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Discussion Starter #1
Hi,

I have a question for you. A few months ago, my wife's 2000 Ranger 4X4, 4.0 Vin X, began to consume coolant, and miss at startup. The problem was coolant in the LF and RR cylinders. Never overheated, never pressurized the cooling system. I assumed a leak into the intake port. Fast forward, problem is much worse, misses at idle always, runs great above 1000 RPM. Actually fouled ALL the plugs with coolant a few days ago- cool morning, no start. Cleaned them, drove it two days, basically the same. Misses, collant smell from exhaust now quite pronounced. NO oil contamination.

I pulled the lower intake. The coolant ports are SO FAR away from the intake ports that I have trouble believing that it is the source of the coolant, although the intake valves on the two cylinders it misses on are QUITE washed of carbon, and there is a nice clean swath through the carbon in the intake port. The rearmost bolt at the RR was quite loose.

I called my friend who runs a machine shop and he said the 4.0 heads are bad to crack between the valve springs (isn't that pre-1998?), and told me where to look. I see no cracks. I have read of the exact same symptoms on other forums, but no EXACT fix. I am about to seal the coolant ports with small plates, fill the intake ports with soapy water, use my regulated cooling system pressurizer to put 18 PSI or so on the cooling system, and look for bubbles in the intake ports, unless someone in the know about these rats tells me this is a common failure, and here's the fix.

Last thing- are there coolant passages sealed by the gasket between the fuel rail and the lower intake? It's dark out back, so I haven't taken that apart yet. SOMEHOW coolant is getting into the intake side of this engine, but not directly into the combustion chambers. No pressurization. Do the heads crack ABOVE the valve seats into a coolant passage?

Just for reference, I am a 30+ year veteran ASE Master, Chrysler Master, blah, blah, blah. Just never seen this before, and having trouble believing the vacuum from the port pulls the coolant over to the intake port without getting enough in the oil to show up. See what I mean?

Your response GREATLY appreciated,

Wayne Wright
 

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I wish you luck...my 1991 explorer sport was suffering from many hard miles at over 200K+ miles, and I dealt with a mystery leak of antifreeze, until I discover it was the intake manifold seals...I took the easy way out however on mine and sold it as is on ebay to a kid because I didn't want to mess with it.
The heads were a problem child, {those, and the 3.8L the mustangs had in the mid-late 90's}, but not honestly sure on the newer stuff such as yours...I assumed they fixed the issues though.

I imagine there has to be some TSB's out there, but I don't have access to Ford's database, after my buddy quit the dealer he was working at.

I thought the leak on the manifold was typically towards the front of the intake?
{sorry, I am probably not much help here-I fought my problem for two years and gave up}
 

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I pulled the lower intake. The coolant ports are SO FAR away from the intake ports that I have trouble believing that it is the source of the coolant, although the intake valves on the two cylinders it misses on are QUITE washed of carbon, and there is a nice clean swath through the carbon in the intake port. The rearmost bolt at the RR was quite loose.








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is that a cammer motor or push rod?

Check out the "Serious Explorations" web site. I have no doubt you will find your answer there or at least someone who has also had your problem.

I have a 99 Exploder with the cammer motor and all the problems associated with it and that web site has been a gold mine of info.
 

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Discussion Starter #7
Hi,

I have a question for you. A few months ago, my wife's 2000 Ranger 4X4, 4.0 Vin X, began to consume coolant, and miss at startup. The problem was coolant in the LF and RR cylinders. Never overheated, never pressurized the cooling system. I assumed a leak into the intake port. Fast forward, problem is much worse, misses at idle always, runs great above 1000 RPM. Actually fouled ALL the plugs with coolant a few days ago- cool morning, no start. Cleaned them, drove it two days, basically the same. Misses, collant smell from exhaust now quite pronounced. NO oil contamination.

I pulled the lower intake. The coolant ports are SO FAR away from the intake ports that I have trouble believing that it is the source of the coolant, although the intake valves on the two cylinders it misses on are QUITE washed of carbon, and there is a nice clean swath through the carbon in the intake port. The rearmost bolt at the RR was quite loose.

I called my friend who runs a machine shop and he said the 4.0 heads are bad to crack between the valve springs (isn't that pre-1998?), and told me where to look. I see no cracks. I have read of the exact same symptoms on other forums, but no EXACT fix. I am about to seal the coolant ports with small plates, fill the intake ports with soapy water, use my regulated cooling system pressurizer to put 18 PSI or so on the cooling system, and look for bubbles in the intake ports, unless someone in the know about these rats tells me this is a common failure, and here's the fix.

Last thing- are there coolant passages sealed by the gasket between the fuel rail and the lower intake? It's dark out back, so I haven't taken that apart yet. SOMEHOW coolant is getting into the intake side of this engine, but not directly into the combustion chambers. No pressurization. Do the heads crack ABOVE the valve seats into a coolant passage?

Just for reference, I am a 30+ year veteran ASE Master, Chrysler Master, blah, blah, blah. Just never seen this before, and having trouble believing the vacuum from the port pulls the coolant over to the intake port without getting enough in the oil to show up. See what I mean?

Your response GREATLY appreciated,

Wayne Wright
Yeah, I hate that too. My sincerest apologies- life has been VERRRY busy for some time, but that's no excuse.

The funny thing is, I found this post by typing in a search string for THE SAME PROBLEM-AGAIN!!! Well, almost exactly...

Back to the original post- I pulled the heads- definitely cracked. Several months went by while we saved for a new set- bought them on Ebay. SUPPOSEDLY an upgrade on the originals, supposedly thicker material in the crucial areas. Definitely a different casting number.

Fast forward to about two months ago. I drove the truck about 130 miles towing an empty trailer- same trip I have made countless times. Did NOT overheat or miss. Would not start the next morning. So much coolant in #6 it hydrolocked.

Cleared cylinder, refilled with coolant and started engine. MASSIVE amount of coolant smoke from exhaust, and quickly contaminated oil. Towed it home the following week.

Now that it's a bit warmer outside, I decide to fix it. CANNOT prove a leak from combustion chamber to cooling system. I put 80 psi on the combustion chamber- no bubbles. Cannot fill cylinder with coolant after 1 hour with steady 15 psi on cooling system.

Retorqued intake (definitely loose) and changed oil. Bubbles begin in coolant as it warms, but will NOT pressurize past 3 psi running. Drive it a bit. So far oil stays clear. Missed at idle at first- no overheat, no overpressure. Came home- running ok. after it sat at idle for about 5 minutes, started smoking VOLUMINOUSLY from exhaust. Temp began to climb, but did not overheat or vent pressure.

Next weekend I am going to refill the system and get to op temp, THEN pressurize #6 combustion chamber and check for leaks. If it doesn't bubble, I'll start with the intake.

Anyone know a way to graft a 5.0 into this without changing the tranny?

Hard to believe I have another cracked head.

I wish my wife would fall out of love with this POS and get something more reliable.

Wayne Wright
 

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Did you check the new heads to make sure they were flat? That much coolant is a head problem or head gasket.
 
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