131mirafiori forum

Hi can anyone help me

I have the 1600 twincam engine.Start the engine works the automatic choke the engine works fine the water temperature  rises at 85-90 Celcius the fan turn  on and also the water thermostat (between camshafts) works ok and the automatic choke "closes"and the engine works in 800 rpm the problem is that the water temperature rises up to 90 celcius and more and the water overheat.
I check the water in radiator if appears bubles ,also i check the oil if it mixed with water but everything is ok.
Does anybody knows what other parts i must check???
The previous owner inform me that the head gasket is new, can i have this problem from bad installation of headgasket???

Check the simple things first.

Is the coolant level correct when the engine is cold?

Is the radiator cap functioning correctly (if it does not hold pressure the engine can overheat)

Does the heater work (if not it could be air locked or the coolant is not flowing)

How have you verified that the thermostat is opening? Does the radiator get hot all over when the engine gets hot or are there cold spots.

If it is head gasket related the head could be warped or cracked but it is much cheaper to start with the simple things first.

do you also have thermostat outside the engine, on the lower radiator hose?
check if temperature of upper and lower radiator hose is aproximately the same when engine temp is around 90"c.
watch your fingers!!!!

I check the temperature to the radiator hoses all of them have the same temperature and the level in the radiator is ok.My car have the thermostat on the lower radiator hose.
Also I have check the heater and works fine.
Thanks for your answers,i will check the thermostat first.

if both radiator hoses are the same temp than thermostas should be ok. nex thing to check is water flow. blocked radiator or worn water pump.

If the heater works correctly then I would think you have flow. If the radiator is warm all over then it is unlikely to be blocked. Check the rad cap as a loss of pressure will cause overheating.

very questionable what is considered "heater works correctly". untill i flushed the system in my 131, replaced thetmostat i thought it was working just fine. after that i realised that it was working 50% capacity at best. when engine temp is around 90'c, and surrounding air is around 0'c, the air coming out of it on full blast should be too hot to keep on longer than 4-5 minutes.

step one - remove thermostat from the engine head. you don't need it anyway.
step two - bolt the housing back on and test the car. turn on the engine, let it run and add water in radiator untill full to the cap. when temp reaches around 90'c, thermostat should open and then you should need to add more water. if radiator fan turns on as it should, close radiator cap and add water to expansion tank.

if problem persists replace thermostat on lower radiator hose. repeat test procedure.

if boiling still, flush the system. let the engine cool down, turn heater valve on fully, remove heater hose from the top of engine head, stick garden hose on it, and turn on the water. pressure from water supply grid should be enough to flush everything.

test again. if problem repeats itself, change water pump.
on my ex 132d i had a case that engine was overheating without thermostat and with system flushed. turned out that rotor in the water pump was worn and was not pushing enough water.

Guys,

All said below is correct. Unfortunately there maybe so many reasons for overheating it is difficult to diagnose. Also typically there is not a single reason for overheating but a combination of several reasons. Diagnosis requires a chain of systematic steps to be followed.

Unless you follow all steps as described below in a systematic manner you will never have any reasonable certainty of what were the actual causes of your overheating  In general the system requires:

Because some of the steps require dis-assembly of some of the ancillaries I suggest the following sequence :

Potential problem : RADIATOR

If normal (not demineralized) water was used in a radiator (or coolant was not changed for a long time) the radiators build a residue and become ineffective. The residue I have seen removed from these channels shocked me. I did not know so much dirt can be in the engine and the engine still runs.)


Remedy : drain the system and flush !!! Make sure the flush fluid you use is suitable for aluminum heads !!! NOTE: turn the heater on when draining, flushing and filling. Take the radiator off ; use water hose to flush it.  Go to radiator shop that repair old style copper radiators. Have it checked - if required replace it with the same capacity radiator. Best solution: buy a new radiator from Yagmur and install it. Also check electric the fan switch located in the radiator. Make sure it is low temp rated : I use Wahler 77 /82

( see : http://www.eeuroparts.com/Main/PartDetail.aspx?id=8547572%2f82)

Again test it before installing and never buy ?no-name? low cost switches ? they work inconsistently and 80 % of them fail in first few days ! While at it check all the hoses ? including those that go to the heater and with any indication of aging wear replace them !!!  

Potential problem : WATER PUMP

Water pump circulates coolant in the engine. Properly working water pump is essential. Though I have not encountered a working water pump not to pump sufficient water it is really worth inspecting. Typical damage ? leaking and worn bearings. Also note it requires proper tension of the water pump belt. (Proper size pulleys ratio) should not be of concern unless these are not original. This ratio assures the water pump speed is sufficient (not too high though because this will damage water pump bearing).  

Remedy : inspect and replace if required      

Potential problem :  THERMOSTAT  

There are different temperature ratings of these thermostats. The higher the temperature you use your car in the lower the thermostat rating required.

Remedy : test and if required replace the thermostat. Note : there is plenty of cheap and low quality thermostats around. Before installing (or reinstalling)  take it out and out it on a pot of water and heat it up until boiling. Use temperature gauge (high scale thermometer) to measure ?begin to open? -lower number of the temp rating-  and ?fully open? temperature The higher number of the temp rating). Even if you get a new one get it from a reliable source and test it anyway.

Potential problem :  COOLANT

Coolant serves few purposes : it cools the engine but it also prevents boiling and internal damage (residue buildup) in the water channels. The system is pressurized  to reduce the boiling point with the radiator cap serving as a safety valve. To serve these purposes the coolant should be of proper quality (I always use Fiat Paraflu) in proper concentration and always diluted with demineralized water only !

Remedy : once you have removed the radiator and the water pump you must have drained the system. Flushing it before removal the radiator and water pump allows you to just refill it coolant. Note : Use always quality coolant concentrate ( I recommend Fiat Paraflu). Use demineralized water only to dilute the concentrate following coolant manufacturer?s instructions. In addition check concentration of the coolant with a simple tester (readily available in auto stores)

Note filling the water system in Fiat DOHC engines is tricky:  never fill through the radiator top but always through the water pump intake (!!!!) between water pump and thermostat. (always drain and fill on a cold engine and with heater on !!!) After filling reconnect the hose from the thermostat housing to the thermostat outlet again and run the system without the radiator cap for a while ? note air bubbles coming out. Top the radiator to make sure it is filled to the neck. When the fluid starts expanding and starts overflowing put the radiator cap securely.  ( Note: the long neck radiators require special - taller- caps.  

Final test : run the engine , the temperature of the hoses , running temperature , any signs of excessive temperature.  

If the problem persists the problem is in the engine and it is serious !!! Several   possible causes (typically at the same time: high engine friction and residue not removed (removable) from water channels by flushing, probably residue buildup in oil channels. You need to rebuild the engine of a new engine.

If however the problem is solved to the point that engine does not overheat, just runs hot ( 100-110 deg. C) you have an option to :

- use oil with high temperature resistance ( i.e. Castrol Edge sport 20w-60; Motul LeMans 20w-60 or Selenia racing SAE 10W-60) ,
- use slightly higher concentration of coolant in the system,
- use a lower temperature thermostat
- use a lower temp thermo fan switch,
- install  twin fans / or a modern fan with much greater airflow capacity

Note these are all measures do not address the real root of the problem, just its symptoms. If the engine is not too damaged it may work even for few seasons.

Overheating was never the problem I encountered on my engines but running hot was almost always the problem with all my DOHC engines (except the one build by Guy Croft . It runs tops 85 deg C.) The 124 spider (2.0 fuel injected) tends to run a bit hot (especially in high traffic during the summer).  In all cars I have a manual fan switch and always watch coolant temp closely.

Hope the above diagnosis list and tips are helpful.

Miro        


        

seems you have more time to type than me.

worn water pump, not leaking, was in the engine that had 400.000km on the clock. pump bearings were replaced at around 270.000kms, not the whole pump.

alu/plastic radiator from lada (after 1999) and argenta is pretty much the same as on 131, mounting brackets need 5 min modification, water hoses are in same plases, and is a big improvement to original copper ones.

water in cooling system is ok for testing purposes, fiat DOHC must run on paraflu (blue coolant) or G12 (pink coolant)

yes, while refilling the system, air pockets do sometimes occur and can be a pain in the ass. usually around thermostat

first thing the radiator electrical thermostat that switchs on the fan, that should be the cause. Change it with a new one certified for switching on the fan at 85? celsius and should be ok.

Well I am in an off season now and have some the time for the forum ....


M