Brown stuff in radiator

I am installing an efi system on my recently rebuilt 350 and I went to change the thermostat and noticed some brown stuff on I t. It’s all in the radiator also but doesn’t seem to really be affecting the cooling. It’s a new motor and radiator what could be causing it?

 

If you have an Auto Trans the cooler maybe the issue in the Radiator. That would be the best issue.

 

Could be stop leak (like Bar's Leak) that was in the old heater core ... just a thought.

 

Rust seems to accumulate there. Just wipes off?

 

I found chocolate mousse in a radiator once; and a corresponding amount of oil missing from the crankcase.

 

This is just on the radiator cap, it wipes of easily. I just don’t want to drive it again till I have it fixed

 

It wipes off very easy but is in the radiator and was building up around the thermostat when I changed it

 

I would flush rad, blk & heater core, replace anti and see if it remains clear of gunk. That cap isn't orig. When system is clean it should look like this.

 

Hope there wasn't Dex-Cool in it...

 

I took the radiator to a shop to have it completely flushed out and they said it was really bad. Is this something that can happen with cheaper radiators? If I get a new radiator is the one from ta good?

 

^^^It can happen with even the original Harrison. Any new radiator is going to be clean and unclogged. I have been running a Modine since '82, flawlessly.

 

Realistically you can run any brand that fits. I have a northern radiator which is the same brand as a summit racing radiator had it for a few years problem free. I understand you got a praise TA where you can but I think they're shipping needs to be clarified. The last order the lady told me $10-$12. Got the order and it was $21.xx. not happy if you're going charge for a signature and insurance you need to state that and not let it be a surprise.

 

Several possibilities.

1. Rad shop is exaggerating to make themselves look like heroes.
2. Electrolysis in the cooling system, causing excessive and premature rusting. Check the radiator voltage; fix any poor grounds, maybe add additional grounds to drain excessive voltage.
3. Buick small-blocks often (or always???) don't have block drains. Were the block and heads properly cleaned when the engine was rebuilt? Core plugs knocked-out so the water jacket gets scrubbed? Crud builds up in the bottom of the water jacket, can re-dissolve in fresh coolant so that the coolant carries rust particles around. They'll lodge anywhere they feel like it--on the thermostat, on the rad cap, etc.
4. If the block was clean, and the radiator was new, there's always the heater core and the inside of re-used heater or radiator hoses to supply an endless stream of dreck.
5. As other folks have said...some rebuilders throw a "stop-leak" tablet into the cooling system. Maybe that's what you were seeing.
6. Most folks don't clean out the radiator overflow tank when flushing a cooling system. Often, they need hot, soapy water, and some sand and loose hardware--small nuts and bolts, washers, etc. Then shake the crap out of the tank. The sand and hardware scrubs the inside of the tank. Flush liberally with clean water to remove all debris and soap/detergent.

 

This was mentioned, but, any chance there were "red" and "green" coolant mixed together in the system? When mixed together it will create a brown sludge.

Troy

 

I’ll check the grounds. The block was cleaned, it also had all new radiator and heater hoses. The over flow tank was never cleaned so I’ll do that now. I think I still might get the ta radiator because the car will get up to 205 in traffic on a hot 100+ degree day. Thanks for the advice

 

The overflow tank top snaps off. Careful with the o-ring type rubber seal. Even SOS pad scrubs the crap out real well.