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Discussion Starter #1
Hi everyone, bought a 1998 156 1.8 TS from a friend who had owned the car for nearly 3 years without a single problem, and within 5 days of me owning it the car has begun to start overheating.

The symptoms are as follows:

Temp reaching well over 110

No warm air in the cabin

Radiator feels cold when temp is about 100

Fan does kick in (2 stage), but if rad cold then making no difference to internal temp

The top rad hose is hot, bottom rad hose not heating up.


First thoughts were that the head gasket is knackered, but I took a good look at the oil and there is no emulsification at all, everything seems tip top in the engine.

Then I thought it may be the water pump, but if I was to leave the top off the expansion tank with the car running then after a while the water starts pumping out of the expansion tank, which would leave me to believe that the water pump is functioning.

The rad is in pretty good shape externally but could have corrsoion internally which may be stopping the water getting into the rad and cooling it down, but this would not be the problem as why would the cabin air still be cold.

I am fresh out of ideas, it could be the thermostat stuck closed, but from what I have read this is as rare as dodo poo, and if the the thermostat was stuck closed would the top rad hose have hot water in it?

Anyway if any of you fellas, or indeed ladies have an idea as to what the source of the problem could be then please let me know.
 

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Thermostat closed is a possible cause followed by over heating the engine, blowing out of the coolant resulting in loss of flow to the heater and blown head gasket possibly.

Once a wax stat overheats it melts the wax out and they used to fail closed. I don't know if this still applies but I recon your first port of call is the stat.

Jerry
 

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Discussion Starter #3 (Edited)
Jerry thanks for your reply. I have just ordered a new stat and it should be here monday, is there anything else that I need to know or be wary of?

And do all the symptoms point to the stat being buggered? Or could they be the symptoms possibly for something catastrophic?
 

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No warm air in the cabin ?
Cold Rad..?
Hot engine ?

Then the water isnt circulating through the system ...

3 main possibilitys ...

Waterpump impeller failed.
Thermostat stuck closed .
Collapsed pipe somewhere .. (Unlikely, but possible )

My money , if I had to bet would be on a faulty water pump.
 

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Other possibilities are an airlock, a completely frozen cooling ststem due to insufficient antifreeze, or simply low coolant level from a leak somewhere.

Thermostats very rarely fail closed on Alfa's. They are designed to fail open so that the engine doesn't overheat.
 

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Discussion Starter #6
thanks for your replies people.

I understand that it could be the water pump, but surely if the impellor is knackered then it would not be able to pump water out through the expansion tank, as I said before if I remove the cap from the expansion tank and run the engine after a little while the water just starts pumping our of the top of the expansion tank, this would indicate to me that the water pump is pumping water. Is that right?

I also understand that it is rare for a stat to get stuck closed, but given that there appears to be coolant pumping around, just not getting to where it is supposed to be going, I am inclined to change the stat first to eliminate that from the equation.

As to an airlock, I am sure that the 156 is self bleeding, so could that really be a possibility?
 

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They are designed to fail ...
+1 to that ...


It is unlikely to have an airlock as the coolant system is self bleeding (that's not to say that it wouldn't though ;)) ... my money is on the water pump, although there is evidence that it is pumping I doubt it's producing enough power to get round the rad (hence hot at top and cold at bottom) ... on other threads I've heard of "suddenly" heating up then the car just midly overheating from then on ... in those threads a change of rad fixed it (it was assumed that an internal part of the rad had broken and caused an temperary internal blockage ... perhaps yours is blocked???)
 

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Discussion Starter #8
+1 to that ...


It is unlikely to have an airlock as the coolant system is self bleeding (that's not to say that it wouldn't though ;)) ... my money is on the water pump, although there is evidence that it is pumping I doubt it's producing enough power to get round the rad (hence hot at top and cold at bottom) ... on other threads I've heard of "suddenly" heating up then the car just midly overheating from then on ... in those threads a change of rad fixed it (it was assumed that an internal part of the rad had broken and caused an temperary internal blockage ... perhaps yours is blocked???)

ok lets take that into consideration if the rad is blocked, is there a test that I can perform on the car to see if the rad is actually accepting liquid? when I said the top hose of the rad gets hot the rad itself never heats up so coolant is getting to where the stat is then it doesn't seem to pump into the rad from there(not circulating) and I understand the ramifications of a blocked rad, but would this cause the air in the cabin to go cold?

Also the water puming out of the expansion tank does it at quite a rate, which again would leave me to believe that the water pump is working as it should, it just seems that no coolant is allowed to circulate futher than the stat.
 

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surely if the stat has failed closed then the pipe going into the top of the rad wouldn't get hot as that is after the stat???? (unless of course you take into account heat conduction) ...
 

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Just had a quick look at eLearn about how the air heater works ... there seems to be a seperate rad used to heat the air coming in that is fed from the engine coolant ... I would have thought that the heater would work even if the stat was closed (as you get warm air even when the car is not yet up to temp) ... so that fact that you have no heat implies to me that the problem is not with your stat (or with your rad) ...
 

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Discussion Starter #11
thanks for your reply chris, right so that leaves possible airlock or water pump.

Could someone please tell me the correct way to free an airlock, or how to determine whether the car actually has one, just so I can rule that out of the equation aswell.
 

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The way an engine cooling system works as i understand it , is as follows .

Cold engine just started....
1. The thermostat is closed preventing the coolant from circulating through the main radiator and thus reducing the volume of liquid to heat ..this is designed to allow the engine get up to the proper working temp quickly and for your comfort . At this point, and at all times the waterpump is circulating is still working and is now just pumping it around the engine block and the heater matrix .

It is always connected to the top up /expansion tank , and so. if you remove the lid ..water will spew up due to expansion and the fact that it is a pressurised system.

2. as the liquid reaches a predetermined temp , the thermostat begins to open and warm coolant starts to circulate through the main rad.. and you can feel the warm air from the vents inside and the hoses on the main radaitor start to warm.
This is because the pump .. is now free to circulate the coolant all around the system.

3.at normal working temp ... good heat inside and a hot radiator .

4. Thermostat stuck closed ? ... heat inside and the rad hoses feel cool while the engine temp climbs very quickly to a dangerous level.

5. Thermostat stuck open ... engine takes ages to warm up and even at tickover may take a long time to get hot.

6. Waterpump impeller failure ... ?
Engine starts .. no effective waterpump , so even the coolant in the block isnt circulating , danger of hot spots . Pretty quickly it will boil in the block and may do so before the stat , even if good gets enough hot water to it by direct heat transfer to start to open... even when hot the interior heater will feel cold and probably wont produce enough warm air to defrost a windscreen properly. essentially at this point the engine is a kettle. the only force causing any type of circulation is the increasing pressure from the expansion of coolant and steam . Steam wont open a thermostat in time to prevent damage usuallly.

I may not be absolutely correct on all points and I ignored the effects of abnormal tempratures on the engine management systems.

Of all the above , the problem with the most potential for causing damage is a failed waterpump impeller . Been there done that ... tried two different thermostats , and the clue to look for is the evidence of the lack of circulation ..a cold interior heater .. so it might be a Thermostat stuck closed which im told is most unlikely , or the my best guess ... a failed waterpump impeller .

Apologies to all for the really long post .
 

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No warm air in the cabin ?
Cold Rad..?
Hot engine ?

Then the water isnt circulating through the system ...

3 main possibilitys ...

Waterpump impeller failed.
Thermostat stuck closed .
Collapsed pipe somewhere .. (Unlikely, but possible )

My money , if I had to bet would be on a faulty water pump.
Closed stat would not stop coolant flow to the heater. So not that.

Sounds like it is the water pump.

Hopefully he has actually checked the coolant level.


DON'T START THE CAR AT ALL UNTIL IT IS FIXED.
 

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Discussion Starter #14
Closed stat would not stop coolant flow to the heater. So not that.

Sounds like it is the water pump.

Hopefully he has actually checked the coolant level.


DON'T START THE CAR AT ALL UNTIL IT IS FIXED.

of course I have checked the coolant level, when a car starts getting warmer than usual surely that is the first place to start.

Bummed out about waterpump though, gonna be expensive I feel.

is it worth getting it done, the car has done a lot of motorway miles 130,000 but is in immaculate condition, just had 12 month mot put on it before problems, what sort of price do you think I am looking at to get the water pump done?
 

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of course I have checked the coolant level, when a car starts getting warmer than usual surely that is the first place to start.
Sorry for the silly question.
But someone else on here left two weeks between the car starting to overheat and actually opening the bonnet...

So it needed to be asked.
 

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is it worth getting it done, the car has done a lot of motorway miles 130,000 but is in immaculate condition, just had 12 month mot put on it before problems, what sort of price do you think I am looking at to get the water pump done?
It means a full cambelt job.

When were the belts last replaced?
They need doing every 3-years/36000miles.
 

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Sorry for the silly question.
But someone else on here left two weeks between the car starting to overheat and actually opening the bonnet...
... and then he was surprised to find that he needed a new engine :rolleyes:
 

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Discussion Starter #19
... and then he was surprised to find that he needed a new engine :rolleyes:
lol @ some people.

I have just got off the blower to jamie over at alfa workshop, and he is adamant that it will be the head gasket that has gone, or is going, he said that in the years he has been servicing alfas, and especially 156's he has only ever had to change the water pump on 4 156's, and that the best course of action is to get the car compression tested to see if it is blowing.

So seems like I have bought a car thats buggered. Cool. :mad:
 

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Lesson number 1 ... never buy a car off a friend (unless of course you want to make them an enemy ... ) ... good luck in getting it sorted though :thumbs:
 
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