98 explorer possible thermostat issue

[torumekian]

Hi,
i have a 98 explorer XLT V6 4.0 SOHC. About a week or two ago i replaced the thermostat in my car. it had been giving me all the signs of a bad thermostat, taking forever to warm up, going well above normal operating temperature before rapidly dropping to normal operating temps. so i did as i read, drained the system, unhooked the batter, air intake and so on. i removed the hoses off the housing and took it out, dropped in my new thermostat and new gasket, reassembled, and took it for a test drive, it started as it should and everything behaved normal. no leaks, no lingering odors. everything seemed fine. i drove it about a week to two weeks and haven't had any real issues but over the last 2-3 days i noticed it was starting to take longer and longer to heat up. since my windows are iced most mornings and i leave to work at 630am, i picked up on it pretty fast and made the effort to start it about 5 minutes or so before i left to work to accommodate the longer warming process since i didn't have the time right then to actually dig in and fix it. i monitored the reserve fluids to make sure it wasnt emptying and checked for leaks and found none. but yesterday it started overheat rapidly. so i popped the hood reserve still full, popped the radiator cap and from how much coolant i had to add id wager it was 1/2 to 2/3 empty.but during the week or so ive been driving ive not seen any coolant under my car. and since i park in my own driveway its not over grass or in a different place everyday where i wouldnt see it if it leaked. so yesterday i took my car apart to get back to the thermostat since the timing was way too much of a coincidence. pulled out the thermostat again checked for damage to the housing or anything, but found nothing.no cracks in the hoses or housing. i ran it while looking under and found no leaks. i went into a kragen for my initial thermostat and got what they had on the books for my year/model/engine size and a new gasket. anyone have any suggestions? although newer to explorers im fairly handy with my car repairs and im drawing a total blank on what it could be. any suggestions or help would be much appreciate.

-Nick

 

[fast_dave]

Nick,

Did you ever replace the radiator cap on your '98?

If not - it's 13 years old.

That's a LOT of hot CA summers - with the A/C on ;-)

The Explorer operates on a "sealed" cooling system, and these caps are a maintenance item - especially in the People's Republic of Kalifornia.

In the PRK - you run into very HOT temps that will cause the cap's sealing gasket to compress to where it is too thin to hold a HIGH pressure (causing overheating), and when the truck cools down, the radiator cap doesn't have an adequate seal, which won't allow it to form a vacuum in the engine, and thus won't allow the engine/radiator to suck in the coolant/anti freeze that's in the overflow bottle. When radiator caps are new, they have a LOT of tension to twist on and off. As they get old, they loosen up. You don't tend to notice because you take on off and place it on so infrequently - BUT your engine/radiator does.

Get a STANT cap - and DO NOT get one with a pressure release lever - get one for a sealed system that does not have that lever.

Up here in PRK/Nor Cal - I replace mine after three seasons of summer driving.

Start simple - maybe $7

HTH -

PS -
Currently - you probably also have a lot of air in your system.
Replace the cap, fill your radiator, and fill your overflow to the TOP.
ALSO - remove the small overflow hose from the radiator neck, and blow through it - it may be clogged with gunk.
Have the lid to the overflow tank open while you do this, and look inside as blowing through that small overflow hose - you might be surprised - and you may need to drain and clean the overflow tank...

 

[torumekian]

i haven't tried that. i inspected the rubber when i had opened it but saw nothing wrong. I didn't actually think that there would be anything else wrong with it. i will definitely swing by a part store on the way home and pick one up. I'm all for starting with the little things. and where i live in CA is baaad in the summer for high heat, 110°F easily for 1-2 months a year and has been higher recently for a few weeks. and then it will drop to about highs of 50° with lows of 30° in about a month or so.

 

[fast_dave]

Yeah - the radiator cap gasket doesn't get torn, it compresses.

You'd be surprised how much "tension" a new radiator cap gasket will have when the cap is first installed.

The old 13 year old radiator cap twists on and off really easily compared to a new one - because the gasket on the old one is compressed.

That lil' gasket does a LOT of work to make the system properly operate.

Also - Blow through the overflow hose, the end that connects to the "neck" of the radiator, while looking into the overflow tank - it might surprise you. All sorts of crap will be swirling around in the overflow tank if it hasn't been cleaned out in the 2-3 years time.

Also, that overflow hose should not have any kinks in it or it won't work.

Start with the easy and cheap stuff -

 

[torumekian]

i havent replaced that cap since ive had the car (4-5 years) and i cant say if it was before i owned it. but this car is almost original everything. im about to break 250k, and the engine has never had a problem or the tranny, from the paperwork ive seen the only major part replaced was the alternator and i had one of the tension pulleys break a year or so ago. only other service was to refill the freon in the AC system. other than that this thing has been flawless over the years. previous owner kept everything even tire papers and there were no repairs needed. i will check out the overflow hose too, it didnt appear kinked or anything but i will take a look today for sure.

 

[fast_dave]

Yeah - lots of guys don't replace radiator caps because they pass the visual test, but that's not what counts.
It's a pressure and vacuum device.
If it doesn't hold pressure, you quickly overheat. They should hold 15-16 PSI (if memory serves me correctly).
If it doesn't hold vacuum, you don't suck in coolant from the overflow tank as you engine cools down.
The little overflow hose that connects the two is regularly overlooked ;-) They clog and kink.
All the "crap" that floats to the top of the radiator gets pushed past the radiator cap, out that little overflow hose, and into the overflow tank...

Report back ;-)

PS - If your thermostat has a teeny tiny "jiggler" valve on it - that has to be facing upwards...
It's a little piece of metal (or brass) that sits loose and is allowed to jiggle around in a hole that's on the flat surface of the thermostat close to the outer edge.
Here's a pic of one gathered off the internet:
https://encrypted-tbn2.google.com/i...AYspdLHJZYsMTOS-8bGtDO177XQBxNXS5NYQUEju1tUmW

Replacement Radiator Cap: Your Ex takes a STANT 10233 Radiator Cap, rated at 16 PSI; Here's a pic of it:
http://info.rockauto.com/getimage/g...eurl=http://info.rockauto.com/Stant/10233.jpg

 

[torumekian]

thanks for the pictures! i dont recall seeing the jiggler valve on it but i will disassemble today anyways to check when im flushing the reserve tank and replacing the cap. appreciate all your help!

 

[fast_dave]

Nick -

No problem - I'm happy to give back as no doubt this forum has pulled me out of countless Explorer jams, and currently I'm working my way through one ;-)

Say man - I forgot to add (I can't believe I'm saying that) but I figure it's better not to assume you thought of this.

OK - presently you have air in your cooling system, and you need to push it out into the atmosphere, and the radiator cap provides this function. Hence another good reason to make a radiator cap part of your maintenance schedule.

So, when you refill your cooling system with coolant/anti-freeze, make sure you also fill the overflow tank in the engine compartment until it is 2/3rds full - this is important!

Then, run the engine up to operating temp, AND then TURN ON your heater on inside of the passenger compartment. Drive around for at least 10 minutes with your heater heat control turned all the way to the right, into the red zone of the temperature indicator and mix your driving up; a little around town, and a little on the freeway. You don't need to turn on the fan, BUT you do need to have the temperature dial turned all the way to the right. This will allow hot coolant/anti-freeze from the block to be "pushed" by the water pump through the passenger compartment heater core, and thus push out the air from the heaters system into the engine block.

When you return home, leave the heater temperature dial turned fully right, into the red zone (yes - you have read this correctly) and park your Explorer. This will allow vacuum produced (as the engine cools) to pull the air out of the cooling lines in the heater system. When you wake up in the morning, open the hood and check the coolant/anti-freeze level IN THE OVERFLOW TANK. DO NOT OPEN THE RADIATOR CAP and don't be afraid if you have to add a quart or so TO THE OVERFLOW TANK. You're now in the process of purging the air out of the system!!! Add coolant/anti-freeze to the overflow tank (and make sure it's at least 2/3rds of the way full). Drive to work with your heater dial turned all the way to the right, into the red zone (you don't need to turn on the fan and cook yourself). When you reach work, leave the heater dial in that position (in the red). It's basically a repeat of the night before. When you're done with work, before leaving the parking lot, pop your hood, and check the level in the overflow tank. You'll probably take some more coolant/anti-freeze - BUT less than in the morning. Keep repeating this procedure until the level in the overflow tank stabilizes at 2/3rds full.

When your system stabilizes - make sure you ALWAYS keep it at LEAST 2/3rds full - and never let it run low below 1/2 full. This is important to ensure that the engine cooling/vacuum effect is allowed to easily suck in fluid to the engine after pushing out air. Keep the radiator cap gasket sealing surface, inside of the neck of the radiator, clean and free of "crap" that will over time accumulate from the normal heating and cooling process.

HTH -

 

[torumekian]

Ok so I just got home from work and a part store on the way home. I replaced the cap, and as you said there was noticibly less resistance as there was in the new one. I also replaced the hood struts since I've had to prop the good up during all this. Not that it pertains to this. I pulled out the overflow hose and blew it out. Was clean. Nothing blew up into the reserve but air. I topped off my coolant and am getting ready to do some driving. I wanted to come in and clean up some and update this. Also as I was really inspecting the old cap I noticed several really fine cracks in the larger of the gaskets and when I pushed on them the whole upper gasket split. Good catch! I'll update a little bit later as I go test drive.

 

[torumekian]

Ok so I drove around for about an hour made some stops just cause I was driving around everything behaved fine. When I got back home to check the fluid levels it had used about 1/4 of the reserve. I looked underneath the car to look for fluid drips and saw a couple places with slow drips. I tried tracking the leaks up but still can't seem to find the origin. I took a short video on my phone with the LED light on to try and help ID the origin but ive not had any luck. Do you know if it's possible to load a video on here?

 

[fast_dave]

Nick,

Good to hear that replacing the radiator cap cured one problem!

It sounds like you from what you have described (no puddles underneath your Explorer) that you have a pinhole leak OR small joint leak that is leaking under high pressure. I'd suggest that you follow the heater hoses, as their are a lot of them and they are fastened at each end - potentially a leak point. So, with this in mind, use your hands to feel for moisture - wrapping your hand around each place that the heater hoses are "joined" or connect to something - i.e. heater control valve.

You either have a 2 or 4 port Heater control valve.

2 port heater control valve picture:
http://info.rockauto.com/getimage/g...http://info.rockauto.com/Motorcraft/YG364.jpg

4 port heater control valve picture:
http://info.rockauto.com/getimage/g...ttp://info.rockauto.com/FourSeasons/74809.jpg

Also, follow the heater hose to the water pump outlet as well as to the engine block/intake manifold return port. Additionally, insure that your heater hoses are NOT rubbing up against something that is metal - such as a metal bracket.

If these areas are OK, the next area I'd check is the front and rear of the intake manifold, as there are water jackets there (and gaskets that can fail).

Also check for leaking around the water temperature sensor.
Water temperature sensor picture:
http://info.rockauto.com/getimage/g...l=http://info.rockauto.com/SMP/TS376_FULL.jpg

You might have to heat your truck up in the daylight, face your Explorer towards the sun, open the hood, let sunlight fill the engine bay, and look/feel around while the truck is hot and the cooling system under pressure - possibly even while it's running. One good thing - with your new hood struts it should be a little easier, as well as no fear of the "mousetrap" effect ;-)

 

[torumekian]

http://www.youtube.com/watch?v=nqo9K2YXz4k&feature=youtube_gdata_player

Loaded the video on YouTube.

 

[torumekian]

It wasn't leaking like this yesterday and it wasn't leaking this way before my test drive, so it must be leaking after it warms up. I'll try and do some more looking tomorrow since I have the morning off. I can't see any coolant leaks from above so I only loaded the video from below. Since there was no puddle yesterday I can only assume its getting worse.

 

[fast_dave]

Nick,

It's leaking like this because when the coolant is under pressure from the new radiator cap, it follows the path of least resistance, and that's where it leaks out. It's hard to tell from the video as coolant is everywhere, but there is a lot on what looks like the engine frame and crossmember. So based on that location, I'd start with a check on the black plastic radiator side tanks, as well as the radiator seams - start with the drivers side.

For a quick check, with the engine off, stick a flashlight inside of the fan shroud and look at the seams on the drivers and passengers side of the radiator. The seam is where the silver aluminum body of the radiator is connected to the black plastic water tanks. When they fail, 99% of the time they fail at the seam. There is a rubber gasket connecting the two, and over time, with heating and cooling, the rubber gasket fails. SOMETIMES the black plastic side tank develops cracks as well. About three years ago that's how mine went bad a cracked plastic tank on the drivers side. The radiator is a throw away - you just swap out the bad one for a new one. For a better look more reliable looksie, unbolt the fan shroud and pull it back towards the engine block and check the radiator seam. Report back and we'll go from there.

Picture of what I think is your radiator:
http://info.rockauto.com/getimage/g...metheparts.com/BIN/images/VistaPro/432559.jpg

 

[torumekian]

ok so saturday will be my next chance to work on it. going to try and work on it. even though im off with some daylight i have to be watching my son tomorrow starting about an hour after i get off work since my girlfriend and i work opposite schedules and finally have a mutual day off. so ill be able to really dive into it saturday morning and realistically have the entire day if need be. im hoping to drive it to get it warm so its leaking, then reach in and towel dry all the hoses to look for a wet point. pull back the fan shroud and check those points on the radiator's gaskets. if i cant see anything then ill have to start disassembling again to get back inside and check out the thermostat housing and heater core areas. any other ideas before i get to a full scale dismantle?

 

[torumekian]

you said a few comments back that you were working on another issue with your car right now, whats on your plate?

 

[fast_dave]

I have a 4.0 OHV that has a coolant leak at the drivers side water passage on the timing chain cover. The gasket started to weep coolant at the end of this past summer. From what I've been reading here on the site, it's a pretty common problem 3.0 OHV and 4.0 OHV engines between 140,000 and 200,000 miles.

http://www.explorerforum.com/forums/showthread.php?t=307250

Parts are scheduled to be here by Dec 20th, so I'll get on it right after Christmas. As my Explorer gets older, we get friendlier and the complexity of the repairs increase...

Regarding your Explorer - I'd wager from the amount of coolant and the age & 250K miles it's the radiator - more than likely at the seam. From the parts I could see in the video - your water pump looked dry. It appeared from the video that the closer to the front of the car you got, the more coolant I saw. Generally, when a leak occurs at the seam, the coolant drips doen to the bottom of the black plastic fan shroud, and from there it spreads out to the left and to the right. That's why on the face of it it's hard to tell where all the damn coolant is coming from. When you pull the fan shroud back towards the engine, you'll probably see the bottom of the fan shroud filled with coolant. Update the thread after you check it all out - I'll check back in Sat. afternoon/evening. Good luck, be patient, and lots of times it helps to take pictures as you're disassembling everything for future reference.

 

[torumekian]

well its looking like its the water pump.i drove it till well heated up and then popped the hood like before i couldnt really ID the spot. so i turned it off and towel dried as best i could all of the coolant drips. the first point to be wet again was a little below and behind the water pump. but i still couldnt really find the first drips. i wanted a better angle so i cranked the wheel to turn the tires as far right as i could, and got inside the wheel well. i peeled back that black barrier that keeps junk from getting inside the engine compartment for a better angle and it looks like the coolant was dripping from near the bolts for the water pump. so im going to assume the seal has gone bad or the pump itself has warped.

 

[torumekian]

ill go shoot a short video of it and post it here

 

[torumekian]

http://youtu.be/S5PeGmWe7eQ