Possible overheating/coolant bubbling/transmission knocking

[MistahYebba]

Just like everything else... you gotta start somewhere to learn the ropes, right?!

Well, I just bought my first car. It's a '92 Ford Explorer Sport (2 door, 4.0L v6). I believe it's a RWD? (Correct me or confirm this please)

There's a few problems with it so far and I want to learn how to correct them myself. So I'm going to list them.

When I first got in to start driving it I reset the trip odometer. My first 50 miles in, it started smoking. I drove home right around the corner and shut it off. There was a handful of puddles coming from the bottom.

You had the standard A/C condensation puddle, some sort of brownish/slightly clearish liquid dripping relatively slowly (oil?), a green liquid (antifreeze), and then one more drip (transmission fluid).

Popping the hood was like standing in front of the sun. It was very hot. I decided to let it cool over night.

So, taking it 1 leak at a time, I started the next morning by turning on the car and seeing if it leaks..

Nothing really. There was A/C condensation again since the AC was on... so.. here are the 3 leaks from the day before:

The oil leak... was this just oil on the undercarriage being washed off by the overheating fluids?

The antifreeze leak... there's a radiator coolant overflow tank (reservoir)... if it's so freaking hot, is it normal for radiator coolant to leak out?

The transmission fluid leak... this was the only concerning one... I knew I must have lost a lot of transmission fluid.

So, I started with the transmission fluid leak. I took off the transmission pan and every screw on that pan was very loose. So it's no wonder it was leaking! Furthermore, the gasket around the pan is the factory-grade cardboard. It was in poor condition and basically just bound to leak.

So I replaced the transmission pan gasket and filter... put everything back on and that would have "hopefully" fixed the transmission leak.

The next question was... why was it overheating at all? There was plenty of coolant.. the temperature gauge was on "normal" the whole time... (must be broken then?)... the heat works fine, so I presume the water pump works (maybe that has no correlation)... So why else could it have overheated?

My only guess was a faulty thermostat.. so I went ahead and replaced that too.

After replacing that... the truck runs fine. I drove probably 40 miles total yesterday... and that raised more questions...

It stalled a handful of times but only when I was at a complete stop somewhere. This wasn't every time I came to a complete stop, but about 5-6 times during my entire journey. This was frustrating as I wasn't sure why.

When I got to my main destination (the beach) and shut off the car, I could hear some concerning "bubbling". I popped the hood and realized it was the coolant/wiper fluid reservoir bubbling. Why does this happen? (I have read that it can be a bad radiator cap, blown headgasket, air in the coolant system, etc... but no solid answer.)

When I put it in to gear, i.e. Drive/Reverse, the car knocks a little bit. Nothing too serious, but why does it knock? Could this constant knocking every time I switch gears be the reason that the original transmission pan bolts were so loose?

If those bolts got loose enough to make me lose so much transmission fluid while I was driving, could that be the reason for overheating? Would you overheat from losing transmission fluid??

So...

lots of questions but I'm open to discussion so please do join! I'm going to check the "Check Engine" light codes today by doing the EEC Self Test or whatever it's called using a paper clip and following some instructions found online. If I get any avid helpers on this post then I'll keep ya'll updated!

Thank you!

 

[BKennedy]

You might need to "burp" the coolant system. There are numerous threads on the forum to help you do that.

I don't know about the stalling, there are also numerous threads on the forum to help you with that. Run the codes and see what you get.

Search is your friend.

 

[Wolfie_85]

For the oil leak, clean the engine up with engine degreaser. It tells you how on the can. Try not to get anything electrical too wet. Look for oil leaks after that. Much easier to tell if valve covers are leaky.

For the transmission knocking...is it one clunk when you put it in gear, or a steady knock? Only at idle or when stopped? If just one clunk when going into gear, nothing to freak out about as long as shifting is ok and there's no slipping. If you get a knocking when standing still and in gear, well, mine did that. Exhaust was rattling against something. Easy fix.

Stalling...lots of posdibilities. I recommend you examine your oil and coolant after overheating like that. Might have cracked or warped a head. If your oil looks milky or your coolant looks like mustard, you should worry. But check your MAF, clean it with MAF cleaner, check for vacuum leaks, TPS can cause stalling, too. Clean or replace your IAC, that will cause stalling at idle if it doesn't work right.


Does it have a button on the dash that says "4x4" on it? If so, you have 4 wheel drive. Or a lever on the floor (rare in these), that's 4 wheel too. If neither, you just have rear wheel drive.

 

[MistahYebba]

You might need to "burp" the coolant system. There are numerous threads on the forum to help you do that.

I don't know about the stalling, there are also numerous threads on the forum to help you with that. Run the codes and see what you get.

Search is your friend.

Hiya BKennedy, thanks for your reply.

I've read a lot about burping the coolant system and I greatly considered doing that.

I have one question about that for you..

When I first got this bad boy (my explorer) This past Thursday.. there was a pretty severe transmission pan leak. Whatever the reason that it's currently overheating...having that transmission leak made it even worse. Since it bubbles at just 35 miles, it's either bubbling from air or bubbling from boiling. I want to assume it's boiling since it overheated and was smoking the other day.

Since I repaired the transmission pan leak... it must have reduced the overall heat that contributes to the overheating in general...

Now.... the day that it overheated, I lost a lot of coolant from the overflow tank and also from purposely popping the radiator cap when it was hot to let it all out. Of course it sprayed everywhere naturally.

I replaced what was lost with water.

However... now I have probably a weird mixture of whatever was left of the coolant after that leak and radcap eruption... and water.

I want a more consistent mix of coolant.. (call me crazy, but I like knowing what's in my coolant tank!)

So.. what am I getting to?

How can I give 'er another go and start fresh with some new coolant? What's the normal method and what's the mixture ratio? 50/50 coolant and water or what?

Please let me know and thank you so much!

 

[MistahYebba]

For the oil leak, clean the engine up with engine degreaser. It tells you how on the can. Try not to get anything electrical too wet. Look for oil leaks after that. Much easier to tell if valve covers are leaky.

For the transmission knocking...is it one clunk when you put it in gear, or a steady knock? Only at idle or when stopped? If just one clunk when going into gear, nothing to freak out about as long as shifting is ok and there's no slipping. If you get a knocking when standing still and in gear, well, mine did that. Exhaust was rattling against something. Easy fix.

Stalling...lots of posdibilities. I recommend you examine your oil and coolant after overheating like that. Might have cracked or warped a head. If your oil looks milky or your coolant looks like mustard, you should worry. But check your MAF, clean it with MAF cleaner, check for vacuum leaks, TPS can cause stalling, too. Clean or replace your IAC, that will cause stalling at idle if it doesn't work right.


Does it have a button on the dash that says "4x4" on it? If so, you have 4 wheel drive. Or a lever on the floor (rare in these), that's 4 wheel too. If neither, you just have rear wheel drive.

Hey there Wolfie. I greatly appreciate your help. I wish I could give something in return! But here we go!

For the transmission knocking.. it's no biggy. Like you said, it's just a single knock when I switch gears at idle. The previous owner told me to let it run for a second on startup or I can expect to feel that little knock. Personally, I don't really mind it as it's not bad at all.. but considering there was a significant transmission pan leak (and all the bolts were pretty loose)... I thought maybe they were related? But hey, I replaced the pan gasket and filter and tightened those bolts up nice and tight so I don't reckon the little "knock" will make it happen again any time soon.

The stalling.. if you read my post above it's explaining the current state of the coolant which is questionable. It's a weird mix of whatever possibly old coolant was in there before and what was left of it after the leak.. and also a whole bunch of normal galloned water... I don't like the sound of that and I'd love to buy some fresh coolant but I don't know where to start on filling it back up.

As for the oil.. should I do the same thing for that too? Just empty out the current oil and get some fresh new oil for it? I don't know the last time the previous owner changed it.. I believe the service sticker on the car says 8/2014? It's probably fine but let me know..

I've read online lots of people saying "check for vacuum leaks". How can I even start researching about this? AKA what is the proper terminology for what a leak like this would be called?

I'll check and clean the MAF Sensor if need be. To save me a few bucks, how can I check if it even needs to be cleaned? Will there be any physical residue? And as for the TPS, do I clean that with the same MAF cleaner??

Now... as for the coolant bubbling/boiling and getting real hot, assuming that the water pump is fine, the thermostat is fine, and the coolant mixture itself is fine, a ton of people were stating that the RADIATOR CAP itself is a common issue.

I went in to my local auto parts store to buy a new one thinking that it could be the problem.. but upon telling the guy in there my issue, he told me to go look around the neck of the rad cap and such for some residue.. Upon looking, there was nothing at all.. He told me if I really needed to replace it, there would likely be some "white" residue around it and all over. So I decided not to buy it instead..

but could he have been wrong? Could my rad cap indeed be faulty but leaving no signs behind?!

 

[natenkiki2004]

Woah boy... I hope you didn't pay much for this Explorer but good on you for wanting to fix it.

The coolant leak... where is it leaking from? Front or rear of engine or not off the engine at all? If it's leaking off the engine, chances are that it's the lower intake manifold gasket. Very common issue on these engines but easy to fix. Check your oil, coolant and trans fluid, make sure nothing is mixing otherwise it could be a head or very serious lower intake issue that needs to be fixed ASAP.

You said it's boiling, is it boiling in the reservoir? Is the boiling slow (like air bubbles coming up) or is it fast & violent? Slow might mean that it's a cracked head and you're getting exhaust gasses into the coolant.

Oil leak... chances are you're not going to fix this one easily so put some high mileage oil in and/or some AT-205 and cross your fingers.

Trans leak, hopefully the pan fixed the majority of it, otherwise if it's leaking a LOT it's most likely the front pump seal. Not a terrible thing but the trans needs to come out to fix that.

Trans knocking... Is it a clunk? If so, does it happen when you shift from D to R with your foot on the brake? If so, that's a driveline u-joint and you should get it replaced soon, before it starts beating on the ears of the yoke, that will be expensive.

Vacuum leaks, run the engine and listen on the driver's side for a hiss. Chances are, most of the hoses will be very brittle and could even be cracked.

Your MAF will need to be cleaned, no question about that. People usually clean it when they change oil. May as well throw a new air filter in at the same time.

 

[MistahYebba]

Woah boy... I hope you didn't pay much for this Explorer but good on you for wanting to fix it.

Howdy there natenkiki; I'm so glad people like you exist on this forum. I paid $1,200 for this badboy which may or may not be a good investment haha. Hey, at least I own it, right?!

I'll start from the top like you did...

The "coolant leak" I believe only happened the first day I got it. I think it was actually an overflow reservoir leak happening normally because the car was severely overheating and smoking. and I believe it was only severely overheating like that because of that tranny pan leak I toldja about. How do I change my coolant? If I want fresh new coolant (not sure when the last time it was replaced was?).

I'm only assuming that the temperature is actually "boiling". I didn't put my finger in there and feel how hot it was haha. So I'm not sure.. but it was most definitely bubbling and it sounded like a pot of spaghetti cooking after a 30 minute driver. I couldn't really tell you the speed but it hasn't come back. Perhaps because I haven't driven it for that long under the hot sun since then to replicate the issue? But in reality it could be anything causing it to "boil" if it's overheating right? I know the radiator has multiple ways of dispersing it's heat... in reality, if even just 1 of these "heat dispersion methods" are failing, it has the potential of getting so hot to boil, right?

The oil leak... I'm going to assume this was only the hot coolant overflowing out of the coolant reservoir and landing on the chassis.. therefore bringing a mixture of coolant and oil down along with it. I say this because my oil level is fine and if in the current condition, if I drive the truck for a bit and then park it, the only leak I have under the car is AC condensation at this point.

I hope the trans pan fixed the trans fluid leak as well! I put 4Qts of tranny fluid in there to top it all off afterwards and it seems to be holding up jsut fine.

The trans knock is not much of a clunk per se. It feels more like... imagine your car is in drive and you let off the brake for a second and then push it down again. You just kinda rock forward a little bit. That's all. I don't think it's anything too serious, just curious why it's happening at all...

I'll listen for this "hiss" when I get out of work. The only sound I can say off the top of my head right now is a continuous "tick tick tick tick" at a pretty fast rate when the engine is running. What is this exactly? Anything related?

I'll grab some MAF cleaner and a new air filter. Just making sure.. I can clean the TPS Sensor (as mentioned above by another poster) with the same MAF cleaner, correct?

 

[murkinstock]

The clunk when going into gear is generally from worn rear end suspension parts, my truck does it too, its from the rear end shifting forward or backward from the torque being applied to it.

If you put your parking brake on (As long as it works properly) then shift it into gear, did the clunk go away?

This reminds me of when I got my Explorer (My first vehicle)

It had a whole heap of problems but I slowly got them figured out, thanks to this forum. Now it seems pretty reliable and I would have no doubt I could drive it to Cali and back.

 

[Wolfie_85]

DEFINITELY what natenkiki said. MAF needs cleaned. The cleaner is cheap, and you won't regret it. I clean mine a every few months. And yes, change the oil and flish the coolant. Buying it the way you did, I wouldn't think twice.

For oil, stick with 5w30, for tranny fluid, good old "DEX/MERC" is suitable and readily available.

 

[MistahYebba]

DEFINITELY what natenkiki said. MAF needs cleaned. The cleaner is cheap, and you won't regret it. And yes, change the oil and flish the coolant. Buying it the way you did, I wouldn't think twice.

Once I get out of work I'm definitely cleaning the MAF.

I don't know how to flush the coolant but I read something about a garden hose?!

 

[natenkiki2004]

The engine would not overheat from a transmission pan leak. Even if you think that a leaking transmission would make the engine work harder... it won't. Lack of oil in the trans will cause the clutches to disengage and the engine will rev freely like it's in neutral.

You need to look at other causes of overheating.


If the coolant did wash oil off the engine, how'd that oil get there in the first place? Either you still have an oil leak or the previous owner fixed it but never cleaned it (I'd then question his work ethic and quality of repair).


If the ticking is light, barely audible then it's just injectors working, nothing to worry about. If it's louder and sounds like it's at the top of the engine, it's likely your valvetrain wearing down. Not a big deal, many here have that problem and have run tens of thousands of miles with that noise.

 

[larrydd999]

MistahYebba, how many miles are on your Explorer? You may not be able to tell because the odometer only has 5 digits but it might be useful information so you can have some idea of what problems to expect. From my experience with our two GEN1 Ex's you will have some oil leaks from the valve covers - both sides - and from the oil pan gasket. Tightening the bolts will help a bit but the fix is to replace the gaskets. There are numerous threads on these and other common issues, just search around. If you have the time and tools, and a few $$, there are very few things you can't do yourself. One thing you might want to do soon is to read the VIN on the door or dash and decode it so you will know what the setup is. You will also want to get a few manuals on the vehicle which, with help from this site, will give you a good idea as to how to do things and when to take it to a professional. Welcome to the forum, it has proven to be a big help to me and I try to give some back when I can.

 

[2stroke]

A real possibility is that the coolant is so old, it boils at normal operating temp. This causes the engine to run even hotter and increase the problem. I would definitely replace the radiator cap, since that is a huge factor in the coolants boiling temp. I wouldn't worry about the engine oil leaks yet. They wont cause problems as long as you always have oil in the engine. I'm assuming you have the auto tranny, and in that case, its common for the cooling lines to start leaking.