4.6L V8 coolant loss

[eeprete]

Hey there, I am new here, and hoping someone can help or has experienced something similar.

Been having a few issues with my 2003 Explorer Limited of which both myself and my father (35 yrs as a top level mechanic) are dumb-founded by.

1. Started having coolant loss back in the fall. It would be slow loss where it would be a month or so and then I needed to add coolant/water (about 1 jug).

2. Vehicle has overheated twice now, once about 3 months ago, and once last night. Gauge always spikes, never slowly goes up, so no hint it's on the verge of occurring. I was within 5 minutes from home on both occasions so went immediately home.

3. Never any evidence of any leaks, no puddles no wetness anywhere etc. We've checked radiator, hoses, water pump, intake, everywhere.

4. Doing a system pressure test, showed slow dropoff of pressure (about 2 lbs over 20 minutes), so it's going somewhere.

5. Doing a system vacuum test showed the system held vacuum fine, and there was never loss of vacuum.

6. My father also has also checked for gases in the coolant. That too was negative, so it's less likely this is a head gasket failure.

7. I recently had some engine miss codes showing up in the last month. Changed plugs and boots and that seems to have remedied that problem, however one of the plugs was rusty.

I am on the verge of tearing apart the whole top end. I suspect maybe the intake is leaking on the underside and the heat of the engine is evaporating it hiding any clues? Is that too far fetched?

Any help, advice, tips on where to look is appreciated. Thanks.

 

[RickM]

Search is your friend.

Most recent thread on the subject.... http://www.explorerforum.com/forums/showthread.php?t=280314

 

[eeprete]

Thanks Rick. I did see that thread, but it provided very little insight. With yours, what was the cause of the engine failure? Did you have an oil analysis done? If so, what did it show?

To other members: Does anyone having any diagrams of the HVAC system? Are there two heater cores on the two zone setups on the Limiteds?

 

[jakedrew]

hard to say. Good luck and keep us updated.

 

[EasyRhino]

Thanks Rick. I did see that thread, but it provided very little insight. With yours, what was the cause of the engine failure? Did you have an oil analysis done? If so, what did it show?

To other members: Does anyone having any diagrams of the HVAC system? Are there two heater cores on the two zone setups on the Limiteds?

If you have the rear HVAC option, you do have two heater cores, one under the dash and one in the left rear inner fender cover panel (along with a secondary AC evaporator).

 

[RickM]

Thanks Rick. I did see that thread, but it provided very little insight. With yours, what was the cause of the engine failure? Did you have an oil analysis done? If so, what did it show?

To other members: Does anyone having any diagrams of the HVAC system? Are there two heater cores on the two zone setups on the Limiteds?

Not 100% sure what the cause of failure was....but, I was losing coolant for quite sometime and every effort to identify resulted in nada. The loss was relatively small and steady so I lived with it.

About one month before failure the loss was much greater.

As mentioned in other threads, the mechanic who replaced the engine commented that there was more sludge than he had ever seen when he looked over the ceased engine. Further, I'm the original owner and used synthetic since new. Unfortunately the engine was disposed of before I could do anything.

So, while there are many causes for coolant loss, I just want to let people know that the possibility exists that catastrophic failure may be at the end of the road if not addressed properly.

 

[eeprete]

Well, as a result of the overheating the other day, I will actually be doing an oil change tomorrow. I will then also save some and get an oil analysis done to rule out moisture and coolant in the crankcase.

I will also be systematically be blocking off my coolant lines to the HVAC to do additional pressure and vacuum tests, to try to isolate where the pressure loss is coming from.

But, I will keep a much closer watch on my coolant overflow tank level to ensure there is always coolant.

@RickM: with yours, were you noticing any fluid pooling or collecting in places? Any strange smells? Sorry to hear yours was a catastrophic failure. Had you brought it in for diagnosis prior to the failure?

 

[eeprete]

If you have the rear HVAC option, you do have two heater cores, one under the dash and one in the left rear inner fender cover panel (along with a secondary AC evaporator).

Thank you EasyRhino! I will check there as well.

 

[RickM]

eeprete: I'm pretty well versed in diagnosing coolant problems...well, at least to a degree. I used my pressure tester and checked in quite a few spots for leakage, including the heater core and found nothing. The only suspicious sign was some mayonnaise-like crap under the oil filler cap. however, some insist it's normal and merely a result of condensation. I don't know if I agree.

If you do a search you'll learn that quite a few members have coolant loss as well. It was only until the volume increased that I planned on having a pro take a look. Unfortunately Murphy's law kicked in ahead of me.

BTW, there are quite a few heater/coolant hoses on these bad boys...may not be very intuitive.

 

[eeprete]

ok, so went back to my father's today to work on the Explorer.

Today, changed the oil and did another system pressure test, which is within spec, and there was no visible coolant in the crankcase oil.

However, coolant loss is still occurring. After again checking all lines and locating the rear zone core, I checked the coolant level, was fine. Then let it run for a while (25 minutes), shut it down, it then returned to the level it was at... THEN.... another hour later after stopping for lunch etc, noticed the level went down, showing coolant is being used somewhere.

So, my father brought up some valid points and ones that may need to be considered by other Explorer owners that have had similar problems.

1. cracked heads can leak coolant into the combustion chamber and it can be such a miniscule amount, it would never be detected via typical white smoke. Also the catalytic converters could also remove some of the tell tale signs.

2. head gasket failure could happen in such a way that when the cooling system is under pressure, there is no shown loss, but after cooling, the pressure equalization could then suck some coolant into the combustion chamber or crankcase.

We are going to be doing a cylinder leakdown test in the morning, which should be able to provide additional insight. We are pretty certain at minimum head gaskets will need to be done, and perhaps heads.

Has anyone done gaskets or heads with the engine in the bay or will it be easier just to pull the motor? If I have to pull the motor, I may also regasket the whole motor.

 

[eeprete]

So, today we performed both a compression test and leakdown test. Being the 4.6 heads plug sit so far in, I actually had to rent a compression tester from Auto Zone simply for the adapter it had. Good thing whatever they charge you, you get back when you return the tool (it was $38).

Compression test
cylinders 1,3,4,5,6,7,8 were all at 180 lbs 4 cranks
cylinder #2 was at 150 and 160lbs with 4 cranks

Leakdown test
Each cylinder was filled to 100lbs, and each cylinder was in it's respective top position, valves closed, etc.

cylinders 1,3,4,5,6,7,8 were all at 100/90-94
cylinder 2 was at 100/75

Additional info
being we knew cylinder 2 was leaking down, we then configured a rubber hose to listen at the intake, the exhaust and the crankcase (oil fill tube). We only heard noise at the oil fill tube hinting at rings.

However, strangely, we still don't know where the coolant is gone/has gone. Yesterday afternoon we were getting milkiness in the oil fill cap (post oil change). This afternoon, it seemed to be clearing itself up after running it this afternoon.

So, now we are sort of in a holding pattern. Do we tear down the motor, and do rings as well. Will a headgasket solve this? Perhaps we tear it down and mysteriously nothing is solved.

Any thoughts?

If I choose to instead simply pick up a motor to swap in, will any 4.6 2V work? ie: Mustang etc? Can I also consider swapping in a 5.4L Triton for some added torque?

 

[jgrimmer]

I think your problem is a head gasket or coolant passage somewhere in the engine, BUT:

Have you ruled out a leak in the coolant bottle. I had a tiny leak in the bottle (which isn't a normal overflow bottle but a pressurized part of the coolant system). It vented with a whoosh of steam about 10 minutes after I shut the engine off, but I couldn't tell where it came from. Filled it up and it leaked steadily for weeks, but only when the engine was really hot.

Finally, I took the bottle out, filled it up, sealed it off and pumped it up. Saw the tiny leak in the bottom immediately. Was thrilled to buy a new one for like $35 (for a glorified milk jug) cause I was certain before that that I had a lot more serious problem.

BTW, I live near Chicago and have had milky sludge on the inside of the oil fill cap all the time in cool weather (02 4.6 V8 Mountaineer, owned since new).

Good luck!

 

[eeprete]

I think your problem is a head gasket or coolant passage somewhere in the engine, BUT:

Have you ruled out a leak in the coolant bottle. I had a tiny leak in the bottle (which isn't a normal overflow bottle but a pressurized part of the coolant system). It vented with a whoosh of steam about 10 minutes after I shut the engine off, but I couldn't tell where it came from. Filled it up and it leaked steadily for weeks, but only when the engine was really hot.

Finally, I took the bottle out, filled it up, sealed it off and pumped it up. Saw the tiny leak in the bottom immediately. Was thrilled to buy a new one for like $35 (for a glorified milk jug) cause I was certain before that that I had a lot more serious problem.

BTW, I live near Chicago and have had milky sludge on the inside of the oil fill cap all the time in cool weather (02 4.6 V8 Mountaineer, owned since new).

Good luck!

hey jgrimmer, thanks. I am not getting a whoosh or anything like that, but I may still try that as well.

You bring up a valid point as well, as between Friday and Saturday, it lost about the same amount of coolant as Saturday to Sunday, yet Friday I drove 10 miles only. Saturday I drove 40+, driving to my father's to work on it. Just doesn't add up.

 

[eeprete]

and the mystery deepens....

So my father has checked a few more things with the Exp and has run it at length and it hasn't lost any more coolant. Level has not changed at all.

He's now using some Marvel Mystery Oil in the crankcase to see if running that through will help the ring issue, as he himself said "everything should be fine with this motor".

And again, pressure test, standing still and running and nothing... definitely a mysterious issue here...

 

[eeprete]

So, here we are about 5 weeks later. If you saw my last thread, you'll know that I parked the vehicle asking if anyone had tips.

Well, last weekend started the tear-down process. First off I have to comment, whoever engineered the engine bay on these Explorers never thought of potential maintenance issues. A lot of poor placement of what goes where and sometimes multiple steps to remove the simplest thing. And the shop manual, while helpful sometimes lacks in thorough descriptions of specific tasks, and because these motors can be very tempermental you're always afraid of breaking things (nothing has been forced or broken)

Because this was our first time really delving deep into a mod motor, we've taken our time, marking, labeling and bagging things, and just paying particular attention to everything. In my other thread I asked about shortcuts, and honestly on these engines there are none. And doing this in the bay, insane mistake from a time standpoint. While we have successfully removed the heads in the bay, like I mentioned above, things are too tight and too many extra steps to ensure everything is done.

Anyway, what we've found with the tear-down. I will add pics later however here is a verbal description.

- There was nothing conclusive with the head gasket failure or not (at the gasket level)
- We've found scoring in both cylinder 2 and 3 even though still visible cross hatching
- Heavy, thick, excessive sludge in drivers side head valvetrain
- Passenger head valvetrain clean
- typical pudding in passenger valve cover, tiny bit in drivers side
- no evidence of coolant in the pan or oil

So, tomorrow I will continue and we'll likely figure out a gameplan as to what to do with everything. Perhaps remove the block next, then check the bottom end.

 

[jhard]

Thanks for coming back with updates eeprete!

 

[zerodevil]

Just a heads up, i would also sugjest you investigate the rod on the #2 cylender if you are still having compression problems after the head gasket and rings, also check the valves for propper seating. if you decide to go ahead and do an engine, you will have no trouble dropping in the 5.4L with a few swaped parts from the 4.6L (intake elbow and some other minor things. also the Y pipe needs to be lengthened an inch or so.

 

[eeprete]

I wish I had taken some pics before even pulling anything off. While it does seem like a "bear" of a job, its more time consuming than hard (same thing with most things). You can even see the custom built bracket my father made for lifting the heads. No sense in trying to wedge 50+ pounds off the block and risk damage. I am trying to talk him into mass marketing them. Since he's about to retire, he may.

 

[eeprete]

no one commented, so not sure I should even update this further.... If anything I hope my experiences here are helping someone....

Sort of good news: the heads don't appear warped or cracked with the initial check, however my valve guides are worn and the valve seats will need to be recut. I'll be dropping them off at the machine shop in the next few days to get checked in the tank to make sure there are no hidden cracks anywhere.

 

[xlt03]

keep us posted on your progress. Any comment on pulling the entire engine out of vehicle rather than leaving it in? Keep pictures coming, especially if you see something unusual.