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White foam in the radiator??

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ScottFromNH

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Hey guys,

I am hoping someone might have an idea of what is going on. I have a 1973 spitfire I have been rebuilding some of you know. Well before I put the car in the garage to fix the rust I changed the thermostat and flushed the system. The car was running really good, temp was about half way after running idle for 20 minutes.

Now that the car is back on the ground and out of the garage it wants to over heat. Today I ran the car for about 15 minutes and it almost went in the red. I am trying to figure out what might of happened. In the garage I changed the heater hoses and also installed a new exhaust header with new gasket.

Tonight I let the car cool off and took off the radiator cap to make sure the water was flowing. I noticed that I didnt see any water flowing so I filled it up while it was running. The next thing I saw was white foam coming to the top of the radiator.

Any idea's what that white foam is and could it be the problem with my over heating? Or any idea's of places to start with the over heating? I was going to by pass the heater core to see how the car runs or pull the thermostat out and see if it ran cooler that way?

Just looking for idea or suggestions.
 
Did you flush out all of the chemicals that you may have used in the initial flush? It sounds like you had an air pocket and were low on coolant and it just may have needed to be filled and burped to get any air out that could be making bubbles.
 
I was thinking of flushing the system out again with just water this time to make sure I didnt miss any flush chemical I used. I thought I got it all but with the way the foam looked I would say I dont know and the color of the antifreeze is brown and it wasnt before.
 
A lot of mechanics will immediately say "head gasket", but leftover chemicals, air lock, even old anti-freeze will cause frothing.

Straight water test is good.....and make certain you are bled to the t-stat, as in, remove the sender and fill until it runs out.

Does your t-stat have a vent or bleed hole in the main outer ring?
 
That is what was worrying me was head gasket but since I was running great before I kind of ruled that out and I check my oil and I have no anti freeze it that.

Ok I will do the straight water to see what happens and also make sure that the system is totally cleaned out.

Not sure I know what you mean about my t-stat having a vent or a bleed hole in the main outer ring?

My temp sensor sits right before the t-stat housing and I also have a rubber hose that comes off the houseing by the t-stat. Is that what you mean? sorry still new to this british stuff

I am wondering if my heat core had crap in it and by swapping the heater hoses dislodged something?
 
Don't rule out head gasket. The foam could be oil in the coolant. Pop off your oil cap and have a look in there. If there is foam in there, then you have a problem. Foam in just the coolant is probably just crap getting stirred up from the flush. Good luck.
 
Did you have your heat full on when you flushed it out?
It is possible that some of the chemicals could have been trapped in the heater core and are still there.
Make sure when you clean it out again that you have the heater core full on.
 
Usually, foam is NOT oil, as oil doesn't readily foam, in fact, "oil on the water" tends to calm water. Usually, if head gasket, or crack somewhere, it's combustion gasses foaming up the coolant.
Could very well be a head gasket, cracked head or bore, but you check the basics first. Once you tear it all down again, you can't test the assembled engine until re-assembly occurs.

Not sure what kind of t-stat you have, but the main ring (not the valve plate that opens) should have a hole in it, I use about a 1/8" bit. This keeps any and all air, combustion gas, from holding AIR against the pellet that senses WATER temperature to open. Takes a whole lot of hot air to do what a little hot water will do.

Safety feature...lot of manufacturers put them in, and a lot of shops do it on new t-stats.
 
I did pull the oil cap off and looked in as it was running and it looked fine. I didnt see anything in their. However I will check again with a flash light.

Yes I did but I have to say that I wasnt getting very much heat and I was wondering if the heater control was not working. Now after I changed the heater hoses and cleaned up that area I can feel the heat when I turn on the heater.

Ok I will make sure I have the heater on full.

Should I also pull the plug on the engine block to drain the block? If I can get that bolt out?
 
Oh ok TOC, Now that make sense. My t-stat has an air bled hose that is attached to it.

Yeah I am hoping I dont have to tear apart the engine as that seemed to be in really good shape when I purchased the car.

I did check the in the oil cap with a flash light and I do not have any foam in the valve area. Also the car runs good and once you pull the oil cap off it drops in idle which I was told was good as it has good compression and wouldnt that mean a good HG?
 
ScottFromNH said:
Should I also pull the plug on the engine block to drain the block? If I can get that bolt out?
Click to expand...
<span style="font-weight: bold"><span style="font-style: italic">Absolutely!</span></span> If you didn't do that, you really haven't flushed the system. Period. It's usually a brass plug and should come out pretty easily. You may well find, though, that you need to probe around with a stiff wire or small screwdriver before anything comes out...and keep probing until you get gushing water! After that, you might even consider another chemical flush followed by thorough water flushing.
 
Ok then that is probably my problem as I did not do that last time. Good point Andrew since I didnt have that plug out then I probably still have a lot of crap in my system.. I will post more in a couple days as I am going to start that tonight.


Thanks for the help guys. I hope this fixes the issue if not i will be a block test kit to check my head gasket.
 
If you still have brown water you don't have all the rust out. Reverse flush, even spray through the block plug if you can; Triumph rust is tuff stuff. And be sure your heater valve is wide open so it will clean out the heater too.
 
unfortunately the radiator flushes of today are not as good as the really good chemicals you could get in the past

Hondo
 
Hey guys, Wanted to say Thanks for all the help. I drained the system pulled the t-stat and block plug and ran water in it until clean water was coming out of the radiator and engine plug. I then button it up and ran it to see if the temp would be back to normal and it was. So this weekend I am going to run another flush kit through it and then put back the antifreeze and see if the temp stays the same.

Right now its running at half temp for an hour of running.
 
That is excellent news. Glad to hear that it was simple.
 
Thanks Brosky, I was starting to get a little worried that something happened while it was in the garage and my head gasket was blown.
 
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