Newby here...but trying to learn...

I have a 2nd Generation '94 4Runner that I have been having a few problems with. After I drove it to Texas from Oregon, It started making a really loud sound in engine compartment, almost like a muffler was blown or something was bad. My uncle suggested changing air filters, so I put a K&N filter in, but no luck. The weird thing is if the engine is revved above, say, 2k, the loud sound goes away, but comes back when idling.. Any Ideas? (Dr. Z? I've read some of your posts, and they are very informative.) After about 7 minutes of driving, the loud sound goes away, until the next start

:mad:Secondly, now my Check Engine light comes on at random times, and then goes away randomly. Anywhere from 200 miles to 5 miles. Checked the codes and got 14 and 25. I ran a fuel injector cleaner through, but to no avail. I don't have a ton of money, so I'm trying to fix it on my own if possible...

Any and all suggestions are more than welcome!

 

Have you gotten your head gasket checked out? I have a 94 as well, and I had my HG replaced recently by the dealer under warranty because of the recall campaign. Is the noise you hear sound like a loud gurgle from the intake?
BTW...welcome to the forum. The people here are friendly and helpful

 

Yeah, apparently the guy who owned it before had the whole engine replaced because the engine block was cracked due to the bad head gasket. That was 45k miles ago. The vehicle itself has 153k...a lot I know, but the new engine seems to work fine except for this deal...

Exactly, a loud gurgle, although I, regretfully, am not a mechanic and could not locate the intake if asked. The gurgle seems to come from the top-center-rear of the engine, close to the firewall. Does a loud gurgle suggest a bad head gasket?

Thanks for the welcome...Wish more people would reply, though...

 

Sometimes but not always. Ever since my 2nd HG blew (and fixed) I've had a gurgling sound from the heater core. Somebody on the internet said that happens after the HG blows and will continue to do that until you replace the heater core.

Other symptoms of a blown HG are water in the oil, evidence by a milky substance on the oil cap, oil in the cooling system, white smoke out the tailpipe, and a rough idle. There could be more, but that's all I know about.

Check your power steering fluid. The pumps tend to leak after while and when mine gets low it taps really loud. Hmm...but I don't think that should throw a code. Did you figure out what the codes mean?

Steve

 

I was told that the gurgle sound coming from my intake was normal. It's a very unsettling noise but I was told not to worry by several sources.

 

I recently changed the oil, and did not see any evidence of water in it. The gurgling sound (basically, my 3.0 4Runner sounds like a turboDiesel) occurs even at a stand still...so I don't know about the power steering fluid. It's currently 30 degrees outside, windchill to 15, so I'll check that tomorrow.

I did research on the diagnotic codes at
http://www.off-road.com/toyota/tech/codes/

The codes are...
14 - IGNITION SIGNAL--NO "IGF" SIGNAL TO ECU
25 - AIR/FUEL RATIO LEAN INDICATOR--LEAN SIGNAL SENT TO ECU FROM O2 SENSOR

Is it possible that my 02 sensor is out/going out? I've heard they aren't too bad to replace...but I haven't looked for it on my runner. Do you know about how much they run/how hard they are?

 

I had the code 25 on my 4runner also. I replaced my O2 sensor. Mine ran me $126 including tax, but that was my price. I think it would have been $140. I bought mine straight from the dealership. I've seen cheaper prices on the internet, but I'm not sure if it is a genuine Toyota part.

The O2 sensor is very easy to replace. All you need is a wrench or a socket to do the job. It is located on the top of the exhaust pipe right in front of the catalytic converter. The catalytic converter is the mini-muffler looking thing located in front of the muffler. It will be towards the front of the vehicle. Just remove the two nuts and O2 sensor will come right out. Then disconnect the wires and put the new one in. Its easy to replace, but make sure you remove the old paper gasket. When I first did mine the gasket blended in with the exhaust pipe and I didn't notice it.

I didn't need any penetrating oil, but you may want to use some if the nuts are hard to get off.

There you have it.

 

Sounds like it could be a leak in the exhaust manifold gasket. I believe a leak in them can also cause an error code that points to the O2 sensor even when the O2 sensor is good.
An easy way to check is to find a long cardboard tube and while the engine is running, hold one end to your ear and using the other end, sweep across the exhaust manifold area on both sides of the engine. Also check where the exhaust manifold bolts up to the exhaust pipe. You'll know for sure when you find the right place. Not only will you hear a loud exhaust sound, you will likely get some exhaust fumes up the tube as well.
It could be that once the engine gets hot and the manifold swells some that the leak gets cut off some. Also, I have found that exhaust leaks like that do tend to be loudest at lower RPMs for some reason. I think at higher pressures the leak tends to "hiss" more than "pop".
I should add, it could be something as easy as tightening the exhaust manifold bolts. Keep in mind however that if there has been a leak long enough it will tend to burn the gasket some and you might not get a good seal just by cranking down on the bolts/nuts. Don't get wild tightening the bolts/nuts either. If you break a stud, things really get to be a pain.
Good luck!

 

It's iceing outside...so it'll be a while before I head under the hood, but...

If it is indeed the manifold gasket, would the sound be as bad in the engine compartment? Also, what is the story with the code 14? Just a side effect, or nothing related.

I was going to pull the spark plugs, but they are WAY down in there on the yota. I use to own a chevy, which was unreliable, but easy to work on because I could sit in the engine compartment. My runner is much more reliable, but more difficult to work on. Any tips on how to pull the plugs?

 

A long extension and a swivel will help you out big time.

 

I did mine this past summer and I think I lost a pint of blood from cramming my hands down in there to #1 pull the plug boots (maybe the hardest part) and #2 break the plugs free. It had been quite a while since the plugs were changed though.

I hope your hands are smaller than my "meat-hooks". I gotta teach my 4 year old how to remove the plugs, cause that's about all the space there is in the 2nd Gen bay.

 

Oh,yeah, it will can be anything from a tiny ticking noise to sounding just like a big hole in the muffler but under the hood. At that point in the exhaust system, the exhaust is under the most pressure. The sound will also follow the revs of the motor. If you can find somewhere to drive where there is a retaining wall or something similar to your left you will be able to hear the report of the sound off the wall. To me it is one of the most annoying sounds a motor can make.