Issues with Daily Driver

[VIN18M]

Ok guys so I'm having a few issues with my shitbox daily which is actually an awesome, cheap and generally reliable little car.

A few months ago the water pump let got and it overheated so we replaced that and I was back on the road no problems. Then a couple of weeks later the temp climbed up but by babying the car I managed to get it to fall again and the car was fine for another couple of weeks. Then a couple of weeks later the temp went up again, this seemed to happen every two weeks for some strange reason but in between the car was absolutely fine.

Since then we've tried fixing this by replacing the thermostat, brand new radiator, new coolant, bled the system, run some chemiweld through the system to close up any tiny leaks...and still every couple of weeks she gets hot.

Two weeks ago we bled the system again and managed to get a few air pockets out and though great it'll be fine again, then last night (two weeks later again) it got hot on the way home from work. I was giving it quite a bit through traffic but not sure if this added to the problem. This morning I thought it'd be fine like it normally is and fifteen minutes into my drive to work it got hot again, I managed to get the temp down by turning the heater on, then twently minutes later decided to turn the heater off and see what happened and again the temps were fine for the remaining half hour of my drive in.

I'm absolutely stumped as to what the problem could be and am contemplating ripping the centre out of the thermostat and not running one to see if that keeps temps down. Obviously I can't use the heater trick during the middle of summer so I want to get this issue sorted before it gets too hot.

Any ideas?

 

[Gianni]

Is the thermo fan running when overheating?
Try wire fan to be on constantly when car is on
Is fluid level dropping and needing to be topped up or simply just over heating?

 

[VIN18M]

Fluid doesn't seem to be dropping at all, well no more than you'd expect from any car.

Thermo is working and A/C fan is also working.

I thought about wiring up the fan to be on constantly but it's a bit of a bandaid fix...

 

[Gianni]

Check wiring for the fan. Maybe on the off occasion something is coming loose so not turning the fan on or is the fan running when it's over heating?

 

[LWNSLW]

blocked radiator by the sounds of it. Did you ensure the system was completly flushed with fresh water prior to filling with coolant? mixing coolants is the quickest way to block up raditators and heater cores.

 

[EVOCPE]

He said he threw in a new radiator

 

[VIN18M]

System was completely flushed before the new radiator was fitted with fresh coolant.

Also fans seem to be working fine at all times.

It's a weird one, everyone I talk to just says the car is on crack...I'm starting to believe the same thing!

 

[bazeng]

Temp sensor problem?
Check the wiring.
Try a new sensor.
Check the resistance through the wire to the dash.
measure the temp with an external gauge/sensor to confirm that what you are seeing is actually happening.

Try the thermostat removal, see if it makes a difference.

 

[EVO-00X]

Avoid driving the car every other week lol.
Well I'll add that perhaps the heater core is clogged. When you have the heater on in the cabin it dispells the heat and keeps temps down. Then when you dont use the heater the heat isnt dispelled into the cabin and the water temp rises.
Try bypassing the heater core from the firewall for a few weeks to see if its solved. By bypassing I mean simply removing both heater hoses from the firewall and using a bit of pipe to join both hoses together.
If the problem is solved then youll need to change the heater core by removing the dash and heater box to get to it. A blocked heater core due to corrosion is very common.

 

[turbovr4]

My Zr4 did that a while ago. for me it was a dodgy plug that was beside the radiator and battery for the thermo fans. I had a bad pin on the plug so now and again the fans wouldn't come on but the next week it would be fine again. It is a 6 or 8 pin connector plug.

 

[4piknup]

as above,
bridge the fan temp switch so the fan runs whenever car is running. leave it like that and see how it goes.

 

[VIN18M]

I was going to run the fans permanently on, however they will no doubt wear very quickly and I've been advised by a friend who is a mechanic that they won't last longer than a month or so before they are screwed. This guy also pressure tested the engine for me over the weekend to check for a blown head gasket. He said it does have a slight leak somewhere, however it isn't bad enough to cause the car to overheat. Apparently after he ran the die through the engine it came out slightly yellow and didn't indicate a significant leak.

I've gone with the heater box as a possible issue and have bypassed it as suggested by EVO-00X, however now I'm a little concerned about getting stuck out on the road if it overheats again as I can't use the heater to bring the temp down. Ahh well, we'll see how it goes, if this doesn't work I really have no idea what to do.

 

[4piknup]

Stupid mechanic,
Bridge the fans, it won't kill them.
So what if it does, fans are cheaper than engines.

 

[Gianni]

Ive had my fan running constantly for a year. No problems

 

[4piknup]

I bridged the fans on the mrs friends car 8 years ago... it still goes, but it is a ford/Mazda Telstar/626.
I don't even remember why I bridged them, faulty radiator switch I think