I plan on draining and cleaning my radiator either today or tomorrow, wondering if there is anything else I should do while I'm at it, like a thermostat? I've got an '86 F250 6.9L and have had some issues with overheating, at least going by the stock gauge, so I was thinking a new thermostat would be good.

Just making sure there's nothing else I should take care of while the coolant is drained.

Zac

 

Be sure to drain the block. Coincidence, I am on my way out to do exactly the same thing. there are two plugs in the block for coolant. One on either side towards the back. One is easily accessible, one is hidden behind the starter. I loosen them to finger tight, then use a piece of 1/2" copper pipe insulation around the plug as a hose to drain the coolant into a bucket. Be forewarned the passengers side yields about a half a gallon of coolant! They are brass 1/4" plugs with a hex head. Make sure you use a Motorcraft t-stat, and test it before you install it. Place it in a pot of water and boil it. Take it out it should be at least a quarter of an inch open. Watch it close as it cools and put it back in the water and repeat the process a few times. Now is a good time to do your water pump, and they are cheap. I think I paid 33 bucks from Rock auto for my last one. If you are overheating check your fan clutch. It made a world of difference on my truck while pulling my 5th wheel. FYI the engineers made the t-stat on these trucks a bear to get to, at least on the 7.3, I've never played with the 6.9. I'd like to give them a size 10 thank you for that one! One last thing, the Motorcraft t-stat comes with a gasket, you do not need to buy one, and if it doesn't, PM me I have several extras!

Good luck,

Mac

 

Speaking from experience, be ready for some other items related to the cooling system to start giving you problems once you're done. I flushed my system when I bought the truck and developed a tiny radiator leak a few months later. Others have experienced similar results, but with the heater core or water pump. It's not a guarantee by any means, but once you start playing around with cleaning out a system that typically doesn't get the love it probably should, things start to domino.

Don't put too much stock into the OEM gage, though. They're notoriously worthless.

Mike

 

Thanks for the help guys. Mac I will look into draining the block as well, so is this going to be something I will get to underneath the truck? Near the back of the engine, so back by the cab?

I thought about doing the water pump too but isn't this a pretty big job? I was hoping to just do the coolant and a couple other things before taking my truck on a 300 mile round trip over the mountains, really hoping it doesn't break down anywhere along the way so I'm trying to tie some loose ends. Again I just bought the truck a month ago and am not positive how well it's been maintained.

 

Yep the drain plugs are accessed from under the truck.

Here is one, Right behind and above the oil filter on the drivers side.



And here is the other. Right in front of and above the starter.



Yours probably won't be this clean!

If you water pump is not leaking, you do not need to replace it now, but it is not very difficult at all with the radiator and fan out. If you need to do it later, you are going to kick yourself for not having done it now for 33 bucks! There is a weep hole on the bottom front of the water pump. Look for any signs of coolant coming out of it.

Again good luck,

Mac.

 

Bragger

Mike

 

Wow thanks for the pics, that helps a lot. The underside of my truck is pretty filthy, I have a feeling they might not be as easy for me to find... do you think it'd help to pressure wash underneath first? Is there anything I should be careful of if I do?

Again thank you SO MUCH for the help, guys.

 

I'd crawl under and have a look, first. Mine were easy to spot and didn't fight me at all when I took 'em out, even though I know I'm the first to ever touch 'em.

Mike

 

Damn straight! I worked hard to be able to say that! I'm throwing it out every chance I get! LOL

Mozzles,

Pressure washing the bottom of the truck is not so dangerous, avoid the top, unless you waterproof some things like intakes and electrical components. Even then I wouldn't do it, for I have experienced hydrolock before and hope never to again! Compressed air and degreaser will get a lot of it.

You should have no problem finding them though, they are pretty visible.

 

new upper and lower rad hoses if miles/age is unknown along with a new 13 lb radiator cap.nothing like being stranded due to a blown rad hose.cost ya much more in fuel/time lost than if you just keep them changed every 60k miles.like every other flush or so.
since the coolant is drained,adding a coolant filter wouldn't hurt if funds allow.
https://www.ford-trucks.com/forums/1...coolant+filter

it removes this trash:

 

I'll second that nothing wrong with changing your coolant early.

I changed mine when i got my truck and i haven't got any leaks. My rad hoses are a tad soft but i haven't had a problem in a year and a half since i changed it.

Use distilled water!

I second that the stock gauge is junk. Mine is always on cold, but it sure ain't cold. Unless its like 100 degrees out then it will go in the middle pretty quick with stop and go. The senders for the gauge are cheap. The new ones tend to behave correctly. Old ones act all funky.

 

I can't even find a coolant filter, usually go to O'Reillys for parts and they don't seem to have one. Did a google search and it didn't come up with anything... where do you guys usually get them from?

I'll look into changing the cap and hoses, doesn't sound like it's very expensive.

On the stock gauge I'm reading around the A and L on NORMAL after a short drive, plus the engine just feels hot to me.. never had one of these trucks before so maybe they just run like that, I'm not sure.

 

Napa has coolant filters. They are just like oil filters. Some have sca additive in them thats the only difference.

 

Fords post above has all the info you need on coolant filters including Napa part numbers and install information. Use Wix for the filter head and first couple filters they are exactly the same for half the cost.

https://www.ford-trucks.com/forums/1...coolant+filter

 

The first couple filters, meaning there are multiple filters? I read through that thread and am still unsure. Oh and is this the filter that is next to the fuel filter and water separator, the black cylinder thing?