Bad Head Gasket? '94 4.0L X

[mtuboi86]

Hey,
I have a couple of questions.

Could a bad head gasket cause poor gas mileage?

My explorer has been getting around 10mpg (normal of 14 city for winter). Back in November I noticed smoke coming from my hood after driving it. Opened it, couldn't figure out where it was coming from, as there was so little of it. After a while, I discovered something to be 'sizzlin' on the exhaust manifold closest to the head gasket and firewall on the driver's side. Later, I noticed a frequent loss of coolant with no signs of dripping. There's no coolant in the oil, but there are one or two drops of oil in the overfill of the coolant. The sizzlin' only seems to happen the first ~10 minutes of driving.

There also seems to be an issue where, when floored, the engine's RPMs will only go up to 4grand then shift, when redline is at 5 grand. Although, this is an improvement from it not going over 3grand, something is stilll wrong. Could this be part of the head gasket problem, if there's bad compression?

It's a 1994 Explorer 4.0L with ~193,000 miles and the transmission is strong. PCV valve has been replaced, it hasn't overheated since I've owned it.

With this many miles, would you recommend just a new head gasket, or a top-end rebuild? If the latter, are there any resources you could point me to? I've never gotten that deep into an engine. Any tricks on getting the rusty bolts off without snapping them?

Thanks

-Ryan

 

[boggs1227]

yeah i would have to agree that if you got a few drops of oil in the overfill then i bet quite possiblly that you may have a small hole in the head gasket thats only going to get bigger and worse the more you drive it.
if i had to drive it (if it's your daily) then i would not try to rev the engine up to 4k on the tach ...these things are OLD and their not as young as they once were .my explorer ....now i dont drive like a old man but i do take it up to 3500 on the tach every now and then ...other than that i treat it easy mine has just flipped over to 193k on the odometer as well.

you mentioned rusty bolts ( header bolts ?? ) ...start soaking them with liquid wrench and keep soaking them .....exhaust bolts are useally the worst to get off because they are to exposed to high heat all the time and oxidize the worst .

as far as the info i gave you i'm sure there are many here that will read your post and give you the correct links to other posts in this forum on how to do alot as far as doing head gaskets and what not .

here are a few links for you ,one is for fixing noisy lifters... it will give you some idea of what to expect as far what all is involved to take the top end apart.

the other ...just incase you have a cracked head ( possible in your case as well) is a place i found online that sells new casting heads with valve springs and vavles installed .


hope this helps

http://www.idealcylinderhead.com/ford-cylinder-heads/idl205-ford-cylinder-head.html

http://www.explorer4x4.com/lifters/lifters.htm

 

[djsk8r33]

i have the eexact problem. my MPG suffers at a lowly 10mpg and loses coolant and sizzled/s simliar

i hope somebody has an answer

edit: i also have tons of water under the engine after a drive. i thought it was ac (using heat obviously) but its way too much for that

 

[Anime]

I'm pretty sure mine has a blown head gasket, enough that it leaks oil, and gas mileage and performance is otherwise normal. No telling what the difference is from one blown head gasket to another, though. If you oil and coolant are mixing as you say, you'll probably want to just bite the bullet and replace both head gaskets ASAP though, since coolant/oil mix causes a LOT of other much worse problems later on if not fixed. If you want to spend the money for the rest of the top end to be rebuilt while going about the gaskets anyway, that's up to you. You might want to pull the heads first, then check the condition of the lifters and pushrods to decide on a rebuild.

Theres no point in revving a 4.0 OHV to 4K, max torque is usually ~2500 RPM. Perhaps theres a rev limiter on some auto tranny models thats set around 4k?

As for getting rusty bolts off, the best trick there is, is to be patient and once you get them to break loose, and have cleaned the exposed threads with a wire brush, back off and "tighten" them again, then loosen, and repeat a few times to clean the threads between the nut and bolt, which are probably rusted as well. Stuff like PB Blaster, WD-40, etc. can help, or using a compressor or canned air to blow away rust dust, and cool the fasteners so they don't build up heat from the friction and break. Just take it easy and don't force them too much, and don't build up too much heat to where the bolt will snap off, and eventually they come loose, even if it takes awhile.

 

[mtuboi86]

Thanks for your thoughts.

As for revving to 4k+ ... getting that beast to accelerate from 40mph on an on-ramp to 70-75mph getting on to the highway takes flooring it, and then some. That's why it'd be helpful if it revved to redline rather than shift before it gets there. I don't know, maybe my X is just lagging in power and acceleration.
I know when I picked up a home-gym from someone 2 hours away (it was cheap), my X couldn't go up the hills in the U.P. of Michigan and keep speed at 55mph with me flooring it. Performance has since improved, but that's just one example. Then, it would barely rev above 3-3.5k. The combination of passengers and the cargo (home gym) didn't exceed 600 pounds.

 

[Alan_V]

Any sign of white smoke when started? Or is your oil overfull? Either is an indication that coolant is going somewhere it's not supposed to.

While the sizzling stopping after time suggest something that seals with increased temperature (and headgaskets will do so), it's by no means a definitive indication of a h'gasket failure. See if you can get your hands on a coolant system pressure tester. Basically it's a radiator cap with a fitting that you put a hand pump on and pressurize the cooling system (WHEN COLD ONLY PLEASE). If it doesn't hold pressure, you have a coolant leak. Then, if you can't find it externally, it's likey a head gasket or possibly an intake gasket.

 

[mtuboi86]

There's no white smoke at all, and my oil may be a little overfull due to my own fault when I changed the oil last. There's no coolant in the oil.

I've noticed a decrease in the quality of how the engine sounds...
It also occasionally has fits where it idles roughly (but not to the point of stalling). It doesn't tend to do it in the winter much, though. Happened the first time yesterday since the snow started falling in October (temperature was a blistering 50 degrees (F) outside... there's still snow on the ground though).

This in combination with the poor gas mileage makes me think compression problem? I'm sure ya'll have much more experience than me, as I am really just guessing.

I can only get about 150 miles per fill-up (I drive until it gets to E, and usually fill up ~16-17 gallons ... tank capacity is 19) ... city driving. Well, more like Village driving, as these towns are too small to be considered a city - can go anywhere between these 2 cities without driving more than 4 miles at a time.