Question: Declogging a Blocked Radiator/Thermostat/Hoses

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Joined
Aug 14, 2020
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Location
Ocala, FL
I tried searching for a thread that could help me with my current issue with my Cruiser build/revival but didn't see anything that seemed similar. Started a separate thread from my build thread for troubleshooting this issue.

Last weekend, I got my Dad's old cruiser running again but had a radiator hose burst when I first started her up (she was running for about 3 minutes) dumping fresh radiator fluid everywhere. I got new hoses in the mail yesterday, but ran into a snag when I went to install today.

From some intense Googling, I am thinking that the old radiator antifreeze crystalized and clogged up the system. I didn't know that could happen, but unknowingly trying to push that slurry through didn't help at all. Thank God that hose burst, as I don't think there was any coolant running through the engine at this point.

I tried digging it out with a screwdriver, but it appears that it is solid all the way past the bypass hose. I tried to flush it using water but couldn't even get it to move.

I am not sure how to proceed... Is there anything that I can use to dissolve this blockage to flush it out without damaging my cruiser, or will I have to take the thermostat housing and the head off the engine to clear it?

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I would remove the thermostat housing, also remove the rear side drain on the block. and see what it looks like.
very likely the block will need to be removed and tanked.
 
Pulling the head will give you a little more access to chisel away at that stuff. But still, probably not enough to really clean it up as much as I would want to....
Do a couple internet searches and see what other people have tried and if it's successful...
And, keep those hoses, etc., to test on.
I'd first of all take that thermostat housing off and put it in pot of boiling water and see what happens...
 
I tried searching for a thread that could help me with my current issue with my Cruiser build/revival but didn't see anything that seemed similar. Started a separate thread from my build thread for troubleshooting this issue.

Last weekend, I got my Dad's old cruiser running again but had a radiator hose burst when I first started her up (she was running for about 3 minutes) dumping fresh radiator fluid everywhere. I got new hoses in the mail yesterday, but ran into a snag when I went to install today.

From some intense Googling, I am thinking that the old radiator antifreeze crystalized and clogged up the system. I didn't know that could happen, but unknowingly trying to push that slurry through didn't help at all. Thank God that hose burst, as I don't think there was any coolant running through the engine at this point.

I tried digging it out with a screwdriver, but it appears that it is solid all the way past the bypass hose. I tried to flush it using water but couldn't even get it to move.

I am not sure how to proceed... Is there anything that I can use to dissolve this blockage to flush it out without damaging my cruiser, or will I have to take the thermostat housing and the head off the engine to clear it?

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You will need all new hoses and clamps for sure and a new OEM thermostat itself

as far as your upper housing ?

its Smoked and should be replaced , hot tanking it will only further break down the sketchy aluminum
Still remaining leading to Total failure

this is if it actually survives the hot tank process at all ?

please throw me a PM , I can help you here with this topic .....

thanks
Matt

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Looks like it's time for complete disassembly and engine rebuild is in your future.
I was hoping it didn't have to come to that, but was kind of expecting it.

I would remove the thermostat housing, also remove the rear side drain on the block. and see what it looks like.
very likely the block will need to be removed and tanked.
I will take a look tomorrow morning, hopefully it isn't as bad as it looks. I'm not gonna hold my breath though.

Pulling the head will give you a little more access to chisel away at that stuff. But still, probably not enough to really clean it up as much as I would want to....
Do a couple internet searches and see what other people have tried and if it's successful...
And, keep those hoses, etc., to test on.
I'd first of all take that thermostat housing off and put it in pot of boiling water and see what happens...
I wasn't able to find much information on such a severe blockage other than advice to try to dissolve with boiling water and the like. I was hoping for some snakeoil cure from the experts. "No problem Sword, just spray some Super Purple Foaming Declogginator 9001 from NAPA on it and let it sit overnight. No worries."

I will try digging in tomorrow morning to see how bad it is. My motivation is currently low when combined with the heat outside right now.
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@ToyotaMatt Thanks for reaching out, I just replied to your PM.
 
I might try getting evaporust into the coolant part of the engine block and let it work. Pull the thermostat and use that port to fill the engine. I’d replace the radiator at a minimum so don’t worry about clearing that. That looks a lot lIke an overdose of radiator sealant crap in those hoses and thermostat housing. The water pump must have spun ok since you have a belt in place. After filling with evaporust and sitting for a good long period - many days - pull the block drain and work from there back to get flow. Poking, prodding, and high pressure air to get that open. And repeat. Drain the oil first completely, maybe even pull the pan. If there‘s a crack somewhere you’ll see evaporust in the pan. If unclearable, or has block leaks, then you can head down the more expensive rebuild or replace path. Good luck.
 

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