Author Topic: 1962 - Bubbles in Radiator  (Read 200 times)

Offline Scott62

1962 - Bubbles in Radiator
« on: September 05, 2018, 10:14:35 AM »
I'm looking for some guidance on my "bubble" issue. 390 Engine is freshly rebuilt by old time professional engine rebuild guy with many new parts. Picture shows what I'm seeing after a short run time of the engine. Thermostat is out as the engine temp gauge was not happy with it installed. I assume the bubbles were causing bad readings as it seems to work fine with thermostat removed and engine stays cool. Here is a list of things I've done so far:
1. Replaced temp sensor to make sure it was reading correctly. Same bad readings until I removed thermostat.
2. Purchased Combustion Gas Testing kit for radiator - performed test with negative results for combustion gas. Confirmed test kit by sticking in tail pipe and it read positive.
3. Drained antifreeze including block. Refilled with distilled water. Ran engine with only water in system. Attached picture is after 8-10 minutes of engine run time - Bubbles
4. Reviewed situation with engine builder and a few other knowledgeable people but nobody can figure it out - go to Cadillac Forum

One thought is the waterpump is drawing in air somehow?? I have a rebuilt pump with the newer style stamped impeller. My original pump had a cast impeller. Is it possible the newer style impeller is creating turbulence and making bubbles???.....getting desperate here.

Any insight would be greatly appreciated.

Offline Externet

Re: 1962 - Bubbles in Radiator
« Reply #1 on: September 09, 2018, 10:22:13 AM »
Hi.
Any sucking of air by the water pump would translate into dripping coolant leak when hot engine is stopped.

Has the pressure holding capability of the cooling system been tested ?  Bubbles are steam from boiling, which happens at 100C if the system is not pressurized.  With an open cap, there will be bubbles at boiling temperature.
Residues and dirt that missed removal from cleaning during engine overhaul favor the formation of hot spots creating bubbles.

Is there a stiffener spring fitted inside the pump inlet hose ?
Do I see a white coolant in the picture ?

To determine the location the thermometer pointer is at 100C, let the water boil idling with no cap.  That is 100C (212F).   Lower temperatures can also be related to the 'no-scale-idiot-dash-thermometer' with a candy thermometer into the radiator opening.

It is frustrating to determine operating temperature with no reading on the dash  :(     
5.0L+700R4 wrapped in a '61
V6 Vortec+4L60 wrapped in a '62
5.0L+THM350 wrapped in a '63
2000 LandRover, modified.

Offline Ramses

Re: 1962 - Bubbles in Radiator
« Reply #2 on: September 09, 2018, 08:50:21 PM »
i have seen bubble in radiator in the past (but not on my cadillac) this was caused by a wrong head gasket, when piston make compression, if the gasket is not good it can push air into the antifreeze.

Sometime, you can see white smoke at the muffler when this gasket is not good (because antifreeze go in piston chamber and that make white smoke when engine burn it)
You can not count the time spent on a car, because it's a therapy!

To see my actual project: www.cadillac1962.com

Offline Scott62

Re: 1962 - Bubbles in Radiator
« Reply #3 on: September 10, 2018, 08:32:26 AM »
Thanks for the two responses.
I did forget to mention that I did a formal cooling system pressure test for 24 hours at 13 psi...system held with no leaks.
No stiffener spring in lower radiator hose.
The "white" looking coolant shown in the picture is actually the fine bubbles (foam) after running the motor to operating temp and removing radiator cap. After a couple minutes the white bubbles settle out and the normal looking green antifreeze reappears at its normal level.

I'm really at a loss at this point. Hard to imagine the system sucking in air if it doesn't leak anywhere under pressure. The bubbles seem to appear in a greater amount once the motor gets warmed up. It sure seems like some internal issue but my testing thus far has not found any issue. I'm not a big fan of tearing the motor back apart if I can't determine the problem first but I may have to do that.

I'm open to all ideas!

Offline rare eldorado

Re: 1962 - Bubbles in Radiator
« Reply #4 on: September 10, 2018, 08:47:26 AM »
The thermostate keeps the correct temp in the motor ,,it allows the coolant to cool down  in the radiator before returning to the motor ,,closing and opening as needed.  Also slows the coolant down as not to get too hot.       Check to see if rad cap is correct for your car /with or    without a/c.  Pressure test system with anti/in at 16lbs running temp/ with motor off.A

Offline rare eldorado

Re: 1962 - Bubbles in Radiator
« Reply #5 on: September 10, 2018, 08:52:18 AM »
Also check the water pump impeller if it is not the same style as old one may be moving   water to quickly and will not be getting into all the water ports . referring to the pitch of the blades ...look at this before taking motor apart.

Offline Scott62

Re: 1962 - Bubbles in Radiator
« Reply #6 on: September 10, 2018, 12:39:33 PM »
I like your idea of pressure testing at operating temp. That will certainly tell me if it is temperature related as far as some weird scenario with a crack in a cylinder head or something.

The water pump impeller is definitely the newer style steel stamped unit that comes with a rebuild kit. At one point I took the pump back off the engine and removed the rear cover to take a look. Everything seemed okay with my only observation being the back of the impeller was very close to the rear cover like almost flush with the pump housing. There was no interference with the rear cover so I just put it back together with a new gasket. Not sure if this tight tolerance to the rear cover would create a condition where the pump is too efficient and pumping too much coolant as you mentioned. The rebuilt water pump was purchased from a supposed good rebuild guy but I'm not a water pump expert myself.

Your comment about impeller blade pitch is interesting but not sure I'd know what to change and by how much without a lot of trail and error. Additional thoughts appreciated.

I still have my original pump with cast impeller but it's a little rough. I may be able to clean the impeller up and try that in the new pump. The Caddy water pumps are not fun to work on...

Again, thanks for the feedback!

Offline Externet

Re: 1962 - Bubbles in Radiator
« Reply #7 on: September 10, 2018, 08:26:24 PM »
I would never run an engine without a pump inlet hose stiffener 'spring'.  But that is me.

This is totally wrong ----> "Also slows the coolant down as not to get too hot. " :'(

Do the foamy bubbles appear when engine is cold ?  Is there any suspicion the cooling system has air trapped in the heater core or elsewhere ?
5.0L+700R4 wrapped in a '61
V6 Vortec+4L60 wrapped in a '62
5.0L+THM350 wrapped in a '63
2000 LandRover, modified.

Offline rare eldorado

Re: 1962 - Bubbles in Radiator
« Reply #8 on: September 11, 2018, 08:26:24 AM »
the therm.. keeps the water in the rad to keep it from going above temp //then opens to recirculate it

Offline Externet

Re: 1962 - Bubbles in Radiator
« Reply #9 on: September 11, 2018, 08:51:34 AM »
Monumentally absurd.
Keeps the coolant in the block superheating the engine and then opens ?
It is a closed loop.  You hold the coolant flow in the radiator and you are also holding the coolant in the block from circulation.
Cooling is improved by mass flow, not holding flow.

Misconcept probably invented by the same guy that preaches a battery on a concrete floor discharges it.

"The thermostate keeps the correct temp in the motor"
Very imprecise.  A thermostat only changes circulation path at its rated temperature.  Keeping the 'correct' temperature depends on ambient temperature, mass of coolant flow, engine power being delivered, radiator efficiency, air flow...  A 190F rated thermostat will not keep the coolant at 190F as in hotter/climbing conditions.  Just acts at such temperature.

If I remember well, our Cadillacs use the bypass method in the cooling system.  Engine block outlet returns to engine block inlet until the thermostat ACTUATES.
I say actuate because is not 'opening' flow, It also closes the flow path for the bypass loop.
In cases that thermostat removal is desired in hot seasons, it may result in very poor cooling because the bypass loop is not blocked when the thermostat is removed.
A proper thermostat for our Cadillacs MUST BLOCK the bypass loop when opening the flow towards the radiator.  An improper thermostat that only OPENS flow towards the radiator will cause overheating if leaves the bypass open.

See there is TWO valves ?
One closes when the other opens.


« Last Edit: September 11, 2018, 10:11:17 AM by Externet »
5.0L+700R4 wrapped in a '61
V6 Vortec+4L60 wrapped in a '62
5.0L+THM350 wrapped in a '63
2000 LandRover, modified.