Burning coolant - intake, head, or gasket?

borjawil · Oct 17, 2017

94 4.0L 216k miles.

Was burning coolant, Then found coolant mixed with oil. Flushed coolant system. changed oil. Replaced driver side head gasket and all three intake gaskets. Put black rtv around coolant passages. replaced head bolts. After this no more coolant burning until now. Maybe 1k miles if that.

Burning coolant again. reused lower gasket but applied more rtv than last time. replace upper 2 gaskets. Not seeing coolant on dipstick, heat gauge goes to 1/4" from red mark. Burning coolant still i believe - white smoke/coolant smell.

Performed compression test- all pugs removed. driver side 120, pass side 130/140.

So my question is, how do I determine if its my lower intake gasket, cracked head, or head gasket? When tightening lower intake bolts to 15-18ft pounds I can easily keep turning the bolts further, as in, they don't feel like they are bottoming out (they are not stripped).

AgPete139 · Oct 18, 2017

It almost sounds like your head is warped. Even if you replace the gaskets, it can still leak again if that issue is not resolved. If you are driving that close to red for the extended period of time, I'd gander that this is the case.

You say they are not stripped, yet that very statement indicates otherwise. If you can continue to turn the bolt in the metal/block, then it is stripped. However, if you are saying that you torque to 15 ft-lbs and you CAN tighten it further, this makes sense. Of course you can. 15 ft-lbs is not a lot of torque.

This also begs me to ask you:

1) Did you follow the correct torquing pattern when reinstalling? Uneven or incorrect torque from the inside of the part -> outwards can lead to badly seated gaskets/mating parts.

2) Is the head pulled from the block material? This would coincide with your original problem of leaking coolant. In this cause, you may need time serts or case-savers.

3) What did the old gaskets look like? Do you have a picture of them? Did you see any coolant leaks or washed away bits on the gasket?

Flat-decking the part or running a metal straight-edge over the parts after you removed them helps you remove doubt from those parts being out.

As far as locating where it is leaking, you already did a compression test. After removing the heads and intake manifolds, if you didnt see visible cracks in the metal or the gaskets, I'd go back and check the 120# cylinder.

I'd go back and look at those heads, and where they are leaking though.

RonD · Oct 19, 2017

Do the Glove Test, it is free and easy

You will need a Latex Glove and rubber band; or a Balloon, or even a condom will work

Cold engine
Remove rad cap and overflow hose from rad
Coolant level should be at least 1" below top of rad, lower is fine, but drain some out to get 1" if higher

Plug the overflow hose port: vacuum cap, hose with bolt in it, putty, gum, ???

Put Glove over rad cap opening and seal with rubber band(or use balloon or condom over rad cap opening)

Unplug the 4 wire connector on Coil Pack(4.0l), you want a No Start

Crank engine and watch the Glove
If it bounces up and down then you have a blown head gasket or cracked head

If it just lays there then you don't

100% effective test

If glove does bounce then remove 1 spark plug at a time and crank engine
When Glove stops bouncing the last spark plug removed was from the leaking cylinder, reinstall spark plug to confirm.

If there is more than 1 leaking cylinder glove bounce will be reduced but not gone when 1st leaking cylinder spark plug is removed, continue on until no bounce is seen

borjawil · Oct 19, 2017

I think the intake gasket is my issue. Ordered an OEM. Will perform glove test - never heard of this. Very cool.

RonD · Oct 19, 2017

4.0l OHV uses aluminum lower intake bolted to cast iron heads, when you add flowing coolant thru the heads and intake you get electrolysis which eats away at the aluminum around the gasket.
It is a non-issue if you change coolant every 2 years

Check the intake at the 4 corners for signs of this wear, adding a bit of RTV around cooling passages(intake side of gasket) seals it just fine even with the wear

Yes, my Grandfather taught me that test, called the Balloon Test back then, people now are more likely to have a latex glove around than a balloon, so Glove Test

Shops now use a chemical test, Block test, to test for hydrocarbons(exhaust) in the coolant, I have tried it a few times and it does work
Glove test is just easier and simpler, and you can pin point leaking cylinder if you want

Shops can charge more for the chemical testing, pretty tough to charge for a latex glove and rubber band(or Balloon) with a straight face, lol
Chemical test just sounds better, and of course costs more

borjawil · Oct 21, 2017

No concerns for pitting or corrosion where the lower and head meet. #5 cylinder is leaking. Got everything apart and the small water jacket holes? on the head gasket are torn and the cylinder seal by those padded piece on the gasket was damaged as well. Maybe I scraped it putting the head back on. No Idea. Ill coppercote this gasket and see what happens.

RonD · Oct 21, 2017

Glad you found the problem, but sorry it was the head gasket

As tempting as it is to reuse the head bolts, don't

They are TTY(torque to yield) type, so a softer metal made to stretch ONCE when tighten that last 90deg rotation
These types of head bolts hold better and last longer over repeated heat ups(head metal expands) and cool downs(head metal shrinks) than the older type.
But downside is that once they are stretched they won't shrink back to "normal" when loosened, so reusing them will cause one of two things to happen.
1. they will snap/break on final 90deg rotation
2. they will snap/break after a heat up/cool down at some point down the road

Burning coolant - intake, head, or gasket?

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