This van is definitely possessed. I just replaced the head gaskets and have not even moved the van out of the garage and there is a massive coolant leak. All three cylinders on one side are wet and while the passenger side is dry, there is this mysterious puddle of coolant sitting the middle of the head bolt. See photo. If anyone can explain how it is possible to get coolant up into the head bolt go ahead. I sure am without a plausible explanation.


Here is a shot of the failed side. There is no obvious evidence of cracked cylinder heads which what I was sure I would find. Heads and manifold were properly torqued down. I've done this twice previously with no problems. The head gaskets show no sign of failure and it would be nearly impossible for all three cylinders to suffer simultaneous gasket failure. One could imagine the lower intake manifold gasket was not seated properly but when I pulled it out, there was no evidence of coolant leakage. It was completely dry. To quote Churchill, "its an enigma wrapped in a riddle shrouded in mystery".

 

Well the only sure way to check your heads for cracks is with pressure testing. I'm not sure what machine shops use to do that, but you can rent a cooling system pump that attaches to the radiator fill neck (or use my trick described below) for testing your cooling system.

Assemble everything (you can re-use your head gaskets for this, and replace later) up to the lower intake manifold so you get a sealed cooling system. Install a Prestone cooling system flush kit into the heater hose you you get a garden hose fitting. Get a garden hose cap from our local hardware store, and drill a small hole in it to fit a tire valve. Then cut the threaded tire valve off of an old bicycle inner tube and install it into the hole. Screw the cap onto the fitting you installed on the radiator hose.

Start pumping (either with a bicycle tire pump on the tire valve or with the radiator tester), and listen for leaks in the engine. Maybe you can put some tracer dye in the cooling system so you can trace where the leaks come from.

 

I'm guessing the coolant on top of the head was found after running engine up to temp?

My bet is on the lower intake manifold gasket leaking and spraying into the VC. Would explain coolant in cyls also
Only time I've seen a 4.0L head crack on top was from a major overheat.

Any coolant in the oil?

may have warped head preventing good seal to intake manifold.

have your heads been decked or ground flat? if so, will require matching machining on the intake manifold. done often on the 4.0L OHV by the creek crawlers to boost performance but requires some highly skilled machine work.

I'd use Permatex Hi Tack on the intake manifold gaskets and mating surfaces. ya, i know ford says nothing but their goop in the corners

Gasket Sealants : Permatex® High Tack

stuff adheres like dog poo on running shoes. remains tacky forever. holds up to all fluids except maybe 100% sulfuric acid.

I like the brush application, can pinpoint where it goes. They have a spray can version, but get it in the wrong place and spend more time trying to remove it.

my intake manifold had one area corroded out on the driver side rear, had to fill with liquid aluminum and file down to smooth even mating surface again.

 

I'm not sure about this engine , but some head bolts go into the coolant passages . In that case they require thread sealant or coolant will leak past the threads . Just a thought .

 

Well, well, well.....looky what I found this evening. Had to search with a fine tooth comb and remove some valves but this, I believe, is the culprit for all the mysterious aliments I've been plagued with recently. I rubbed the cracked area with some blue chalk to make it stand out better. Crack is contiguous with both valves and goes all the way through to the coolant galley behind.

This would pressurize the cooling system possibly causing some coolant blow by at the head/lower intake coolant passage. That head bolt shown earlier is immediately on the other side of the passage and thus some coolant may have been blown over and into the head bolt cavity.

Sitting overnight, I can see coolant leaking through and collecting around the valves and dripping onto the piston concavity. Start up would force coolant out the exhaust port and possibly up the intake port. I say possibly because I still cannot ascertain how the coolant gets into the next two cylinders. If it were forced up the intake portal and distributed via vacuum to the other 5 intake ports, all cylinders should be equally affected but the opposite bank is clean.

 

Nicely done. Great work on isolating the problem. I would have guessed a cracked head, but would have taken it to a shop for dye pen or mag particle inspection. Cracks aren't always easy to find, but you must have an eagle eye (and/or are young enough to still have good eyes).

Glad you found the problem but it sure stinks that you had to go in and remove the heads again. I've done it once and didn't enjoy it. Doing this a third time, I'd have to say that you have the perseverance of a saint.

 

The head cracked because the valve seats on that head are gone. These heads do this all the time. You should get new heads, but make sure the new ones come with valve seat inserts. If the head is just flame hardened, they will last long enough to clear the new head warranty, but over time it will crack again.

I'm not sure what brands come with the seat inserts.

 

Naw, it cracked because its old....like me! With over 300,000 miles I'm surprised its only a small crack like this. The head was in the machine shop a few months back and they said the valves and seats were okay. I'm a little leary of valve seat inserts. One of my kids had an Escort that managed to drop one of the valve seat inserts... made a huge mess.

Now that the engine is so stripped down I've decided to forego dropping everything from the bottom. I'll just pull it through the front as before. There was some coolant in the oil, so I want to check out the bearings.

 

300,000 miles, you got all the goody out of that head.
hope you have the other side magnafluxed for cracks.

Ford has had head crack problems with the Cologne engine since it brought production to the US with the 2.8 and expanded the block design out to the 4.0L
Ford never could engineer a correct thin wall cast head that held up in the US. Ford tried several changes to the 4L OHV head over the production run years with no success.
the fact the engine has no knock sensor and cut back algorithm makes the head crack situation far worse.
fuel mix off slightly too lean and the head self destructs.
reason Ford had to go to knock sensors in all their later engines especially the expensive aluminum block/head designs. replace 10 of those on warranty and it's some design engineer's job.

Europeans aka Germans who designed the engine never had head problems.
Auzzies redesigned the head casting in the 90s when they were racing the Cologne's. lots were imported to the states but production ended long ago. still see a few on creek crawlers and mudders.

the 4.0 head design was expanded out so much to fit the large valves in that the casting between the valves is far too thin. the cast iron Ford used is not the strongest.

the only 4L heads being cast now for our rigs are from China, quality unknown. believe there is only 1 4L importer left in the US, they source from 1 Chinese foundry.

is this the engine that had the new pistons/rings/cyls "treated" with white lithium pig fat grease Slik 50 breaking lube?

 

I must be in luck, I found an Australian cast head for $95. At that price, I'll order two!

The same one! Hey what's wrong with a van that smells like bacon? You shouild have seen the recent start up with all that coolant in the exhaust system......same dense white smoke...but a sweet smell. I nearly had apoplexy seeing that white smoke again.

 

Some of the most tense moments in my life have been the 10 - 20 minutes after starting up an engine that has been rebuilt/replaced or had major work done on it. Talk about nerve-wracking.

 

Tell me about it ! Just put in a short block . All good Ran 15 min. Wrist pen knock . Could kick myself now ! Got to drive her for a while though , My 53 is still needing work . She will be my daily driver , instead of this new 78 I got !