Lexus XX470 Exhaust Manifold

Our June Repair of the month features a 2005 Lexus GX470 4.7L V8, with an exhaust manifold leak. The exhaust manifold is the part of the exhaust system that comes directly off of the engine block. There is a gasket between the manifold and the block that seals the gap and keeps  any exhaust gasses from escaping. In this case, the gasket needed to be replaced. When the manifold is leaking like this one, it makes a ticking sound that can sometimes be confused with an engine misfire, tick or knock. The sound is apparent upon first startup of the vehicle when the engine is cold and sometimes may go away as the engine heats up, or may stay consistent.  

A leaking manifold can cause serious problems if left untreated for too long. Besides the obvious health risks of exhaust leak making its way into the cabin for you to breathe in, the exhaust valves can get burned from the heat not being expelled efficiently from the cylinder. This can also cause  damage to the piston rings, oxygen sensors, and catalytic converter. Another symptom of a leaking manifold can include increased fuel consumption and loss of efficiency and power. 



This customer heard the ticking from the manifold and decided to take care of the issue, avoiding serious damage. It is normal to hit a few bumps in the road while performing this repair in regards to bolts and studs breaking from corrosion and rust. This requires extra time to extract the broken pieces so new hardware can be installed. Extraction can be done a number of ways, and it depends on how much of the stud or bolt is sticking out of the engine block. Using a “stud extractor” which locks on to the stud so it can be removed, is good to use if the stud sticks out and you can grab onto it. Another method is to drill a hole in the center of the stud and use a bolt extractor/easy out, which is almost like a reverse drill bit. It grabs into the metal of the bolt and, theoretically, pulls the bolt out with it when removing. However, this does not always work and sometimes the tool will break. We have found the easiest and most efficient way for us to remove broken studs/bolts is welding a nut on the end of the broken stud so we can just use a socket and remove it. The last straw would be to fully drill out the stud and use a heli-coil kit to re-tap a new hole with fresh threads. 

After reading this article, we hope that you are able to take away some knowledge about exhaust manifolds, why it is important to keep up with them and some of the methods we use to remove them. We are always committed to providing our clients and community with the best service we can. That’s the magic touch!


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