Project 4Runner

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While working on the rear end I got a much better look at the dual exhaust setup that came with the truck.  What I saw did not impress and I pray it was not done by a muffler shop.

The whole setup was pretty cobbled together from the horrible mounts, poor bends and craptastic second tailpipe addition. I had planned on replacing all of the gaskets at the flanges due to an audible exhaust leak so I started pulling the system apart.

Turns out the exhaust leak I was hearing wasn't one of the flange gaskets but a much bigger leak on one of the exhaust pipes where it had corroded thru.

I ended up ordering a replacement setup from AutohausAZ for roughly $180.  Losing the dual exhaust pipes did not bother me as I figured they would get crushed on the first ledge I dropped off of.

It was finally time to start on the engine. The first thing I removed was a sign of things to come; the factory air box was cracked around one of the mounting tabs.  Some shoe goo and drywall tape from my RC car supplies made for a sturdy repair.  As mentioned all of the vacuum hoses I was removing were in terrible shape, many crumbling at the ends so I was going to replace them all when everything went back together.

Next up was removing the supercharger to gain access to the valve covers.  Here’s where things got real interesting.  I removed all the bolts that hold the S/C to the intake and upon removing it just fell apart in 3 pieces.  The wastegate actuator mounting tab fell off and the rear mounting tab at the base of the S/C was still sitting in the truck. Now normally I would chalk this up to myself but all signs pointed to the previous owner.  On closer examination I noticed both broken parts had been glued back on using what looked like gorilla glue.  That in itself isn’t enough to incriminate the previous owner except that the same adhesive was used elsewhere.  While working on the truck I discovered the same hard epoxy was used to seal the rear 3rd member and to glue the driver’s side mirror onto the mirror stalk.

The buyer’s remorse kicked in at this point because without the S/C this truck was not a good deal.  After a few days of contemplation I decided to try repairing the S/C housing with some aluminum brazing rod as seen on YouTube. While waiting for the rod to arrive in the mail I fabricated a fixture to hold the broken mounting tab so the bottom mounting surface would be flat. Once the brazing materials arrived I used a torch to heat the S/C housing but could not get the brazing rod to adhere well.  I did manage to get the wastegate actuator mounting tab re-attached by drilling and tapping the S/C housing and bolting the tab back on using some M3 hardware.

Plan “B” was to try TIG welding the mounting tab but I do not own a welder capable of welding aluminum. Luckily my neighbor had a friend who could do it so after some more prep work I took it over and had the tab welded back on.  Since I did not want to have to re-surface the mounting flange I planned on using JB weld to fill in the crack on the inside of the manifold and on the bottom surface.   I

Next up was pulling the valve covers and installing new seals.  All signs were pointing to these being the source of most of the oily residue down the side of the engine block.

Once the valve covers were re-installed I moved on to the timing belt and water pump.  Both were in really good shape so maybe the 150k timing belt change sticker was not the most recent service. Either way I replace the belt, tensioner, water pump, thermostat and related gaskets. The job was pretty easy once I made a tool to hold the lower main pulley.

While I was digging into the engine bay I realized I was going to have to change out all of the vacuum lines since the existing ones were all cracked and brittle.  I ended up ordering a whole box of different sizes from Summit Racing since they had everything I needed for .99 cents a foot.  One thing i missed was a 3 foot piece of 1/4" fuel line to replace the fuel return line with but luckily the local auto parts store had some in back.

The last modification I chose to do was to re-route the transmission cooling lines from the lower part of the radiator to a dedicated cooler. This takes care of a common issue with older 4Runner's where the internal cooling passages crack allowing the transmission fluid to mix with the anti-freeze.  This typically takes out the transmission if not caught immediately and I figured with all the miles on this particular radiator a $50 transmission cooler would be cheap insurance.

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