93 explorer overheating, cooling system problems...HELP

[rstumpy]

Picked up a '93 explorer XLT, auto, 4.0L v-6 for my wife the other day. It only has 92,000 miles and appeared to be extremely well-kept. Runs great, by the way.
After driving it a few hundred miles the cooling system began acting up. It would peg the temp guage now and then, but only for a second or two. When that happened the heater would only produce cold air, and it would go hot again when the temp dropped. I replaced the thermostat, temp sending unit, lower hose, and completely flushed the system, and carefully "burped" any air out of it. At that time I noticed that the freeze plug at the back of the passenger-side cylinder head and been popped-out and a rubber compression/expansion plug is now in it's place (holding fine and not leaking at all).

Sitting in front of the shop I ran it to operating temp tonight...everything was great...drove two miles down the road and the heater started producing cold air, the temp guage was at "M" in the "normal" range (it had been moving up and down in the normal range), and about that time, POOF-- the freeze plug on the block near the starter blew out. Obviously my cooling system is building pressure in the extreme?
There is NO visible oil in the water/coolant, and NO visible water/coolant in the oil. On the other hand, when the engine was warming up there seemed to be a lot of water vapor in the exhaust (the usual white dissipating clouds of exhaust, but more than I might expect on some rigs).
I'm fearing a cracked head or blown head gasket. BUT again, the fluids are not cross-contaminated and the thing runs absolutely great. None of the earlier symptoms where consistant either. The rad cap is a 13 lb. unit and functional. It overflowed the overflow tank two days ago. Clearly the pressure overcame the cap's ability today. Oh...the lower hose split three days ago, but it was an older hose...now I think it was the pressure issue.

I'd sure like some outside input before I start tearing things apart. We need the rig and can't afford to go looking for another just now.

Thanks much,
Rob

 

[shamaal]

Welcome to the Forum. A moderator will be along shortly and probably copy/move this post into a forum with more visibility.

Blown freeze plugs, wow! Sounds like early in it's life it was neglected anti-freeze wise. The cap should pop before the plugs go.

Regarding the overheat cause, the only thing you didn't mention is the fan clutch. An easy test is to spin the fan blade by hand while the engine's cold (engine off of course). It should move easily. Then spin the blade when the engine's hot. It should be difficult to spin.

To check head haskets, run a cylinder compression test. All readings should be within 10% of each other. Examination of the pulled plugs may lead to clues if a cylinder has coolant in it. There's been enough anecdotal evidence presented here that head gasket problems don't always result in visible cross contamination.

Do some research using the search functions and ask questions. Everyone's friendly.

 

[insane3082]

wow sounds like the problem i use to have. but u said you already changed the thermostat. after a while my overheating problems came back but i was away on vacation let my sister drive the car and now it doesnt even turn on she said it overheated had it checked and it turned on but then they tried it again and hasnt turned on since. i dont know if i should blow the car up or her. anyway learn from my mistakes dont drive it till your sure what it is or your gonna be looking at other problems like water pump, headgaskets, time and more money

 

[rstumpy]

Greetings all,

Looks pretty clear that I have a head/head gasket problem. I can pick up a set of new, aftermarket "improved" heads ready-to-go for $350, and another $100 for the gasket and bolt set. Not too bad, can't rebuild mine for that, and then the rig will have a new top-end. I'd have to at least mill my old heads....seems a waste to pull the the apart and not freshen the top end though, eh?

Gonns start the tear-down this afternoon.
There goes the tax refund.

Sisters, like many holders of the "dos equis" chromosomal factor, can be the cause of many mechanical difficulties. (had to throw that one in there to irritate "dos equis" gene holders in my household)

 

[insane3082]

you can always do the compression check first im just letting you know before u end up in the same place where it doesnt even start back up. im there with you im gonna start with replacing the water pump too i need to go get some RTV sealant and all those other fluids. luck with your 93 X

 

[rstumpy]

Yup....I'm gonna quit "tinkerin'" and start "mechanicin'" With a hose and two freeze plugs gone due to pressure rather than high temperature, it's time to wrench it or park it, one or the other.

But, like you said, I will do the compression test first, 'cause I have a gauge, and if the readings are what I expect them to be it will let me know where I really have to examine things closely.

The nearest Ford dealer wants $1350 just to change the head gaskets....any real work to the heads, etc. is added to that. Estimates for doing the heads and the R & R job have gone from $1650 to $3400....ha ha ha ha ha ha. That's why I have a small shop and tools. Granted, I did have to buy a T55 torx socket for the head bolts (could only find a 3/8 drive....would rather have a 1/2, but...), but the job is straight forward enough albeit probably filled with some frustration-related vocabulary expansion.

Good luck on your rig. It won't even spin over? Geeze. (meaning the engine is "locked-up?") If so, I'd yard the sparkplugs out first and then try to spin it over, assuming the electrics are all fine. I remember a buddy of mine had a Nissan that wouldn't spin over...he put in a new starter, etc. etc. to no avail. I looked it over and found evidence of water in the oil, popped the plugs out, and it spun just fine, with the number 3 jug doing a fine imitation of a water fountain. Milled the head, a new gasket and proper torque sequences and it lasted another 85 grand. I flushed the crankcase real good with diesel oil and we crossed our fingers regarding possible water damage to the bearings...worked out OK though.

Good luck

 

[moneypit92]

im getn ready to do the same job on my ex i have a couple ?

first should i replace the heads or have mine resurfaced?

second what book would be the best for step by step directions on doin head gaskets?

thanks

 

[rstumpy]

Moneypit92,

While I've done this on a lot of different rigs, I'm sure there are folks here who could help you who have considerably more experience with the ford 4.0L

Nonetheless, here's my impression on the deal at this point:

On your heads:
Best case scenario you have a blown head gasket and the heads are in good shape (no cracks, not warped beyond spec, etc.)....even so you'll want to have them surfaced so the mating surface is true and tanked to check for cracks, etc.. Unless it only has a few thousand miles I would also get the valves ground and seals replaced, since your spending the bucks for the gasket kit and new head bolts (cost: $150-$200 kit & bolts)...be a shame not to do things while they are accessible. Lot's of other things can be done too but I would at least attend to those items. The butcher's bill will likely be anywhere from less than $150 to $??? for the work depending on the issues and your local machine shop.
BUT if one or both of your heads are beyond spec, cracked, etc. then the scenario is different. You could find some donor heads and have them gone through ($???), buy a set of remanufactured stock heads (have seen for less than $300/pair and up), or buy a set of new, "improved" aftermarket heads (have seen for around $380/pair and up). The "improved heads have beefed-up castings in the spots known to be weak and prone to cracking and warpage. Worth the extra bucks? Someone on this site might know...I'm thinking about going that route....My heads are likely not in great shape, but we shall see.

Used to be two general choices in relatively inexpensive available manuals for the do it yourself mechanic...."Chiltons" or "Haynes." Unless it's a Brit rig I like the Chilton manuals, however, I went looking and was told that Haynes had bought the competition out and they were no longer available. This may or may not be true, since I have since seen a Chilton manual for the Explorer (might've been new-old stock though). The Haynes manual I have is #36024 for "Explorer, Navajo, Mountaineer, and Explorer Sport, 1991-2001" While I have found a number of typos already and references in the text to several "phantom" photos (that I happened to really want to look at, of course), it is fairly easy to follow and a decent guide considering the number of model years involved. The sections on rebuilding the pushrod 4.0L versus the SOHC 4.0 are actually pretty decent. Cost is from $15 to $20.

Good luck

 

[moneypit92]

so where do i get the aftermaket heads i plan on keeping my explorer for awhile and im kinda hard on it so anything beefed up will help

 

[old mechanic]

The only input I have is that I have installed many many of the rubber freeze plugs and never had a problem with any of them. Although if I could easily replace them with a regular metal freeze plug I would.
With the glues that they offer today the rubber ones should hold even better.

 

[insane3082]

turning over is not my problem its doing that perfectly but not turning on.

 

[rstumpy]

Greetings all,

My kids brought home the red death, AKA kid flu, so I've been unable to hold a wrench let alone turn one for a few days. Finally felt up to building a fire in the shop woodstove today and checking compression on the Exploder.

So, these readings were taken cold and dry:

#1: 134
#2: 142
#3: 152
#4: 114
#5: 140
#6: 148

Wasn't thrilled with the readings, particularly on the #4 (front driver's side)jug. Of course, I was expecting a couple of adjacent jugs to be low. Anyway, I squirted some marvel oil in the #4 and tried it again twice....came right up to 112-114 pounds again...no improvement.

So...I'm thinkin' that I probably have a small/slight crack in the head in or around the #4 combustion chamber. That would likely explain the rapidly increasing pressures in the cooling system to the point of failure, particularly when accelerating up a hill, etc. Am I barkin' up the wrong tree? Seems that there'd be a couple of low readings on adjacent cylinders if the head gasket was bad, correct? I'm thinking it has to be the gasket or a cracked head to do the pressure-thing to the cooling system, correct?

Just trying to identify places I need to give particular attention to examining during the disassembly process. Would appreciate any additional thoughts or inputs greatly....

Thanks again,
Rob

Insane3082-- If she turns over but doesn't fire that could be any number of things...air flow sensor, main computer, coil pack....etc. Are you getting any spark? I haven't had much luck with the 100 buck computer analyzer boxes available at parts houses. One might work for you thous, or borrow one from somebody and check the error codes.