Replace Head Gasket or more? 2000 Explorer - first timer

[UMD]

I've been poking around the forum here for about a year on and off in regards to a 2000 Explorer AWD. I bought it 2 years ago for $3,000 and it became my wife's daily driver.

I've got an issue with it, and am looking for advice prior to digging into this project. Please bear with me as I explain the history.

When I bought it the owner pointed out the fault codes P0171, P0174 banks too lean. He said he had replaced the O2 sensors a few times but they kept faulting. Sometimes the CEL would be on, other times it would be off.

Shortly after purchasing I noticed it lacked power going up hills, and had trouble accelerating quickly above 45mph. Getting to the State speed limit of 70mph was difficult if going up a slope. The CEL then came on, and stayed on.

Last summer I noticed it was a little low on coolant and had it topped off. After a cross country trip my wife continued to drive it locally and a few months later it was significantly low on cooland and had it topped off.

In December / Janurary the heat went out so she had the heater core replaced. Within a week the temp was high so the thermostat was replaced. Around this time one of the shops determined that there was a coolant leak, with the milky appearance of the oil. The vehicle has since sat parked in the yard. It has about 150k on it.

I appologize if these questions are redundant. I'm in Afghanistan and don't have a lot of time to search. I plan on replacing the heads, the head gaskets, spark plugs, and *maybe* the O2 sensors next month when I come home on leave. I have little experience working on cars, but want to learn; and have had no problem rebuilding small engines and carburators, or computers; so a car I imagine should be within my abilities. I've got the Chiltons (or Haines) manual at home, and should have about a week to tackle this.

What types of damage should I be looking for on other parts of the engine during this time? I don't have a lift, so I don't plan on removing the engine. I am aware that internal parts may have been damaged, as I am unaware how long this coolant leak had been occuring.

Could this problem have caused the O2 sensor codes for too lean? or should I be looking at a vacuum issue as well?

I am making an assumption that this problem is also the cause of the lack of power and acceleration, is this accurate, or should I look at the transmission as well?

Aside from new gaskets, new head bolts, sealant, and proper torque and sequence of tightening; what other components should I take a close look at / replace / etc.

I estimate $1,500 for this project (including purchasing of a torque wrench and other necessary specialty tools).

The shops all estimated $3k+ to take it apart and look at it, then more to replace necessary parts.

I've got a few other small repairs to make (cruise control, door locks, trailer wiring harness, slight rust, and rear wiper), but I won't dig into those until I am confortable that the engine is good to go.

Thanks in advance for all the advice.

 

[2000StreetRod]

Thanks for your service!

First, I want to thank you for your miltary service!

Which engine do you have: V8, OHV V6 or SOHC V6?

Leaking intake manifold gaskets on the SOHC V6 are common and result in lean codes. See my thread: Starting my 00M12 Installation

Before pulling either head I suggest performing a compression test on all cylinders and check for DTCs. Keep track of the plugs when you pull them and inspect for signs of leaking coolant. The OHV V6 has a tendency to blow head gaskets.

The engine oil pickup is a little above the bottom of the oil pan. If you have water in the oil it will be at the bottom of the pan. If the water lever is far enough below the pickup tube then there may be no bearing damage.

 

[TonyTiger2004]

As dale said the 4.0 OHV is known for head/ head gaskets being blown. It does sound like the symptoms you describe does sound like a blown head gasket.

Almost all the vehicles ive worked on that had bad head gaskets had. Smoked, Over heated very quickly, Loss of Power, Antifreeze smell coming from vents (on some) milkshake oil and antifreeze on the plugs. I would definitely test your compression before disassembling anything.

While alot of the symptoms u describe point to a blown head gasket it still could very well be something else.

 

[UMD]

Thank you for the information. I know it is a 6 cylinder, but am unsure if its the SOHV or not.

I will do the compression check prior to disassembly. I found a thread on that, and it was informative. I only had a few questions after reading it, and I am sure most of those are due to not being able to physically see the item or have access to the book. I'll be sure to ask if it's unclear when it's time to do the task.

Likewise I've dug around a bit more and found more threads on replacing the heads. Sounds like an impact wrench is the way to go. What is the consensus on these? Are electric (corded) good enough, or should I get a air system? I consider these items to be investments for future uses, and not a one time use given their cost. How about torque?

 

[TonyTiger2004]

Tools

If you considering it as an Investment i would Buy a good air compressor and air impact, electric impacts are good under certain circumstances. The more Air Pressure = more power. But different impacts are rated for specific Ranges of Air. Bigger the tank = More power without it clicking on so often.

As for torque your going to need a good torque wrench, I like my Multiplier Torque Wrench. But you don't need anything of that sort for general automotive. Any 1/2 Torque Wrench will do the job. My Torque set comes with a 3/8 drive torque wrench and a 1/2 Drive Torque Wrench. I like having the option, somethings on vehicles require a lot less torque and less room to work. Like on the SOHC the plastic Upper and Lower Intake require a lot less torque and 1/2 is just overkill too bulky hard to feel/hear the click when using low torque setting.

Regards, Tony

 

[UMD]

Tony,

My appologies for not being clearer. I will be getting a traditional torque wrench, but am also curious about what specs I should be looking for in an air system's impact wrench / drill. What is the recommended tank size and PSI, and how much torque am I looking at needing? Do I look at the economy ones with 150lbs of torque, or the 500lbs?

I'd hate to drop the cash and find I didn't buy something capable of handling the job, likewise, spending 3x more than what I needed.

 

[UMD]

Wife looked at the VIN and the 8th digit is an "X" so it is the 4.0L V6 OHV.

 

[UMD]

Got started on the project today. And we're off to an slow start.

Since it hasn't been run in 7 months, the battery was dead. Tried jumping it and couldn't get enough to turn it over more than a few rotations.

After that failed I tried putting the dead battery on a charger, but it kept faulting out. So I put in a different battery from another car.

Took some time and did a little cleaning under the hood. Covered and or taped all electrical connectors I could see, and gave a light rinse, then a good wipe down.

Got started but it was real rough. Would shift into gear, but not move. I'd rock forward or backward a few inches, but it wouldn't go farther than that. Pedal on the floor and the RPMs didn't go to far up, it just kept chugging and shaking. Finally broke free and got into the garage.

Used canned air to blow rust away from the spark plug holes, and then removed the plugs.

Attempted to do a compression test, but couldn't get the fitting to thread into the spark plug hole. I matched up the plug to the fitting to ensure I was using the right size. After trying 4 of the cylinders and not getting any bite, I deduced that my compression fittings are too short, as the plugs' threads are double the length of the compression fittings. Off to the store tomorrow to get different fittings. Or the threads at the outer edge where the compression fitting would go were rusted out.

 

[UMD]

After finding a 14mm long compression fitting I was able to do a compression test. All had an initial reading of 90-110 and rose in equal increments to their final number after 4 stokes. Results are as follows:

DRY --------- WET
#1 - 140 ----- 150
#2 - 135/140 - 160
#3 - 155 ----- 160
#4 - 155 ----- 160
#5 - 150 ----- 170
#6 - 150 ----- 160

Appears that there is a problem between #1/#2 as they are 10% less than the max.

Also appears worn rings on #2, maybe #1, and #5.

What is the acceptable difference between the wet/dry before determining if new rings are necessary?

If I can get my hands on an air compressor, I'd do a leakdown test.

The rough idle was most noticeable at low RPMs, and evened out when RPMs increased. There was a weird popping noise from under the vehicle when it was in gear and moving in and out of the garage. After parking I observed white smoke coming from the transfer case.

Suggestions? Further analysis of compression results?

 

[UMD]

Finally got the heads off today.

Throughout the disassembly process I observed the classic milkshake color of oil and antifreeze.




I inspected the rocker assembly and the pushrods, and didn't find any obvious deficiencies. I know that replacing these items is recommended, but that's a few extra hundred bucks I'm not willing to commit at this time. So unless anyone has any suggestions on what to look for in order to determine if these are unservicable, I'll stick with the existing ones for the time being.



There was no way the exhaust manifolds were coming off the heads. I got one nut to turn with a 13mm socket, but the others refused to accept any size; all were either too big, or too small, and the bolts were heavily corroded (the threads aren't even visible on many of them). I had planned to replace these anyway, so it wasn't a huge deal.


Cylinders appear smooth, with light discoloration, and small debris that fell in during disassembly. There is slight carbon buildup on the piston heads.


I didn't see any rips or tears on the head gaskets, although there were a few patches stuck on the block that I'll have to remove. I don't see any cracks on the heads, so I'm going to assume that the problem is internal to the head... least I hope so, and that it's not in the block.

I placed the parts order with a local store a few days ago, so the parts should be in tomorrow of the next day.

New gaskets, heads, plugs, thermostat, exhaust manifold... and I got to find a new ERG valve pipe (if that's what it is called). When taking off the driver's side exhaust manifold I saw that the ERG valve pipe was badly rusted and had a hole in it near the downward turn where it joins the exhaust manifold.

 

[UMD]

Well I got it all back together, and so far I see no evidence of coolant loss.

Although I will need to replace some LIM bolts and a valve cover bolt next spring because the old ones snapped while being torqued to spec, and the replacements available are lesser quality.

I burped the radiator, and checked the oil for the milkshake color. Much to my relief the oil looks like just oil, and the coolant level isn't dropping mysteriously.

When I started it up there was a good amount of white smoke coming off the drivers side exhaust manifold, but after about ten minutes it ended, so I'm guessing it was spilled oils burning off.

The tailpipe has white smoke (what I consider a normal amount based on what I grew up with), and water dripping out (again at what I consider a normal rate) with a drop every few seconds.

Brake light didn't work and I traced that down to a blown fuse. Simple fix.

Replaced the rear window wiper.

Still lacks power, so I've got to look at the fuel pressure, filter, and pump I guess.

Also found a torn CV-boot, so I'll have to replace that in the near future as there isn't much grease left in there and I can hear it grinding.

Lastly the brake pedal pulsates and pushes up on my foot, but not in the rapid and shallow fashion of ABS that I am used to, more like once every time a pad hits a certain spot on a rotor. Rotors are probably in need of replacement.

This forum has been a great help.

 

[janolsson]

Good wrenching fella

 

[UMD]

Update and list of new problems.

Last month I was able to diagnose the lack of power. The floor mat was interfering with the gas pedal, allowing it to only open the butterfly about halfway. Removed floor mat and it's got the power like I'd expect.

The pedal pulsating went away. I'm guessing it was rust on the rotors that has now been cleared after 2 months of driving. It was very noticable at first and now it is gone.

Replaced the rear wheel speed sensor and the ABS light turned off. ABS works. But now when coming to a rolling stop <5mph the ABS kicks in.

Also when it's cold <20 degrees, there is a squeak from the brake pedal area went depressing the brake to stop. Seemed to happen more when we had a cold spell a few weeks ago (around zero degrees), and didn't do it again until last night (15 degrees).

Had the CEL come on for about 5 days in early Feb for EGR flow insufficient. It self-cleared one day while driving on the freeway.

I noticed I was loosing coolant in Jan (when I started driving it again) and tracked down the source to the upper radiator hose connection at the thermostat housing. Coolant was leaking out and being blown back by the fan all over the other components. I figured the hose was bad and the stock spring style hose clamp obviously can't be tightened, so I replaced the old hose and bought some screw-on hose clamps. But the hose clamps keep loosening up. Some days I find a leak at the connections for the hose and retighten the clamps, other days it's fine. I tried clamps from the auto parts store and hardware stores. Anyone got a suggestion?

I replaced the broken driver's door lock actuator, and got the rear lock core to function with the existing key set, but the driver's and passenger door lock cores won't break free. Driver's door lock core will see a locksmith to get it working.

Went to change the fuel filter and found I was still leaking coolant. Tracked it to the general area on the front driver's side of the block, in the vicinity of the block and the power steering pump / AC pump bracket. I can see white smoke in the gap between those items and the block when looking up from underneath. I'm thinking LIM gasket. There is no CEL, no codes (I checked after the above self-cleared to rule out a broken bulb and the bulb lights up during self test). There is no oil visible in the anti-freeze. There is no milkshake colored oil on the dipstick. Since I replaced the heads last September, and it has not overheated since that point, I doubt I cracked the new head, and am leaning with a problem between the block and LIM. I am pulling off the PS / AC pumps' mount this week when it gets warm, and hopefully verify the leak is coming from the LIM area, and not a head.

I also have a noticeable loud ticking noise coming from the front left side, but only while driving, and only when accelerating. Once I step off the gas, the noise gets quieter or goes away completely. Resume speed / accelerate and the noise comes back. Seems proportional to speed. I can not replicate the ticking in park. There is a slight tick when idling I notice in the line at the drive though (in Drive, brake holding position), but I attribute that to likely be the lifter ticking I've read about so much here.

 

[morbid81]

The ticking you are hearing is most likely a exhaust manifold leak if it only does it when the car is under load, mine does in on the passenger side, got new gaskets gonna put them on soon as i get my washer project finished, it can be mistaken for a lifter ticking, but you would hear that at idle or cold start, and would go away one the block fills with oil.