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Eviljohn

Mk2 breadvan overheating

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steveo3002

aftermarket stats can be terrible , i'll only use genuine ones now

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Eviljohn

I won't have chance to check any of this until tomorrow. Will get back when i've done it. 

Thanks for the guidance folks. 

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caretakerplus

There really is  a lot of crap aftermarket stuff out there, it is possible that your new switch comes under that category.

 

The only ways that you can 'overload' that switch are (1) there is a short circuit on the wire between the switch and motor - in which case the fuse should have blown. (2) The motor is drawing too much current (which could happen if the motor was seized or there was an internal short)   This COULD also blow the fuse. Check that the fan is free to turn by hand, (do this when the engine is cool, otherwise, if the fan starts up, it can give your fingers a nasty bite.) -  and that it cuts in when you bridge out the switch.

 

Regards

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Eviljohn

I've checked the fuses but will check again to be sure, didn't see any issues with those. 

Bridged the wires to the fan and it starts up straight away. Seems pretty smooth. I may hit it with a little gt85 just to keep it sweet. 

Switch had been in my shed for a while and i have moved house at least once so could have been damaged. 

Have one arriving tomorrow that is supposedly a lucas one. I'll give that a swing and see how that gets on. I couldn't find one through ecp. Didn't try gsf. I don't tend to use vw heritage very much. Not a concious decision, they have been helpful in the past, just don't happen to use them. 

I do still need to get a new thermostat in there. 

I am also running what i think is a mk2 golf radiator. Could be a mk1. All i know for sure is it's top fill. No expansion tank. Courtesy of a previous owner. 

Thanks for replying.

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Eviljohn

Core plug leak! 

New thermo switch arrived this morning so i whipped the old switch out, fitted the new one. I had a drip tray underneath the car for coolant that came out. Didn't really get any come out. Thought that was odd but thought i may have just compensated with the plastic bag under the coolant cap. Went to top up and put in 1.5litres of water. That was even weirder. As i was looking for any signs of leaks on joins and hoses, saw rusty water p**sing out the engine, between the filter and alternator. Turns out there's a very small hole in the core plug that you can only see with a mirror and a torch. So reason for overheating is lack of coolant/water. 

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caretakerplus

Don't try and bodge the core plug, replace it - they rust through over time, so once they start to leak, they can only get worse.

 

Another 'don't' - don't try and drive the old core plug in - it needs to come out (I have found engine with core plugs that have been driven in rather than removed, presumably because it is easier), but old plugs in the cooling system can obviously restrict coolant flow.

 

Note how far the old plug is fitted into its bore.

 

Use a hammer and flat ended punch to turn the old plug  90° to its bore, avoiding damaging the the bore.

 

Clean up the bore with some fine emery cloth and coat the edges of the new plug with some jointing compound, use a socket spanner of slightly smaller diameter than the plug and a hammer to tap the plug into the recess TO THE SAME DEPTH AS THE OLD ONE.

 

Regards

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Eviljohn

I've literally used some high temp jb weld putty to plug it until i can at least get hold of another plug. I do still need the car to get to work for another couple days. If it seems to be worse, i'll try to sort somethin else out until i can get it done properly. I'm only a fan of bodging things that you can get away with. Like things that won't my engine go bang. 

Thanks again for xp.

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zob

Did you ever resolve this? I had the exact same problem with my radiator fan switch and it turned out to be a plug of radiator crud that dislodged during a coolant flush and blocked the small waterway to the switch sensor. So even though the switch and fan worked the plug of crud (more like a disk really) was preventing hot coolant from circulating around the switch sensor. Picked it out and everything runs fine.

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Eviljohn

Hey. 

I had the frost plug replaced. Another one blew when it fired up but that one was replaced too. I haven't had any issues since, but it hasn't really been hot until now. 

With the warm weather we've had lately, the temp gauge does creep up if she's either idling or just not going real fast. Putting the fans on does help a little bit, but i suspect there's an issue with the fans too as there is no real difference in air temperature whether i have it set to hot or cold air. 

I'm planning on another round of flushing and coolant replacement before summer really kicks in and also trying to fix the fan issue. 

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zob

Sounds like the coolant leak you were experiencing through the core plug was limiting the amount of coolant passing the temperature sensor in the radiator. Not sure on the differences (if any) between the Mk2 and Mk2f rad designs but it sounds like a good flush and making sure the whole system is fully bled for airlocks will sort it.

 

19 hours ago, Eviljohn said:

Putting the fans on does help a little bit, but i suspect there's an issue with the fans too as there is no real difference in air temperature whether i have it set to hot or cold air.

 

Did you bleed the hot air heater matrix when you pulled the temp sender out of the radiator? As the highest point in the system it may well be full of air.

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