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Discussion Starter · #1 ·
What the heck could cause this? Picture taken on a 90 degree day. Temp gauge read around 180.
Iron block and heads with aluminum radiator. It's probably been 5 years since filling the system with 50/50.
 

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Looks like a lot of rust debris from the block and heads for the age of what it is. I have seen engines that were very old and the block and heads regardless of being aluminum or iron would accumulate a lot of debris like this after many of years of service and the system was never flushed and also come out of a heater core that was all plugged up.

Sometimes it is just because of an old engine and the cooling system was never changed on a regular basis and also from using straight tap water in the system which will make corrosion even more worse then using an already made 50 50 mix or by using straight antifreeze and then adding distilled water instead of using tap water. Some other factors can play into things as well. Looks like rust debris to me and some corrosion from just the age of the engine itself.

If this engine is not very old then there could be something else going on and that is not a good thing. I have only seen that on really old high mileage engines that have not ran very well and the cooling system is pretty much all original and the antifreeze was not changed on a regular basis and stuff.
 

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The engine is in my buddy's 37 Chevy. I don't remember the type of antifreeze, but water was probably tap water. As for the cap being greasy, I haven't seen it except in the picture, so I may have him join the forum and chime in here.

Engine is a 1-piece main seal 350. Don't know its history before 2003, but all we did was check the bearings before installing ZZ4 take-out cam and slightly used Dart 180 heads. (It was a budget deal at the time.) The car was driven a few hundred miles after that, then the engine got pulled at sat for many years, possibly with coolant still low in the block. However it runs great, no smoke, good oil pressure, and 180-200 coolant temps.

Sounds like the way to go is to flush the cooling system. Any tips on doing that? Radiator and intake manifold are aluminum.
 

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5 year old antifreeze is done , worn out out. I have the same crusty stuff in my Phord 1962 Falcon 200 cid cooling system. Aluminum cross flow rad in the car. I have tried several brand of antifreeze with distilled water. Same results: Crusty stuff. When i installed the radiator I hooked a ground wire to the rad to help reduce electrolysis.

Flushing the system I use distilled water bought at Wally WOrld. It is not expensive and I have no idea if distilled water really helps.
 

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50% antifreeze, 50% water. Supposed to be distilled, but I always use tap water.
The question was or is who’s 50/50 the choices are fairly wide but are.

1. Conventional green ethylene glycol based with silicate/phosphate based corrosion inhibitor. This now obtainable only as parts store house brands. Old time Preston.
2. Conventional blue propylene glycol with silicate/phosphate based corrosion ingibitor. Old time Peak.
3. Organic Acid Technology (OAT) the stuff developed as life time coolant that the factories use as original fill since the 1990’s. DexCool being an example, but these come in a wide range of formulations and colors.
4. A universal coolant a mix of silicate/phosphate and OAT in either an ethanol or propanol base which is representative of current off the shelf Preston and Peak and others. Being partially pregnant.

Then comes the question as to what the water is?
1. Factory bottled 50/50 where we assume the factory uses deionized but who really knows what the Chinese or Indonesian source is actually using.
2. Home brew of something in my previous question of the base coolant formula with?
a. Tap water?
b. Bottled water
- Human drinking water like SmartWater; not a good choice.
- Pee also not a good choice.
- Distilled water, a good choice.
- Deionized water another good choice.

Turns out based on more info from the OP the mix of 50/50 something with assumed to be water rather than pee is unknown both in what coolant and what other liquid(s). The engine sat unused for some time but is assumed the cooling system stayed wet but who knows?

To my eye the material stuck on the cap looks like pale rust colored cubic forms in some sort of a greasy or oily slime. Not the usual layered rusty crud one finds in cooling systems. Hence my questions as I’m trying to discern what chemistry would leave behind the deposits I think I’m seeing.

I really don’t know if flushing is of any real value. My experience is it’s pretty good on not very corroded systems but if the rust is a gooey layer on the bottom of the cooling jackets up to the soft plugs the process is useless whether it produces clean water or not it doesn’t take out these thick and heavy deposits to any great extent.

Like many other things extended life coolant is the auto manufactures response to the EPA trying to reduce hazardous chemicals in the water cycle of the planet. So you lost block drain plugs and gained 5 year (that’s their idea of life time) coolant instead of a two year cycle of the old silicate/phosphate stuff. But of course without drain plugs the typical coolant recharge leaves a sizeable residual of old coolant in the system just like with a auto transmission without drain plugs on the converter leaves a lot of old oil behind on you feel good oil change. The big trucking and heavy equipment operators use an additive package to boost the inhibitors without the nonsense of fluid “changes” every so many operating hours. We know that water doesn’t wear out and glycols don’t either unless exposed to oxygen. So the other modern element is essentially a closed system featuring an expansion tank so heated coolant is not lost to circulation, but in case the expanded fluid over pressures the system it bleed to a reservoir where the inlet/outlet tube is kept submerged in a little coolant as an air block similar to a P-trap in plumbing systems prevents sewer gases from backing into buildings by way of sink and toilet drains. In the case of your overflow tank it isn’t perfect as whatever residule sits in the tank to isolate the transfer tube is obviously exposed to the air we breath. Early Dexcool (an OAT base coolant) proved to be a bad actor when air got into the system.

Anyway things have gotten a lot more complex since the days of the cylinder being encased in an open top cast box where someone simply added enough water to keep the cylinder submerged.

Bogie
 

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I flush engines using a 5 gallon bucket after pulling the radiatior(you need a extension for the upper hose). Just use a garden hose to add cool water to the bucket to keep the engine within operating temp as it idles.

I flush and reverse flush the radiatior(and heater core) or just replace the radiatior at that time depending on the age/condition.

The amount of stuff that comes out when flushing these independently will surprise you.

I also almost always pull the engine when doing a clutch(almost always much easier) filling with fresh new fluids at that time.
 

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Looks like silicate precipitant. It sometimes happens when impurities (rust, air cavitation, dirt, incompatible gaskets, etc) cause the dissolved silicates to come out of suspension.

Is it like jello? If so, it's silicate precipitation.
 
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