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zar162b4
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Oil Cooler

Post by zar162b4 »

Hello,
I was planning to install an oil cooler on my car (alfa 75 twin spark 2.0, standard engine). In fact, last Sunday I went to the Appennini mountains and the day was pretty sunny and hot. I noticed that when going uphill, the oil pressure tended to drop to non optimal values after some time. The oil light never switched on, but anyway I felt a little concerned.
My plan would be to do as follows:
- Mocal OTSP1 plate with integrated thermostat (on their website, they say it is possible to costumize the temperature at which thermostat opens, stock temperature is 80°C, would you recommend 90°C?)
-Alfa 164 or Alfa 166 2.0 v6 Turbo oil radiator (I can relatively easily find them at the scrap yard too, or would you recommend to buy a new one?)

I would greatly appreciate your comments and suggestions on this.
Thank you
Regards
Oscar
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MD
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Post by MD »

Oscar

You don't tell us where you live in terms of the climate which may give a clue to your needs. Having said that, Alfas generally have a large oil capacity and plenty of "heat sinking" via aluminium fined sumps and so for a regular road car it should not require an oil cooler.

If you regularly use the car for towing, perhaps you should get one and the transmission too but you should get a Jeep instead. :D

Oil coolers are more appropriate for race cars or very modifed engines producing excessive amounts of heat that may cause the oil to break down.

You dont say what actual pressures your engine drops down to but it's normal for it to get lower under such conditions. There is also the possibility that your oil pump needs servicing and you should get a pressure test done by a master guage to see if this is your actual problem.

Your oil viscosity may also be too light.
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zar162b4
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Post by zar162b4 »

Hi MD,
you are right, I'll be more precise. I am Italian, I live in Florence during working days and in Rome during weekends.
The oil I use is the one prescribed by the factory, that's to say Agip 10w40. In normal conditions, the pressure when the engine is at 800RPM is between 1 and 2 bars. Last day it dropped to 0,5 at the top of the ascent. The car has low mileage, 100.000 km, it does not smoke at all and it is in fairly good conditions. This morning, I took it again, and the oil pressure values were correct, as usual.
I was asking that, just because I'd like to keep the engine in this shape as much as possible. I do not race it, and I generally run it between 2500 and 3500 RPM.
I was thinking of an oil cooler with thermostat for 2 reason:
1) It does not seem to be a big and complicated modification to do
2)My father's alfa 75 turbo was equipped with it at the factory (like 164 and 166)

Furthermore, the presence of the thermostat in the plate prevents to overcool the oil, so when it is cold the oil is not driven to the cooler. I was thinking of the cooler just for safety reason, because it can really be hot some days here and when the engine is stressed (going uphill for instance) it might really be helpful to install a radiator. Am I saying sensible things?
Thank you again
Oscar
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Post by zar162b4 »

This is my car (please scroll down until you see the black car): http://www.alfasport.net/forum/topic.as ... chpage=315
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Post by Mats »

1600Euro for that? :shock:
You lucky bastard... :)

As you said it's quite easy to add an oil cooler but it sounds strange that you need it. You say it was a hot day, what kind of temperatures are we talking about? Seems like "hot" is different depending on who you talk to, me in Sweden for instance.
Maybe it's another problem, a problem that only shows when the oil is hot. Like a stuck overflow valve in the oil pump or a loose plug in the crank?

Where in the Appennini where you going? I've been over the Abetone pass (Lucca) a few times and I know it's very hard for an old car in difficult conditions. 8)
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MD
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Post by MD »

Oscar

Nice car.

If it eases your mind, by all means fit the oil cooler but I repeat, it is not necessary and a waste of money.

In Australia, the road base temperature can get so hot that the tar actually melts and you can get "road spray" up into the mudguards but guess what, we dont need an oil cooler on an Alfa. If that doesn't convince you, I don't know what else to say.

Get an oil pressure test done of your engine. That will show up faults as suggested by me and Mats.

In summer you could also run with a different oil. I use a 20W-60 multigrade.

Buona fortuna
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Post by Zamani »

Hi Oscar,

For a TS, do you need such a big radiator? Maybe your current one is partly clogged? I have V6 and a 75 2.4 TD radiator, even with the thermostat (well maybe the thermostat is bad), it runs too cold on the freeway (around 170F) and I cannot get good gas mileage partly because of this. Maybe around 27 mpg (Imperial). I would say get your radiator tested first, then get a calibrated mechanical pressure oil pressure gauge (maybe your mechanic has one, although many don't have a calibrated one) to test the actual pressure when warm at idle. Also 20w50 oil doesn't sound like a bad idea for summer.

Unless you drive on the track in the summer, I think an oil cooler is unnecessary for the TS.
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Post by zar162b4 »

Hi,
First of all thank you for the nice words for my car. I was pretty lucky with it in this case :D . Let's say that with this car I could balance the lack of luck I had with my other car, in which I spent a lot of money to bring it to its current good conditions. Here they are together in Rome:
http://img444.imageshack.us/img444/9686/foto2op3.jpg
http://img444.imageshack.us/img444/5315/foto1nv2.jpg

Mats for hot I mean temperatures higher than 30°C. Consider also that the route I did included 3 Passi (I am sorry, but I am not sure I know the English word for Passo, which is the point of the street at the top altitude to cross a mountain instead of driving thru a tunnel) and in some points you needed to downshift to first gear to proceed. To see the route I did, you might find convenient using Google Earth. I left Florence, heading for Pontassieve, then first Passo "Passo della Consuma", then 2nd Passo "Passo della Calla", we ate in a small city called Premilcuore and then last Passo "Passo del Muraglione".
The car actually shows correct values of the pressure when driven on the highways and in the city, (I mean when warmed up pressures between 1 and 2 bars at 800 RPM and pressure non lower than 4 bars at 3000RPM). I also know that pressure sensors are notorious for being a bit unreliable and the fact that the low pressure red light in the dashboard never switched on makes me feel somehow better.
Mats, Abetone is not very far from the place where I was, and it is a very good place for skying during winter!

MD, I will follow your suggestion, I will have the pressure values checked and see if something must be done in this area. However, you suggest to use an oil with higher viscosity, like 20w 60, but isn't it too thick? Maybe would not it be better to use the oil recommended by the factory and keep it to design temperature with the help of an oil cooler? I am asking that because sometimes we have snow here, and maybe I should change the oil again when temperatures fall.

Zamani, last year I changed the radiator (Valeo), water pump and thermostat. I actually run with an alfa 164 thermostat, which keeps the engine temperature at 90°C instead of 80°C. So far everything works fine. A positive fact of the 164 thernmostat is that the engine temperature looks more constant. I mean that with current settings, as engine passes 90 °C, the fan activates for say 10-15 seconds, and switches off bringing the temp back to 90°C. The fan activates often, but temperature keeps fairly constant. My other car has a thermostat that starts opening earlier (roughly 80°C) and fan activates at 90°C, deactivating when temperature reaches roughly 85 °C. In this case temperature variation is higher, so maybe the black alfa 75 setting looks better as the temperature is more constant.
Thank you again for your suggestions
Regards
Oscar
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Post by MD »

Oscar

If you read my post again, you will see that I meant for you to use a summer oil of 20w60. Yes you would need to change it for winter but in our climate, I use the same oil all year round.
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Post by Jim K »

People from different parts of the world trying to talk about temperature and heating problems...unless you're there you usually can't fathom the problem. Right now we're having ~37-42*C here and the 3liter has a tough time coping with stop-and-go traffic, even with a new TD rad, twin fans and the oil cooler. Of course there's a/c and this is the time you want it ON! If you demand performance in the open road in this heat (with a/c off) the gauge climbs to ~95*C and pretty soon you have to quit! Then, it takes forever for the gauge to come down....I don't know if you've experienced these conditions, but my view is the engine has to be bulletproof, rain or shine! A difficult proposition with a huge lump under the hood! So what has to be done? A number of things: Unfortunately, we don't know the std Alfa fan cfm (nowhere to be found) so we must invariably (somehow) compare to a high performance SPAL fan. From my latest search, I found that the highest flowing fans use plain old-fashioned paddle blades (usually 5) driven by hefty motors drawing 9-15A (depending on size) and not the modern curved-blade jobs with the flat motors. These designs are run-of-the mill and they're shaped for less noise, NOT airflow. Then there's the rad! Hmmm, the TD one has 2 rows of 12.7mm flat tubes and a core thickness of ~33mm. Find a reputable maker and have them build you one with 3 rows, all brazed construction, NO epoxy! Then, you must arrange the fans diagonally, so that they cover the entire core area, not like the TD where the bottom 25-30% is not covered!! I believe that with a combined flow of 2300-2600cfm and a good 3-row rad, you'll be laughing in the hottest of summer days. I'll let you know myself how all this fares out, if I can have the rad made soon.
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Post by superfly tnt »

oil in my sump is about 60-80 C in heavy traffic. at the track not more than 110C , while drifting or lowspeed massacre its over 140C . it maybe a little hotter in the pressure lines but i guess not much. oh, and its a TS with very good oilpressure and running smooth.

i forgot, water is never over 90. i have standard TS radiator and big fan which i think is a monster. i can feel hot air blowing around the car when i put my hand out from the window.
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