi David,
Do you know the temp range for that sensor and where did you get it? If nobody else wants it I'll take it for the $20.
Cheers
Steve Adelaide
To be honest ill have to check i think its got it stamped on it somewhere, ill let you know. I got it from mille miglia years ago from memory.
Alfamania, have you done a basic check with the multimeter to see if you have a major voltage drop possibly causing the fan to run slower? Also is it blowing correctly, as in pulling air backwards and not forwards? Also may wanna check your cooling hoses all connected properly, recent headwork rings alarm bells to me, was the car doing this before the work??
Does the v6 create a lot more heat than the TS? My TS was able to handle 45C (Dubai) in traffic without a problem. If I had the AC on whilst standing still it became a problem but once on the move it was fine. Alternatively I just turned the AC off while stationary. All I did was make sure everything was in perfect original condition and new hoses.
Obviously if the v6 creates much more heat then I guess this doesn't help much!
Have you considered something like these?
Water Wetter
http://www.redlineoil.com/Products.aspx?pcid=10
or waterless coolant
http://www.evanscoolants.com.au/all-automotive-products.html
Maybe with the high temperatures and air con we use in Australia something along these lines will do the trick or if you want you can get a custom radiator made from someone like this mob.
http://www.autocooling.com.au/
I have heard good things about Water Wetter but have not heard of waterless coolant until recently so do a bit of homework. I use Autocooling for stuff other suppliers cannot fix at work so I am happy to recommend them but I work with buses and they have very large and expensive radiators as standard so check with them first as I spend $2500.00 (not my money and time off road is expensive) on a recore without batting an eyelid.
Good Luck.
Bosey
Get a replacement Thermo fan , the original design of blades of the Alfa one of that era is very poor for both airflow capacity and quietness.
Alfa and any italian car for that matter have never been good at design of thermo fans and interior blower fans. That is why in the older era Alfas the internal heater airflow is so poor and noisy. Not that much improved on the later cars either. As someone else suggested get the biggest aftermarket fan you can source for it. This will allow one less cycling of the thermo fan and in turn a lower draw on and already marginal electrical system and much quieter operation. Have you ever noticed how quiet the equivalent Japanese cars is in terms of thermo fan compared to a blaring thermo fan on an Italian car.
Or you could just convert to a clutch fan, most japanese cars of that era seem to use those :)
Quote from: Andrew Bose on October 24, 2013, 07:38:37 PM
or waterless coolant
http://www.evanscoolants.com.au/all-automotive-products.html
I have heard good things about Water Wetter but have not heard of waterless coolant until recently so do a bit of homework.
The funny thing is, pure race cars like V8 Supercars and Formula 1 cars just use straight, distilled water.
There aren't many, if any other liquids that can absorb and dissipate heat like pure water can. And anti-freeze/boil additions actually reduce the water's ability to do it.
In motor racing they need a coolant that will dry up quick when spilt on the track, some coolants and anti freezes are too slippery and don't dry up as quick as good old water, Colin.
Quote from: colcol on October 25, 2013, 05:45:49 PM
In motor racing they need a coolant that will dry up quick when spilt on the track, some coolants and anti freezes are too slippery and don't dry up as quick as good old water, Colin.
A good point, but pure water is still a better coolant than anything else you or I can get our hands on...............
Correct Duk, i run my 33 with the most water i can to prevent overheating and with the least amount of rust inhibutor to prevent rust, always a finely balanced ratio, the thinner the coolant, the better the heat transfer will be.
Some coolants are approved for motorsport, due to they dry up quick when spilt, from my memory, Nulon green coolant is ok for racing, the red Nulon as used in 147's and 156's isn't.
The more crap you have under your bonnet the worse the airflow will be through the radaitor, as the hot air has nowhere to exit, when you take some of the plastic engine covers off the modern cars, they cool better, Colin.
Just to clear up the 2.5Lt 3Lt thing, the 3Lt radiator is thicker than the 2.5Lt by about 10mm.
Just bought a 16 inch Spal High Performance fan , will let you know how it is when fitted :)
I purchased a SPAL 6 inch thermo fan for the 33, very good little jigger, but not a cheapy, no quality parts are.....and the best thing is that it is ITALIAN!, which suprised me as i thought they were Chinese.
It was the smallest fan that i could fit in, and it moved a good volume of air, Colin.
May I ask whether these super duper 16 inch Spal High Performance fans are light or not, ie lighter than the standard Alfetta fan for example.
cheers
neil
As hinted at earlier in the postings, try running a direct power wire via a relay to the fan (as often done for the headlights). I think standard the fan power runs through the thermofan switch in the radiator, which deteriorates with age, lowering voltage to the fan. Activate the relay with the standard thermofan switch, but bypass all the old wiring for fan power. Cheap option!
the 16 inch spal fan is lighter and slimmer than the original v6 75 fan. I still havent fitted it because I've been lazy to make brackets for it. Does anyone know a place i can buy flat steel brackets so I can make them to fit? Cheers
Yes, go to a steel supply outlet, and get some 3 mm thick - 10 - 12 - 15 mm wide, or however they come, not too thick as you want to be able to bend them in a vice, attach the brackets to the radiator support.
Don't use the ones that go thru the radiator with fibre washers, as the vibration can ruin the radiator.
The ITALIAN Spal is a nice piece of work, unlike some of the cheaper fans i have seen, Colin.
You can get Spal fan brackets - check out eBay no. 151130505291
Might give you a more professional finish?
Ive just noticed something interesting.....i was having a look at a 164 engine bay and looks like the radiator is the same but the hose end connectors are opposite orientated to the 75, fair enough. The 164 has a fan with a steel shroud that covers the radiator two thirds. I can also see that the thermo fan is smaller than my 75 one. can I ask if anyone has tried a 164 fan and the shroud in their 3.0 75? only reason i say is that I sourced one recently as a spare?
The problem with the frequent thermofan operation on the 75 and the 90 is not due to:-
Insufficient fan capacity
Insufficient coolant volume
Inadequate coolant circulation
Incorrect thermostat operation
Blockages in the radiator or hoses
Faulty kick in temp of thermoswitch
Coolant flow throughout the engine galleries.
What is it? It's too many fins per inch of the radiator preventing adequate airflow to extract the heat. From memory there is around 20 FPI.
To fix the problem, leave everything as is and reuse. Install a new radiator core with around 12FPI and your problem will be solved.
I have explained this point before but perhaps the topic wasn't preceded by a search...
My 75 3.0 struggled to lose heat at anything over 30°C. Using a bit of smouldering cardboard as a smoke source, I was amazed at how little air was drawn through the grille. Much of the air was drawn from below the bumper and then expected to flow up then turn at a right angle and flow evenly across the full face of the radiator! At best not much more than 2/3 of the radiator saw any decent airflow.
I then spent around 6 hours removing much of the honeycomb type plastic latice from the grill, however managing to retain a much more open honeycomb pattern. I figure I have removed maybe 2/3 of that part of the grill. The smoking cardboard confirms a more even distribution of air through the radiator.
The next measure was to install a front splitter. More to reduce lift and drag, the splitter reduced air pressure under the car - much of this just forward of the sump. The reduced pressure assists removal of hot air from the engine bay without the need for a more effective fan.
The final measure was to track down the source of a rough idle. Replacement of EVERY vacuum hose has resulted in a very smooth idle even though the engine is fitted with tuned cams. The elimination of vacum leaks due to life expired hoses has resolved the lean mixture at idle issue. Restoring the correct mixture means the engine runs a bit cooler and idles smoother.
Quote from: Colin Edwards on February 25, 2018, 09:58:16 PM
My 75 3.0 struggled to lose heat at anything over 30°C. Using a bit of smouldering cardboard as a smoke source, I was amazed at how little air was drawn through the grille. Much of the air was drawn from below the bumper and then expected to flow up then turn at a right angle and flow evenly across the full face of the radiator! At best not much more than 2/3 of the radiator saw any decent airflow.
I then spent around 6 hours removing much of the honeycomb type plastic latice from the grill, however managing to retain a much more open honeycomb pattern. I figure I have removed maybe 2/3 of that part of the grill. The smoking cardboard confirms a more even distribution of air through the radiator.
The next measure was to install a front splitter. More to reduce lift and drag, the splitter reduced air pressure under the car - much of this just forward of the sump. The reduced pressure assists removal of hot air from the engine bay without the need for a more effective fan.
Most cars get the majority of their cooling air from the bottom opening. The opening is in a high pressure area when the car is moving. Look at something like an EF/EL Falcon, they basically have no grill at all.
A well designed undertray that goes from the leading, lower edge of the front bumper to just under the cross member that is in front of the engine and extends to the wheel arch liners (if you still have them) should tidy up the airflow under the car a bit and help the air exit the engine bay.
Most people think that the plastic pannelling under the car is for dirt and rock protection.
It aint.
It's to smooth the air flow under the car.
With approximately 1/3 of the air that the car moves out of the way when it's driving down the road going under the car, keeping that air flow a smooth as possible reduces aerodynamic drag and improves cooling system performance.
Yep. The underneath of the 75 is pretty rudimentary compared to my 159. And the underneath of the 159 is prehistoric compared to the new Giulia!
Agree managing the hot air exhausted from the cooling system is critical. Although at a lower density, the hot air increases in volume by more than 50%.