Leaking coolant from the back of the engine - 1996 3.4L V6 5VZ-FE ATX 2WD

TimGFL

New member
Hello! I'm stumped and needing help, so I appreciate any guidance you fabulous folks can offer. As a DIY'er, I have turned to this site many times in the past and pretty much always found the information I needed but not this time, so far. Here's what's up:

There is no water in the oil or transmission fluid -- no coffee or strawberry milkshake. There is no smell of exhaust in the radiator, though I didn't do a chemical test. However...

I've had this truck as my daily driver about 3 years, and I had been losing coolant slightly for about 2 weeks, but I chalked it up to a hose going and figured I'd tackle it on a weekend very soon and swap out all the old hoses.

Then Murphy struck. I parked after a short trip to church and back last Sunday, and when I shut the truck off I heard quite a hiss -- I turned the key back to "on" and the temperature gauge was at my normal, a little under half-way. I popped the hood and noticed some steam, but not a lot -- about like a tea kettle simmering, and I couldn't visually pin down the source listening to the hissing. It almost sounded like it was coming from the center of the motor. I didn't see any leaks underneath at that time. So I let it cool a couple hours and then filled up the radiator with distilled water to look for leaks, and it took about 1.5 gallons. Lo' and behold! after 15-20 seconds, there began a steady trickle from the bottom of the motor side of the transmission bell housing where it meets the engine, almost square in the middle but an inch or two to the passenger side. I couldn't get any better angle to see the source from the top, side or bottom.

By the power of the internet and great forums such as these, I determined the problem must of course be either the intake manifold gasket or the bypass pipe that runs underneath the intake. After a fun-filled couple of hours today dismantling the top of my Little Engine That Could under an old oak tree in my dirt driveway in the middle of a Florida summer, dodging mosquitos and intermittent rain showers, that's not the problem. The gasket definitely needs replacing due to oil and minor water seepage (need to figure that out, too, because I'm getting some oil blowback into the rubber intake tube going to the throttle body LOL), and the top of the "V" is orange and rusty and crusty looking, but the sensors look to be in great shape and neither the gasket nor the bypass pipe showed any signs of water when I slowly started to fill the radiator... and still got the same steady trickle down the back of the motor somewhere, before I could even see any water in the intake manifold channels. None of the hoses are leaking either, that I can see.

I've had to replace one failed freeze plug on the passenger side about 2 years ago, and two of what appear to be freeze plugs under the intake look pretty rough. I'm thinking I should do those while I have the top apart (maybe it's just funk from the manifold gasket seep?). However, the "V" stayed dry (no pun intended), despite the trickle out of the rear. I have also heard rumors of freeze plugs on the back of this motor on the firewall side. I was able to see one that faces the firewall on the driver's side tucked in behind the exhaust crossover, but it's shiny silver and no leak. I couldn't get to an angle where I could see a freeze plug on the firewall passenger side. Is there one there?

Please tell me I don't need to pull the motor (unless that would be a lie). :) It's only got like 280K miles on it... it's barely broke in!!!

Help! I've heard the factory manual recommends against running these 5VZ-FE motors without coolant.

Sorry for the novel, but I wanted to provide as much information as possible. My sincerest thanks in advance for any help (or even comic relief at this point) you can provide.
 
Register to hide this ad
Can you also confirm that your heater control valve and it's hoses are not leaking?

Yes, confirmed. In fact, the heater control went bad and I removed it last summer I think. I spliced it together with a straight-through fitting (actually for a garden hose LOL), and it is not leaking there. The cabin air controls block off the heater core so it doesn't roast me. I couldn't seek coolant leaking from any of the hoses.
 
Already ruled that out by pulling the intake, but I appreciate the suggestion!


I had fantom coolant loss on the 97 Puppy Hauler and thought is was a head gasket and it ended up being the intake gasket leaking at the rear crossover. The whole valley was filled to the top with antifreeze. I did head gaskets anyway.


Sent from my iPhone using Tapatalk
 
I had fantom coolant loss on the 97 Puppy Hauler and thought is was a head gasket and it ended up being the intake gasket leaking at the rear crossover. The whole valley was filled to the top with antifreeze. I did head gaskets anyway.

Yes, that's what I was hoping it was so I pulled the intake, but the leak was not there or at the heater bypass pipe. Now I have a new intake manifold gasket installed, but still have the leak. I'm afraid it may be a freeze plug on the transmission, as a previous poster just mentioned. I've had to replace one before so it's a strong possibility. However, I don't seem to have any water in the transmission fluid, so that might not be it. It may be a freeze plug on the back (firewall) passenger side of the motor, but I haven't been able to see it yet. For some reason my boss thinks I should be working for him instead of working on my truck during the week. LOL!

However, I'm still open to any other suggestions before I try dumping some Blue Devil in it and crossing my fingers. I hope not to have to part ways with this truck, it's my first 4Runner and has been pretty reliable!

Thanks for the feedback! :)
 
it could be the oil cooler and the fluid is just getting blown back there while you're driving

Thank you for the suggestion! That's a good thought. I also looked at the oil cooler, and it doesn't look like that's the source. I'm getting the coolant leak just sitting still, engine off and cold, and only from one spot, almost at the center of the transmission bell housing. I think I have pinned down the source, I'll post that next.
 
there are also 2 freeze plugs in the bell housing

I believe you've got it. I had a chance to get way up underneath and watched as it leaked, and the leak is coming from a hole (looks like it's designed to be there) in the lower bell housing flex plate cover, passenger side.

As you say, I think the culprit is the passenger side rear freeze plug in the block (point A) because where it's leaking is just off center underneath it (point B). See below. Unless it's the block itself, but I hope not.

I watched TTM's (Love those guys!) ATX swap and clutch plate swap, and it definitely looks like a beast of a job to pull off in a dirt driveway with no lift and no help, but I may go ahead and try it. :der: :pray:

Thanks again for the help!

4runner%20rear%20freeze%20plugs.png
 
This is a reminder to everyone to change your coolant! :horn:

Parts like those rust from the INSIDE of the motor if coolant gets old...

-Charlie
 
With your truck being 2WD, it shouldn't be too bad. Rent a transmission lift and grab a buddy for help. With a helper, you should be able to get it fixed in one long day.
 
Hey! So how did this turn out?

Did replacing the passenger side freeze plugs stop the leak? Were you able to determine if any other freeze plugs were leaking once the transmission was out?

Apologies for all the questions but I'm dealing with he same problem but it;s so hard to find anything on the subject - on a 131k and the idea of taking out the engine breaks my heart.

I put my 4 runner on the lift and pin pointed two freeze plugs with leaks but there was another trickle quite possibly coming from freeze plugs that cant be seen.

Thanks !
 

Members online

Forum statistics

Threads
278,315
Messages
3,554,131
Members
248,016
Latest member
Advally Service

Trending content

Back
Top