5.0 Coolant leak from bottom of engine

[beach]

Great. Put in new radiator, did full flush over this week like normal and new tstat yesterday. No leaks, let engine run today for about 40 min at idle (let gasket sealant for tstat housing cure) no leaks from anywhere whole time.

Ok cool, run over to Lowes, get home. Walk out front, notice a continuous leak/drip from bottom of engine. Wtf. Just distilled water right now as was going to flush out heater core again and fill with coolant.

Attacched pic

 

[gmanpaint]

T-stat installed upside down, and boiled over from the reservoir?

 

[beach]

T-stat installed upside down, and boiled over from the reservoir?

Tstat def installed correctly always make sure of that, resovoir tank is good to go.

Edit - wait not sure what you mean by upside down? You mean backwards wrong direction? I have it installed correct direction.

 

[gmanpaint]

Yes, mistakes happen sometimes. Was just throwing that out there, at random, not insinuating anything.

Sometimes a new in the box t-stat can be bad. I have had the housing crack on me, and didn't see the leak until under pressure, at temp, and hitting the throttle by hand.

I have also had the lower intake gasket crack at the water jackets, and cause the leak. This repair is a pita!

 

[beach]

Yes, mistakes happen sometimes. Was just throwing that out there, at random, not insinuating anything.

Sometimes a new in the box t-stat can be bad. I have had the housing crack on me, and didn't see the leak until under pressure, at temp, and hitting the throttle by hand.

I have also had the lower intake gasket crack at the water jackets, and cause the leak. This repair is a pita!

Hope it's not a faulty tstat but don't believe so as doesn't appear to be any boil over, temps are good and gets to temp normally and stable. Faulty tstat would throw temp/guage out of wack, had that happen once on another vehicle. I'll murder someone before dealing with the stupid 5.0 housing design and water hose after yesterday lol, my hands look like I went bare knuckle fighting.

Weird thing, let idle for 40 min, no leaks anywhere. Go to Lowes and come back. When I went back out front that's when I saw the driveway

 

[lobo411]

What year and engine?

 

[beach]

What year and engine?

Oops forgot that in title, 2000 5.0. Just edited title

 

[974X4BLACKSPORT]

Ruusty freee pppluug maybe? Probably where it is most dificult to get too!

 

[CDW6212R]

Check the area below the thermostat housing, for coolant. It's kind of common to have the T'stat shift/drop down as it's installed, and that will get between the housing and intake, leaving a slight gap. I've had that happen once and it did leak immediately, nut I have a friend who swore his didn't leak, until the next day. We use plenty of RTV, so it's possible for it to seal just enough to start, but later it lets go.

Other than that, check the hoses and clamps for tightness and a good even seal. I had one new WP(SOHC 4.0 NAPA brand) with a casting seam on the inlet, create a big leak, I had to file the inlet surface smooth to seal it.

 

[RandomNerd2000]

I'd have to agree, check the T-Stat housing for leaking, mine when I had to change the thermostat I had a royal PITA getting it to align, even with RTV, and aligned it leaked some, then it quit two or three days later, but it'd run over towards the driver's side and down, just a tiny bit too, just enough that one would notice the slightest hint of coolant odor.

 

[beach]

Check the area below the thermostat housing, for coolant. It's kind of common to have the T'stat shift/drop down as it's installed, and that will get between the housing and intake, leaving a slight gap. I've had that happen once and it did leak immediately, nut I have a friend who swore his didn't leak, until the next day. We use plenty of RTV, so it's possible for it to seal just enough to start, but later it lets go.

Other than that, check the hoses and clamps for tightness and a good even seal. I had one new WP(SOHC 4.0 NAPA brand) with a casting seam on the inlet, create a big leak, I had to file the inlet surface smooth to seal it.

I'd have to agree, check the T-Stat housing for leaking, mine when I had to change the thermostat I had a royal PITA getting it to align, even with RTV, and aligned it leaked some, then it quit two or three days later, but it'd run over towards the driver's side and down, just a tiny bit too, just enough that one would notice the slightest hint of coolant odor.

Yeah that was my first guess as I had that happen once with the housing as the 5.0 as the most beyond stupidest tstat housing design and location, ever, lol. No leak there though. I clean the surfaces, and let tstat sit with permatex water/gasket sealant on housing for few hours, than applied another layer to other side of gasket mating to the intake housing. Let cure over night. No leaks in that spot. All hoses etc, no leaks.

Here's the odd thing, I drove again, parked. Check no leak. Came back out from store, checked again no leak. Drove back to house, same thing, no leak. I have no friggen idea what happened before as it was dripping heavily from that bottom housing as you can see from pics, except the engine at idle for 30+ min was fine, it was when I came back from Lowes the leak started, but checking all around (hoses etc) nada.

So fricken weird. I'm going to watch and check next few days and see.

 

[RandomNerd2000]

Check the rad cap for a good seal? Check your hoses too just to make sure, though I'd doubt a hose would do what you're describing.

 

[1998Exp]

Great. Put in new radiator, did full flush over this week like normal and new tstat yesterday. No leaks, let engine run today for about 40 min at idle (let gasket sealant for tstat housing cure) no leaks from anywhere whole time.

Ok cool, run over to Lowes, get home. Walk out front, notice a continuous leak/drip from bottom of engine. Wtf. Just distilled water right now as was going to flush out heater core again and fill with coolant.

Attacched pic

View attachment 162205

View attachment 162206

Gravity brings anything that leaks to the bottom of the engine. We can keep guessing, but if you don't see the source, get a radiator pressure tester, pressurize the system, arm yourself with a good flashlight and carefully poke around. Hint: take a good look behind the top corners of the timing cover - not easy to get in there, but worth the effort - it's a common spot for the V8.

 

[gmanpaint]

Did you burp the air out after the work?

 

[beach]

Did you burp the air out after the work?

Yeah but I could only get two jugs of coolant in even after running an hour. Flushed out heater core, and engine through the heater core inlet hose till water ran clear. I have ice old air and hot heat. Temps are correct inclusing upper radiator hose.

Yet I couldn't add distilled like normal? Usually on 5.0 two jugs of coolant and two gallons of distilled is what it takes, unless I'm having a brain fart....

Maybe new radiator has smaller capacity?

Gravity brings anything that leaks to the bottom of the engine. We can keep guessing, but if you don't see the source, get a radiator pressure tester, pressurize the system, arm yourself with a good flashlight and carefully poke around. Hint: take a good look behind the top corners of the timing cover - not easy to get in there, but worth the effort - it's a common spot for the V8.

yeah bud owns a shop so had him check it and pressurize, everything's fine. Explained the leak and showed him the pics and he was stumped as well.

 

[RandomNerd2000]

If it checks fine under pressure, I'd just change the cap? That's the ONLY variable you eliminate when you put a pressure tester on there.

 

[koda2000]

There's no way your going to get 2 gallons of straight antifreeze plus 2 gallons of water into a 5.0L. The reason is that there's no good way to get all the water out of the engine block after flushing because there are no block drains. Draining the radiator only gets about 1/2 the coolant out.

Check your cooling system capacity in your owners manual. After flushing and rinsing about 1/2 the capacity (in water) will be trapped in the block, then put straight antifreeze in the radiator and coolant reservoir and you should be at the recommended 50/50 mix.

I don't recall the total cooling system capacity of the 5.0L, but I'd guess it's around 16 qts. After running the engine to get the water and antifreeze mixed, test the freezing point with a coolant hydrometer. -34F is a 50/50 mix.

 

[CDW6212R]

I just went through my 302 cooling system in May. It takes about three gallons to fill it after the radiator and hoses are off/empty. I don't use 50% anti-freeze, water transfers heat better than anti-freeze. I use about 1/3 anti-freeze, I put one gallon in, plus one bottle of Water Weter, and topped it off with distilled water, less than two gallons.

I see high temps of around 190-195 through a 100 mile day here in TN, with the outside temps close to 90. The engine usually runs about 173, I put in a 180 T'stat.

 

[RustyMacintosh]

Bet the water pump weep hole is leaking. Just had the same area wet on my 94 4.0, pulled the front of the engine down, found the water pump weep hole leaking.

 

[beach]

I just went through my 302 cooling system in May. It takes about three gallons to fill it after the radiator and hoses are off/empty. I don't use 50% anti-freeze, water transfers heat better than anti-freeze. I use about 1/3 anti-freeze, I put one gallon in, plus one bottle of Water Weter, and topped it off with distilled water, less than two gallons.

I see high temps of around 190-195 through a 100 mile day here in TN, with the outside temps close to 90. The engine usually runs about 173, I put in a 180 T'stat.

There's no way your going to get 2 gallons of straight antifreeze plus 2 gallons of water into a 5.0L. The reason is that there's no good way to get all the water out of the engine block after flushing because there are no block drains. Draining the radiator only gets about 1/2 the coolant out.

Check your cooling system capacity in your owners manual. After flushing and rinsing about 1/2 the capacity (in water) will be trapped in the block, then put straight antifreeze in the radiator and coolant reservoir and you should be at the recommended 50/50 mix.

I don't recall the total cooling system capacity of the 5.0L, but I'd guess it's around 16 qts. After running the engine to get the water and antifreeze mixed, test the freezing point with a coolant hydrometer. -34F is a 50/50 mix.

yeah 5.0s are just under 16 quarts. Checked notes last time and it took just over 3 gallons. This time even filling heater core with a little coolant than distilled until showed in my flush line pushing coolant out. Filling radiator and burping seems I only got about 2 gallons. And other day added tiny amount of coolant left and little distilled. Weird.

Now have another issue. Like one thing after another lol. Now my AC is shutting off under normal moderate acceleration, then once cruising at speed starts blowing again. I check all around and found the tiny gray vacuum line snapped that goes to the heater control valve. Not sure if that's the cause? Worked perfect before and that line is so small have no clue if it was broken before or when I pulled the heater core hoses out to flush. Or if low on refrigerant but I had that evac'd and filled last year.

As far as coolant leak, everything seems to be ok. Drove today and around, kept checking underneath. No leaks. Have no clue what happened before, as even the drip left the rusty water stain on my driveway.