ugghh! so it looks like my exhuast manifold is cracking at where it bolts up to the exhaust. I'm getting tired of having to replace this. My exhaust is new front to back. I was told by a fellow rodder that summit sells something that is like a flex tube that you bolt up between the exhuast to take the pressure of the manifold, from all the flexing that goes on while driving. Do you guys have any idea how I can solve this problem so I don't have to go through this again. Is this common for these exhaust manifolds, I know they are potmetal or cast iron. If you guys know anyone that has a good working exhaust manifold pm me Please. I plan on checking Owens Salvage yard again. thanks!
Do you have some flex in your exhaust hangers all the way back ? The motor moves a little in its rubber mounts, the frame twists a little while driving but the exhaust is fastened rigid to your manifolds. So the exhaust pipes cannot be mounted rigid to the frame.
You failed to mention what engine. Are the motor mounts bad? Does the motor move a lot when you apply power? On my Y block, to prevent excess movement, I put two 5/16 grade 8 bolts through each motor mount from one side to the other but left them loose and double nutted them. They can move a little, but not a lot.
Manifolds are cast iron. Iron is good under heat, durable and strong. What it doesn't like to do is flex or bend. Then it cracks. Start looking as suggested by the previous tips. There's a problem somewhere in your exhaust system.
yeah, I will look today at the hangers. I know what you guys are talking about. I will see if those are on im pretty sure those are on the exhaust system. the motor mount bolts are tight, I just checked the motor mounts and they are not worn at all. I will look closer at the exhaust system. thanks
Motor mounts can look good, and still be bad. Open the hood, start the motor, put it in gear and with the park brake on, try to move the car ahead while watching how far the air cleaner moves.
Here in Oz we used F350 with fuel injected 302 and 351 Windsor up to about '88 and these things always cracked manifolds even with brand new replacements. It was possible to crack them in a day if driven hard for 50 miles and then parked with no cool down period. Next time you started it they were cracked. Eventually got around the problem by fitting good quality tube headers. No more cracking. Didn't make the mechanics happy changing exhaust manifolds every day of the week, not to mention the costs involved. Regards
I had a 351 in a 150. Cracked like you said, so I bought a used one. It was warped so bad the holes didnt line up. I made up a threaded "pusher" to spread one end. No more trailer pulling and it didnt break again.
Its a 215 inline 6. I checked and all my mounts are new. Ole don I did what you said and no movement. the first manifold was cracked from old age then the 2nd one went to **** after I had a complete new exhaust done.
Ford's fix on the cracking 302 and 351 exhaust manifolds was to make the mounting holes larger, which let the manifold move during heating and cooling.
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