Overheats in traffic

I have had my 1988 X for about 3 months, she is in fantastic condition, but in the last few weeks, she tends to get very hot in traffic. We are just coming into summer and I wonder if the ambient air temp might be the biggest problem.

Can anyone offer some advice on what I can check/ do to improve my cooling system.

make sure the cooling fan comes on
stat is functioning
flush the cooling system
perhaps consider a lower stat opening temp
also fitting a fan overide switch for traffic

Thanks this may seem dumb, but what do you mean by 'stat'?

sorry thermostat.see the cinq FAQ for a method of modding yours ot a different heat range if nothings a direct fit though kiwi spec may be lower opening anyway

Thank you!!!! Will read and then tinker.

The X1/9 in good working condition should have no trouble keeping cool.

The radiator is large, the cooling system holds a lot of water and you have a nice big fan on the radiator to assist in slow moving traffic.

If the car is overheating in traffic the most common cause is a faulty otterswitch (the one that operates the fan) or the fan itself is not operating at full capacity. Many people fit an override switch to manually control the fan but it should not be necessary. An electrical fault (most likely the earth) can stop the fan rotating at full speed.

A more subtle fault is the radiator itself. Even the youngest X1/9s are getting on for 20 years old now and most still have the original radiator. Couple this with generally low mileage (an average motor would have done 200,000 miles in this time) and you have a recipe for a dead radiator. The problem is the accumulation of debris in the radiator cores and the loss of radiator fins from the body. If the debris is allowed to sit for any length of time it starts to harden and form a hard solid that is practically impossible to remove. Backflushing the cooling system may dislodge some of it but the general solution is to just have the radiator recored (or replaced).

As the solids form you start to lose the cores from the radiator, from the outside it looks perfectly normal but internally the flow of coolant is blocked. You only have to lose a few cores to reach a point where cooling starts to become marginal - just as you have described!

Cheers Jimbro

My X has only travelled just over 80kms, but has obviously not been driven regularly. As you suggest, the radiator looks fine, is there an easy way to tell if it needs replacing? Or should I just take the bull by the horns and get a new one?

The tubes in an X19 radiator run horizontally, and over time debris tends to block the lower tubes. An easy way to tell if this is your problem is to feel the temp of the radiator with your hand .... if the lower tubes are blocked, then the lower portion of the radiator will be noticably cooler than the upper portion.

Another thing to check at the same time, would also be to ensure that the thermofan is actually switching on.... when your gauge gets to just above halfway, the engine will be 90degrees C, but the radiator will be quite a bit less (due to convection losses thru the rest of the system) so you will have to wait a while longer for the fan to turn on.

Thermo fan switches are available in different on/off temps ... X19 is 90/85 ish ... and when the bottom of the radiator is 90C the engine is usually showing closer to 100C

Another thing to check for is that the cooling system is correctly bled of air... there is a bleed point at the top left corner of the radiator accessed thru the front boot (8mm hex) be careful as they can strip and this then means radiator removal.

If the cooling system has a large bubble trapped, the boiling temp of the entire system is lessened, as there is no pressure over the system, you simply compressing the bubble a little when the system heats up, and the boiling point of the system is dropped quite dramatically.

No need to replace the radiator just because you can, they are quite expensive... if you can feel the lower portion is cold, a good radiator shop can sometimes "rod out" the core ... ie they remove the end tanks and physically push a rod thru the core tubes to dislodge any debris ... unfortunately this can also sometimes result in dislodging some corrosion and create a leak. Recoring them tends to be quite pricey, as the core is quite large and has a high number of fins per inch.

SteveC

There is a nice trick to bleeding the air out of the cars equipped with autochokes is to jack the rear of the car right up and use the water pipes to the choke as your bleed point. This is much, much easier to do that than try and use the bleed point on the radiator which is tricky to get at in the best of situations...

It also makes sure that the autochoke works properly too as these are very prone to airlocking.

Ummm... that's MY car I took that photo!

I used to drive in heavy traffic in the height of summer and not have problems. How hot do you mean, exactly? Normally the gauge would run about a third of the way up the scale (80 degrees), but in traffic I'd expect it to reach half way simply because there is no airflow with the car stationary, and then just past halfway the radiator fan starts (about 100 degrees). I believe this is normal behaviour. After all, the cooling system is pressurised, so the boiling point would be at least 120 degrees.

I flushed the cooling system less than a year ago, and the coolant that came out is pictured. I think this says all you need to know about the lack of debris in the system. (and note the wooden fence in the background for proof of location)

Filling the system, I had no problems bleeding out the air with the 8mm hex plug mentioned.

Next time you take 'Bertone' for a drive, perhaps just let sit and idle afterwards and report what temperature the gauge reaches/when the fan cuts in?

If I had to nominate a fault, I'd say the electric fan switch wires fallen off, relay loose in fuse tray, or something like that. Like Custard says, or like SteveC (Mr. Chechelle, another familiar name from XWeb, pity I can't remember the spelling...) I reckon a lower temp. fan switch would be the way to go if you are trying to keep the temperature gauge down. Another related question would be, does the temperature drop quickly when the fan does start?

Cheers!
-Alex

Hey Alex

Yes that is your car! I havent had this problem until 10 days ago. The fan seems to kick in at about 100, and doesnt seem to drop temp very quickly! I have had some gurgling noise after switching off the motor on one occasion, this was coming from the expansion tank.

The puzzling thing is, a did a Rotorua- Auckland day trip in her a few weeks ago (600kms) and oil pressure and temp were extremely constant, when in traffic it got sligthly hotter, but then sorted as soon as we got moving again.

So problem seems to be new, maybe she is a bit shocked from so much sudden use!!!!

Cheers David

PS Weber Spec are reconditioning the carb next week, will report on progress

Problem Solved!!!!!

Sometimes it is the simplest things that get overlooked, the radiator cap had perished and rubber seal was in bottom of expansion tank!!!!!!

Thanks to all for help and advice

doh! And the daft thing is that you are not the first one to suffer the same problem. Well done finding it!