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Eviljohn

Mk2 breadvan overheating

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Eviljohn

Hi all. Hope you're well. As above, mk2 breadvan is overheating. Had new radiator in January, new water pump about 3 months ago, coolant flush and replace twice since then. Still overheating i have noticed the fan doesn't kick in. Fuses are fine. Is there anything else i can rule out fairly easily? Bookee in for another coolant change in a coupl weeks anyway as previous owner put sealer in the cooling system and i'm trying to get all that out.

Thanks for stopping by and any xp you can drop.

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steveo3002

you can bridge the wires at the fan plug...if it run then it confirm the fan and wiring are good , next step would be a fan switch

 

are both top and bottom hoses hot?

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caretakerplus

I am assuming that you have also changed the thermostat - using a good quality replacement?

Other things that can cause overheating include retarded ignition timing and weak mixture.

 

Regards

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Eviljohn

I will check out the hoses tomorrow. I'm assuming that would tell me whether the water pump is any good or not? 

I'll also do the bridging the wire thing. 

I haven't changed the thermostat yet. I do have one that i managed to track down from the FAQ section, that opens at a lower temperature. I have heard the fan kick in before but over the last week, since i has been running itself really hot, i have not heard it at all. 

I recently had it on a rolling road, just for proper setup of a weber carb. The timing is bang on, as is the mix. It's pretty much using what is going into the engine fuel wise. Far more economical since i did that. 

Thanks guys. Any more leads are welcome. 

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steveo3002

both hoses hot would say the thermostat is working 

 

lets see if the fan still works and go from there

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Eviljohn

Top and bottom hoses are both hot after a run. 

Bridged the wires at the thermo switch and the fan kicked in.

Does it matter which way round they are hooked up to the thermo switch or can either wire go on either terminal?

Thanks so far guys. 

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steveo3002

id guess that it wont matter , although surley its got a plug that only fits one way ?

 

ok so the fan runs that proves the motor is good and its got power to it , it would suggest the rad switch isnt working if the fan doesnt work when parked up

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caretakerplus

As said above, it does sound as if the switch might be dodgy, but do remember that, when driving on the open road, it is unlikely that the fan will cut in anyway. BUT if it fails to cut in after long(ish) periods of idling, or stop/start driving in heavy traffic AND the temperature gauge goes above normal, then the fan should definitely cut in.

 

Regards

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Eviljohn

As far as i can make out, normal running temp, ( for mine at least,) is the gauge at half way. Even with the gauge almost hitting the point where it overheats, still no fan kicking in. At all. 

I may have a spare one in the shed but according to the Haynes, i can't just whip the old one out and swap it. Have to drain the cooling system. 

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steveo3002

well yeah its sitting in coolant...you can whip it out and swap it if you have a little bit of top up 

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caretakerplus

A little trick that might work.

With the engine COLD, remove the coolant filler cap - wrap some polythene (shopping bag) around it to form a seal and put it back in place.

When you remove the old switch, some coolant loss is to be expected, but the polythene will help to form a partial vacuum, (hopefully) preventing a massive loss of coolant.

 

Fit the new switch and top up with a 50/50 coolant/water mix

 

Don't forget to remove the polythene.

 

Regards

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Eviljohn

I may have to try that. It's booked in for a flush in a week anyway but i can't see it lasting that long the way it's going.

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steveo3002

why are you paying for a flush , thats something you can do yourself , prob buy a new rad for less than a garage will charge

 

before the forsty nights get here , you can drain and refill with tap water , run it around and drain /refill untill its clear then redo with proper coolant

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dvderlm

I have even drained, filtered and reused coolant. Large plastic box for underbed storage with wheels, funnel and kitchen roll.

You get to see if it is rusty. Or someone used a load of radseal vegetable matter.

 

(Reverse flush system with hosepipe. Rad off and same for that upside down) 

 

It's harmful to wildlife/pets, so wash away any that does spill. 

Bleeding is easy, small white tap on heater airbox. Fill slowly, squeeze the tubes.

 

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Eviljohn

I'm happy to get stuck in and do it. Only thing holdin me back is that i'm heavy handed. Almost every time i've tried to fix something, i've ended up breaking something. That's the way it seems anyway. Not a massive issue when i had a spare breadvan on the drive that i could raid for parts, but since that one is gone now, this one is my main ride and my job is no longer in walking distance, i'm paying to get it done. If i break something, 9/10, it will be something i can't bodge or have to wait to get a new one. I also don't have as much spare time at this point as i used to. 

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Eviljohn

Found a thermo fan switch in my shed this morning so at 05:30 this morning, armed with a set of pipe pliers and a little plastic bag, i changed that over. Didn't lose very much coolant. I did catch what came out and put that to one side. 

Temp gauge didn't go over 1/4 way this morning but it was a lot cooler and raining. I'll check it this afternoon when it's warmer and see what happens then. 

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steveo3002

yeah id expect the fan to cut in on a hot day after its stood for 5 + mins

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caretakerplus

There you are you see - you CAN do it ! 🙂

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Eviljohn

Not gonna lie. I did do a little dance. I put a plastic bag over the filler cap and did it up a bit. Don't know if that helped but i didn't really lose much coolant/water. Topped it up, (took nearly 1l litre of water,) and all seems to be good. Don't know if it's the new switch, the top up or the weather is changing. Gauge didn't get up over 1/4 way on the way back this afternoon.

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dvderlm

To be absolutely sure you could buy or borrow an infrared laser thermometer with digital read out (under £15) and point it at top radiator hose. You should see around thermostat rated temperature.

And bottom hose will be 10 or more degrees cooler depending on ambient temp and airflow. Fan drops it even more when stationery / or queueing.

 

 

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Eviljohn

Genuinely helps that there are dudes like you dudes out there, imparting xp and encouraging goons like me to grab a spanner and get stuck in.

Thanks dudes. 🍺🍺

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Eviljohn

So this has reared it's ugly head again! Think the thermo switch i replaced was either crap or faulty. Either way, doesn't work. Is there anything that would cause a switch to fail? Overloading maybe from bad wires? Coolant issue? Worked fine till i took it for a long run up the motorway last night. This morning, nearly overheated on the way to work. 

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Eviljohn

Bridged the wires, fan kicks in straight away. Just checked coolant/water level and i had to put in about a litre of water. Only topped it up a couple weeks ago when i replaced the switch. I can't see any signs of a leak at this point but will put a box under it to see if i can spot any drips. Have new switch on the way.

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steveo3002

looks for whiteish green /blue powdery marks near any hoses /rad /water pump area , would indicate a leak

 

is the oil clear no mayo?

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courior

Sure the thermostat is working properly? If you suspect the fan switch, hard wire it temporarily and go for a drive, if on the same drive it's now not overheating you know it's the switch 🙂

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