Author Topic: Exhaust manifold to Cat mounting bolts (Read 12830 times)

JactwistJazz · « **on:** November 21, 2023, 02:23:25 PM »

Hi. New to this forum. Have a question about the flange on the Exhaust Manifold to Cat connection. Is this threaded with bolts screwed in to the flange? Or does the flange have 2 studs with nuts? My car has an exhaust leak and one of the mountings is missing. Could it be that the bolt is sheared off in the flange?

embee · « **Reply #1 on:** November 22, 2023, 02:26:35 PM »

Very possibly sheared off. Yes it's a bolt which goes into a tapped hole (welded on nut). Easy enough to check whether there's a hole there, feel though the flange with a thin screwdriver or stiff wire etc to see if the hole is clear.
I've successfully removed rusty flange bolts in the past using plenty of Plus-gas and copper grease and an impact wrench going forwards/backwards repeatedly a little at a time, but it can be a touchy business. Try to avoid shearing them at all costs, a sheared bolt in a hole is a PITA to solve.

Those bolts are almost always a metric fine series thread, make sure any replacement is the correct thread pitch, plenty of copper grease.

Steve_M · « **Reply #2 on:** November 23, 2023, 12:29:31 PM »

Its a special shouldered bolt to get the tension on the springs right. The threaded part is actually a welded on nut, which often can be sheared off to leave just the hole in the flange, so you can then just use a separate nut.

E27006 · « **Reply #3 on:** December 27, 2023, 07:58:58 AM »

Probably sheared, the tip of the bolt may have enough thread showing to fit two nuts, one as a locknut, to enable removal of the sheared part.
The bolt is available as a spare part from Honda and non-oem on Ebay, neither sources are expensive. you will need the spring lost when the bolt went astray.
I would fit the Honda part,less than £5 from memory, cannot find the invoice, I'm not sure if the cheap non-oem parts are made of the correct strength metal to withstand removal at some point in the future, they might shear. Access to undo the bolts is only "enough" , so I would not like to tackle removing a sheared bolt, I bent one of the old Honda bolts due to the access problem, not easy to get a straightand direct turn with the socket/extension/ ratchet.
The joint is a ball and socket style of coupling, the springs in the image are the tensioners for the ball and socket coupling, you may need to replace the "doughnut" fire seal in the joint too, again, not an expensive part