Overheating - Bigger Radiator?
Posted 08 July 2010 - 08:46 AM
firstly at idle its not uncommon for the temp to go up as the water pumps only tickling along often if you open throttle to 2000 rpm you will see temp drop
secondly its not uncommon to get air trapped if not bled correctly best way is to jack car up at rear as high as poss then fill header tank we put a small bleed screw in the top of the rad open this till clear water comes out
all the air in the system should rise to the rear of thecar and into the header tank
you should have a header tank mounted above the radiater height in the rear engine compartment with a pipe from the top hose fiting in the engine block this goes to the top of the header tank the return pipe goes on the bottom hose into a T piece
thirdly if its getting that hot that fast is the head gasket gone ?
i had a customer with a hayabusa that kept losing the water getting hot quick and he tried everything but the head gasket it turned out to have a very very small leak that only manifested itself under extreme conditions
water also cools the oil on the honda and typically should read 10 to 15 degrees hotter than water temp
top hose to top of rad bottom to bottom of rad
lastly some of you are running around on startup maps in the ecu if the fuellings not correct then it will affect the temps the engine runs at equally advancing and retarding the ignition will make the engine run hotter or cooler
Posted 09 July 2010 - 10:23 AM
One of the problems with the original setup is that the outlet/return pipe from the expansion tank goes only to the radiator side of the thermostat (which wont open below 65deg C (in photo labelled C green)) it means that when filling the coolant system the coolant liquid has to first fill the coolant pipe from the thermostat to the rad, then the rad, then the cooant pipe back to top hose of the engine before it starts to fill the block, so you end up filling from the very hole your trying to get the air out of.
I was asking about your coolant connections to your throttle body (TB) because if your not using them then I would recommend that you tee off from your expansion tank outlet/return pipe and connect to the redundant 8mm pipe connection on the black steel pipe (in photo labelled B red), this way when you fill the expansion tank with coolant it feeds to both sides of the thermostat at the same time, filling from the bottom upwards through the water pump into the block. Remember if the TB pipes are in use that you will need to blank off the feed from the housing of the top engine coolant hose to the TB (labelled A yellow).
Lets face it your probably not going to need to heat your throttle body as you most probably wont be using the car is such inclement weather that would require it to be heated, also the heat in the engine bay should be ample to stave off ice and if your out in snow and ice your a proper nut job.
Once the system is bled as Chris has described it wouldnt hurt to jack up the N/S of the car a little bit as the bleed is on the N/S of the engine allowing any last bit of air out the system. Also if you can leave the cap off the exp tank until the engine gets up to above 65deg C so the thermostat is opened and the coolant is flowing all around the system as the coolant level might drop at this point and might start sucking in air if too low, do this when the back is jacked up and also once the thermostat is opened then bleed the radiator again.
I have not had any overheating issues utilising this system (my feed to the top of the thermostat is slightly different but the principal is still the same).
In a previous post you had said about the under bonnet temps being high - I wouldnt worry too much about that, consider that normally the engine is under the bonnet with the radiator and it get freekin hot in there.
Photo below to help if you decide to do it:
Edited by cptkirk, 09 July 2010 - 10:32 AM.
Posted 09 July 2010 - 02:00 PM
i have my plumbing quite different, with the header outlet on the out of the engine.
good tips about the bleeding also.
i will report back.
Posted 09 July 2010 - 11:20 PM
Posted 01 August 2010 - 05:15 PM
its got to be an issue with how its plumbed really ive just had a lad drive from derby today in a v tec no problems at all in 30 degree heat through motorway driving then hull itself and lastly country roads round here
It was the plumbing. i added the bleed whole in the top of the rad, bled it how chris stated and added the t-peice, removing the heated throttle body. also moved the water feed to the input side (bottom) of the engine rather than the output. its now great. so thank you all for you time and efforts on this.
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