I am pretty sure I have an exhaust leak under the hood (annoying ticking that seems to be louder when the engine is warmed up). I am suspecting either the connection between the exhaust manifold and the lead exhaust pipe, or the gasket between the manifold and the cylinder head. The small block lead pipe connections use a special sleeve-type design that doesnt use a gasket. So, I am suspecting I will have to remove the manifold to check the manifold to head gasket. As one might expect, the bolts and nuts holding on the exhaust manifold are pretty rusty. Anyone have any tips on removing the manifold safely? What I really dont want to do is have a bolt break during removal, resulting in a major disaster. Perhaps prayer and lots of penetrating oil are all that can be done...
Joined: Sat Dec 10 2005, 04:28PM
Location: United States
Posts: 4954
Pretty tough to avoid Greg, but there are some things you can do to reduce it. Just keep in mind, sometimes the rust is deceving. I've seen some pretty bad looking stuff come right out.
On the studs, (One on each end) they are nutoreous for breaking. The best of us snap them off. If they come out with the nut, REPLACE THEM! You can use a bolt in their place, it's just a bit harder to put the manifold back on that's all.
Best Penetrating oil is BP Blaster. Stuff works miricles. I know it's pretty easy to get here. Let the car cool off. The night before, soak them down with PB. The next morning, soak them again. Just as you start the job, hit them again!
Use as little torque as you can to loosen them. In most cases, a 1/4 ratched will take them off with some human effort. If they are stiff, work them back and forth. They could be binding in the bore. Keep spraying the stuborn ones, waiting a few minutes.
Suggestion. Look for Black trails around each joint. You'll see a carbon build up around where the leak is. If that's a big block Mopar, the last stud on the back of the engine is known to loosen up. The exhaust pipe flanges are held on with bolts, not studs. You didn't say if you were working on a Mopar orr not.
Joined: Sat Apr 29 2006, 05:11PM
Location: Cincy
Posts: 269
If you are careful, you can put your hand arpound where you suspect the leak is and feel it (best to do it when engine is cold for safety reasons). The second method is to hold a small piece of paper in some pliers and look for blowing air. Looking for the leak is more effective if you have someone hold a rag over the exhaust pipe outlet. Creates more back pressure and more exhaust leaks out - - easier to find.
My first guess would be the manifold to pipe connection, not so much the manifold to head, but it could be.
If you take the manifold off and break the studs, the best way to get them out is to mig weld a nut to the broken stud.
First of all, of course this is a MOPAR engine. I wouldnt be talking about anything else here. The engine is a 1967 318. I am kind of suspecting that the leak may indeed be around the pipe to manifold connection, as opposed to the manifold to head connection. I plan on starting it up tomorrow and feeling around the flange when its cold. Hopefully it is just a loose connection at the fitting and can be cured easily. I will let you all know what I find out...
Well, I checked everything today. While still cold, I felt for leaks around the manifold and exhaust pipe connections. Initially, I felt nothing. I was beginning to wonder if the problem wasnt a leaking exhaust after all. Either way, I decided to tighten up the bolts between the manifold and lead pipe on each side. I had the bolt soaked with penetrating oil from the day before. The bolts were tight, but I did manage to tighten them a little more (maybe just one rotation), just to make sure they hadn't come loose. After tightening up the first bolt on the passenger side, I noticed that the second bolt had become totally loose... flopping around loose! It took several turns to tighten that bolt up. With that, I thought I had found the problem. I started the car up, but still noticed the ticking. Thinking it must be the manifold gasket, I felt around the manifold again. Lo and behold, I felt a steady leak on the passenger side. However, it was coming right out of the bottom of the manifold. There is a port on the bottom of the namifold coming out at an angle. It looks like there is a metal tube inside it, flush with the base of the opening. Exhaust is just pouring out of this opening! I took a picture to show you all what I am talking about:
The manifold is at the top of the picture with the opening shown as the little nub protusion. The reflection in the mirror shows what the opening looks like from the underside. What the hell is this for anyway? Is it the remnant of some sort of heat tube? Is there a way that this can be easily plugged up short of welding?
Joined: Sat Dec 10 2005, 04:28PM
Location: United States
Posts: 4954
I can't tell from the picture. . .
Is the heat riser present?
Sorry about the Mopar Engine thing. . . Every time I "assume" something, I end up eating my foot. You mentioned something about a "sleeve Type Design" you threw me off. They are a flare fitting as far as I knoe. The big blocks had a flat flange and gasket.
Joined: Sat Mar 04 2006, 01:49AM
Location: Phoenix, AZ
Posts: 154
I don't know what the purpose of that is but when I removed that little flap in the pass side exhaust man I just drilled and tapped the holes and put short bolts is it.
What is the purpose of that flap anyways, faster warmup?
Joined: Sat Dec 10 2005, 04:28PM
Location: United States
Posts: 4954
Ho Boy. I have been in numerous debates on that device.
Yes, you are correct. It has a temperature sensitve spring that holds it closed. As the spring heats up, it relaxes the spring to allow the heat riser to stay fully open when hot. It's supposed to create some back pressure on the right side, and push the hot exhaust across the intake manifold cross over to heat the choke riser.
Half the time they are stuck open or the springs are broken. I am not going to get into a heated debate about it, but I have yet to see any harm, nor a significant difference in the way the car runs cold without it.
Technically, they are there for a reason.
Now I'll probably pay for that statement. . . Usually do <span class='smallblacktext'>[ Edited Fri May 12 2006, 08:01PM ]</span>
Joined: Sat Mar 04 2006, 01:49AM
Location: Phoenix, AZ
Posts: 154
The one on my car was stuck partially shut when I bought it. And I don't really need it for warm up living in Phoenix; 60* winter temps. I Don't even have a choke on my carb, and the car doesn't stall. I do get some hesitation for a bit but after a block or two it's ready to go.
Just as a side note,you can use a length of tubing to find noises and leaks.Put one end close to your ear and move the other end around till you can zone in on the sound.Careful,cause it is concentrated sound,(kinda like me at my kids ball game)ha ha. Charlie