Rust in block issues

[FordDuck67]

Greetings. I'm seeking a bit of help here regarding rust issues with my 1967 F100's 240 I6. I had it rebuilt about a year ago when I purchased it. It had been sitting about 31 years. It runs fine, but almost immediately had heating issues caused apparently by rust washing out of block into radiator. So radiator was replaced and the issue almost immediately resurfaced. I have driven it about 500 miles since purchase. Has anyone had this problem before? It would seem at some point you'd wash out all the rust!. I'm looking for solutions, advice, ideas--anything. I'd like to drive the truck further than 5 or 6 blocks at a pop! Many thanks,

[Ranchero50]

Pull the freeze plugs out and scrub / flush it out manually. You should also be able to run a high concentration of CLR treatment through the system. I dipped a pair of risers in it last year for a week and the CLR did a good job of dissolving the rust from the base metal.

[Bill Ramsey]

Use pantyhose as a filter to catch the crap entering the radiator.

[Manny]

Both spot on but I will also add that on the big six 240 Replace the water pump it you think you have bad issues or at least remove it while cleaning. Its right in the front water jacket. With the plugs out you can pressure wash it do whatever you want. Won't be a issue to get it clean again.

[RyansFord]

Use pantyhose as a filter to catch the crap entering the radiator.

Filtering the coolant sounds like a good idea. I just wouldn't want to run the risk of ending up with a piece of pantyhose stuffed in an engine block. No telling how much temperature or pressure a pair of pantyhose can withstand.

I think I would stick with flushing the system with about 100 gallons of water, under fairly high pressure. Also think about replacing thermostat, hoses, gaskets, etc. Pulling the water pump certainly wouldn't hurt either. Corrosion can easily build up in the thermostat housing, water neck, hose flanges/fittings, etc. Water plugs are a good spot to collect corrosion, and a good spot to access a coolant galley for cleaning.

I doubt CLR would hurt anything, I just don't know if I'd take the chance of it eating away at gaskets. Soap and water's probably safer, if you're just looking to loosen up pieces of rust.

If it were me, I'd start by flushing with a good hose/fitting and replace the thermostat and clean it's housing. If that doesn't solve it, keep digging. That booger's in there somewhere...

[Bill Ramsey]

Use pantyhose as a filter to catch the crap entering the radiator.

Filtering the coolant sounds like a good idea. I just wouldn't want to run the risk of ending up with a piece of pantyhose stuffed in an engine block. No telling how much temperature or pressure a pair of pantyhose can withstand..

it would have to get thru the radiator tubes, to get into the engine block. i have done this many times. do whatever you want.

[FordDuck67]

Thanks for al the advice. I probably wasn't clear enough...this would all apply to the assembled motor while it is in the truck, correct? Or not? Many thanks.

[RyansFord]

Thanks for al the advice. I probably wasn't clear enough...this would all apply to the assembled motor while it is in the truck, correct? Or not? Many thanks.

Not sure what you mean. You don't have to disassemble or remove the motor to flush it or replace/clean the thermostat or water pump. No need for an engine hoist.

[RyansFord]

Use pantyhose as a filter to catch the crap entering the radiator.

Filtering the coolant sounds like a good idea. I just wouldn't want to run the risk of ending up with a piece of pantyhose stuffed in an engine block. No telling how much temperature or pressure a pair of pantyhose can withstand..

it would have to get thru the radiator tubes, to get into the engine block. i have done this many times. do whatever you want.

I'm not saying it won't work. Just that I wouldn't trust it. If you've done it many times, you obviously got more gall than I. Either way, give us the run down of how you do it. Any specific type of pantyhose? I assume you're wrapping it around the engine side of the lower radiator hose. Are you leaving plenty of slack to catch inside the hose, or are you pulling it pretty taught. School us...

[Ranchero50]

Water goes into the engine from the bottom of the radiator, comes out the top. I assume you'd wrap a 'foot' worth of hose around the hose nub at the ankle and push the hose over it. Clamps tight and hope it doesn't leak. The 'foot' will reside in the top radiator tank catching funkies.

[Manny]

Water goes into the engine from the bottom of the radiator, comes out the top. I assume you'd wrap a 'foot' worth of hose around the hose nub at the ankle and push the hose over it. Clamps tight and hope it doesn't leak. The 'foot' will reside in the top radiator tank catching funkies.

He is right done it myself. Kinda strange buying them though.... Depending how bad this block is rusted. Had several really bad sludgy. I would say that pulling the water pump and thermostat then putting a water hose thru it back flushing is a fairly quick. Then filter and flush then get it full of fresh coolant with anew T stat. Just my

[FordDuck67]

So here's any update and followup question: The guy who rebuilt the motor has agreed to flush it for free. He rebuilt it, my mechanic assembled it and installed it and has been the one trying to solve the problem since. However, the rebuilder wants the motor brought to him, meaning the mechanic will charge me to pull the motor--understandably. Is there an advantage to pulling the motor and flushing it, or does this simply make it easier for him without making it possible to do the job differently? I'd like to know before I throw the bucks at it. Thanks,

[Ranchero50]

I see absolutely no reason to pull the engine. Ask the builder what he would do differently with the engine out versus in the truck. That's the important answer.

[RyansFord]

Engine builders aren't necessarily mechanics... He's probably not prepared to fire up a torch to remove a water plug from under a set of jack stands. Or he can't imagine doing it the hard way. Or maybe he want to disassemble and give it an acid bath.

[ButtaBean]

Just my 2 cents but I don't think I would trust an engine builder that would leave rust in the block to put air in my tires. I cant see how it would be possible for any concerning amount to accumulate internally in a year let alone immediately unless you filled it with straight water.
You didn't use that crappy GM dex-cool in it, by any chance?