New Member = so Hi everyone I have overheating problems: I have checked w/pupmp - hoses -pipes - block - thermostat ( removed ) = all ok replaced = new radiator - new coolant temp sensor - new mat sensor - new temp gauge sender the electric fan is not cutting in = did fault finding from the manual used a jumper on terminals A AND B of diagnostic link connector (ALDL) and fan runs fine so the fan circuit is satisfactory ( via the manual ). My question is = can I just jumper the diagnostic link connector permanently and just let the fan run all the time = will this do any damage ??? Thanks for any help. whispers
If you leave the diagnostic plug in then the engine will only run in diagnostic mode. Not good really. Put a thermostat in it, it needs one for best performance of the cooling system. Have you replaced the radiator cap? IF the system doesn't pressurize properly it will overheat. What do you mean by "checked w/pump"? Has the engine always run coolant? is the coolant full of rusty water? What makes you say it's overheating? BTW, welcome to the forum
THANKS FOR YOUR REPLY { immortality } ok will put new thermostat in = old one was stuck closed the motor runs red hot and boils all the time. replaced with new radiator but it has no cap = just a plastic cover pulled w/pump apart and pulled off all hoses to check they were clear and clean . have checked all fuses and relays. yes motor has all ways had coolant and all hoses are clean and clear did diagnostic check via manual and fan runs ok ( jumpered a-b on ALDL ) = manual says if it runs then the electrical system is ok. BUT fan still wont cut in ?? replaced new radiator - new coolant temp sensor - new mat sensor - new temp gauge sender
Without radiator cap and thermostat it will boil. thermostat controls temp of coolant in the engine and the radiator cap controls the pressure in the cooling system. With no pressure the coolant will boil at much lower temps than normal which is what your problem will be.
is possible you could have a blockage in a coolant line somewhere else too. your radiator cap will be on your plastic recovery tank. all you need to do is find someone that stocks it and get a new one. sometimes that cap goes brittle and cracks or the seal goes. try replacing it and see what happens.
Couldn't hurt doing a reverse flush on that radiator as well. Engine this old muck build up easily block an after market thermo two core? Possible reason been changed once before? Wouldn't use radiator flush either. Trident high flow thermostats still allow radiator to hold coolant for sufficient cooling time. That fails check if bubbles in overflow (after bleeding) in case, damage done from over heating?? After that ef/el ford thermos (wrecker) even new alloy radiator will stop your worries permanently. (Worst case head gasket, add bottle of 'seal it up/chemi-weld). Re-tighten those hose clamps too before pressurizes with new cap.
Hows the coolant temp sensor wiring/plugs? And did you replace the correct one, there's 2 on these, 1 for the dash temp gauge (single wire connection) and another for the computer (2 wire plug).
Thank you all for your advice, will do all your suggestions and see how i go Thanks again for the help
Sounds like you have the early type engine which has a surge tank, no cap on the radiator? If the cap on the surge tank is not holding pressure the coolant will boil at a lower temperature. The other thing you could check is to make sure the small diameter hoses from the surge tank are not blocked. One in particular goes to a metal pipe which goes to each side of the engine. This is mainly to allow air to bleed out. I remember my VN the metal pipe was blocked up with crud. Does the cooling fan come on when you turn the AC on?
hi wortus. no , fan does not cut in have so put in a manaul bypass on dash and run fan all the time, this has made a big difference with temp
Try changing the relay under the bonnet for the engine fan for the one for the highbeams. My old VN used to randomly cook the fan relay and I was always changing it once a year or so. If swapping the relays over gets the fan working, grab a bunch of spares from a pick a part wreckers and keep em in the glovebox.
Yea nothing worse than heating issues. Probably don't touch anything else but, what Stockies and Wortus advise hahaha. Problem with running the fans constantly is the draw on the electrics. If, you have a multi meter just check the alternator is still rating at idle, fans running and lights on. Otherwise you might not get to work on time after several days even idling her at home... Check out those youtube posts on Epsom salts rejuvenating collapsed battery cells and cranking amps too
Sounds like the electronics that controls the fan has a problem or the temp sensor and/or it's wiring has a problem. The temp sensor for the fans is just a resistor that changes in value as temperature changes, it is on the earth side of circuit so there will be a resistance across it which you should be able to measure at the other ends of the wires with them disconnected from where ever they plug in. As stockies said check your relays, also check there is power on the relays. If you take the fan relays out find the 2 connectors in the socket that connect to the relays normally open contacts (circuit is on the side of the relay). One of these should have 12 volts on it and the other goes to the fan. Bridge these 2 out and the fan should start if there is 12 volts present. if the fan starts it's the control circuit at fault, if it doesn't check for 12 volts and try to figure out why if it's not there. You could also rig up your own temperature controller for the fan off the gauge. Try online for a suitable circuit or go to jaycar. How have you wired up your manual bypass? If your going to stick with that best if you have used a relay and come straight off the battery for your 12volt power. Put the relay near the fan and wire your switch up through the ignition to the relay's coil this way it will stop the fan automatically when you switch the engine off.
