both top and bottom radiator hoses hot

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neilcmusic

Active Member
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383
My series 3 2.25 petrol is overheating in traffic , both top and bottom hoses are hot , thermo is OK because water is flowing into radiator by top hose , however when it comes from bottom hose it is still hot , surely this isn't right , the radiator should be cooling the coolant ?

Thanks
 
I would think most likely is the radiator fins being bunged up with dirt. To clean them out I took the radiator off mine then blasted a hose through it. At a quick glance mine looked clean but after looking more I realised only about half of the area was clean! Might as well give the radiator a flush through if you have it off the car too.

Other thing is your fan might have something wrong with it that it isn't pulling enough air through? I'd check the radiator first though.
 
Radiators 2 months old and i ran a hose through it and it flowed great , is it possible to get a plastic fan , I have an old series fan which is heavy , someone advised me that if a plastic fan was ava it would increase bhp
 
Do you have the fan shroud on the radiator? If not they will get unhappy in traffic as the ducting does a lot to make sure the air is pulled through the radiator and not everywhere else.

If not then either dig one out of a scrappy or fit an electric fan. I have an electric fan on my 110 and love it - very effective and let me get rid of a load of stupid ducting at the front of the engine.

Alan
 
Do you go off roading much? Even though the rad is new the fins could still be blocked up by mud or something. If you only use it on the road this is unlikely.
 
It's actually quite hard to overheat a series petrol - I've driven one for miles with a big hole in the radiator with no issues. Is the engine running lean and producing too much heat? Are you sure the thermostat is working properly and opening fully? Does it run cool if you take it out? Are there any bubbles in the coolant? Water might be getting through the rad core, but is air getting through the fins? Good point about the ducting.
 
When you say they're both "hot" - is that as in "sticking your hand on it and squeeling then withdrawing it rapidly"? Or have you checked their actual temperature?

Remember, the thermostat stays closed below 74 or 82degC - your hand is just going to say "OUCH!" to either of those, no finer detail.

Get a cheap IR thermometer - less than a tenner off the 'bay. Fantastically useful for trouble-shooting cooling systems. Point it at the bottom and the top hoses, see if you actually are losing some temp or not.

Swapping the metal direct-drive fan for a plastic/electric one won't "increase bhp" - but it will reduce the power that's being wasted in spinning the fan, so you'll have more left for forward motion. But an electric one's something else to go wrong. Remember, with an electric fan (like on almost everything more recent than a series), apart from what's pushed over the rad by forward motion, there's no forced airflow until it all gets properly hot.
 
You can't break the laws of Physics. Energy has to come from the engine to drive either the direct fan or an electric one - there's only an advantage if you can fit a thermostat somewhere to control the fan.
 
True...

But the mechanical one is being spun all the time, whilst the electric one is only spun when needed - and is probably a lot more efficient. I've never seen an electric fan that didn't have an automatic (or manual) switch controlling it.
 
Replacing a metal fan with a plastic one won't get you a noticeable gain in power - the inertia of the fan is quite small compared to the resistance encountered pushing all that air around! An electric fan is worthwhile - I toyed with getting one off a small car but in the end bought a Kenlowe kit which has worked well. Advantages are it does save BHP 90% of the time when it's not running and also the engine warms up much faster in winter.

Overheating could be:

- maybe the new radiator is crap? What make is it, is it painted? If so, is the paint blocking it - I've seen some real ****e being sold
- head gasket - what is the water / coolant like, any losses?
- lean carb. mixture can cause more heat but still shouldn't be overheating.
- Are you sure it's over heating? Is it actually boiling up? Don't trust the guage! As others have said buy an IR temperature tester
 
ok so now things have change slightly , top hose is warm and bottom hose is cold , depending on what you read this is normal/irregular ,
doesnt seem to be overheating now , im assuming this is correct , hot water in top and cools through radiator and goes back into block via bottom hose , am I right?
 
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