Overheating 1983 Mondial

You might want to also post this in the Mondial section and maybe also try a search on overheating in the 308 section

I'm not too technical but your later ideas sound like they don't address whatever is causing the issue

 

1, is the air side of the radiator clear and can you feel the airflow when the fan is on- check fan is turning in the correct direction.
2. Have you flushed the cooling system with a radiator cleaner to ensure no sludge in the radiator core.

Once you have this done see how you go.

 

Eoglesby, have a read of this post: http://www.ferrarichat.com/forum/144720425-post7.html

It may help you with your troubleshooting.

40 degrees deltaT across your radiator is quite a bit - to me, it indicates the radiator is doing its job.

If you're truly getting that much temperature differential between the "top" and "bottom" tanks, I would be looking at the coolant circulation side to see if the water pump is doing its job.

p.s. IR "guns" can't really be depended upon to give accurate readings, because the surface reflectivity affects their accuracy. Try strapping some contact thermocouples on the pipes of the top & bottom tanks and see what you get.

 

this...

 

Putting special coolants in the system is not addressing the problem, better to clean the system first.

Another post on here mentions the water pump, do you know its history as it is a valid point. Check belt is not slipping

At lower powers driving around the system should cope, as it has since the car was built.

As an experiment you could remove the thermostat and see what happens to the temp, this would get you the max flow rate through the system, ie engine and rads

 

Two things regarding the Mondial, make sure all of the air is completely bled out. And, given that all is well, the car has a way of finding it's balance. In other words, it's common to spew out any excess coolant.

 

This problem sounds like lack of circulation.

In another post I they mention a lost rubber pad found in the piping. Tis pad sits on the thermostat element (not all types).
You might also check the water pump impeller. It can break.
Please check for air into the top of the radiator: remove the filler cap from the expansion tank and then open the air bleeder on top of the radiator to let air out.

 

Nope, it will not shut the engine internal circulation off and deviate the coolant into the radiator circuit at the relevant temperature.

You must use the thermostat or overheating is guaranteed.

 

Interesting as most cars you can run without a thermostat, thanks for the info

 

Looking at how the cooling system is laid out you need to make sure you bleed it at the upper rad hose (elbow 21). Undo clamp, pull if off slightly and fill until you get fluid out.

COOLING SYSTEM - Ricambi America, Inc.

 

Looking at the diagrams more carefully you need to open the vent on the thermostat cover and and the elbow at the rad to bleed the system when you're filling it. Also, it looks like this thermostat has an integral bypass shut off valve so if you've not put in the RIGHT thermostat you'll have a problem as well. Older Jaguars (I had several) were notorious for boiling over when a generic thermostat with no bypass shut off was used. I suspect this engine would boil over with no thermostat.

 

That is why it needs to be there for the car to cool.

Beware of aftermarket thermostats with a rubber seal on the valve.
It has come off on my car in the past blocking the coolant from reaching the radiator.
This leads to very fast overheating.

 

We need all the info not just the symptoms - what is the history of the motor and the cooling system. Did this problem develop gradually, or all at once? Has there been recent replacement of any component with unknown condition prior to this issue?
Radiators unless really plugged only cause overheating on warmer days, in combination with high power demand or very low air flow conditions. It doesn't sound like that is the issue.
If your system pressurises very quickly after cold or lukewarm startup, look for combustion gas pressurising the system or a circulation problem. A thermostat indeed needs to be correct so it will close off the radiator bypass when hot.

 

I was wondering about this, with the engine cold the thermostat is shut, preventing the water going to the radiator so it warms up. Once hot the thermostat gradually opens up allowing water to the radiator to cool it.
On the same thinking you would think that if the thermostat was removed then all the water would go through the radiator and you would struggle to get the engine up to temperature.

What am i missing here in regard to this bypass valve you mention ? Most engines will run cool with the thermostats out ?

 

Without the thermostat channeling the coolant one or the other way, the coolant will go both ways (that is the case during the open and close movement). Some of the hot liquid will go straight back into the engine, some may go through the radiator, but I suspect the resistance through the radiator and all the piping being much larger than through the engine. Much of the cooling capacity will be lost and the hot coolant going into the engine accelerates the heating effect.

 

Depending on the thermostat design, they will just run at full cooling capacity all the time. The thermostat just speeds up the warm-up period by recycling the heat already generated. It has no influence on how hot the engine runs once it's warmed up, since it's fully open.

 

I am sorry to hear about your trouble. I have the same car and can assure you that it's not normal, even in the tropical climate here in HK.

Is the pump pumping?

So the switch is good.

I think your coolant passage is blocked somewhere and pump pushes the fluid out of the least resistance - the cap. These were the symptoms when the rubber seal on an aftermarket thermostat became loose and blocked the water passage from the pump.

The original rad is perfectly capable of handling the engine provided it works and is in the loop.

No need. A regular coolant works perfectly fine.

Solve the problem, don't bypass it.

What for? The stock rad is perfectly fine with the heat load. My car NEVER overheated with the stock rad - unrestored from the looks of it.

That's a good idea. The car does run hotter (but not in idle) with only one. That is how I noticed one of the fans in my car failed. It didn't overheat though, just ran at the limit during a summer traffic jam.

Find the problem. The stock system works, trust me. Absolutely no need for fancy parts and additives. Your system has a big problem somewhere. Find it Good luck.

 

Here's what a bypass thermostat looks like

http://ww2.gates.com/common/images/australia/ezlit/BypassDiagrams.gif

The old American half-ton iron V8's used a tiny bypass line to help the engine warm up. They could run without a thermostat because of the low flow in the bypass. Modern (European) engines have a large bypass (probably to ensure even warm-up in a mostly aluminium engine). Water is lazy, when the thermostat opens but the bypass doesn't close most of the coolant just continues to flow through the large bypass and the engine slowly overheats. Also the cooling system is designed to run with a closed bypass.

 

Can someone post pictures where to 'bleed'....