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blue flare
Starting in the driveway
4 Posts
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 Posted - 12 Mar 2010 : 1:19:48 PM
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Hi everyone, I am new to forum.
I have a 1990 vn (toyota lexan) that has the plastic resivour as the radiator cap.
The problem I have is the thermostat was playing up and caused this plastic bottle to expand and snap off the bottom hose. This water bottle has been replaced, as well as the thermostat.
The problem now is that the car continually overheats.
Driving along normally it is fine but if you are caught in traffic and not moving or barely moving the temperature goes right up and depending on the weather sometimes quite fast to the point where I need to pull over and let it cool down.
Does anyone have any idea what may be causing it as I have travelled long distances and not had any problem with the temperature rising as long as the car was moving causing the air to circulate.
I have not been using the aircon as with this problem it worries me to do so as I don't want to add to the problem.
thanks
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Mr Persistant
P Plater
72 Posts
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Posted - 12 Mar 2010 : 10:39:07 PM
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| Sounds like the fan's not coming on. Check for that if you can get it hot at home where you can easily have the bonnet open to visually check. If it doesn't, see if it will come on when you turn the air conditioning on. It should. |
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blue flare
Starting in the driveway
4 Posts
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Posted - 13 Mar 2010 : 6:09:51 PM
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Thanks Mr Persistant, will look at that but since posting it hasn't happened due to coolness and rain.
Will check that out as I know fan is on when I start it.
Did however find a fuse for the engine/fan in the fuse box that is next to the radiator water bottle and had trouble pulling it out to check, when I did however the fuse looks a little sus as the silver contact on the bottom on one side has a black hard melted substance on it (may mean it has blow) as the metal bumpy bit in the plastic casing of the fuse looks fine.
Changed it anyhow just to be sure as it could have possibly got water in it when the water bottle hose exploded as the fuses box is right next to it.
Will keep an eye on it and if it does overheat again will see if the fan is comming on.
Thanks very much for your help and ideas. |
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Mechknight73
National Driver
1001 Posts
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Posted - 13 Mar 2010 : 11:19:41 PM
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Also, check to make sure that your radiator isn't clogged as well. If the water in it is brown, there's a good chance you have some rust particles in the radiator.
The heavier fuses (the ones that look more like a plastic block with a fuse wire across them) can sometimes have problems in the contacts underneath. As another "elimination process" Find the relay box, and find the relay that runs the fan, and swap it with something else in the relay box you can test easily e.g. horn. This is just so you can eliminate all the cheap to fix problems before paying $45-$50 an hour for an auto electrician. |
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Mechknight73
National Driver
1001 Posts
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Posted - 13 Mar 2010 : 11:20:43 PM
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| Also, there is a 25 amp blade fuse associated with the cooling fan. Traditional colour code of this is a clear or white body |
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blue flare
Starting in the driveway
4 Posts
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Posted - 20 Mar 2010 : 12:54:30 PM
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Thanks Mechknight73, the water bottles were brown so I cleaned them and flushed out the radiator last year, but will check them all again.
Will look into the fan relay as well, as I have changed the blue 30amp fuse for the fan which is probably the one you call a blade fuse as it had black residue on it and was hard getting out but it hasn't fixed the problem.
Thanks for the suggestions, and yes who wants to pay for an auto electrician only for them to look at you funny and possibly find the problem to be a tiny fuse you can check yourself????????
Will have to do some more investigating thanks |
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Mechknight73
National Driver
1001 Posts
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Posted - 20 Mar 2010 : 1:12:07 PM
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There is, of course, the most basic test of all; grab two lengths of 15 amp wire, crimp some blade terminals onto it, and run the fan directly off the battery. That will at least get rid of a possible "elephant in the room;" the most blindingly obvious reason why the fan might not work.
The circuit that runs the fan is marked by a dark green wire and an orange wire. At the back of the intake manifold is a sensor with two wires in these colours. It is the fan sensor, and is supposed to tell the system when to turn the fan on and off. It should cost you not more than $20 to buy (quote from a Holden dealer), but there's no guarantees this will fix the problem.
There is also something else you might have missed. On top of the thermostat housing (where the top radiator hose joins) in these, there is a bleed valve. Whenever you fill up the cooling system when it's very low, you have to open this valve to bleed the air out. Keep filling the radiator and tighten it down when the coolant starts to come out of the bleed valve. |
Edited by - Mechknight73 on 20 Mar 2010 1:16:08 PM |
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blue flare
Starting in the driveway
4 Posts
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Posted - 21 Mar 2010 : 12:39:09 PM
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thanks may have found the problem.
When the thermostat was replaced shortly after we had to take the fan housing out to get to one of the sensors, think it was the crank angle sensor?
Anyway when this was done the fan housing was unplugged.
And guess what when checking the fuses and relay noticed the thermo fan was unplugged derrrr, so plugged it in again and hopefully that is the problem. (the obvious as they say).
Just have to wait till the car has a good run again and heats up to know for sure.
thanks |
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Mechknight73
National Driver
1001 Posts
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Posted - 21 Mar 2010 : 1:31:46 PM
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| Lazy way to check it in the driveway; put a piece of cardboard in front of the radiator, and let it run until it gets to operating temperature. If it gets slightly above normal range without the fan kicking in, then you know there's more to it. The cardboard in front of the radiator is only there to speed up the process of warming it up. Once the test is complete, take it out and use it for something else, like catching any oil leaks or something |
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