47-55.1 250 coolant sludge or hose lining breaking down?

[leegreen]

The 250 6 in my '52 is a good runner from a 78ish c10.
It keeps turning the coolant brown, It was flushed before I installed it and I changed coolant twice last summer, once to try and get it cleaner, then again after the water pump took a dive..

Radiator is old, but appeared fresh rebuilt in a parts truck I bought decades ago, it sat empty until last year. I flushed it before install and it seemed clean inside. Heater core and all hoses are brand new.

truck does not leak or use coolant or oil at least not noticeably. no evidence of oil in rad or coolant in oil

I have the radiator off to fiddle with front sheet metal alignment and flushed it.
I kept getting these crumbly chips out of it, they are up to finger nail size:

They are rust colored but not rust, not magnetic

Flushing the rad, it ran brown for quite a while until all the sludge was washed out

The rad hoses are new Dayco flexible hoses, both are coated with the same hard crumbly stuff inside. The upper (outlet) hose is worse

and lower


the thermostat is stuck open and will be replaced but the housing and neck are both clean, no sludge.

Has anyone seen this before?
Could it be some kind of hope-in-a-can leak stop gunk that was hardened inside rad or block until I started running it?
Suggestions for removing it? it seems flushing just carries away the loose stuff

[mr48chev]

It could be something like that if it isn't rust breaking loose. It might be a danged if I do, danged if I don't deal if you were to run some good radiator/cooling system flush through it or better yet have it power flushed if there is a shop around that does it. I used to power flush engines when I worked in a dealership back in the 70's and that worked great as the machine that they had pulsed the coolant and flush through the cooling system to break crud loose. If it had had stop leak in it to stop a crack or head gasket from leaking either may break that loose though. I had that happen on a Ford Tarus my daughter had years ago. we had the cooling system flushed and ended up with a coolant leak and had to put more radiator flush in it.

[dsraven]

my first question would be, have you been using a coolant/antifreeze or just water? second question would be is the sludge an oily kind of residue that has congealed together to form a lump or is it a hard crusty kinda chunk like rusty scale that has fallen off due to having been heated past it's normal range or possibly been subject to more coolant flow than it was used to in the past?
if its apart anyway I would pop a frost plug and look inside the water jackect with a light and a mirror or boroscope. look for any build up that has settled in the bottom and heavy scale on the walls of the cooling jacket. if you pull a rear frost plug the cooling jacket can be flushed out fore to aft. if it is back together, or can be put back together quickly, you could run some commercial cooling system flush chemical through it, which would involve running the engine to temp, possibly several times, and then draing. as a heavy duty mechanic I have had to flush large diesel engines that blew a gasket or whatever and ended up with oil in the coolant. we used something like dishwasher soap, the powdered style premixed in a bucket to disolve the powder. after that the system should be flushed with a hose but be careful of the water pressure in the hose or you may also be on the hook for a new heater core. there are cooling system flush "pistols" made to use a garden hose and possibly air pressure. I have never used one but have seen them. you could check with a local rad shop for advice on flush chemicals. after a flush I recommend a system pressure test, that pressures the system to slightly more than the rad cap rating, for 1/2 an hour or so. no pressure drop is what you're looking for. also think about some sort of water pump lube when done.

https://www.princessauto.com/en/cool...t/PA0008072605

https://www.matcotools.com/catalog/p...1lbnRfMTQ0ODUy

[dsraven]

if its an oily residue you will need to use something to flush that out because if it has adhered to surfaces in the cooling jacket it will cause hot spots because it works like insulation. then find out where it came from. if it is rust then it should have a frost plug popped so you can check the amount of scale on the cooling jacket side of the cylinders etc. a very small amount of rust scale acts like adding thickness to the cast iron that needs to be cooled, like insulation kinda.

[mr48chev]

I'd think that any water cooled vehicle that spent it's life in BC ran antifreeze year round but some folks never change the antifreeze like we did back in the 60's and 70's when we usually changed it every fall.

The more I think about it I wonder if that isn't radiator stop leak from the engine's previous life if the radiator or engine had a coolant leak.

I'd see if I can find a shop with a power flushing machine that can power flush it. That should shake more of it loose and get it out of the system quickly rather than having to pick pieces out a few at a time. Maybe Surrey radiator and Air conditoning as a place to ask about it.

[leegreen]

It is a hard scale, evenly deposited inside the hoses. I thought the upper rad hose was worse, but when I took the lower off and flexed it, it is just as bad. I got about 1/4 cup of scale out of the lower by slapping it on the ground. It is not specific to the dayco hoses as I found it inside a short section of Gates heater hose as well. I'll have to pull the rest of heater hose off and give it some bending, but I can't see any in the ends (different unknown hose, some NOS vintage dodge stuff I had).
The aluminum thermostat neck and housing have no buildup at all. The brass rad just appears to have some muddy sludge.

I think I have to bite the bullet and pull the water pump and a frost plug to look. I'm not thinking it is rust, or not entirely rust as it is totally non magnetic. I've never seen rust re-deposit itself elsewhere. This is like some sort of flocculation agent has an affinity for the rubber....it may be colored by rust? or some combination of antifreeze colorants?

I ran some experiments overnight, kleen-flo rad flush, vinegar, hydrogen peroxide . None of them appreciably broke down samples of the flakes. I might try bleach or a stronger acid out of curiosity but would not flush with them, at least not while this is still a good running motor.

The donor truck for this motor came up from Eastern Washington state, any weird stuff in your water down there?
I've never played with radiator flushing products before, we have pretty soft tap water around these parts. Kleen-flo was on the shelf at the parts place. Any recommendations?

(I need a deal on a 292!)

[leegreen]

It had antifreeze in it when I bought the motor, I would have dipped my finger into the rad to look for oil. I don't recall it being dirty antifreeze either.
The truck was a super clean running and driving rust free SB fleet that was going to get hot rodded up. This was about 4 years ago so I don't think it could have been too neglected by previous owners to have made it this far.

[dsraven]

once you get it figured out you could install a bypass coolant filter i the heater hose line, if you think there could be more to catch after the flush.
stop leak usually has a metallic look to it, like metal flake paint. maybe not if it's been in there for awhile
coolant, in general, slowly goes acidic over time and I have seen it eat a hole right through a casting. the long life stuff is good for about 5 yrs. there are test strips availabe to test the level of alkaline or acid.

[dsraven]

is this an engine you have had laying around waiting for a ride to fit into or is it in your AD currently? what do you run for coolant?
lots of guys run tap water to mix straight antifreeze down to the required level they want but distilled is really the best way to do that. no impurities from the local water supply that way.

[leegreen]

I bought it about 6 years ago, first ran it in the truck 3 years ago and had it on the road and driving regularly a year ago. It did not mess up the coolant other than some slight darkening until it was on the road.

I've always run whatever name brand coolant is on sale, mixed with tap water. Everyone uses tap water around here. Snow melt lake water from nearby mountains with some chlorine added municipally to kill giardia and what not.
We don't have issues with mineralization. Water from the same sources gets bottled and sold internationally.

[Hcb3200]

Could be a Iron Bacteria. Water wells get them here in the south especially if they get contaminated. This brown sludge looking stuff sticks to pipes and the rubber would be a good candidate for it to cling to. Bleach flush 1/4 per gallon is what is used on the wells. you dump it in your well. run the water in your pipes then let soak for 24 hours. over bleaching the mixture does not speed up the process I hear.
you could soak your hoses and see if that works.

[leegreen]

I had not thought of it being bacteria based.

I have some stuff to learn here....

"bacteria can live on glycol but not above 20%"
if that is true it is unlikely the cooling system could support any bacterial flourishing. At least in my ownership it would be closer to 50% and >20% would seem necessary for washington state

that said pictures of iron bacteria scaling in water pipes may be similar to what I have going on. Color matches but mine looks harder and less fluffy

I had some of the flakes in bleach overnight, it did not break down. But maybe flushing with bleach would be a good preventative measure in case there are bacteria spores.

[Hcb3200]

I am with you on the chemistry just not sure how long it had sat with water and less mixture of ingredients. And like you said was not fluffy. But thought I would throw it out there. It is perplexing but I am going to go with that hose makeup must not gel well (pun intended) with the flavor that was in there before. if it was located other places might think otherwise.