Head gasket failure on the 3.0 - how common?

[98v70dad]

I've got a '96 XLT that has been having the coolant level drop a little every 6 months or so for years. I never had any puddles under the truck or white tracks indicating a leak. This was my dad's truck and he didn't maintain it. But, when I got it 5 years ago I did a flush and fill . I'm thinking there may be an internal leak since the coolant has been disappearing slowly without a trace for years.

Yesterday on a short trip (half mile) driving home from the store the engine sort of hesitated and "recovered" a couple of times. A block from my house some steam came out from under the hood on the passenger side. Another bit of steam came out in my driveway. When I popped the hood more steam and I found several of the inlets/outlets on the heater bypass valve snapped off.

The temperature gauge showed the coolant temp about halfway between normal and hot. Maybe the coolant was hot enough due to a low coolant level (hadnt checked it for about a month) to degrade the 28 year old valve enough to fail.

So, anyhow I'm just trying to nail down the diagnosis and helpful comments would be appreciated. To start, I ordered a new valve. My plan is to install it and see what happens. I also plan to see if there is any coolant in the oil or oil in the coolant.

 

[rusty ol ranger]

If compression is pressurizing the shit out of the cooling system i could see something like that happening.

Pull the radiator cap off (when cold) fire it up and watch for bubbles

 

[Uncle Gump]

I've seen some talk of the timing cover on these leaking. Hard to see and slowly gets worse.

I think I remember the cover actually pitting.

 

[RonD]

+1 ^^^

Blown head gaskets are caused by overheating(not a chicken and egg thing), when over heated the head metal expands more than normal and crushes the head gasket between head and block
Caused by low coolant level or blocked coolant flow

So you are probably OK if temp gauge only got to 3/4

The plastic by-pass valves often cracked, common issue

White smoke out the tailpipe is a more common sign of head gasket failure, very obvious

Cooling systems don't have pressure until engine has warmed up, so a smaller leak won't start to leak until engine is warmed up and when it leaks it evaporates so no sign of a leak on the ground

To find a leak like that rent a cooling system pressure tester, $10-$20
Its a radiator cap with a hand pump and pressure gauge
Cold engine
Top up radiator
Install cap and pump pressure up to 20psi
Watch the gauge, if its slowly dropping then there is a leak
Look under vehicle for the dripping coolant and follow it back up

You can get pin hole leaks in hoses, these spray an INVISIBLE stream of coolant back onto the engine so the dripping coolant is NOT where the leak is, lol

 

[98v70dad]

The engine used in the Ford Taurus and Mercury Sable's of the same vintage was known for head gasket failures caused by the new technology (then) of "stretch" head gasket bolts. The bolts were tightened intentionally until they stretched and the bolt material yielded. This was a new approach and it had a higher than normal failure rate because measuring torque is a bogus way of measuring strain in a bolt. So, head gasket failures aren't always caused by overheating. My 94 mercury head gasket failed due to the factory bolts not properly sealing the gasket. The guy who sat next to me at work had his fail for the same cause. We proved it by looking at one of them under the electron microscope. Ford refused to do anything about it even with proof and it being a known issue on those cars. The design was clearly flawed. All engineering mistakes should be covered under warranty. Anyhow, that is why I asked the question. Some cars are prone to head gasket failures because the weren't designed properly.

 

[RonD]

Not trying to start anything because what you are saying is what most people think about the 3.0l Vulcan head bolts, but................

The 3.0l OHV Vulcan engine didn't use TTY head bolts until 1999
1986 thru 1998 use standard head bolts with final torque at 63-73ft/lb
1999-2008 used TTY and 2 final turns of 85-95deg then another 85-95deg

The 3.0l DOHC Duratec used TTY bolts but engine was first used in 1996

You can look at page 22 here, it has the Ford specs: http://www.mascaroporter.com/mpc/2009TorqueSpecsGuide.pdf

TTY bolts are better as head bolts because they can stretch, which is needed each time an engine is warmed up and then cools down, especially with aluminum heads, lol
But I think the main reason to switch to TTY was engine assembly cost
Final torque sequence of say 70ft/lb needs to be correct, and torque wrenches need to be calibrated every 4,000 to 5,000 uses, so every 300 V6 engines, which can be every few days if not every day
With TTY and just degrees of rotation no calibration is needed for final sequence(s), and the first torque of 36ft/lb, loosen then 24ft/lb are not as critical
Also easier for automated assembly, 90deg rotation is easier for a computer to see/control, than a torque reading


I don't doubt one or two head bolts failed but they were standard bolts in a 1994 3.0l 12valve, but could be replaced with TTY
And I don't think you can even get standard head bolts for the 3.0l OHV they would all be TTY

The 4.0l OHV 1990-2000 did use TTY bolts in all years, as did the 4.0l SOHC

 

[98v70dad]

Well, you are up on all of that so you know what you're talking about. Its been a long long time so I may not have the year right. But I know my sable had the new bolts and Ford was having a problem with them at the time. Today I just want to get my old truck running again and I want to fix the root cause instead of just replacing the failed part. I agree that a leaking timing belt cover is probably the culprit in my case. I crawled under the truck this morning to investigate and that area on my truck is damp and has stains.

 

[98v70dad]

My part arrived today so I'm putting it in tomorrow morning. Thanks for the comments.

I know that the heater core is a loop so the two hoses going to the heater core can go on either way. How do the other two hoses attach to the bypass valve? I know the whole thing is a loop but it seems like the hose orientation on the engine side of the bypass valve would matter. Please help me figure out what hose goes where. I should have looked before I took the bypass valve out but I didn't think of that at the time.

 

[Josh B]

I don't see a photo but here's their definition

1996 Aerostar/Ranger/Explorer Contents/Index ​
		Group 03: ENGINE ​

Coolant Flow


Coolant flows from the radiator through the lower radiator hose (8286) to the engine-driven water pump, which forces it through the cylinder block and cylinder head passageways. If the water thermostat is closed, coolant returns to the water pump through a bypass hose from the thermostat housing. If the water thermostat is open, the coolant passes back into the radiator through the upper radiator hose (8260) where air passing over the radiator tubes removes the excess heat.

 

[98v70dad]

I don't see a photo but here's their definition

1996 Aerostar/Ranger/Explorer Contents/Index​
		Group 03: ENGINE​

Coolant Flow


Coolant flows from the radiator through the lower radiator hose (8286) to the engine-driven water pump, which forces it through the cylinder block and cylinder head passageways. If the water thermostat is closed, coolant returns to the water pump through a bypass hose from the thermostat housing. If the water thermostat is open, the coolant passes back into the radiator through the upper radiator hose (8260) where air passing over the radiator tubes removes the excess heat.

Unfortunately the link and picture don't work for me. Maybe I need to update something. I haven't been on therangerstation for a while.

The text doesn't help me decide which hose goes on which port of the heater core bypass valve. The heater core loop is separate loop as I understand it and the heater core bypass valve is in that separate loop.

My valve disintegrated in my hands when I took it out. So, I was left with the valve body and 4 stubs stuck in the hoses

 

[Josh B]

This its verbal description (These are not links but simple copy/paste of their descriptions from the 96 Ford Manual on CD)

1996 Aerostar/Ranger/Explorer

Coolant Flow

Coolant flows from the radiator through the lower radiator hose (8286) to the engine-driven water pump, which forces it through the cylinder block and cylinder head passageways. If the water thermostat is closed, coolant returns to the water pump through a bypass hose from the thermostat housing. If the water thermostat is open, the coolant passes back into the radiator through the upper radiator hose (8260) where air passing over the radiator tubes removes the excess heat.

 

[alwaysFlOoReD]

Heater core bypass valve... it shunts the water flow from the heater core? Then it shouldn't matter which way the two hoses are connected on the motor side or the heater core side. But it would matter if you got one of each side on the wrong side.

 

[superj]

The gage will always read good if the coolant drops below where it last marked. That what sucks about having a leak. If it iverheats and coolant is still in, the gage will go red. No fluid, no gage movement

 

[98v70dad]

I got the valve in. Figured out the orientation. Filled it with coolant, drove it 20 miles and its running fine. I don't know how low the fluid level dropped but it only started steaming about a block from my house driving 25 mph. I think it will be OK but time will tell.

 

[Josh B]

It;s hard to tell man, I recall my dad dumping any bucket of water he could get on a motor to cool it down some after it overheating