Exhaust manifold gasket replacement

[95WhitePrix]

How hard would it be to replace the exhaust manifold gaskets on a 1995 Pontiac Grand Prix SE 3.1l?

 

[digitaloutsider]

Not really hard, but I guess that would depend on how rusty things are on the car. Unbolt the crossover, remove the bolts/nuts that hold on each manifold, remove old gasket, install new gasket, bolt it all back together.

[95WhitePrix]

So I would have to tear down the engine to get access to them then?

[digitaloutsider]

Nope, just remove the bolts/nuts that hold the exhaust crossover on, and get it out of the way. That'll give you more room to maneuver the exhaust manifolds themselves around once they're unbolted.  Shouldn't need to take much apart, maybe remove the airbox to get more space (it's been a long time since I've wrenched on a 60 degree motor). 

[95WhitePrix]

Thanks so much for your help!

[digitaloutsider]

No problem. But don't the 60 degree motors have reusable metal exhaust manifold gaskets anyway? What's leading you to replace them?

[95WhitePrix]

It has an exhaust leak, I figured that it's probably the gaskets but maybe it isn't

[digitaloutsider]

In my experience, exhaust manifold gaskets rarely fail unless they've been installed incorrectly and pinched or something.  If you're up north, the exhaust tends to rust either right before the mufflers or the mufflers themselves.  Also seen them rust on the weld joints around the cat.  Check there first. 

[95WhitePrix]

It sounds like it is coming from the back of the engine. It doesn't have alot of rust on it, but I guess something could be rusted out.

[digitaloutsider]

I believe they also have an exhaust donut between the rear manifold and downpipe. Maybe check there, too. You should be able to see black soot around the joints if they're leaking.

[95WhitePrix]

I think it's leaking from the right rear engine and from the exhaust crossover where it hooks into the rear exhaust manifold, but I don't know how to get the exhaust shield off the crossover.

[55trucker]

i take it that those pesky tiny screws that hold the shield to the crossover are seized into place.

[95WhitePrix]

1 minute ago, 55trucker said:

i take it that those pesky tiny screws that hold the shield to the crossover are seized into place.

Actually they came out, but the shield is blocked from coming out by the master cylinder.

[55trucker]

If memory serves one has to remove the intake snorkel, the throttle body, the coolant thermostat housing & hose to rad, can't remember if the fuel lines are routing directly over top of the crossover. The master shouldn't be an issue.

[rich_e777]

You may have to go up the back of the engine and disconnect the downpipe at the flange, also remove the fan assemblies to give you some more room on the front. 

 

I had someone hack my cat converter off years ago and they actually broke the rear manifold in the process, IIRC I rocked the engine forward to get better access to the rear manifold once the front one was off and downpipe disconnected, the coil pack can be removed for better access. I cannot recall and exhaust shield giving my issues though, they are just bolted on and might be rusted together.

[95WhitePrix]

I looked at it again and it was actually the brake booster that it was hitting on.

[55trucker]

That doesn't surprise me, that booster is the larger 12" dia item, still shouldn't be an issue to get the crossover out. Release all the crossover bolts, swing back the front portion away from the front manifold, move the entire assembly forward in the direction of the rad & swing up the front half & out it comes.

[95WhitePrix]

Does the crossover pipe have gaskets on it?

When I searched for them online I couldn't find anything about there being a gasket on it.

[55trucker]

No, both ends are a ball & socket design.

[95WhitePrix]

2 hours ago, 55trucker said:

No, both ends are a ball & socket design.

I wonder why it's leaking then?

[95WhitePrix]

I found out that it's the joint that the down pipe connects to on the manifold that's leaking, I'm not sure how easy it would be to replace that gasket.

[55trucker]

That gasket will be a *donut*,

depending on when the last time the flange bolt/spring/nuts were undone will more than likely dictate how awkward the job will be.

[95WhitePrix]

1 hour ago, 55trucker said:

That gasket will be a *donut*,

depending on when the last time the flange bolt/spring/nuts were undone will more than likely dictate how awkward the job will be.

I figure it was never removed.

I wonder how easy it is to get to it because it looks crammed back where you can't get to it.

[55trucker]

Usual course of action is from under the car, acetylene for heat, impact gun with a very long extension and a deep socket/swivel on the end.

[digitaloutsider]

It'll depend on rust, really. It's been a long time since I worked on a 60 degree, but I think the manifold points down at really awkward angle almost necessitating getting at it from th bottom. Regardless, take a look at the back of the motor and see if you have any clearance from the top. When you're ready to take it apart, I'd let the engine run for a while and get warm, then shut it down, spray some Deep Creep on the threads, then attack it when it's cooled down.