95 Cordoba Heater cold and engine overheating.

[fixitfast]

OK I got a 95 SEAT Cordoba automatic with a 1.8 8v adz motor.

It started during winter with the heater not working but everything else was ok.
Now that spring has come the car overheated and i found that one of the welch plugs had rusted out.

So i replaced the welch plugs.

Started the car and it still overheats with water leaking from the 2 plastic head flanges.

Replaced the 2 head flanges.

Still overheats. Removed the thermostat completely to see if it would run cold.

Still overheats and is doing it at the same rate as if the thermostat is in.

The fans only come on (half speed) if he a/c is on.

Replaced the thermo switch on the radiator.

Still overheats. This time i discover the switch doesnt come on because it doesnt get hot. The left side of the radiator is cold and right side is hot.

Flushed out the radiator - water moves freely through it so at this stage i thought must be the water pump.

Removed water pump - looks ok cant see any reason why it shouldnt work. The housing looks a little corroded but water path still looks clean.

I have flushed out the heater core and everything yet it still runs cold and engine still over heats.

Has anyone an idea what the problem could be?

The logic just doesnt work?

[jaimo]

Hi Dude,

I think the plastic fitting on the side of the cyl head (between # 3 & 4 spark plugs) might need a mod. Take it back off & check to see if the small plastic pipe fitting that goes to the coolant bottle has been drilled out, if not use a 1/8 drill bit to open up the hole. This will help the engine to bleed up.

Jaimo.

[Dub_Star_V6]

Heater core bypass

FIF,

You need to bypass the heater core altogether.

I had the same thing happen in (both) my Subarus and experienced the same symptoms: leaking endtanks, overflowing expansion bottle, radiator and pipes with one side cold with the other hot. And buggered if I knew what it was?

It was traced to the heather core and as a heater core replacement is a dash-out job, I whacked a solid brass bypass in and never, ever had another problem again.

I'm unsure how easy it will be in the VW (as changing the headlight bulbs in the Bora proved illogically difficult, yet is a 30sec job in my Liberty) but here's a guide of what it should resemble when you're done.

Sight the coolant flow hoses and clip them in two. Don't be worried about spilt coolant, as you can top that up when you're finished.

A bypass provided by the brass H-joint means it solves the overheating problem caused by the blockage of the heater core, and allows some passage of heat from the engine. Adding this will mean that the fluid won't go to the blockage rather, will go straight through the bypass and back where it should be (radiator).

[Golf Loon]

Thanks for that. I dont reckon its the heater tho mate.

[fixitfast]

Thanks for replies

Thanks for replies, I've decided to pull the whole engine down as it was due for a rebuild anyway having done 280k without ever being apart.

The whole thing has been an excuse to pull it apart.

Gonna change the heater core and radiator while i'm at it.

Learned the hardway to call the new parts people locally(imparts brisbane) before calling the wreckers.

Got stiffed $100 for a 2nd hand radiator (which i thought was a good deal at the time) as it looked good inside and out only to find the next day the a brand spanking new radiator only costs $100.00 - not very happy to say the least.

Thanks for the idea of bypassing the heater but doesnt bypassing the heater mean the pressure in the coolant chambers goes up potentially leading to premature head gasket failure?

[Golf Loon]

There shouldnt be that much pressure in the motor. Perhaps it has a blown head gasket.

I`d just get the head serviced and change the gasket and see how it goes. Bottom ends are tough on these cars.

[hugh.venables]

Engine overheating and no cabin heating.

Hi Fixitfast,
You seem to have a rather bizzarre problem. Your diagnosis will be helped by figuring out whether the two faults are independent or have a common cause.

Let's start with the heater since that was the first problem. Have you checked to see if water flows freely through the heater including all the hoses? It's a good idea to flush the heater in both directions from time to time anyway as the core gets sludged up a bit. If you can get good flow through the heater with the garden hose then you have to suspect lack of coolant flow in the engine.

I can't see how bypassing the heater could be useful under any circumstance, except if the heater core was leaking. The heater core is a heat exchanger just as the radiator is. They both have the same task of turning hot water into hot air. In this way they both help cool the engine. The heater flow circuit is a parallel one, not series, so being blocked or having the control valve turned off does not affect flow through the radiator. The rest of the cooling syatem will function satisfactorily with or without the heater.

You haven't said how you are measuring the overheating of the engine. But if the coolant in the engine is boiling at the same time as the radiator is partly cold, that also points to a lack of coolant flow through the engine. Lack of coolant flow through the engine can only be a blockage or faulty water pump.

You have already tried the thermostat for blockage and it's hard to imagine what could be inside the cooling passages that could be large enough to cause a blockage. Sometimes people use far too much silicone sealer when assembling an engine leading to big ugly lumps floating around but it would take a really extrordinary one of these to block coolant flow. There would be a horrible mess of silicone lumps around the outside of the engine for evidence.

I would be looking a bit harder at the water pump. It's unusual but not unknown for the impeller to come loose on the shaft. The shaft will turn but the impeller will not turn or turn slowly. Can you think of a way to disconnect the radiator hoses and extend them into a bucket or drum so you can watch the rate of circulation? If you can measure it, it should be close to 100 litres per minute per 1000 RPM.

I definitely wouldn't dismantle the engine. You will be frustrated when you don't find anything and the problem is still there. 280 km. for one of these is not a lot and if it's not using oil or rattling leave well enough alone. If you're bored and looking for a project, that's another matter.
Good luck,
Hugh.

[Jmac]

Hi mate the easiest way to test your water pump is to squeeze one of your Rad Hoses and give the engine a handfull and feel if the pump pulses or tries to swell the pipe. If yes the pump is ok if no then the pump is U/S
Cheers
Jmac