Milky "froth" from radiator overflow hose

5fty7vn

Member
Joined
Dec 14, 2014
Messages
51
Reaction score
14
Location
Buckeye, AZ
Hello.............the past week or so i've noticed a brownish milky "foam/froth" coming out of the radiator overflow hose. The car doesn't run hot or seem to have any issues while running.......anyone have any ideas what this is and how to stop it? I have a 1966 Chrysler Newport with a 383 2bbl in it. Thanks.
 
Sounds like a head gasket. Have you checked your oil to see if it has a similar milkshake like froth to it ?
 
The gasket may have deteriorated just enough to allow oil to get into the coolant passages, but hasn't made its way to the cylinders yet. It could also be just sediment that built up over a long period of time. I would suggest doing a coolant flush and check it periodically afterward to see if the problem persists.
 
I checked the oil and didn't find any of the foamy substance in it. Outside of the normal oil wear and tear I didn't see anything unusual about it.
 
You didn't say weather or not you had a catch bottle so I'll assume not. If this is the case, the expansion of the coolant overflows out the tube but as it cools air is likely to get sucked back in. Overflow bottle type cooling systems use a rad cap that allows fluid to be drawn back into the cooling system as the engine cools down. The froth is probably just that, coolant whipped up with air in it, sitting at the top of the upper tank mixed with rusty engine crud or sealant like Bars Leak. Next time this happens, let the engine cool completely and then remove the cap on the rad an see what level the coolant is at. It should be right to the top of the tank (bottom of the filler neck). If the presence of air is causing the whipping action, best invest in an overflow tank and the matching rad cap. Air is the worst enemy of engine cooling systems.
 
This is the milkshake you do not want to see.

2008-10-13_03.jpg



Alan
 
Check also the transmission fluid, the cooler integrated into the rad could be leaking.
 
MrMoparCHP...............I take it that is oil mixed in with the coolant?

This was on a used engine I put in my Barracuda, from day one it overheated. Much of the water I was adding was going into the engine. This is what I drained out of the oil pan. I never looked into that engine, it was a 273 and I had another.


Alan
 
MrMoparCHP...............I take it that is oil mixed in with the coolant?

This was on a used engine I put in my Barracuda, from day one it overheated. Much of the water I was adding was going into the engine. This is what I drained out of the oil pan. I never looked into that engine, it was a 273 and I had another.


Alan
 
You didn't say weather or not you had a catch bottle so I'll assume not. If this is the case, the expansion of the coolant overflows out the tube but as it cools air is likely to get sucked back in. Overflow bottle type cooling systems use a rad cap that allows fluid to be drawn back into the cooling system as the engine cools down. The froth is probably just that, coolant whipped up with air in it, sitting at the top of the upper tank mixed with rusty engine crud or sealant like Bars Leak. Next time this happens, let the engine cool completely and then remove the cap on the rad an see what level the coolant is at. It should be right to the top of the tank (bottom of the filler neck). If the presence of air is causing the whipping action, best invest in an overflow tank and the matching rad cap. Air is the worst enemy of engine cooling systems.

No, I don't have an overflow tank on it. I did check the coolant and level and it was very low. I added coolant so it it fills up right underneath the cap and took it out for a test run and also let it sit in the garage running. So far, nothing has leaked out!!! Thanks for the tip!!
 
No, I don't have an overflow tank on it. I did check the coolant and level and it was very low. I added coolant so it it fills up right underneath the cap and took it out for a test run and also let it sit in the garage running. So far, nothing has leaked out!!! Thanks for the tip!!
pressure test will answer a lot..unless your leaking coolant from somewhere the level should stay up.
 
I'll cast a 3rd vote for a leaking transmission cooler putting ATF into the coolant. If its going that way, you know coolant is going the other way too.... and the transmission won't like it. The old-school silicate based antifreezes precipitate out a fine brownish sand when mixed with hot coolant, and it really eats up clutch packs.
 
I'll cast a 3rd vote for a leaking transmission cooler putting ATF into the coolant. If its going that way, you know coolant is going the other way too.... and the transmission won't like it. The old-school silicate based antifreezes precipitate out a fine brownish sand when mixed with hot coolant, and it really eats up clutch packs.
I checked the transmission fluid and it's still nice and red.........so I don't think coolant is going that way..........
 
I checked the transmission fluid and it's still nice and red.........so I don't think coolant is going that way..........

Maybe not, but oil is lighter than water. The coolant goes to the bottom of the trans pan and the dipstick still looks clean, or at least it did on the 904 trans I lost this way ;(. The oil goes to the top of the radiator, so it's obvious there.
 
Back
Top