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Technical Ever since I've changed the thermostat...

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Technical Ever since I've changed the thermostat...

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nunesaf

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Hi guys

First of all, thank you for your help. I am quite irritated at this point after days of unsuccessful attempts to bleed my Uno cooling system.

It all started when I replaced the thermostat and washed the cooling system with a hose. I've put the cooling not too carefully but first bleed with the plug on the top of the expansion tank. I also had the hoses going to the heater open as I have no bleed screw there. Once no more air was coming out that plug, I've connected the hoses and let the system work, and work fan on a few times. Squeezed all the pipes I could see, everything with the expansion tank cap off. I even went for a 5 miles run with the cap off to let all the air come out.

The net result is I still have air in the system. On higher revs, I can hear the air bubbles in the heater matrix. And yes I did all that with the heater on.

Practical consequences, the fan comes on at 100 degrees only...

Have I missed anything? Am I doing anything wrong?

I am fully lost with no more ideas and I would be truly humanly grateful if someone could give me any guidance on how to get rid of the air in the system.


Thanks,
Afonso
 
Wierd, I've always found Unos and Pandas easy to bleed. You have done a lot of the right things to get rid of air. Something you need to check is that air is not being introduced by a head gasket failure. With the car idling, do you see bubbles in the expansion tank?
 
Hi,
Thanks for the reply :). With the car iddling there are no bubbles at all. I have no symptoms of a head gasket failure expect... air in the system. I've therefore decided to change it as at least this variable is eliminated. I know it sounds radical but I cannot stand see the temperature gauge in the 100 degrees and the fan off... Yup, I am pretty much desperate :)
 
I agree with the above poster, you have done the normal things. A question though, does the heater work well. Is it possible it is partially blocked. Check by disconnecting the hoses, and forcing some water through the heater with a garden hose. If that is clear, then use the same garden hose and loosen the outlet from the heater core enough to allow the water to escape, and put the hose in the top of the radiator, use a rag to seal the hose in the top of the radiator and force some water through the system, maybe you will expel some air.

Having said all this, I have this issue in one of my cars, but I think it is because I use radiator clean, and I didn't flush it all out properly before I put coolant in, so it was left with bubbles. From time to time I "bleed it again, but I do have the bleeder up by the heater.

Gotta love these little cars (y)
 
rawill said:
I agree with the above poster, you have done the normal things. A question though, does the heater work well. Is it possible it is partially blocked. Check by disconnecting the hoses, and forcing some water through the heater with a garden hose. If that is clear, then use the same garden hose and loosen the outlet from the heater core enough to allow the water to escape, and put the hose in the top of the radiator, use a rag to seal the hose in the top of the radiator and force some water through the system, maybe you will expel some air.

Having said all this, I have this issue in one of my cars, but I think it is because I use radiator clean, and I didn't flush it all out properly before I put coolant in, so it was left with bubbles. From time to time I "bleed it again, but I do have the bleeder up by the heater.

Gotta love these little cars (y)
Click to expand...

Good hints and questions - thanks, I truly appreciate it.

The heater works reasonably well. To my memory (I had a Uno when I was in Uni :)), it should produce more heat than it does, but still at acceptable levels.

I've also thought that the previous owner could have put radweld or any similar product and could have blocked the system somewhere. But the flow is good, no traces at all in the system and I've flushed the system too (in the reverse direction too).

I think I'll have another closer look to see if I see any bubbles in the expansion tank, even if tinny (as for sure there are no big ones).
 
Sounds odd that there are no bleeds at the back :confused: it's not like the turbo where the headder tank is the highest point so will need bellding. I looked at your other pics to try and work out whats going on back there, but it's out of view (n) get a pic up of the hoses at the back.

You wonder if it's been changed and not done right. On my 1.0ie I seem to recall a long pipe about 12mm that also split off from the T where the bleed screw is and wend down the drivers side wing round to the front, but can't remember where it went.
 
Last edited:
Louie Bee said:
Sounds odd that there are no bleeds at the back :confused: it's not like the turbo where the headder tank is the highest point so will need bellding. I looked at your other pics to try and work out whats going on back there, but it's out of view (n) get a pic up of the hoses at the back.

You wonder if it's been changed and not done right. On my 1.0ie I seem to recall a long pipe about 12mm that also split off from the T where the bleed screw is and wend down the drivers side wing round to the front, but can't remember where it went.
Click to expand...

Hi Louie

Indeed AlexGS says in one of his guides the possibility of not having this bleed plug. The hoses are all original so it must be a built configuration management issue (some cars have, some don't).

I'll take more pictures next week as I am currently overseas on duty (y).

Thanks,
Afonso
 
I am also overseas, for work... Know the feeling, lots of things I want to be doing in my garage...

I think it might be best to remove and check the heater valve - it's probably jammed or not fully opening? This will unfortunately mean draining the system again. Take care to reconnect the one remaining heater hose only once coolant has filled the heater. Good luck and let us know how you get on :)

-Alex
 
Thanks guys for all your support :). After having thought long and hard about it, I've decided to replace the head gasket. When I got to the car, realised the engine was suspiciously wet nearby the coolant temperature sensor and the water pump...
And I am glad I did it, as this is what I've found out:
26112011135.jpg

By nunesaf at 2011-11-28

26112011134.jpg

By nunesaf at 2011-11-28

So... it was the head gasket I think but I haven't finished the car just yet.

I'll keep you posted (y)
 
Hi Alex

Thanks for the words of encouragement. Yes the car is back on the road and took it today to the office. When arriving to the office I had only 3rd and 4th gear. Managed to park the car and realised what the problem was... anyhow during lunch time put a wire around it and managed to get home safe :).

The engine is smooth and now idles perfectly, before was idling too high. Modesty a part, I did this job really well and clean.

Happy days :) and thanks again
 
Apologies for turning this into a "yet another thread about bleeding the cooling system", but several weeks have passed and I still have this problem.

I run out of options, hence desperate to fix this. Mind you, I have no bleed screw at the back of the engine.

The symptom is: car gets to 100 degrees and fan kicks in.

I've changed the headgasket, changed the temperature sensor, changed the thermostat (again!), flushed the system (4 times now), removed the heater valve (to my happyness it is perfect) to no avail.

I've managed to have it working well only once, unfortunately I had water in the system, so I had to get rid of it and put coolant. Then back to square zero.

I have been trying several variants with the rear hose that goes into the heater matrix.

The first fundamental problem I have is with the radiator bleed screw. With the system empty, I poor the coolant really slowly with this bleed off. Once the coolant starts getting out, I put the bleed screw on... and then nothing happens. The coolant stays at the MAX level. Ok, I disconnect the rear hose (either before or after, doesn't make any difference) and again nothing happens.

Right... time to start the engine. With the engine running, the first thing that happens is the coolant overflows until it comes somewhere in between the MIN and MAX. So what's the point of the bleed screw then? Anyhow, moving on. With the temperature rising, the air expands and even more coolant comes out until it stabilizes. I increase the revs several times, can hear the air passing through the heater matrix (so it finds nice and warm places in the engine and stays there...). In this process, as I said, I tried several combinations of gently opening the rear hose to let air come out, etc.

So what's the deal? What am I doing wrong?

Thanks to those that might be able to help me as... I am on the verge of giving up. And if that happens, it is the end of this Uno and the end of my will to have a project car.
 
Don't give up.
The fact that you have no bleed screw by the bulkhead is problematic.
However, you need to get the engine warm, have the cap off, loosen the pipe where the bleed screw should be, see if any bubbles come out. If not, then try forcing some water into the system at the filler cap (radiator cap)

you can do this by putting the garden hose in there, and "sealing" it with a cloth. That should force the water in (yes it will dilute it a bit) and out the loosened hose clamp.

That is what I did, and with one car I needed to "bleed it" a few times to get rid of the gurgle. One car still has it a bit.

The fan will not come on till near 100 so that is not too much of an issue.
 
That head gasket looks fine to me :D

Have you tried pressurising the system with one of the heater matrix hoses removed - similer to how rawill describes but with a cold system.

All you need to do is remove a hose, apply pressure to the air in the radiator (under the rad cap). this should push the air out of the matrix and remove the air lock. - have the heater set to hot and either give the place the rad cap fits the kiss of life :slayer: or cut a ball up and use a foot pump (there is something about this in my cold leak test guide :D https://www.fiatforum.com/uno-guides/62853-detecting-miniscule-coolant-leaks-cold-uno.html

Kiss of life is quicker but don't suck :yum:

you may need to block off the other open end so water is forced the harder rout. When water comes out the heater matrix side, reconect and cross your fingers...
 
Last edited:
Hi

Thanks rawill and louie, some valuable suggestions for me to try!

Louie you must be a kind of a mind reader, I've tried once giving the kiss of life but that was really awful... (I feel tempted to leave here a joke, but it could be distasteful as it would be a sort of sexual innuendo... so I guess I have to laugh alone :)).

I know what, I would love to find Uno enthusiasts here in Surrey so one could put two heads and four hands together. But this place is so posh, all you can find is Alfa Romeo aficionados. Opps... I am also an Alfa Romeo owner :) .

Once I fix this, time to move on to the next bits. The engine is doing really well but still have some idle issues (too high at normal working temperature).

I'll keep you posted!

Thanks again
 
hello all,

I'm not strictly an uno man as i have an x1/9 but i had this problem with my car.

I found that the bearing was just starting to collapse on my water pump and was letting air through the seal, but there was no water getting out.

also i checked the thermostat on my car and it wasn't opening at the correct temp (it should have been 82deg but the one in was 89deg)
 
littlephil said:
hello all,

I'm not strictly an uno man as i have an x1/9 but i had this problem with my car.

I found that the bearing was just starting to collapse on my water pump and was letting air through the seal, but there was no water getting out.

also i checked the thermostat on my car and it wasn't opening at the correct temp (it should have been 82deg but the one in was 89deg)
Click to expand...

Hi there

Thanks for the idea. The water pump is brand new so I am excluding that. Indeed I have the 87 degrees thermostat hence the temperature getting to 100 degrees which is the normal working temperature of the 999 FIRE. The Uno S has a temperature gauge ranging from 60 to 140 degrees, hence 100 right in the middle. Don't understand why the base version goes from 50 to 130 - 90 degrees in the middle only :confused:! Don't know if I have the wrong thermostat... any thought would be appreciated.

I think I've found out the problem. The hose connecting to the thermostat was leaking (with coolant dropping right onto the flywheel causing the clutch to judger a bit!), and air was constantly entering into the system!!!
I didn't have any opportunity to test yet but will let you know as soon as I do :worship:
 
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