Coolant problems?

[Stu Bailey]

Hello my trusty diesel techs. I have come to a bump in trouble shooting my truck. I have an 86 F250 6.9 with 159,000 miles. I’ve never had any real problems I’d say, just minor little fixes here and there. Currently, I am having a coolant problem, or so I believe.
I drained and flushed all the coolant the other day and installed a new block heater and motorcraft e5tz-8575c Tstat along with the gasket. Ran a thin bead of rtv sealant for it as well. Filled her back up with about 4 gallons of coolant and then ran the truck for about 20 minutes with the radiator cap off. At this time, coolant was pushing up out the radiator and the stock temp gauge still read C. My aftermarket numerical temp gauge read about 160. Obviously one is invalid. And what’s going on with my coolant? I thought it is supposed to suck back into the block and lower the level from the radiator so I can fill the last galling or two and call it quits. Manual says 29 quarts is capacity with 5 in the reservoir. No leaks anywhere. Oh, and I’m blowing cold air out the cab vents with heat setting on max.

 

[Stu Bailey]

Also, I want to say it isn’t safe to plug in my block heater at this time?

 

[Cubey]

Coolant expands as it gets hot, so leaving the cap off that long would allow it to overflow. That's why there's an overflow bottle. The extra gets pushed out when it gets hot, and sucks it back in when it gets cold.

When my overflow was low after a drain/flush/drain/replace, it was sucking in air when it cooled off, making my upper radiator hose collapse in. When I opened the cap, it poofed back out because it removed the vacuum. Once I properly filled the bottle, it hasn't happened again since it's getting fluid, not air. That's also why you don't completely fill the bottle, it needs room for the expanding coolant.

Did you boil test the new thermostat? Even new Motorcraft ones can be faulty. But in that case it would be overheating, if it's not opening.

You need to just get out and drive it to burp the system, if that's what you were trying to do by idling it for 20 minutes with the cap off. Just bring the extra coolant and a funnel with you.

 

[Stu Bailey]

Hell yeah. I was thinking I just needed to drive it and see what happened but I didn’t want to **** anything up. But I’m doing it now, thanks for the advice! Will update after I get off and see what happens.

 

[Cubey]

Hell yeah. I was thinking I just needed to drive it and see what happened but I didn’t want to **** anything up. But I’m doing it now, thanks for the advice! Will update after I get off and see what happens.

In the day following the final flush/drain and refill, I forgot to double check the level and I got on the freeway. My factory temp gauge (didn't have aftermarket then) was CLIMBING HIGH! Yikes! I was only going 1 mile to the next exit so I just babied the throttle until the next exit and the temp gauge stabilized. No harm done thankfully. Just stick to city driving where you can quickly stop/turn off, and keep your foot out of it, and you should be ok, as long as you aren't insanely low on coolant. I was still a couple gallons short I think. But I couldn't get it to burp out the air by just idling, so I had to drive it. Just... don't get on the freeway to do it.

 

[Stu Bailey]

HAha yeah good call. Luckily for me there are plenty of low traffic highway roads around the house that I can go anywhere from 25-60 on without getting too far from home that also have unlimited pull over sites. Hopefully that burp does her good. When I took off the stat housing gooseneck I noticed that ball valve but can’t remember if it was shaking free? Any knowledge on that ball being essential? I read it was for helping purge air from the system.

 

[Cubey]

HAha yeah good call. Luckily for me there are plenty of low traffic highway roads around the house that I can go anywhere from 25-60 on without getting too far from home that also have unlimited pull over sites. Hopefully that burp does her good. When I took off the stat housing gooseneck I noticed that ball valve but can’t remember if it was shaking free? Any knowledge on that ball being essential? I read it was for helping purge air from the system.

It needs to be there, mine was but I didn't pay much attention to it besides making sure it was there. I did my thermostat many months later after doing the flush and it didn't take too much to burp it. I saved about 99% of the drained new coolant (spilled a little) to 1 gallon milk jugs, so when I went to put it all back, I knew if it was reasonably close to being 100% full to how it was before changing the thermostat. I had 2 extra gallons of coolant on hand in case of losing a lot by mistake somehow.

I think the vibrations, bumps, turns are what help burp it, something idling can't do. It could be how the ball bearing works. Topping off from the thermostat change (about 3 gallons drained) wasn't as much of a pain to burp as the full radiator drain was.

 

[gandalf]

You have a genuine Motorcraft thermostat? That's a firm requirement. What temperature is it supposed to open? I can't remember, but I believe it's above the 160* your gauge is reading. If the thermostat isn't opening, that will throw all other functions off kilter. Is the upper radiator hose getting hot?

Yes, burping the system is necessary. If you try burping without driving, I think I remember that it helps to do so with the nose high.

 

[riphip]

192* on the Motorcraft. If cap is off, will not build pressure. Running parked, nose up for burping. 7# rad cap is good for your rad life. 13# is original.
Engine running/driving should be at least 180*

 

[Stu Bailey]

Roger that guys. Just got home from work. Took a few tools from the shop so going to throw on the bibs and head out in the cold to burp this sonobitch!

 

[Cubey]

192* on the Motorcraft. If cap is off, will not build pressure. Running parked, nose up for burping. 7# rad cap is good for your rad life. 13# is original.
Engine running/driving should be at least 180*

With a new fan clutch and thermostat, even my big/tall RV only runs at 180F at 55-60. It ran around 190-200 before. I put a new 13# "safety" cap almost a year ago and it's fine.

 

[Stu Bailey]

Well shoot, that’s good to to know. I went out today to purge any trapped air out the heater core hoses but said f that. It was too cold. Supposed to be above freezing tomorrow so I think I’ll do it the then. Thanks everyone for the advice thus far though, tired of driving my wife’s minivan around :/

 

[riphip]

My 86 warms up pretty quick I guess, depending on the cold. When it is rolling, it will get you sweating.

 

[Stu Bailey]

You guys think I could plug in the block heater this morning to help her crank up when I go to work on it? The coolant should have flowed into the block from the bottom hose correct?

 

[Cubey]

You guys think I could plug in the block heater this morning to help her crank up when I go to work on it? The coolant should have flowed into the block from the bottom hose correct?

How much did you drain vs put back so far?