Should I do a complete coolant system flush?
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Cross-Country
Joined: Jun 2019
Posts: 90
Likes: 3
From: Nashville TN
Should I do a complete coolant system flush?
Old thermostat housing
Hello and thanks in advance.
I'm the proud third owner of a 1989 ford f150 4.9L it has over 305k on it and I have started doing my own truck work. I did the thermostat a few months back and saw this. I am about to do the water pump amd fan clutch. Should I flush the system and if so to what degree? I dont want to adversely cause harm by doing too hard of a flush. I know I might be overthinking it and or worrying to much. However I am enjoying greatly doing my own truck work and learning. Plus it's my only vehicle.
Thermostat port
Last edited by 300KRob4.9L; Jun 17, 2019 at 07:35 PM. Reason: Spelling correction
Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
Conventional green coolant is pretty limited to 2 year flush intervals. It looks alright inside, I would flush it very well and replace the hoses. Fill it with a ELC coolant and be good for 5 years.
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Cross-Country
Joined: Jun 2019
Posts: 90
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From: Nashville TN
Any suggestions how to best flush?
I'm not looking to spend a bunch of cash I've watched a few videos. Would it be ok to drive it for at least a few days with a full system flush product circulating through the whole system? The whole idea on using a garden hose doesn't seem wise since its water not distilled water. Again I'm not wanting to cause any harm or damage by doing a flush I know I might be overthinking and or worry too much. It's my only vehicle right now.
Elder User
Joined: Jul 2011
Posts: 793
Likes: 2
From: Vernon, BC
When you flush the cooling system, if you use a coolant flush product, simply follow the directions. If you don't use a coolant flush product then use a garden hose to flush the system and then drain the rad and the block before you refill the system.
Post Fiend
Joined: Apr 2002
Posts: 19,311
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From: Waterloo, Iowa
Coolant doesn't lose or wear out the antifreeze protection, but the corrosion inhibitors get used up. I don't stress too much about it, flush it and get some fresh stuff in there every couple years.
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Lead Driver
Joined: Jan 2003
Posts: 9,893
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From: Ohio
Stick a garden hose to it and run it with the lower radiator hose pulled off. Then flush radiator. Pull the heater hoses and back flush them both ways til it comes out clear. You'll be amazed what comes out and how well the heater works afterwards.
I am NOT a fan of Extended life coolant. Stick with the standard green stuff.
I am NOT a fan of Extended life coolant. Stick with the standard green stuff.
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Lead Driver
Joined: Jul 2017
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From: San Jose, CA
Another product I'm using now is called Thermo Cure (by the Evap-o-Rust people) and that's meant to be used to dissolve any rust that's in the system. Literally turns it to liquid and is flushed out after. Yours really looks pretty good I think, considering what it could have been after 30 years!
And don't worry about tap water for short term use. It's not a death-knell for a cooling system to use it to clean things out. We're talking long-term here. Not a few days.
And speaking of a few days... The advice to read the label is key! Some flushes (the ones I prefer now) can be left in for extended periods to do their work. While some still require you not only to flush them back out within a few minutes, but to follow them up with a neutralizing chemical to stop the action!
Those actually work really well too, but are likely to cause leaks too, in parts that were borderline to begin with and only the old rusty scale was clogging up the holes. First time I used one of those my heater hoses started leaking through multiple pin holes. But boy, was that system clean!
Good luck. As said, yours is looking pretty decent for it's age. A simple flush and re-fill with the right stuff and you should be good to go. Hopefully nothing else is needing replacement that would require a re-drain, but I guess you'll know soon enough.
Paul
And don't worry about tap water for short term use. It's not a death-knell for a cooling system to use it to clean things out. We're talking long-term here. Not a few days.
And speaking of a few days... The advice to read the label is key! Some flushes (the ones I prefer now) can be left in for extended periods to do their work. While some still require you not only to flush them back out within a few minutes, but to follow them up with a neutralizing chemical to stop the action!
Those actually work really well too, but are likely to cause leaks too, in parts that were borderline to begin with and only the old rusty scale was clogging up the holes. First time I used one of those my heater hoses started leaking through multiple pin holes. But boy, was that system clean!
Good luck. As said, yours is looking pretty decent for it's age. A simple flush and re-fill with the right stuff and you should be good to go. Hopefully nothing else is needing replacement that would require a re-drain, but I guess you'll know soon enough.
Paul
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Cross-Country
Joined: Jun 2019
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From: Nashville TN
Thanks
Thanks for all the input. I think I'm gonna leave well enough alone for now. No symptoms coolant is bright green. If I do change my mind I'll be doing Prestone rad flush+cleaner two bottles maybe just 1.5 bottles. Wait and see what comes out when I do water pump. If it needs it I'll do it after new pump.
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Cross-Country
Joined: Jun 2019
Posts: 90
Likes: 3
From: Nashville TN
I did it.
New pump perfect fit.
Cleaned up.
Coolant flush per new water pump instructions. I didn't want to void warranty. It kinda needed it some orange tent to it. Used 9gal of distilled water and two bottles of prestone radiation flush. Took 5hrs with 5 drains and 4 fills once fan blades get here. Learning as I go😁.
Elder User
Joined: Jun 2005
Posts: 542
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I usually drain out and catch what I can, then “pressure flush” it with a garden hose through the heater hose ports - I have various chunks of hose with garden hose ends for doing it. Then use a jumper hose to bypass the heater, and run a flush product, and pour a little into the heater separately (plugged a few in the past, don’t want to do it again ): ). If there’s a lot of loose scale, forcing water in through a heater hose port and out through the cap helps float it out, worst-case you may have to pull the radiator and flip it to get it all out. There will be a little tap water left in the system, but I figure it’s still better than what was in there before.
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