Cooling Issues Engine Hot-Radiator Not

texyoung

texyoung

Husband to X1/9
Just recently replaced the head gasket due to overheating issues.

Before replacing the head gasket; When it was overheating it was mainly on the freeway, I know odd, right? I burped it several times. I tried it with a new thermostat and with no thermostat or actually a gutted one, so I could keep the gasket in place. Replaced the water pump belt, Took out and checked the water pump and it "looked" fine. Ran water through the pipes underneath of the car to be sure they were clear. Ran water through the radiator to be sure it was clear. None of this fixed it.

Then I replaced the head gasket, which was blown between the 1 and 2 cylinder. When I replaced the head gasket I also replaced the radiator with a new aluminum radiator from Vicks. Added a fan and bypassed the thermo switch on the radiator, so the fans run all the time. Also re-checked the tubes under the car, replaced the thermostat. It ran fine without over heating for about two weeks after replacing the head gasket.

This past weekend it overheated, The odd thing was that even though the engine was at 260, the radiator wasn't even hot to the touch. Not getting good to flow to the radiator.

Before I work on it this weeknd, I was looking for some trouble-shooting ideas. Here are my thoughts; Burp it again, Check pressure to overflow cap, maybe double up the gasket on cap, replace water pump, try w/o thermostat again, check to be sure hoses are correct on tubes to front of car. Any other suggestions would be a big help.

This is my wife's car, and life is not happy around my house when the wife's X is not running right. :)

Thanks!
 
How old is the water pump? Poor circulation could be caused by a failing pump. Which hoses coming out of the thermostat were hot to the touch after the car overheated? Did you have the heater valve open or closed during your previous burpings? Is there a reason you bypassed the thermo switch? Was the air coming from the heater warm or cold? Blowing cold from the heater indicates that there is likely no coolant in the core.

On another note, did you re-torque the head after putting a few hundred miles on the car? Did you have the head rebuilt while it was out of the car (new valve seals and such)?

As far as troubleshooting goes you might want to start by double checking that all hose clamps are tight. A loose hose can suck in air, which will make its way up to the radiator leaving it cold (and empty) while the engine is slowly overheating. Once you've checked the hose clamps are tight I'd make sure the system is full of coolant, let it get up to temp, and see which hoses coming out of the thermostat are hot to determine whether or not the thermostat is opening/closing properly. This can also be done in a pot of boiling water if the thermostat is out of the car. If everything is functioning normally, you might have a small leak somewhere that's causing the engine to suck air when it's running. You can check this with the car running and the cap off the overflow tank. If there's foam in the coolant in the overflow you have an air leak. Make sure that any adjustments made to the cooling system are done while the heater valve is fully OPEN.
 
JT, Thanks for the response.

Some good things to try this weekend. To answer your questions:
  • Maybe 5000 miles on the water pump. Relatively new.
  • I didn't check which hoses were hot coming out of the thermostat to see which ones were hot. Will do when diagnosing this weekend.
  • This car has no heater or heater core, all has been removed.
  • I bypassed the thermo switch so that I could run the fans when it was sitting between autocross runs. I plan to add a switch to both fans soon, in the meantime, that was an easy fix. Is there any harm with having the fans running all the time?
  • I was waiting for about 500 miles to retorque the head. I am doing that this weekend as well.
  • Yes, the head was milled slightly to make sure it wasn't warped and new seals were installed and a complete valve job was done.
 
texyoung said:
JT, Thanks for the response.

Some good things to try this weekend. To answer your questions:
  • Maybe 5000 miles on the water pump. Relatively new.
  • I didn't check which hoses were hot coming out of the thermostat to see which ones were hot. Will do when diagnosing this weekend.
  • This car has no heater or heater core, all has been removed.
  • I bypassed the thermo switch so that I could run the fans when it was sitting between autocross runs. I plan to add a switch to both fans soon, in the meantime, that was an easy fix. Is there any harm with having the fans running all the time?
  • I was waiting for about 500 miles to retorque the head. I am doing that this weekend as well.
  • Yes, the head was milled slightly to make sure it wasn't warped and new seals were installed and a complete valve job was done.
Click to expand...

I doubt the water pump is suspect then.

When you removed the heater, did you also remove the lines going from the engine bay to the heater core? If so, did you plug the coolant ports or run them together to complete the circuit? If the hoses are still in place and the core is bypasses you may have air getting trapped in them. If they are capped off rather than run together you'll have circulation issues in the head, and possibly a pocket for air to collect.

There's no real harm in having the fans run all the time, but it will take considerably longer for the car to warm up. I only ask because people seem to bypass that switch thinking it's the core of their over-heating issues and it often isn't. (I've had to correct more than a few of these "upgrades" in cars I've worked on.)

Some notes on head re-torquing:

Make sure the engine is completely cool when you re-torque. Do you have the factory tools to re-torque without removing the cam tower? This makes the job considerably easier. I would also re-torque the cam housing and the intake/exhaust nuts working from the head itself up. I always re-check the valve clearances while I'm doing a re-torque to make sure none of them have changed dramatically (I've only ever had to change one shim doing a re-torque).
 
I checked with the previous owner and he said that the hoses were removed and capped off. He ran the car for a few years after removing the heater and had no overheating issues, so i "think" we can rule that out as a problem.

Yes I have the factory tool to retorque the heads. I will retorque the cam housing and manifold nuts as well. I do plan to re-check the valve clearances. All good advice.
 
DO NOT run the car without a thermostat. The stat is a bypass type which means that it serves as a directional valve in the system. Take the valve out and you have equal water pressure to both undercar lines so there will be severely limited circulation to and from the rad.

People take a LOT of shortcuts with these cars but half-assing the cooling system on a street machine will make your life miserable with head gaskets and head warping; on an autocross car, you'll just look like the idiot with the Fix-It-Again-Tony to the rest of the participants when you trash the engine.

What stat did you put in?

I'd skip retorquing since it's likely the head gasket has been compromised again. Start over, pull the head, have machine shop check for flatness to spec and correct as required, replace the head gasket and follow the shop manual to the letter for installation.

Recheck the stat by OBSERVING function while heating it in a pot of water. Use a cooking thermometer to check opening temps.

How did you determine the water pump was "OK?" Looking at it and saying, "Yep, it's a water pump" does not count.

When it comes time to reassemble and refill the system, follow the shop manual procedure---open the rad bleed screw and SLOWLY fill the system until the coolant comes out of the bleed screw, then close it. Continue filling. When the cooling system has been opened to the degree it needs to be to change a water pump, a rad, or a head gasket, expect to bleed the system AT LEAST twice if not three times. Be ruthless about removing air pockets.

BTW, how the previous owner bypassed the heater circuit could have an impact on whether air pockets are being trapped in the system, provide detailed description or better yet pix of how it is capped off.
 
Rod Midkiff said:
the water pump has a critical clearance that is often overlooked.
Click to expand...

Yes, the waterpump has a critical clearance from the body of the pump to the impeller of the pump.

One has to take the housing off the engine then fit the pump to the housing and measure the distance from the face of the impeller to the face of the housing. One adjusts the spacing by moving the impeller up or down the shaft of the water pump. The clearance is stated in the manual found on the Wiki and downloadable or downloadable by becoming a member over at the Mira website https://www.mirafiori.com/forum/?do=listmsgs&conf=Gener._F_I_ which offers other goodies and a whole other crew of somewhat offbeat Fiat owners. Actually exactly like us and not any different at all...;)

A good discussion of dealing with the waterpump and its housing can be found here (its about the AC housing which is harder to remove but you get the gist) https://xwebforums.com/forum/index.php?threads/water-pump-replacement-help.33931/#post-289523

The clearance of the impeller to the housing has a large effect on the efficiency of the pump and as we all know, we need all it can give.
 
It rained all weekend and I didn't get much done on the diagnosis of the problem this weekend. I did manage to get the thermostat out and test it in boiling water and it is working correctly. I also took the radiator cap to AZ to pressure test it and it is working great. Will be doing more this weekend, weather permitting. Where can you buy some high-quality hose clamps?
 
kmead said:
Yes, the waterpump has a critical clearance from the body of the pump to the impeller of the pump.

One has to take the housing off the engine then fit the pump to the housing and measure the distance from the face of the impeller to the face of the housing. One adjusts the spacing by moving the impeller up or down the shaft of the water pump. The clearance is stated in the manual found on the Wiki and downloadable or downloadable by becoming a member over at the Mira website https://www.mirafiori.com/forum/?do=listmsgs&conf=Gener._F_I_ which offers other goodies and a whole other crew of somewhat offbeat Fiat owners. Actually exactly like us and not any different at all...;)

A good discussion of dealing with the waterpump and its housing can be found here (its about the AC housing which is harder to remove but you get the gist) https://xwebforums.com/forum/index.php?threads/water-pump-replacement-help.33931/#post-289523

The clearance of the impeller to the housing has a large effect on the efficiency of the pump and as we all know, we need all it can give.
Click to expand...

I got set up as a member of the Mira site and then clicked on the above link and the only manula I saw was for a 238 Van???
 
The link likely goes to my account without being logged in, sorry.

As a member at Mira the manuals section looks like this:

8FAA1D11-72EB-4FBC-92CE-AE7F667D4BF3.png

A5501782-E0DB-4FD7-93B0-6E88BF185A4C.png
131C95CC-454C-4178-8E02-785834AC0C76.png
 
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