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Motor mount and exhaust clearance

Old 09-30-2016, 11:36 AM
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Default Motor mount and exhaust clearance

I had the motor mounts changed on my jeep a few days ago while the exhaust has been off. So yesterday I go to put the exhaust in and it wont clear the motor mount. I'm baffled. Before the mounts were changed, before I realized the two studs that hold the exhaust on were broken, I test fitted the new exhaust BEFORE throwing the old one out. I compared both side by side and they matched. (I thought) Now the new mounts are in and the new exhaust is hitting the bracket and it seems not long enough to reach the exhaust pipe. I had a mechanic do the mounts and he is trying to tell me the exhaust is the wrong one. I kept saying it fit fine before. I asked if the mounts are adjustable and he said no. I mean does this make any sense? Does having the new mounts change the way everything lines up? Here is a photo of both my new and old exhaust. tell me your thoughts please.


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Old 09-30-2016, 11:58 AM
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Double check the part #'s for the exhaust many are for quite a few different years and fudge a little here and there. If it is correct and you want to keep it you may need to take it to an exhaust shop who builds custom pipes and has a bender. He may be able to "Make" what you have fit with a custom massage to it.


If you assemble it loosely not tightening anything see if can you get it to go together. If you can start there and work it into place starting with the header first, do this gently not forcing them.


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Old 09-30-2016, 12:29 PM
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Ok here is some photos of it attached. It is about 1/4 of an inch from resting flat against the block. Only on the one side. Im wondering if I tap it with a rubber mallet at the spot where its resting on the mount to get it in. Or it was suggested to grind the mount a hair to get it clear. But Im wondering about long term with vibrations and shock if the clearance is to tight will this cause problems? Is it suppose to be that close to the mount normally? Maybe Im just being overly cautious.



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Old 09-30-2016, 12:42 PM
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In the comparison photo I see a subtle difference in the bend of collector tube. Bend appears to begin its downward turn sooner, too soon to clear motor mount.

New mounts can change the position of engine slightly, especially if old mounts were broken or compressed due to age.
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Old 09-30-2016, 05:50 PM
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It's not the mount, but the mount BRACKET that's the problem. You can either get another header or a well placed dent will take care of it. You wouldn't believe the way I've seen headers "massaged" to fit on race cars! The dent should be done with a press rather than a hammer. You don't want to crack the weld on the #3 downpipe. Mark the spot and take it to a good muffler shop.

There is one point I'd like to make on your new header. I think it needs to be welded around the pipes where they are attached to the head flange. This is where constant flexing can cause the internal welds to crack. JMHO.

Last edited by dave1123; 09-30-2016 at 05:59 PM.
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Old 10-01-2016, 01:57 AM
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I would heat and beat the header tell it clears.I have had to do it on other stuff before its a pain but worth it.
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Old 10-01-2016, 09:12 AM
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This is what I experienced with my '99 XJ when the original header pipe weld split at the "Y" before the collector. In fact, I got the same manifold (by appearances) with those "accordion" sections. Dimpling that down-pipe to clear the bracket was the right solution. The welds can be damaged if not done properly. Mark the "dimple zone" on the pipe and bring the new manifold, with photos of the manifold resting against the bracket, to a pipe shop. There may be a little more "trial and error" needed but it will be worth it in the end. Also note, after installation the front pipe may be very close to the floorboards, resulting in a little pipe rattle against the floor under certain conditions. This too can be adjusted if it occurs.
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Old 10-01-2016, 01:14 PM
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This brings back memories of "tuning" tailpipes in a forked tree to "adjust" the fit. NAPA tailpipes were the worst for fit. They always rattled. Walker was the best. After a while, NAPA started selling Walker.

Soft motor mounts can cause the front pipe to rattle against the floor. When the engine torques, it tries to lift the driver's side up, forcing the passenger's side down. It may make contact on the floor under your feet or the crossmember on the other side.

Last edited by dave1123; 10-01-2016 at 01:24 PM.
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