Author Topic: Cooling air not enough?  (Read 3036 times)

0 Members and 1 Guest are viewing this topic.

Ricardo Regalo

  • Member
  • *
  • Posts: 19
  • Karma: 0
  • Location: Sintra Portugal
Cooling air not enough?
« on: January 22, 2018, 05:42:22 PM »
Hello mates,

I've recently joined the club, and I've already read some threads about cooling/overheating issues, but I still have lots of doubts. :$
Here's the thing: my aircooled 126p ELX from 99, as a oil temp gauge. In city driving and low gears the oil temp stays around 115 degrees C, but whenever I drive on a motorway or some road that allows for 80km/h oil temp raises up 120/130 degrees after just a few minutes. The only time I drove it for longer on the motorway recently, I had to keep the car around 70km/h hardly pressing the gas pedal, because temp was at 130 degrees. This temp is the limit for red zone on the gauge. :(

Is this to be expected or is my engine actually overheating? As well, has anyone, tried the light alloy sump from Nanni Sport (the one with the air duct in the middle), does it really helps cooling, and shell I go for this? Thank you for your insights.

Gerhard

  • Newbie
  • *
  • Posts: 9
  • Karma: 0
  • Location: Deutschland, Augsburg
Re: Cooling air not enough?
« Reply #1 on: January 22, 2018, 06:26:01 PM »
Öffnet diese Klappe?

Opens this flap?

1973/126

  • Super Member
  • ***
  • Posts: 1753
  • Karma: 23
  • Location: Tunbridge Wells
Re: Cooling air not enough?
« Reply #2 on: January 22, 2018, 07:09:35 PM »
 Welcome Ricardo. As Gerhard pointed out first thing to make sure is that the thermostat flap opens. Second thing to check is the big intake hose that brings the cold air to the engine is connected where it should be.
 If both are OK the next thing would be to check the timing and general condition of the engine(spark plugs, fuel mixture, oil).
 A bigger sump would definitely help keeping the temperature down. There is a lot of choice on Italian eBay or the main suppliers. You can also use an engine prop like the one in the picture.
 I used to run a modified thermostat housing in the summer with the hot air blowing out.
 Btw I don't know what the normal engine oil temperature is on an a/c but they do get pretty hot.
 
 
1972 Fiat 500
1980 Fiat 126

DEYAN IYI

  • Super Member
  • ***
  • Posts: 418
  • Karma: 2
    • Bulgarian Polski FIAT 126p Fanclub
  • Location: Plovdiv/Bulgaria
Re: Cooling air not enough?
« Reply #3 on: January 23, 2018, 09:32:14 AM »
Hi Ricardo,

Also make sure that the oil you use is the correct one for your location and engine condition.

PS- About 20 years ago a friend of mine went to the seaside (300-350km), 4 people with luggage in 40*C and burning sun. He was running it at 90-100km/h to keep up with the traffic. They decided to have a rest and eat some sandwiches in a shadow. My friend went to open the rear hood, then touching it jumped back screaming and maybe cursing. It was bloody hot. He said the rubber of the rear window was soft like a turkish delight. :D And no signes of overheating.

Ricardo Regalo

  • Member
  • *
  • Posts: 19
  • Karma: 0
  • Location: Sintra Portugal
Re: Cooling air not enough?
« Reply #4 on: January 23, 2018, 02:23:31 PM »
Thank a lot guys.

This is something that's been going on for some time now.  Picking up on what Gerhard wrote, the thermostat is working, and the flap opens with the high temp. As well, I've already checked the intake hose, and shove my hand down inside to check if there was something inside or if the fan was loose, both negative.  To add to my puzzlement, it doesn't seem to make a difference, when I drive it with that bracket to keep the engine lid partly open. The same is true, for summer or winter conditions, being the only difference, the time it takes the temp to rise.

About the timing, for the spark plug, mine is electronic, so I'm not sure how to change this. Could it be related to valve clearance? My car was fully reconditioned in Poland before I brought it to Portugal (more or less 3 years ago), and I haven't check the valve clearance since then (I don't even know how much the clearances are  :$).

The oil I'm using now is 5w40 synthetic, from a Portuguese brand. Before was 10w40 semi-synthetic and the problem was the same. My first idea regarding this synthetic oil was that it flows a lot better on cold start up, but remains with a good viscosity at running temp. However, I've considered changing to a higher viscosity oil like 20w50, with the running oil temp as it is. 

I think I read somewhere that some version of the cooling fan have less fins, and therefore have less cooling efficiency, can anyone confirm this?

I'm definitely going to buy a aluminum alloy sump, because I believe that it's heat dissipating characteristic is worthwhile. I was just wondering if some one had one like it, and what they thought of it. The one I'm looking in to is:

http://www.fiat500sport.com/special-offers/nanni-light-alloy-sump-with-central-air-crossing-way-for-fiat-500-126-0270.html

I also thought about, wrapping up the exhaust pipes with thermal tape to reduce the heat on the engine compartment, but I guess it won't make much of a difference, otherwise keeping the lid open would do the trick.

On the post from 1973/126 I noticed that your car has the combustion air intake, separated  from the discharge from the fan. This is something that I considered doing, more so, to increase the amount of air, available for cooling, (since the combustion air is no longer drawn from the fan). Are there kits to this transformation available for sale online?

The funny thing is that during the time the temp gauge was broken (a few months), I continued to drive it with no care in the world :D, and I never had any problem, like oil warning light (for the oil getting to thin and pressure getting to low).  Now that the gauge is ok again I fret with the idea of damaging the engine by overheating it. ::)

From the beginning, the oil temp probe was incorrectly fitted, with a large protruding cooper pipe coming out of the oil dipstick. The temp reading was always around 100oC, but I suspect the reading wasn't correct. After I had a major breakdown on a long voyage (exhaust system came apart), the probe was broken too. Only when I repaired it, did I notice this temp rise.
   

 

1973/126

  • Super Member
  • ***
  • Posts: 1753
  • Karma: 23
  • Location: Tunbridge Wells
Re: Cooling air not enough?
« Reply #5 on: January 23, 2018, 05:15:31 PM »
 Ok so few questions. How confident are you with the accuracy of your temperature sensor? Also do you have any problems starting the car when it is hot?
 You should definitely check the valve clearances just for a piece of mind.
 Also check that the bottom of your oil sump is not squashed. They often get damaged when people jack the engine up. This would prevent the air circulating through it properly.
 The sump in your link looks good. I had one of the cheaper alloy ones fitted but never monitored the oil temperature.
 
 
1972 Fiat 500
1980 Fiat 126

DEYAN IYI

  • Super Member
  • ***
  • Posts: 418
  • Karma: 2
    • Bulgarian Polski FIAT 126p Fanclub
  • Location: Plovdiv/Bulgaria
Re: Cooling air not enough?
« Reply #6 on: January 23, 2018, 07:45:06 PM »
Hi again,

Valve clearence: intake 0.20mm, exhaust 0.25mm, every 10.000km or once a season.

You can adjust the static ignition advance with a stroboscope, moving the plate with the sender on the crankshaft pulley. Not sure what is the correct degree for EXL.

Check if the vacuum sender and the cut-off valve are working correctly.

I suggest that your Maluch had originally a cat converter and if it is with a simple silencer now, would probably need adjustment of the air/fuel mixture at idle. I have no idea if the EL and the ELX share the same jetting.

Do you use this model of thermometer?

Best!


drcdb15

  • Super Member
  • ***
  • Posts: 509
  • Karma: 6
  • Location: East Grinstead, West Sussex
Re: Cooling air not enough?
« Reply #7 on: January 23, 2018, 10:09:30 PM »
Ok so few questions. How confident are you with the accuracy of your temperature sensor? Also do you have any problems starting the car when it is hot?
 You should definitely check the valve clearances just for a piece of mind.
 Also check that the bottom of your oil sump is not squashed. They often get damaged when people jack the engine up. This would prevent the air circulating through it properly.
 The sump in your link looks good. I had one of the cheaper alloy ones fitted but never monitored the oil temperature.

And also the oil, if the underside of the sump is pushed in/up until it obstructs the oil pick up.

On Ladislav's point about the oil temperature accuracy, 'ordinary' temperature gauges have been known to read as much as 30-40 degrees too high, so your "115" degrees may only be around 80-90, which is quite normal. But even higher temperatures are nothing to worry about. Typical sump temperatures can be anywhere around 120-150 degrees depending on the engine's running conditions. Engine oils don't start to seriously break down until prologed exposure at around 250 degrees and up.

Best indication of the engine running too hot will be if the oil starts to blacken and char. If the oil looks good, suspect your temperature gauge.

drcdb15

  • Super Member
  • ***
  • Posts: 509
  • Karma: 6
  • Location: East Grinstead, West Sussex
Re: Cooling air not enough?
« Reply #8 on: January 23, 2018, 10:15:59 PM »
My friend went to open the rear hood, then touching it jumped back screaming and maybe cursing. It was bloody hot. He said the rubber of the rear window was soft like a turkish delight. :D And no signes of overheating.

Bear in mind that the human body, including the skin on your fingertips, is pretty useless as a temperature sensor. Anything over about 45 degrees feels very hot, and that's only 8 degrees above your body core temperature! 60 degrees will visibly mark your skin and 70 degrees will cause severe burns, so engine oil temperatures are way way above what your own senses can reliably gauge, whilst in engineering terms still being quite cool.

drcdb15

  • Super Member
  • ***
  • Posts: 509
  • Karma: 6
  • Location: East Grinstead, West Sussex
Re: Cooling air not enough?
« Reply #9 on: January 23, 2018, 10:23:07 PM »

I also thought about, wrapping up the exhaust pipes with thermal tape to reduce the heat on the engine compartment, but I guess it won't make much of a difference, otherwise keeping the lid open would do the trick.


The "difference" wrapping your exhausts will make is that they will overheat, distort, corrode and eventually fail. Popular myth is that wrapping the pipes is to keep the exhuast gases hotter - which it does, but that's NOT the reason it's done. It originated in NASCAR racing in the USA and it was done to keep the engine bay COOL, because heat from the pipes was causing overheating of other items in the engine bays.

The fact that wrapping causes premature corrosion and failure of the exhaust pipes didn't matter in race cars as the exhausts were often replaced anyway. But in an everyday car in normal use, this is NOT a good idea.

Ricardo Regalo

  • Member
  • *
  • Posts: 19
  • Karma: 0
  • Location: Sintra Portugal
Re: Cooling air not enough?
« Reply #10 on: January 24, 2018, 05:05:38 PM »
Hi guys,

you've been fantastic sharing your knowledge :)

And I think we have a very likely "winner", on this  subject. As a matter of fact I did use the jack to support the engine when I had to take out the engine bracket. I used a board, (not very well apparently), but still, it made a dent on the sump, though not very pronounced. I had already seen this, but dismiss it as a possible cause for the problem, because, I could still fell quite a good air flow coming from it. :$ I will punish myself for the stupid thought. I guess replacing the sump, with the aluminum alloy one will fix the problem.

About these sumps that you find for sale online, I can't see any duct for the air cooling on most of them, like the original part has. Is the cooling effect increased so much by the conductivity of the material, that it can do without the forced air flow. And I wonder what about the discharge port from the fan casing? Is it "plugged" by the new sump or the air flows freely out? I think this wouldn't make much sense.

Responding to Deyian Iyi, yes that's the thermometer installed, the probe is slightly different, more so because I had to rebuilt it. Regarding accuracy I've tested it with boiling water, and it was spot on the 100oC. And thank you for all the info regarding valves and timing. I confess my lack of knowledge regarding the vacuum sender and cut-off valve... erh what are those? :$

I got a bit happier with what drcdb15 said regarding the oil. Mine still looks good. It's actually looking better than the oil in most other cars (which is very surprising for me), still retaining some of its translucent quality. I had that same idea about the oil being able to withstand those kind of temperatures. But anyway, I wasn't sure if those temps were to be expected.

It seems that I'm not wrapping up my exhaust after all. 8)

So, in conclusion, the alloy sump is a given. I got convinced this is going to do the trick. This was on my mind before, now I'm sure is the way to go. I'll check the valve clearances for peace of mind (and it's due), and see what happens. The thing is, I won't be able to order this sump until I get back home next week (I'm a seaman currently at sea). As well, I have no idea how long it will take for the sump to get to Portugal from Italy. I look forward to try it and check the temps afterwards.

I'll keep you guys posted on developments. Anyway, more inputs are always welcome.
Cheers mates!