How to Fix an Exhaust Leak on a 1985 4Runner 22RE

Hello Ladies and Gents and Kiddos! Today’s topic is an easy one, but can seem quite daunting if you have never done it before and don’t know what’s involved. We get to fix an exhaust leak that is caused by a blown gasket at the exhaust manifold. If you want to skip all of the colorful commentary, and are ready to get a little dirty, grimy, and greasy, then skip ahead to the fix it steps!


Fixing an Exhaust Leak by Replacing the Manifold Gaskets on a 1985 4Runner 22RE Motor


The MORR RunnerCrawler is an incredible piece of machinery. It has all of the bells and whistles to go anywhere we want. Which makes getting lost so easy to do! Maybe that is why getting lost is one of our favorite past times…



She is an 85’ 4Runner and she comes complete with roughly a 8” total lift (5” suspension, 3” body)(it might be 9-10″ total lift if I would stop being lazy and get fresh leaf springs). It has the chevy 63, 2.5 ton springs in the rear. The TrailGear 5.5” springs up front with 18” shocks all around. Chromolies on all 4 corners with ARB 5.29 difs and trussed housings front and rear. 37” Goodyear MTRs on 15×10 weld on DIY beadlocks. The W56 transmission has been swapped out for the lower geared R151. We have the Toyota 2.28 transfer case and a Marlin 4.7 crawlbox. And lots more goodies to make sure that we are able to get lost in stellar fashion.



The only thing that is suspect, is the good ol’ 22RE motor. These motors are notorious for being unkillable (we litterally mean you can’t kill them… ask Top Gear, they tried). However, it seems like the previous owners of the MORR RunnerCrawler did absolutely zero maintenance on this motor. And, when you do zero maintenance to a 30 year old motor, things stop working correctly. So we have been slowly going through and replacing parts in the engine.



This time, we had an exhaust leak going on. It really came out of nowhere and took us for surprise. The symptoms first appeared on our first MORR-Wheeling Meetup at the Bear Valley OHV Loop past Truckee, California. But the symptoms corrected themselves and went away on the ride home. So, we didn’t think anything of it. Keep goin until its broken, right!?

Then they REALLY showed themselves 2 days before Winter Fun Fest. Unfortunately, there wasn’t enough time to try and fix the exhaust leak prior to the weekend long event.


What Are The Symptoms of an Exhaust Leak?


So what are the symptoms of an exhaust leak in a 22RE motor? Typically they will be:

  • Your engine will be quite noisy. Generally, with lots of popping noises at certain RPMs or on deceleration. It sounds a lot like backfiring, but instead of one big backfire every once in a while, it continues while you are at specific RPMs.
  • You can smell a burning exhaust smell in the cab when you are driving slowly.
  • You can smell a burning exhaust smell in the engine bay while the engine is running
  • If you check at night, with a flashlight, you will be able to see exhaust fumes coming up from your engine.
  • Your engine burns very rich and you are getting lots of black smoke coming from your tailpipe.
  • Your gas mileage greatly decreases (in our case we went from 18mpg to 5mpg).


All of these symptoms relate to the engine thinking there is more air in the combustion air:fuel ratio than there really is. Why would the engine think this?? Because you have an exhaust leak before the o2 sensor! Essentially what is going on, is the engine is sucking in excess air AFTER the combustion stage, but BEFORE the o2 sensor.


Why Is It Important To Fix An Exhaust Leak?


Your o2 sensor measures how clean of a combustion you are getting and tells the computer to add more fuel or less fuel to the combustion ratio depending on the amount of oxygen showing up in the exhaust.

So, by there being more air at the o2 sensor, your computer will try to dump in more fuel. Which causes everything to run VERY rich and decreases your gas mileage. If it is bad enough, it will even cause your engine to stall when you are at an idle due to being flooded.


Testing To Find The Exhaust Leak in a 22RE 1985 4Runner


There are 2 ways to test and find an exhaust leak. The first way is to pressurize your exhaust system. This is easily done by taking your Smittybilt 5.65 CFM air compressor and pushing the hose through a plastic bag. Then tape the plastic bag on your tailpipe, with the hose inside your tailpipe. Then turn on your compressor! It doesn’t take much to pressurize the system.

Once the exhaust system is pressurized, spray it down with a soap and water mixture. Since most problematic exhaust leaks start at the manifold, start there. With the system pressurized, you should see air bubbles form wherever your leak is.

In our case, it was easier to spot where the leak was. We were burning so rich, that we had a little plume of carbon buildup coming out of the top of our exhaust manifold flange. So we knew that we either had a warped flange, or a bad gasket. There is only 1 way to figure out which one is the culprit… take it all apart! The above and below pictures are the old flange gasket compared to the new one. The ones on the left are the old ones. In the below picture, you can see why the gasket was leaking… You can literally see through the old gasket haha





How To Replace An Exhaust Manifold Gasket in a 22RE 1985 4Runner

Parts and Tools You Will Need


Brake Cleaner – $8.99Check Today’s Price!


Carb Cleaner – $12.00Check Today’s Price!

New 22RE Exhaust Manifold Gaskets – $17.00Check Today’s Price!

14mm Wrench – $9.00Check Today’s Price!

13mm Wrench – $10.00Check Today’s Price!



Step 1 – Remove all of the 8 14mm nuts, and the 2 bolts that hold your manifold onto your engine. If you end up pulling out one of the studs from the engine head, that is fine, just remove the nut from the stud, then thread the stud back in.


Step 2 – Remove the flange plate that holds on the top of the manifold. Under these 2 plates are a gasket. As you can see in the pictures, our gasket was so bad that you could literally see through it. We nicknamed it the “holy header gasket”. Even if this is the cuplrit for you as well, continue taking apart everything so that you can clean it all down. Since you have been running rich, you will want to clean out all of the soot and carbon buildup.


Step 3 – Pull the headers off of the bolts and clear up the exhaust openings.


Step 4 – Clean everything! We used brake cleaner to spray down each exhaust port, and then a toothbrush to get in and scrub them down. You can use carb cleaner if you’d like, but we prefer brake cleaner since it dries out much quicker and doesn’t leave residue at all. Let the port dry out a little, then wipe the fine soot out with the same toothbrush. Repeat that process for each port. Then do the same thing on the headers. Then spray down your flange plates, bolts, and nuts and give those a good scrubbing. Your engine has already lasted for 30 years now, give it a good clean here in this step, and it will help you get another 30 years.

Step 5 – Remove your o2 sensor and clean that off as well. O2 sensors are an important part of the engine. They tell the computer how well or bad the engine is combusting. This tells the computer to use more or less fuel. You want to make sure this is always functioning correctly and stays nice and clean. Our o2 sensor used a 13mm wrench, but our bolt heads were a little grimy. Your’s might use a 12mm wrench if they are nice and clean.

Step 6 – Get your new gaskets and put them on. They should line up directly to the bolts on the side of the engine.


Step 7 – Put the headers back on the bolts.


Step 8 – Put your flange gaskets on, and then your flange plates.

Step 9 – Put your 8 nuts and 2 bolts back in their original places. Torque them down to 31FtLbs


Step 10 – Make sure your o2 sensor is back in and all of your spark plugs are plugged back in.

Step 11 – Have a drink!


And that is it! Since you used brake cleaner to clean down everything, you should be good to crank the engine over and see if your sputtering has stopped. If you used any kind of penetrating oil to get the nuts and bolts off in step 1, then you will get a burning smell and smoke when the engine starts heating back up for the first time. This is normal, and is just oil residue. As long as you have everything torqued down to 31 ftlbs, then you should be good to go!


Congratulate yourself, have a drink, relax and know that you just did something like a boss!


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