Does your engine temp rise when towing in stop/start traffic?
Submitted: Monday, Feb 21, 2011 at 10:50
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garbage
I have a standard 2.0L car with a towing capacity of approx 1100 kgs. I have previously towed a fully loaded 750 kg ATM box trailer without any issue. I have recently upgraded to a camper trailer, also 750 kg ATM but certainly feels heavier than the previous trailer (has a couple extra leafs and a bigger tent). I went up the coast on the weekend and went through the Pacific Highway crawl through the north shore of
Sydney where temps were around 30 degrees. The temperature which normally runs at 50% of the guage was around 75-80% but still one bar below the red line point. As soon as we hit freeway speeds, engine temps went back to 50%. On the way
home, we hit traffic again at Wahroonga and the temp went back up to 75%. The car has a transmission cooler and the coolant levels were normal.
Is this normal? Should I be concerned? My next trip is up to
Jindabyne, so I wonder if I'll run into issues with
hill climbing. Should I be easing off when going up hills and doing only 70-80 km/h?
Reply By: Allan B (Sunshine Coast) - Monday, Feb 21, 2011 at 11:25
Monday, Feb 21, 2011 at 11:25
Hi Garbage, Engine cooling, and hence temperature, is dependant on both the load and the amount of air passing through the radiator. Generally, sufficient air passes at vehicle speeds of about 60km/h to maintain design engine temperature and normal load. At 60 or higher speed more air is pushed through the radiator than the fan can produce. At lower speeds the engine is more dependant on the fan for air volume and it is usually only capable of handling enough air for low loads such as idling. A good electric fan does better at low engine speeds as it is not slowed to engine idling speeds. So you can expect a rise in temperature under some conditions.
The worst zone is of course a high vehicle load combined with a low vehicle speed such as you encountered in the traffic crawl. An electric fan would help here but running the air conditioner would make the situation worse as it consumes more engine energy but even more dissipates heat in front of the radiator.
Certainly
hill climbing will exacerbate the problem and it could be wise to not use full throttle but still keep the speed up to 70-80 in order to maintain the air flow. Keep an eye on the temperature gauge but expect it to rise under load conditions. As long as it stays below the "red line" you should be OK. If on a long
hill you are becoming concerned, switch off the air conditioner until over the
hill top.
AnswerID:
446155
Follow Up By: Road Warrior - Monday, Feb 21, 2011 at 11:48
Monday, Feb 21, 2011 at 11:48
Great advice Allan, makes a lot of sense.
Also with the air con, it would depend on the make/model of the car.
For example, in stop start traffic in hot weather, especially if I am towing, I always have the air con on not just for me, but for the engine because the BA Falcon has two thermofans, the second of which is a high speed unit and is tripped by a pressure switch in the system so in hot weather, the second fan drops in and out all the time. The effect this has on coolant temp on really hot days is quite remarkable, it literally drops like a stone.
It even has a failsafe so that if coolant temps get to critical levels, it will kick the air con out but keep the high speed fan running.
But of course, all of this is a mute point if the state of a car's cooling system is pretty poor from the outset.
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Follow Up By: Allan B (Sunshine Coast) - Monday, Feb 21, 2011 at 12:06
Monday, Feb 21, 2011 at 12:06
As you say Warrior, much depends on the make/model of the car.
Even those with two electric fans will depend on just how good the aircon fan is.
But even with extra fan assistance, they assist little compared to the ram effect of vehicle speed. To get an idea, hold your hand in the air stream behind the radiator with fans operating and vehicle stationary and compare that with sticking your hand out the window at 60km/h or more.
Some years back I assisted at
Adelaide University with taking air flow measurements of vehicle electric fans and whilst I no longer have the result figures I
well remember the much greater flow from the ram effect. I expect today's fans to be better but not that much.
FollowupID:
718462
Follow Up By: garbage - Monday, Feb 21, 2011 at 12:17
Monday, Feb 21, 2011 at 12:17
Hi Allan,
Thanks for the great explanation. I was playing around with the air conditioner and noticed some of the things you've mentioned. Turning off the air conditioner helped a little as did turning on the heater. I also noticed that with the air conditioner blowing in air from the outside, the air wasn't quite as cold as when the engine wasn't so hot.
The engine still stayed at least one bar (approx 20%) below the red line at all times, so I'm thinking this may just be expected behaviour. I take it the transmission cooler would also be very much ineffective at low speeds?
Can anyone with a more serious towing rig comment on whether they experience this as
well?
FollowupID:
718463
Reply By: Ruffy-Dan - Monday, Feb 21, 2011 at 11:41
Monday, Feb 21, 2011 at 11:41
Most temperature gauges are designed to work effectively from approx 60 degrees through to 110-115. The mid range of this 85-90 is roughly what most cars thermostats will maintain the engine temperate too. Most later model vehicle with thermo-electric fans will switch on around 95 degrees and under all conditions are designed to cool the temperature, not just maintain it.
If your gauge is reaching75-80% i'd suggest you gauge is doing it's job in alerting you that their is a potential problem and you need to get it checked. A partially blocked radiator (internally or externally), low coolant level, failing water pump and many other things will give you these symptoms.
Take it to your mechanic and have them
check it thoroughly.
Manufacturers design the cooling system to cope with towing loads, if it's not cooling correctly, there's an issue.
A five degree hotter day could see you parked on the side of the road with a very unhappy family.
Dan
AnswerID:
446157
Reply By: Dave(NSW) - Monday, Feb 21, 2011 at 11:51
Monday, Feb 21, 2011 at 11:51
garbage,
"I have a standard 2.0L car with a towing capacity of approx 1100 kgs. I have previously towed a fully loaded 750 kg ATM box trailer without any issue. I have recently upgraded to a camper trailer, also 750 kg ATM but certainly feels heavier than the previous trailer"
It might also pay to load your trailer up as if going away and take it to a weigh
bridge to get a real idea on what it actually weighs.
Cheers Dave.
AnswerID:
446158
Reply By: Kimba10 - Monday, Feb 21, 2011 at 13:11
Monday, Feb 21, 2011 at 13:11
Garbage, what type of vehicle do you have ?? Regards Steve
AnswerID:
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Follow Up By: garbage - Monday, Feb 21, 2011 at 14:00
Monday, Feb 21, 2011 at 14:00
It's a Subaru
Liberty with 120,000 kms.
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Follow Up By: AGNI4x4 - Monday, Feb 21, 2011 at 17:23
Monday, Feb 21, 2011 at 17:23
A clutch hub type fan operating efficiently will pull more air thru a radiator core than an electric fan generally. I removed a clutch fan and fitted duel electric to find they had less effect. If you are only getting over heat condition during low speed or idle situation then I'd have the radiator core checked for blockage. This involves removing both tanks and at times even bayonets are used to clear the core. Partial core blockage is usually the biggest cause of over heat in this given situation. If problem still persists after that then
check water pump for corroded impeller remembering that the pump in fact does not pump (displace volume) but creates circulation. Have seen impellers that have nothing left but the hubs and hence no coolant flow (no circulation ap[art from thermal movement)
Cheers and happy trails
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Follow Up By: Kimba10 - Monday, Feb 21, 2011 at 20:34
Monday, Feb 21, 2011 at 20:34
Have you checked the electric fans are actually cutting in ?? Most Vehicles are different eg most toyota's I ve had the temp virtually doesnt move once its reached operating temp, normally sits a mil or two under half and generally might move up a mill or two at most this can be at 2 degree or 40 degree's. My wifes old pulsar use to worry me till I worked out the way it operated. Cruising along would sit on 1/4, when sitting in traffic with air on or off it would climb to 3/4 before the electric fans would cut in but would pull the temp guage down to nearly 1/4 and would sit their doing that, never a problem, First thing I would
check would be the fans are working both with air on and off then let it sit an idle (keep an eye on guage) and see if fans operate, most vehicles with electric fans are two speed. so make sure its really booting up when required, if working properly then next I would replace the thermostat (cheapest option), Then if still climbing I would do as AGNI4X4 has said and start from there. Better to get it 100% then get cought out and possibly do major engine damage. Regards Steve
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Follow Up By: garbage - Monday, Feb 21, 2011 at 22:32
Monday, Feb 21, 2011 at 22:32
My temperature gauge doesn't move either in normal driving (without towing). The only exception was when it was 42 degrees a few weeks back.
But no, I haven't yet checked if the fan runs. I'll double
check it when I get a chance.
FollowupID:
718558
Reply By: Fred G NSW - Monday, Feb 21, 2011 at 18:30
Monday, Feb 21, 2011 at 18:30
Garbage, yesterday was an absolute stinker of a day, and what you describe for the F3 crawl, seems pretty normal to me, especially with the traffic jam you encountered.
For peace of mind, I would
check that you have adequate coolant additive in the water, even if it means changing the lot and refreshing it, and also maybe have the thermostat & waterpump checked. You struck a stinker of a day for that trip , and everyone elso on that road would have had similar problems.
You will find on your trip to
Jindabyne, that your temp will be much more constant once the "big Smoke" is in the rear vision mirror. There are not too many hills to worry about from
Sydney to
Jindabyne, via
Canberra.
Safe travels, Fred.
AnswerID:
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Follow Up By: garbage - Monday, Feb 21, 2011 at 20:34
Monday, Feb 21, 2011 at 20:34
The coolant I have is an off the shelf pre-mixed bottle from Subaru which I changed 22,000 kms ago. In that time, I haven't had to top it up. Would that mean it's fine?
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