General Bravo overheating

[irishpete]

Hi folks,

My recently aquired fiat bravo is overheating. i found the radiator to be leaking so replaced, but car is still overheating. bled the system. the return hose from the heater matrix is not heating up and the heater is not getting warm. the return pipe to the radiator is getting hot, so probably not faulty thermostat or water pump. anyone any ideas? Please?

 

[Deckchair5]

Your heater matrix system is recieving no coolant flow so it might be air or it may be a blocked matrix.

BLEEDING
For air, drain the lot out again and refill slowly carrying out the correct bleeding procedure

BLOCKED HEATER MATRIX
Try disconnecting both the heater hoses and attaching a household hose pipe to one of the hoses and blast water through it in the opposite direction to normal flow. That will often clear built up sediment away. If done correctly the inlet heater hose should be too hot to hold on to and the return not quite so hot but defingtiely neither being cold

RADIATOR FLOW
When the engine is fully warmed up and the heater switched off then you should feel the radiator top hose get hot showing the thermostat is open and excess hot water is being pumped around the radiator like it should

RADIATOR FAN
Make sure this works as it should. It should start long before your eng temp gauge goes towards the red band

A blocked heater circuit won't necessarily cause engine overheat on its own but it won't help

 

[JoskeJTD]

Make sure the heater temperature dial is set to max heat/temp. This will open the heater matrix to the engine coolant.

 

[irishpete]

thanks for responses guys. just out trying to bleed system again. Was feeling the pipework again. The top radiator return hose is geting hot but the bottom one is not. should the bottom hose not get hot as the water in the radiator heats up and sends water around again?

 

[Deckchair5]

Radiator bottom hose should be the coolest of the lot as that is after the radiator has done it's work but it wont be doing much cooling when the car is stationary with no air flow if the fan isn't going (watch your fingers as the fan could come on at any time) so it should be pretty warm/hot too until the rad fan kicks in

Is there a bleed valve on your radiator?

How are you heater inlet/outlet pipe temps?

Do you hear gurgling noises at the dashboard of air present?

Did you follow the correct procedure for bleeding? Not difficult but you need to follow it

 

[irishpete]

Thanks for reply Deckchair.
The bottom pipe does heat up a little after a time running, but the return from the heater matrix doesn't even get warm and no heat from heater although not quite cold air. Have followed the bleed procedures. removed the thermostat to confirm it's working and it is. Also fed a garden hose to the return side of the heater matrix and the water came through the engine block, so matrix not blocked.
The fan is not working properly. needs a bit of a push to get going, then doesn't seem to go at ful tilt. definately doesn't help bring the heat back down. seem to have a combination of faults. The car has been lying up for a few months and took a chance when buying it cheap...
When car is turned back off after running to hot, I car hear a little gurgling from the radiator at the plastic side.
Checked the oil filler cap and no white substance. also no smoke form cooling system when bleeding.
But maybe it's head gasket at this stage.....

 

[Deckchair5]

If you've pumped water through the heater matrix and there are no restrictions then it sounds like you have a flow problem ie water pump as coolant goes directly to the heater without touching the thermostat. Sometimes the vanes on the pump corrode, wear away or even fall off. That'll certainly cause engine overheat. I would slowly and carefully, with a rag over the top, release the coolant refill cap and see if you are getting a good normal pressure build up in your coolant system

Have to get that fan sorted, should be a few around on eBay but check out the earth there just to make sure its getting good supply AND earth. Put battery voltage directly in it and see if it flies (watch your fingers!). Don't want an inoperative fan to wreck your engine the first traffic queue you meet

You can test a thermostat without removing it just by feeling the pipe from the thermostat housing to the radiator top hose connection. Feel a sudden rush of heat through the pipe a few minutes after starting from cold and you know the thermostat has just opened

 

[irishpete]

Hi again deckchair!
Thanks for continuing info on this. Fan definately shot. Will get one today or tomorrow, but this not the main problem, as still not getting heat through the matrix. Thermostat is definately opening, so only left with either pump or head gasket as problem. What's the weigh up on cost per job, and is there any way to know which is the cause of the problem? Would hate to pay for one job, for it only to be the other. Is the pump a DIY job?

So is the best way to check if the pump is working, to take cap off gently after car has got to temp and see pressure behind?

thanks,

Pete.

 

[Deckchair5]

Not quite certain how you checked the heater matrix flow, ideally you simply want to pump water in the heater return pipe and see the flow out of the heater hose inlet

But if you're absolutely sure there's no restrictions through the heater matrix then it can only be air in the system, a blocked pipe or a duff water pump.
What engine is it? Bravos aren't usually difficult to bleed although each has different bleed points so make sure you've got them all.

You don't seem to be having symptoms of a head gasket- losing water- steam out exhaust- misfiring- coolant reservoir boiling over-sudden overheat

Simply checking for pressure at the coolant reservoir cap tells you the pump is producing pressure but doesn't say a lot about the flow

Water pump is quite do able but involves cambelt and tensioner renew and cam timing setting up

 

[irishpete]

Deckchair,

Model is 99 bravo 1.2SX.
Bleed screw on L.H.S of rad and one on input to heater matrix and ouput. While had rad disconnected for replacement, disconnected the return pipe from matrix and connected to garden hose. Flow of water then came out of engine head as didn't disconnect inlet heater pipe. Assume this is as good a test......Have used water in coolant system for test purposes as opposed to coolant. Does this matter?

Is there a way of being sure the water pump is faulty or is it just a case of changing it and seeing. It would seem unusual to me to get a leaking radiator, faulty fan and now possibly faulty pump, as none would seem to be the cause of the other?
Haven't interferred with cambelt before, so think will leave to experts.

thanks

 

[irishpete]

Hi,

Fitted new rad fan this evening. When temp got just above halfway fan kicked in and maintained temp between halfway and next notch for about 20mins(Thought I'd sorted overheating), then it started to climb and climb till I turned off just before red. Heater obviously still wasn't working during this.
I only have cooling system filled with water, while I'm trying to sort problems so don't know if this is a cause as i know it boils at lower temp than coolant. Also was getting very slight leak from cap when temp went above halfway before fan kicked in.
Haven't taken this car for a drive yet as am afraid will overheat when have it out

By the way the 2nd hand rad I got was from a 1.4 so has the electrical connector down near the bottom of rad for a wiring loom that seems to be part of fan assembly on this model. what's this do?

Thanks,

Peter.
99 Bravo 1.2SX

 

[Deckchair5]

Sure sounds like a water pump failure.

I only have cooling system filled with water, while I'm trying to sort problems so don't know if this is a cause as i know it boils at lower temp than coolant.
No that won't make any difference, best to have the system fully functioning and check for leaks before putting in antifreeze

While had rad disconnected for replacement, disconnected the return pipe from matrix and connected to garden hose. Flow of water then came out of engine head as didn't disconnect inlet heater pipe. Assume this is as good a test
Sure, that should be fine

As the coolant flow route goes immediately to the heater matrix (or should do) then there's no flow there so with no blockages and no air then that only leaves water pump. The water pump fins are prone to corroding away especially if the car has been left for a while empty of coolant

With a cold engine, see if water flow to the inlet of the heater is occuring by disconnecting the heater inlet hose

By the way the 2nd hand rad I got was from a 1.4 so has the electrical connector down near the bottom of rad for a wiring loom that seems to be part of fan assembly on this model. what's this do?
Can't really tell you without seeing it. Each Bravo engine seems to have a completely different set up for rad fan operation. With the 1.2 it gets the engine temp purely from the engine temp sensor ( ie no other rad fan coolant temp sensor) and the ecu works out which speed to run fan at lo or hi speed

 

[irishpete]

Hi Deckchair,

Flushed the system out this evening, then re filled and bled. Heater worked for a couple of minutes, then went cool again. re - bled, heater got luke warm. Thought I was probably getting air in system some how. decided to chance taking car for run. She seemed to lack power momentarily as hitting accelerator through each gear. a bit like a misfire. As I was reversing back into driveway after run out noticed a little bit of white smoke from the exhaust, so assume that confirms worst fears and it is head gasket....

Peter.

 

[Deckchair5]

Whether you have head gasket gone or not your heater should get hot regardless and a head gasket wont affect that until the coolant flow stops. If you havent got coolant flowing freely around your engine then all manner of hot spots will occur which will cause misfires

Did you pull off a heater hose with engine running and see if you have good flow there?

 

[irishpete]

Seemed to have flow when took pipe off but wasn't convinced of the pressure behind it. Would the small amount of white smoke coming from the exhaust not imply head gasket?

Peter.

 

[irishpete]

A mechanic is going to bring home a pressure test kit next Tuesday to test the car out, so will let you know how I fare out, but reckon it's going to be bad news and be the head gasket.....

 

[Deckchair5]

If you say it often enough then it probably will be

But with no heat from the heater then you have a poor flow, blockage or air bleeding problem

Wiht head gasket gone things tend to get very hot rather than cold, pipes bursting, coolant reservoir overflowing, loss of water, sudden cold then bursting hot at the heater, that sort of thing