Exhaust Leak

[Quatervois]

About 4 months ago my 1991 Land Cruiser developed what appears to be an exhaust leak. It's driving me nuts, so I've decided to dig in to attempt to resolve it.

Before I do, I figured I'd ask the forum members their advice and opinions.

The leak appears to be coming from near the top of the motor, just below the plenum...so I figure it must be the exhaust manifold. I figure it must either be cracked, or the gasket is shot. I did the trick where you blow air into the exhaust pipe, and squirt soapy water on various exhaust componants to see where the bubbles form....but no luck. I did it a few times, and couldn't get the soapy water to form bubbles. I think the heat shields are preventing me from seeing the air escaping / bubbles forming.

In your opinion, is it most likely the exhaust manifold, or might it be something else?

If it is the exhaust manifold (cracked or bad gasket) is it a difficult job to do, or pretty straight forward?

Thank you in advance.

 

[MissahPapaJ]

Start hitting stuff with your favorite penetrant when engine is cold rinse and repeat a few times for best results. Take your time and if something gets tight on the way off retighten hit affected fastener with a wire brush and brake fluid ( trick on rust ) keep going back and fourth till you feel confident. I would track down some new hardware back ups just in case you have stubborn or FUBARed hardware. Exhaust manifolds can be tricky at times, check how true the manifold is once you get it off if it’s warped you’ll have to find somewhere to deck it. Good luck buddy!

 

[Quatervois]

Start hitting stuff with your favorite penetrant when engine is cold rinse and repeat a few times for best results. Take your time and if something gets tight on the way off retighten hit affected fastener with a wire brush and brake fluid ( trick on rust ) keep going back and fourth till you feel confident. I would track down some new hardware back ups just in case you have stubborn or FUBARed hardware. Exhaust manifolds can be tricky at times, check how true the manifold is once you get it off if it’s warped you’ll have to find somewhere to deck it. Good luck buddy!

Thank you for the response.

It's a California truck, so there's virtually no rust so I have that going for me. It's still a 35 year old truck, and doubt these bolts have ever been out before.

Have you done an exhaust manifold on a 3FE engine before?

Do I have to take the intake manifold off to fully access the exhaust manifold?

Other than a new exhaust manifold gasket, are there other gaskets that I'll need, or should replace while I'm in there?

Thanks again.

 

[MissahPapaJ]

Thank you for the response.

It's a California truck, so there's virtually no rust so I have that going for me. It's still a 35 year old truck, and doubt these bolts have ever been out before.

Have you done an exhaust manifold on a 3FE engine before?

Do I have to take the intake manifold off to fully access the exhaust manifold?

Other than a new exhaust manifold gasket, are there other gaskets that I'll need, or should replace while I'm in there?

Thanks again.

I’ve got no 3FE experience but when it comes to exhaust even on CA vehicles is regardless of rust or no rust you’ll wanna take precautions when removing even if you don’t have to the constant heating and cooling of a very hot manifold causes issues I’d look at what needs to come off and get those gaskets. If you take a few pics of the manifold so I can get an idea of what your tackling I can steer you in the right direction. Also start using penetrating oil now just for added ease of removal. Might stink up the engine bay but a couple of lube cycles will never produce worse results.

 

[MissahPapaJ]

When it comes to fixing old stuff plan for war, prey for peace. I’ve had to get fairly western working on 5-10 year old exhaust parts. Get a wire brush and wire brush anything off of the studs prior to removal use penetrating oil, get a few cans of brake clean to blast off the dirt / grease / debris / surface rust and I think you have a decent time.

 

[Marvelicious]

I’ve got no 3FE experience but when it comes to exhaust even on CA vehicles is regardless of rust or no rust you’ll wanna take precautions when removing even if you don’t have to the constant heating and cooling of a very hot manifold causes issues I’d look at what needs to come off and get those gaskets. If you take a few pics of the manifold so I can get an idea of what your tackling I can steer you in the right direction. Also start using penetrating oil now just for added ease of removal. Might stink up the engine bay but a couple of lube cycles will never produce worse results.

Totally agree with all of this. California vehicles are the best case scenario, and exhaust studs still suck. I will probably pick up one of those hand held inductive heaters the next time I have to worry about it.

 

[Broski]

Before you start taking stuff off do yourself a favor and figure out what’s leaking first.
In the morning when the engine is cold start it up and run your hands around where you think it might be leaking.
The leak should be worse before the metal heats and expands and you will be able to feel the exhaust coming out.
If you don’t find it before it gets to hot to put you hands around it repeat the next day with a cool motor where you left off.

 

[petegangies]

Hi.. you can just spray soapy water around the suspected areas (when car is stone cold), and then start the vehicle and get someone to rev the motor while you inspect for bubbles. I also use a method of a length of smaller diameter semi rigid plastic clear tubing that fits into your ear canal, and run the other end around the area. If there's a leak, you'll hear the noise increase a spitting noise.