Flushing the engine

[chicofuentes0224]

What 's the best way to flush the coolant passages going thru the engine to make sure absolutely nothing is in there?

[CWLONGSHOT]

Install a flush fitting. HELP area has them. It goes in line of the heater lines and you attach a hose.

 

Now that I think about it... I wonder if that funky valve we have will stop this from working... Some one will post up. In any event, You could remove that add a bypass hose and still use the flush with the hose as I said.

 

Remember, if the thermo stat is in it will stop flow if engine is not warmed up.

 

 

CW

[chicofuentes0224]

Yup CW, got that. I read to get it to run thru that valve I'm going to have to have the heater on full blast.

Here's my plan of action because I want to make sure I get all the crap outta the system.

1)Attach the T-fitting in the heater hose that runs into the heater core.

2) Drain fluid out of my plastic tank, then add Prestone Coolant flush sollution.

3)Close everything up and run the engine till it hits operating temperature to loosen up all the crap in the system that's accumilated after 20 years.

4) Let the coolant cool back down a bit.

5)Attach my garden hose to the T-fitting on my heater hose.

6)Turn on the garden hose with the cap off my plastic tank.

7) Turn on the engine with the heater on full blast and watch crap fly out of my tank.

8) Once all that comes out is clear clean water, shut off the truck and then the hose.

9)Disconnect both upper and lower radiator hoses and let water drain from the system.

10)Send water from the upper radiator hose thru to bottom to make sure the radiator has a good flow.

11) At this point I'm replacing my heater hoses, heater valve, plastic tank will be replaced by an aluminum one with another hose being run to a resorvoir tank (like Eagle's and PIKE.) converting me to an open system.

12)Zip evrything back up and add 50/50 mix.

 

So, anyone think I should do anything else or do things differntly to make sure there is nothing bad (rust, corrosion, bubblegum) left in the system to hinder the flow of coolant?

[mvusse]

That valve is vacuum operated, but it defaults to wide open. So all you have to do is pull the vacuum hose off it.

 

As for the thermostat, I would not run cold water through a hot block. The certain change in temperature could technically crack the block, but more likely would be damage to gaskets from the metal moving (shrinking) too fast. Plus, as soon as the cold water hit the thermostat it would start to close anyway. I can't remember for sure what the thermostat housing looks like on the inside, but I believe the bypass hole that goes to the heater hose (to the heater core and overflow/pressure bottle) also opens to the radiator hose.

 

But all back flush kits I have seen are meant for an open system. To work on our Jeeps, and make sure you flush the radiator as well, I would run it with the upper radiator hose disconnected from the radiator, but still hooked up to the thermostat housing. That way, if too much water comes through the hose to properly flush the heater line, cover it with your hand. The water will back flush the radiator through the bottom hose and out the upper hose hole.

 

I would connect the T fitting in the hose between the thermostat housing and heater control valve (that funky vacuum valve).

[chicofuentes0224]

That valve is vacuum operated, but it defaults to wide open. So all you have to do is pull the vacuum hose off it.

 

You mean instead of putting the heater on full blast?

[mvusse]

Yes, instead of putting the heater on full blast. And reread my last message, I edited it to add some stuff to it.

[chicofuentes0224]

Got it. Thanks MV :cheers:

[maddzz1]

I have a question about this. Once you flush with the hose and drain the radiator, the block is now full of water. If you then add a 50/50 mix of antifreeze and water; once it all mixes won't you have a overall mix of like 75% water and 25% antifreeze?

[mvusse]

No, you then drain the radiator and block, and then fill with a 50/50 mixture.

[mjeff87]

I just put new freeze plugs in a 4.0 block that I'm rebuilding. There were chunks of crud inside the block between the middle cylinder walls (between #3 and 4 especially) that I guarantee would never come out with a regular flush. I ended up loosening them up with a screwdriver and sucking them out with a small shopvac.....

 

not suggesting you pull all the freezeplugs to flush the block, but that would be the most effective way (although probably the most pain in the #&$#^ way) ;)

 

Jeff

[chicofuentes0224]

I just put new freeze plugs in a 4.0 block that I'm rebuilding. There were chunks of crud inside the block between the middle cylinder walls (between #3 and 4 especially) that I guarantee would never come out with a regular flush. I ended up loosening them up with a screwdriver and sucking them out with a small shopvac.....

 

not suggesting you pull all the freezeplugs to flush the block, but that would be the most effective way (although probably the most pain in the #&$#^ way) ;)

 

Jeff

 

 

Yeah, I'm afraid of having the same problem. I wonder how hard it would be to do with the engine still in the truck....

I'll take a look at it later.