Cooling System Bubbles - Origin Unknown

[69Midd4Stang 10]

I have just installed my rebuilt 390 4v and have experienced the engine running hot 200+. I have undertaken several steps to try and burp the system and check for issues but have yet to find the solution to the problem.

 

That stated here is a brief description of a concern that continues regarding high heat of the engine system:

 

• 
  
• The engine at Idle gets up to the 180 level and the flow in the rad is very strong as the therm opens up. There are bubbles visible in the rad once the thermo opens and they do not dissipate.
  
• The engine will sit at the 180 during idle but when it is run higher the idle the engine slowly creeps up to the 200+ level
  

Noticed:

 

• 
  
• Bubbles in the flow of the rad after thermo opens up. They do not dissipate and continue to be consistent during the time of watching the flow over several minutes.
  
• The system does not build up pressure during operation of the motor. I can remove the cap during running at the 180 level with out any pressure or bubbling of the system.
  
• The system does build pressure once the engine is turned off.
  

 

Steps to date:

 

• 
  
• Gauge, sending unit, and operating temp confirmed by means of thermo gun.
  
• Installed new 180 thermo, recently dropped to a 160 thermo
  
• Rebuilt Carb, Rebuilt Dist
  
• Confirmed Timing and fuel mixture
  
• Pressure Test cooling system, Pressure test Rad Cap
  
• Confirmed Head Gaskets are not installed backwards
  
• Rebuilt Rad - 3 core - Sprayed water on the front of the rad and entire surface dried
  
• Rebuilt Waterpump
  

 

I have the large spacer plate under the carb which has the cooling system flow thru it.

 

Looking to see of anyone has any thoughts on what to check next or steps for determining why the motor is running hot.

 

Also why and where the intake of air in the system is coming from once the thermo opens up. This is the one item that has me wondering where and why they are in the system.

 

Your time and assistance here is Greatly Appreciated!

[LoneWolf2U 136]

Bubbles in cooling system are generally from compression gases. I would recheck head bolt tork for loose bolt.

You lack of pressure build with cap on is another indicator of seeping headgasket problem.

[det0326 179]

Are you still running the OEM belts and pulley configuration on the FE?

[Dave R. 85]

A crack in the block or cylinder head maybe. That allows compression and therefore heat to seep into the water jacket. Bubbles and heat are the result.

['70MACH1 10]

Head gasket issues if the bubbles are tiny ones!

[69Midd4Stang 10]

Mach1Rider - Thank you for that point. I will review the torque on the heads. This would be a strong possibility based on the potential transition during the start up. I recall reading on the internet that it was a good practice for yearly review of the head bolts on the big block engines.

 

Block was tested for cracks prior to rebuild. So I am limiting that this can be in the play at this point BUT one never knows.

 

det0326 - Yes to running OEM belts and Pulleys on FE. Can you please add why you asked this question. Thanks

 

I am always appreciative as to brainstorming that this forum presents! It is amazing to gain the insight of the many who participate here.

 

Thanks!

[det0326 179]

Mach1Rider - Thank you for that point. I will review the torque on the heads. This would be a strong possibility based on the potential transition during the start up. I recall reading on the internet that it was a good practice for yearly review of the head bolts on the big block engines.

 

Block was tested for cracks prior to rebuild. So I am limiting that this can be in the play at this point BUT one never knows.

 

det0326 - Yes to running OEM belts and Pulleys on FE. Can you please add why you asked this question. Thanks

 

I am always appreciative as to brainstorming that this forum presents! It is amazing to gain the insight of the many who participate here.

 

Thanks!

 

 

Wasn't quit sure on the fe engines but some guys that changed the Winsor's over to serpentine belts there was an issue with the way the belt wound around different pulleys it caused the stock water pump to drive in the reverse direction so the pump had to be changed too..

Some got these pulleys from the later model ford trucks and some were just simply after market stuff. Haven't worked on the FE engines in a very long time and wasn't sure if this could be your problem are not. So if you are running stock pulleys and belts this would not be the problem. Would have been nice if it was tho sure beats taking heads off.

Dave

Edited June 17, 2014 by det0326

[miketyler 15]

I am not an engine guy but the fact that you don't get any leak down in the cooling system is promising but is it conclusive? Since the bubbles don't appear until block is up to temp I wonder if you need the block nice and hot to simulate the condition?

 

Also when you pumped up the cooling system did you pull plugs? if only marginal leaking (or crack that closes when its cool) you might miss some trace amounts of water in the cylinder and would just get blown out the next time you cranked it.

 

I have never used one but isn't there an exhaust gas analyzer you can use on radiator opening to check for presence of exhaust or combustion gases? It wont tell you where the problem is but it can sure narrow things down for you

Edited June 17, 2014 by miketyler

[69Midd4Stang 10]

We continue the search :detective: to see where the problem lies and I will update then. Cheers!

[danno 128]

You can usually smell exhaust in your radiator cap if it is leaking into the cooling system. Or pour some oil into your carb while running, so the exhaust is full of smoke. Then see if your cooling fluid has oil on the surface.

 

Could a wrong connection of the timing chain cause overheating? Just wondering...

[stangnet33 88]

Here's the exhaust gas analyzer I use at work, very simple to use. Probably cheaper to buy one vs an hr of shop labor diag, not really sure what the kit is worth anymore. A leaking head gasket 90% of the time will also cause excessive pressure build up in the cooling system while running ( usually after warm up ) .

 

 

Edited June 17, 2014 by stangnet33
spelling

[stangnet33 88]

also forgot to ask what machining work may of been done ?

[69Midd4Stang 10]

All surfaces on the block, head and exhaust were machined. It was my intent to do it right the first time to avoid this sort of situation. I will look into the gas analyzer after re-torque of the head bolts.

 

I am optimistic that re-torque of the heads will solve the problem.

[LoneWolf2U 136]

For those without a fancy tool to use, But using that spare condom from their wallet you can test for gases entering the cooling system.

First plug off the overflow port and place said condom over the rad neck and run engine up to operating temp of stat rating.

If the condom puffs up like a balloon, Then compression gases are entering the system.

 

Besides your not going to use that condom anyway.

[miketyler 15]

Well thats another good use for a condom. However, isnt some pressure build-up normal in a cooling system? Wouldnt a healthy non bubbling system also inflate a condom as it come up to temp?

Edited June 18, 2014 by miketyler

[Midlife 814]

Using the condom works only if the water is up to the overflow tube. The test is to see if additional air is added to the condom. If everything is working correctly, the condom will inflate with liquids, not gas.

[stangnet33 88]

A page right out of high tech redneck lol. Didn't think I was suggesting such a high end tool.

[SA69mach 39]

You mentioned you had a water pass-thru on your carb spacer. Can I suggest you bypass this and test again, just to eliminate a leak there?

 

I also suggest you check with a good auto parts store about hydrocarbon test for radiators. I am sure they are around.

[69Midd4Stang 10]

Update:

1. rebuilt my rebuilt radiator and add the dimple tubes to assist with cooling.

2. Replaced Clutch fan.

3. Tested bubbles and confirmed no presence of fuel.

4. Re-Torque of head bolts no concerns here.

5. Bypassed the heater core and found no change.

6. Reconnected the heater core and found that the bubbles were no longer present in the system. (somehow?) and system began to pressurize.

 

Assumed Air lock was released (some how) as the engine began to run cooler but still not correct as heating up when in slow moving traffic.

 

Received advice from fellow big block owners to replace the clutch fan system with a fixed fan and spacer.

 

Removed the radiator to exchange the fan system and have found the engine now running hot again!! Assume air lock has returned.

 

Believe that the problems could be related to the 390 GT Alum Carb plate which has the cooling fluid running through it.

 

I am going to bypass the plate and see if this indeed can be confirmed as the source of the air lock, overheating aspect.

 

Looking to see if anyone has a similar carb spacer and has experienced anything similar related to air locks and engine heating conditions.

 

Seems a very suspect item in the system and is at the top of the cooling system which could potentially trap any air in the system.

 

Thank you in advance for any feedback!

[det0326 179]

Update:

1. rebuilt my rebuilt radiator and add the dimple tubes to assist with cooling.

2. Replaced Clutch fan.

3. Tested bubbles and confirmed no presence of fuel.

4. Re-Torque of head bolts no concerns here.

5. Bypassed the heater core and found no change.

6. Reconnected the heater core and found that the bubbles were no longer present in the system. (somehow?) and system began to pressurize.

 

Assumed Air lock was released (some how) as the engine began to run cooler but still not correct as heating up when in slow moving traffic.

 

Received advice from fellow big block owners to replace the clutch fan system with a fixed fan and spacer.

 

Removed the radiator to exchange the fan system and have found the engine now running hot again!! Assume air lock has returned.

 

Believe that the problems could be related to the 390 GT Alum Carb plate which has the cooling fluid running through it.

 

I am going to bypass the plate and see if this indeed can be confirmed as the source of the air lock, overheating aspect.

 

Looking to see if anyone has a similar carb spacer and has experienced anything similar related to air locks and engine heating conditions.

 

Seems a very suspect item in the system and is at the top of the cooling system which could potentially trap any air in the system.

 

Thank you in advance for any feedback!

 

I am an old timer myself and have worked on a lot of old cars in my day.

The carb plate is not going to make your car run hot. If you leave your radiator cap loose or off while the engine is running and the thermostat opens as it gets to operating temperature the air if any trapped will be expelled through the top hose and out the radiator cap opening. This is when you will need to add more water if a lot of air was trapped. While watching the water through the radiator cap opening and it seems to have good circulation then the only possible reason of it running hot would have to be as some already said it may be a leaky head gasket or a crack somewhere allowing hot compressed gases to get into the system causing the coolant temperature to rise. I know this isn't what you want to hear but is the only logical explanation. It does not seem likely or possible for air to stay in the system after it starts to circulate. That's just my opinion tho I hope I'm wrong.

 

Dave

[jmlay 80]

Park the car on a slope or put the front end on ramps so the radiator cap is the highest point in the system & fill. I agree with Dave's comments as well.