Loss Of Power On The Way Home Last Night

[Jimjific]

So about a mile from my house I was following a car when a car coming the other direction cuts in front of us and we have to hit our brakes pretty hard. Nothing crazy happened, but I then tried to accelerate back up to speed the truck suddenly sounded loud and it lost its power. I limp home the rest of the way thankful that I was able to make it. Oil pressure was fine as well as the temp. Over the past few weeks I thought I was hearing what sounded like a small exhaust leak. When I opened the hood you could definitely tell that there was now a big exhaust issue on the left side manifold area. This morning I took off the heat shield and you can see a nice long crack running down the center of the manifold. So my question is, can the loss of power be caused by this leak? Napa has the center dump for that side $140 - Ouch!

Thanks,
Jim

[Jimjific]

Here is the fender side of the manifold I just pulled off.

Here is the other side.


I was wondering what you all do with this part?

How important is it that it work properly? I freed up the valve but the post that holds the spring doesn't hold to well. Should I just jam the valve so it stays open?

Jim

[71K20chevy]

I can't see how an exhaust leak could really produce a noticeable loss of power. You might consider switching to headers (about $120 at Summit) since it's still cheaper than getting a new manifold.

That valve is for the exhaust crossover. When the motor is cold, the valve is closed and it redirects the exhaust through the intake, into the other manifold. This is for faster warm up time. It is not required. I wonder if maybe when you slammed on the brakes the valve got stuck closed, causing loss of power?

[Jimjific]

Andy,

Great thought. I didn't think of that. I wish I noted how the valve looked before I started messing with it. That would also explain why the exhaust got loader instantly since it would be forcing it through the cracked manifold. And it makes sense with the brakes causing it. I'm tempted to throw it back together and see if it goes away.

I thought about the headers idea, but for speed of getting it back on the road, I will just get a new replacement. With headers I'd have to replace exhaust pipe.

Thanks,
Jim

[Bigdav160]

You can buy a new exhaust manifold on Rockauto for $85

[Stocker]

You can safely toss that heat riser valve. I've been running without one for many years, with no noticeable difference in warmup time.

[Molberg]

Originally Posted by 71K20chevy

I can't see how an exhaust leak could really produce a noticeable loss of power. You might consider switching to headers (about $120 at Summit) since it's still cheaper than getting a new manifold.

That valve is for the exhaust crossover. When the motor is cold, the valve is closed and it redirects the exhaust through the intake, into the other manifold. This is for faster warm up time. It is not required. I wonder if maybe when you slammed on the brakes the valve got stuck closed, causing loss of power?

Thats a good thought right there... Depending if that valve was functioning properly before as well.(stuck open...then slammed shut) I've seen some of those heat riser ports blocked right off with carbon deposits too.