Fans cut in at higher temp since system drain.
Discussion
I have recently drained my cooling system. And now the fans seem to cut in at around 100 as opposed to just over 90 before hand. As far as im aware there are no air locks(system ffully bled), it hasnt overheated, i have no signs of leaks. Any thoughts why this should be. Other things I did was remove otter switch and clean it, remove engine temp sensor and clean it and replace 6 inches of the wire connceted toi it. My only view is perhaps the temp gauge is giving a better reading of the temp due to a better electrical circuit. Or the ratio of water to anti freeze is different which effects the temperaturs somehow. I have sat with engine running and it dosent get above 100 and fans go on and off as normal. any thoughts boys and girls.
Zippy, iam surprised the experts have not answered you, here is my opinion. The temp sender has to go "more to ground" to show a higher temperature, so adding a short lead could not cause it as it it would if anything show a lower reading. Cleaning the otter!, i do not see how this could delay its cut in point as its only temp related. Having changed my thermostat on many occasions i would say the "air lock" theory is tops, just this week i changed again and thought it was ok, only to see a 5 degree higher reading until i let the air out.
I have undone the rad bleed screw again, with no air coming out, the only thing to try now is to run engine from cold with expansion tank cap off for a few minutes I suppose. Weird this, I would have thought the fans would cut in at less than 90 if I had an air lock, not higher. Most odd. The investigation continues.
Zippy,
when you run the engine make sure you have the heater control set to hot, so as any air in the heating side of the pipework is able to be purged through. You can sometimes get the odd air lock in the inlet manifold pipework too which normally clears after the heater system checks. Leave the expansion cap off like you sugested and this helps air escape easier than if the system is pressured.
heliox
when you run the engine make sure you have the heater control set to hot, so as any air in the heating side of the pipework is able to be purged through. You can sometimes get the odd air lock in the inlet manifold pipework too which normally clears after the heater system checks. Leave the expansion cap off like you sugested and this helps air escape easier than if the system is pressured.
heliox
air lock is still favourite, but...
changing the lenght of wire to your sender MAY change the reading. these often have a balancing resister in line and usually covered in black tape (looking like a cr@p join) which matches the gauge to the sender. also the wire does have a resistance so will affect the reading but a doubt by this much. if you still have the old wire in the bin in the garage, check it out. pull off old tape.
air locks still favourite. fill it, then warm it up then fill it again to correct level cool it first!
a/c cars have a high point fill (alloy pipe sticking up vertically on l/h/s of engine above rocker. or pull the swirl pot pipe off and fill from there. 50mm right angle pipe on top of engine.
granny sucking eggs ? hope not
cheers
changing the lenght of wire to your sender MAY change the reading. these often have a balancing resister in line and usually covered in black tape (looking like a cr@p join) which matches the gauge to the sender. also the wire does have a resistance so will affect the reading but a doubt by this much. if you still have the old wire in the bin in the garage, check it out. pull off old tape.
air locks still favourite. fill it, then warm it up then fill it again to correct level cool it first!
a/c cars have a high point fill (alloy pipe sticking up vertically on l/h/s of engine above rocker. or pull the swirl pot pipe off and fill from there. 50mm right angle pipe on top of engine.
granny sucking eggs ? hope not
cheers
All previous bleeding was done with heater on hot setting. The length of wire was cut the same length to allow for resistance change. One thing I did notice the old wire was very stiff, due to either old knackered isulation or higher gauge wire, this will change the resistance a little. The actual engine does not overheat, so if no air lock can be found shall i just forget about it( but keep a watchful eye on the gauge just in case)
Quick update:
run the car this morning with cap off and heater open for 5minutes, then drove to work. Heater is luke warm, but car has still not overheated. So looks like a very stubborn airlock in the heater matrix. Anyone have a tips fpr getting it out. Would leaving the filler cap off even when the thermostat opes work. Although im a bit conserned about doing this for the obvious reasons.
run the car this morning with cap off and heater open for 5minutes, then drove to work. Heater is luke warm, but car has still not overheated. So looks like a very stubborn airlock in the heater matrix. Anyone have a tips fpr getting it out. Would leaving the filler cap off even when the thermostat opes work. Although im a bit conserned about doing this for the obvious reasons.
i have left cap off and waited for thermostat to open to remove airlock from my griff with no problems.as coolant doesnt boil until 100oc or thereabouts(with added antifreze)then 'no pressure' shouldnt be an issue.i let my temp gauge get to just over 90oc,fans were on and so it stayed this way for a couple of minutes,even if your fans dont come on this early you could always override them.this removed all the remaining air from my system.just watch gauge and dont let get too hot or then of course it could boil.i didnt find all this too difficult.dont forget thermostat should be fully open at 82oc so youre way off boiling point when starting to cure your problem.
Zippy, Keep the heater on. Remove the blue cap from the expansion tank and check the level is just over the weld line about half way up. If you over fill it it will find its correct level when the engine reaches temperature. Humour me and remove the drain plug at the off-side end of the radiator and slacken the plug on the header tank (brass plug with slot). Let a cup full of coolant run out and replace drain plug. Top the header tank right up to the very top so it overflows. Wrap a bit of rag around the tank so you don't make a mess! 
Replace the brass plug and tighten with a large screwdriver using the side of the blade to maximise leverage. Obviously, make sure that you do your topping-up with a mix of universal antifreeze and water (I live in a hard ater area so use distilled water to prevent radiator furring).
If this all does not work I suggest that you replace the thermostatic switch which is screwed in the base of the header tank...should cost about 12 quid.
Good luck!
Toffer
Replace the brass plug and tighten with a large screwdriver using the side of the blade to maximise leverage. Obviously, make sure that you do your topping-up with a mix of universal antifreeze and water (I live in a hard ater area so use distilled water to prevent radiator furring). If this all does not work I suggest that you replace the thermostatic switch which is screwed in the base of the header tank...should cost about 12 quid.
Good luck!
Toffer
I have a pre serpentine engine so no seperate tank. Im going run it up later with cap off until the thermostat opens. I have done this once allready but switched off engine as coolant level dropped rapidly as not enought fluid in system. Im sure this will get the air lock out, I will then quickly piut the lid on and allow to run for a few minutes. I have tried the bleed valve on the rad several times. would be a good idea to have one on the heater matrix also me thinks. Cheers for the help people. Much appreciated.
Gauge temperatures do not apply, ie 80 degrees = will not boil. as this is 80 degrees pressurised!
the cap off will mean the water SHOULD boil, as in "don't take the rad cap off when hot, it'll boil over!"
by the way, filling, topping up on a steep slope car nose in air, will help to move air in the system. heater will be low at the back. try jacking the car up. fortunately my drives on a slope anyway.
one more thing, try filling from the 90 degree pipe. many thermostats dont close totally as a safety thing. you can pour water through the 90 degree pipe straight into the block from here!
good luck
the cap off will mean the water SHOULD boil, as in "don't take the rad cap off when hot, it'll boil over!"
by the way, filling, topping up on a steep slope car nose in air, will help to move air in the system. heater will be low at the back. try jacking the car up. fortunately my drives on a slope anyway.
one more thing, try filling from the 90 degree pipe. many thermostats dont close totally as a safety thing. you can pour water through the 90 degree pipe straight into the block from here!
good luck
Right another update, ran engine with cap of again, until thermostat opened, kept cap of until water level started to rise then put it on and ran for a few minutes more. I now have heat from the heater, but the fans still cut in at 100 C. Im puzzled now, I will try this method again but Ill be amazed if its still an airlock. Dont know why im fretting really, It wont overheat, tonight he fans came on and it dosent budge abve 100. PS I know the gauges arent the most acurate things, just going on the readings I have. Just cant see why it should be about 8 degrees higher when nothing has changed other than the coolant and a bit of wire. Curious
You have checked that the old bit of wire didn't have a small resistor in it? If this has not been replaced, the guage will overread big time. Have you measured the temp using an external thermometer?
It could be that there is no air lock but just an inaccuarte guage. The heater issue could be a stuck or blocked valve as well.
I would check the gauge first.
It could be that there is no air lock but just an inaccuarte guage. The heater issue could be a stuck or blocked valve as well.
I would check the gauge first.
The wire was just wire, it was pretty well knackered so im wondering if it was causing a really high resistance itself and thus messing up the gauge readings. Of the top of your head what sort of temperature should fans cut in? The heater goes very hot or hot now, which is normal I believe. I have found another thing which probably isnt causing a problem, the connectors to the otter switch are covered in corrosion products from a slight mishap when I filled up the coolant tank, this may be causing a crap circuit and causing the fans to come on later. I have now put some new conectors on, but havent run the car up since
Gassing Station | Griffith | Top of Page | What's New | My Stuff