Cooling modification

I think your plumbing approach is the problem.

You chose an easy way to plumb this rather than ensuring the turbo coolant goes directly to the radiator. I would recommend buying or making a transition for the coolant leaving the turbo to go around the engine to join the coolant going directly to the radiator. This could be placed inline into the rubber hose leading from the engine to the main hard cooling line.

This would ensure coolant coming from the turbo always bypasses the thermostat entirely and the resultant heat is properly dealt with in the radiator rather than mixing into the cooled water bringing the overall temperature up.

The thermostat never completely closes off the flow from the return line so there will always be flow through the turbo.

You could also consider a small coolant pump like many other turbo cars to pull coolant out of the cooled return flow to the turbo and back into the radiator hot side as an entirely separate system which shares the same supply.
The factory setup on the UT has the turbo's return coolant going to the overflow tank as part of its after run cool down action. The design brings water from below (the block), up to the turbo, then further up to the top of the tank. So there's a temperature differential between the turbo's inlet and outlet. And a elevation difference from low to high. That creates a cycling of water after the engine is shut down, until the temps neutralize (i.e. turbo cools off). Rerouting the turbo coolant elsewhere will negate that effect.

However utilizing a auxiliary pump as you suggest would be even better, for turbo cooling both during operation and during after run.
 
@Mxgrds I hope your oil temp is 90 deg. C not 190 C when cruising for long time at high speed. I share your theory about the flow and that's why I am thinking about having the X1/9 thermostat housing instead of the UT housing if nothing else helps. BUT the radiator fan is starting at high temp so that must mean that coolant is flowing correctly?
I have not much to add to the discussion until I've testet the car in hot weather with the new aluminium radiator I am afraid. My problems differs a little bit from yours. In ambient temp around 15-20 deg. C I could cruise in 120 km/h for hours (with stock radiator). -And just like you say, with no boost at all. But when on track, pushing hard, cooling temp starts to increase after a couple of laps. Oil temp stays normal at 90-95 C and intake temp is still below 35 C.
Also note that my engine has 205 whp @1.5 bar boost so I assumed stock radiator couldn't handle the extra heat generated by the turbo. I have an oil cooler and removed inner skin from engine hood to obtain maximum air flow.
The forecast says 20-25 deg. C next week so I am looking forward to see if the new alu rad is working as expected.
 
I am thinking about having the X1/9 thermostat housing instead of the UT housing
Hey, I just realized something. All through this discussion I've been thinking of, and referring, to the X1/9 thermostat housing. Honestly I didn't realize the UT has a different design? My turbo engine is based on a X1/9 engine, so I've never had a UT engine to look at up close. How does the thermostat housing design differ on it from the X?
 
How does the thermostat housing design differ on it from the X?
1620492260096.png

1620492383380.png

As you see the cooling system differs. Another consequence with UT thermostat housing is that stock X1/9 cooling hoses do not fit.
 
The factory setup on the UT has the turbo's return coolant going to the overflow tank as part of its after run cool down action. The design brings water from below (the block), up to the turbo, then further up to the top of the tank. So there's a temperature differential between the turbo's inlet and outlet. And a elevation difference from low to high. That creates a cycling of water after the engine is shut down, until the temps neutralize (i.e. turbo cools off). Rerouting the turbo coolant elsewhere will negate that effect.

However utilizing a auxiliary pump as you suggest would be even better, for turbo cooling both during operation and during after run.
Yes the UT does that but it is also an old design which on an X is clearly less than ideal given his current experience. Putting an after run relay for a separate pump would be a simple matter and work better in any case.
 
The factory setup on the UT has the turbo's return coolant going to the overflow tank as part of its after run cool down action. The design brings water from below (the block), up to the turbo, then further up to the top of the tank. So there's a temperature differential between the turbo's inlet and outlet. And a elevation difference from low to high. That creates a cycling of water after the engine is shut down, until the temps neutralize (i.e. turbo cools off). Rerouting the turbo coolant elsewhere will negate that effect.

However utilizing a auxiliary pump as you suggest would be even better, for turbo cooling both during operation and during after run.
I am glad you cleared that Dr. Jeff.
@Mxgrds I hope your oil temp is 90 deg. C not 190 C when cruising for long time at high speed. I share your theory about the flow and that's why I am thinking about having the X1/9 thermostat housing instead of the UT housing if nothing else helps. BUT the radiator fan is starting at high temp so that must mean that coolant is flowing correctly?
I have not much to add to the discussion until I've testet the car in hot weather with the new aluminium radiator I am afraid. My problems differs a little bit from yours. In ambient temp around 15-20 deg. C I could cruise in 120 km/h for hours (with stock radiator). -And just like you say, with no boost at all. But when on track, pushing hard, cooling temp starts to increase after a couple of laps. Oil temp stays normal at 90-95 C and intake temp is still below 35 C.
Also note that my engine has 205 whp @1.5 bar boost so I assumed stock radiator couldn't handle the extra heat generated by the turbo. I have an oil cooler and removed inner skin from engine hood to obtain maximum air flow.
The forecast says 20-25 deg. C next week so I am looking forward to see if the new alu rad is working as expected.
Yes was a typo. 120 degrees on hot days with 130km/h continually. Normally it is around 90/100.
i am using the thermostathousing from the X.
My UT is pretty standard, just a bit more boost 1 bar. But not often used
 
Yes the UT does that but it is also an old design which on an X is clearly less than ideal given his current experience. Putting an after run relay for a separate pump would be a simple matter and work better in any case.
Just to remind you, I own 2 X’es with exactly the same setup. One is giving me no overheating problems at all. So the suggestion that the setup is wrong, is simply not true.
 
View attachment 46972
View attachment 46973
As you see the cooling system differs. Another consequence with UT thermostat housing is that stock X1/9 cooling hoses do not fit.
Today I have helped a clubmember with an UT with this type of thermostathousing. The hoses had to have an extra bent, but it is possible. Takes a lot of space in the already packed engine bay. What also can be seen is there is no overflow to the tank. The overflow is on top of the radiator.
 
The X thermostathousing. As can be seen on the photo the outlet to the radiator and the outlet to the tank are at the same height. The outlet to the radiator is much bigger, so most coolant will go that way. If air is generated in the engine or the coolant tank, most of the air will also travel to the radiator. Looking at the setup of the Uno, the overflow starts from the radiator to the tank. Given the fact that the tank is higher than the rad, all air will be pushed to the tank and purged from the system. The weak point in the X design is that air that reaches the radiator is trapped there and can not be purged by the system itself which wiill not happen in the original Uno.
A7BC85E2-5972-4024-882D-3D5EEEF66155.jpeg
 
View attachment 46972
View attachment 46973
As you see the cooling system differs. Another consequence with UT thermostat housing is that stock X1/9 cooling hoses do not fit.
It looks a bit different, although the principle is the same for both engines. And the routing of the hoses is almost the same, utilizing a similar bypass. However that doesn't mean both work as well in practice. Regardless, I'm not sure the X is better - lots of X owners have complaints about the cooling system design.
 
Given the fact that the tank is higher than the rad, all air will be pushed to the tank and purged from the system. The weak point in the X design is that air that reaches the radiator is trapped there and can not be purged by the system itself
Agreed. As I look at it, the problem with the X is the radiator is too low on the vehicle. But I don't think air is the reason for the issues discussed in the original post. I also don't think blocking a portion of the thermostat will help. Sounds like something else altogether is the cause, like possibly the things already discussed (faulty water pump or t-stat, etc).

Speaking of water pumps, there is a "advanced" design impeller sold for Lada water pumps. It offers 15% increased circulation over the stock impeller. It comes installed on a new Lada pump. The overall pump design is the same as on the X (I'm not sure what the UT pump is like), and I believe the impeller could be installed on the X's pump (other aspects of the pump are slightly different, so cannot use the whole pump). I contacted the maker to see if a pump with this impeller is offered for other similar engines (like the x). Unfortunately they only specialize in Ladas. I also asked if I could purchase just the impeller; the Lada pump isn't too expensive, but with shipping from Europe it is more than I want to spend for a test sample. Unfortunately no. However maybe it is cheaper for one of you guys in Europe, and worth looking at? Here is a link:

Here a pic with the difference in the impeller shown:
Lada 'Turbo' pump +15%.jpg
 
This is my setup for the automatic radiator bleeding. Don’t need to bleed at all anymore. View attachment 46978View attachment 46979
I've never seen something like that before. But I've never lived in areas that use radiator heating for properties, so I'm not experienced with them.
I assume that mounting location height is above the top of the radiator? Seems it needs to be in order to work correctly?

I looked on Google for it. Did not see that style but found different looking ones and this article:

Here is another one that may be very interesting:
It appears to be small enough to mount directly on the radiator, with the vent hole tapped to a 1/8" NPT thread. Automatically bleeds, but can also be manually bled. Serviceable inside and not too expensive (about $8 USD).
 
Agreed. As I look at it, the problem with the X is the radiator is too low on the vehicle. But I don't think air is the reason for the issues discussed in the original post. I also don't think blocking a portion of the thermostat will help. Sounds like something else altogether is the cause, like possibly the things already discussed (faulty water pump or t-stat, etc).

Speaking of water pumps, there is a "advanced" design impeller sold for Lada water pumps. It offers 15% increased circulation over the stock impeller. It comes installed on a new Lada pump. The overall pump design is the same as on the X (I'm not sure what the UT pump is like), and I believe the impeller could be installed on the X's pump (other aspects of the pump are slightly different, so cannot use the whole pump). I contacted the maker to see if a pump with this impeller is offered for other similar engines (like the x). Unfortunately they only specialize in Ladas. I also asked if I could purchase just the impeller; the Lada pump isn't too expensive, but with shipping from Europe it is more than I want to spend for a test sample. Unfortunately no. However maybe it is cheaper for one of you guys in Europe, and worth looking at? Here is a link:

Here a pic with the difference in the impeller shown:
View attachment 46980
It is not that the radiator is to low, but the pipes under the car are lower. Air in the rad will not be pushed down again to find its way to the tank.
Yes my original question was what the thoughts were of pinching off the thermostaat to inlet tank to force that hot coolant flow to pass the radiator first and not bypass the rad through the tank.
 
I've never seen something like that before. But I've never lived in areas that use radiator heating for properties, so I'm not experienced with them.
I assume that mounting location height is above the top of the radiator? Seems it needs to be in order to work correctly?

I looked on Google for it. Did not see that style but found different looking ones and this article:

Here is another one that may be very interesting:
It appears to be small enough to mount directly on the radiator, with the vent hole tapped to a 1/8" NPT thread. Automatically bleeds, but can also be manually bled. Serviceable inside and not too expensive (about $8 USD).
Your right. To be above the radiator top it is extended to the light cavity. The first is a right type, but with the connection at the bottom it is difficult to get it higher than the rad top. The second one works with a celluloid membran. That one will not work. Tried that. When the membran is wet it locks up. When dry (air in the system) it dries and air can pass until it gets wet again.
Flamco H 1/2 float air vent, quick air vent, thermostat valve, Flexvent vent, nickel-plated 27710, nickel https://www.amazon.nl/dp/B008CPEYI4...t_i_0RCZB9XWA4X31S738115?_encoding=UTF8&psc=1
 
It is not that the radiator is to low, but the pipes under the car are lower. Air in the rad will not be pushed down again to find its way to the tank.
Yes my original question was what the thoughts were of pinching off the thermostaat to inlet tank to force that hot coolant flow to pass the radiator first and not bypass the rad through the tank.
With the rad lower than the top of anything else (engine, overflow tank, pipes, t-stat, etc), the air will be trapped in it. That is why I sat the radiator is too low. But we agree on it. ;)

Too bad that other style bleeder won't work, because it would fit directly on the rad. :(
I saw other bleeders that I believe are the same design as you linked, but we don't have that particular one here. I see they refer to the other a "coin" type vs "float".
 
These looks like two of the smallest "float" valves I could find so far:

This one mounts laying on its side, kind of like yours. That may be easier to fit in the X:

But none just like what have. It isn't offered in the USA.
 
Update. Think I solved the quick rise in temperature problem. I had a look on the hose to the Sirocco rad. One was a little bit twisted and somewhat pinched. Loosend the clam, twisted it back so the hose was perfectly round all the way. Test drove it on the highway 120 to 160 km/h. Temperature rose till just above 90 degrees. Which is good. And also not a quick rise. Amd today’s temperature was considerably higher 25 degrees then my earlier test. Happy.
one question: I noticed the hose on the rad are switched. The inlet is at the bottom, the outlet at the top. Is that a problem?
 
You want your radiator outlet hose at the lowest point on the rad and the inlet at the highest. With the outlet at the lowest point, there will always be coolant available to be sent back to the block to provide cooling (unless the system is basically empty). If you have the hoses switched and you get an air pocket at the top of the rad, you have a greater risk of drawing that air back to the block, which can cause quick temp changes as the air bubble flows (hopefully) through the block and back to the rad.

Here is the thermostat flow page from the manual you can use to check your hose set up. The Sirocco rad is different from the stock X rad, so do a thorough check to be sure of what you are looking at.
thermostat housing flow.jpg
 
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