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How to get access to tighten exhaust manifold nuts?  Rating:  Rating
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 Posted: 05-12-2010 08:02 pm
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SpeedyMitch
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Location: Hailey, Idaho USA
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I have a leak at the exhaust manifold. The few nuts I can get access to have all been somewhat loose. I'd like to properly torque all of the nuts and use a lock washer but how to get access?

From other posts it appears you can jack up the engine to widen the gap between the frame and engine block.

Do I need to loosen only the driver side motor mount or both?

Where to place the floor jack under the motor to make sure there is no damage?

Ultimately I expect to need to replace the exhaust manifold gasket but can't imagine how to get enough access to do so.

Any hints are greatly appreciated!

Speedy Mitch
Jensen-Healey Mk 1 12827

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 Posted: 05-12-2010 09:05 pm
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subwoofer
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With the factory headers you will be hard pressed to get a torque wrench anywhere near a few of the nuts, I had to keep flipping an ordinary spanner to tighten three of them (tightening 30ยบ at a time). Even with the engine hoisted as high as possible, tilted and moved to the right, a few of the nuts still requires some yoga to reach.

Have the car on axle stands so you can crawl under it, cyl #4 nuts can really only be reached from below/behind. Remove both rubber motor mounts, then you are able to move the engine about 2" to the right, you need that extra space. With a polyurethane jack pad on your floor jack, you should be able to jack the engine on the oil pan with no damage. Just make sure you place the pad as close to an edge or a corner as possible. Tie the right motor mount tightly to the crossmember, so that any lifting force tilts the engine.

I replaced all the nuts with modern type "copper" nuts while I had the manifold off. They where about 80 cents a piece at the local car supplies, and should not vibrate off anytime soon (the threads are distorted to pinch the bolt). You may find that some studs are missing, Ms. Jensen only had 9 (out of 12) studs left when I pulled the engine.

If you go through the trouble of getting to the studs, you could just as well spend a couple of hours extra and change the manifold gaskets. It won't get easier by waiting it out.

Warning: This is stuff I have found out through trying it myself, not something read out of the shop manual. It may not be a good idea, but it worked for me. YMMV, proceed at own risk.

--
Joachim

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 Posted: 05-12-2010 11:54 pm
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JodyKerr
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This is one of those wonderfully fun jobs, generally exacerbated by PO wonking.

Ironically, I was just writing in a notebook today that holds my diagrams for this. :)

My preferred method:

1) Jack up front end on jackstands and remove front manifold side tire (driver's side for those in the US)

2) place a board with width of the oil pan on to your jack, fold over a towel on top for extra padding.

3) Start slowly jacking up the engine. Mark the points where the bolts are on the motor mounts (makes setting it back easier). When the jack supports the engine loosen the two front engine mounts (on either side of the car).

4) continue jacking up the engine, should come up a few more inches easily. Take care for clearances and the rear dog bone mount.

5) Do your Yoga/Contortionist warm up exercises.

6) Remove the nuts on all flange surfaces.  The lower inner nuts are always the worst. With a numbering configuration of 1-2-3 (one being top nut, 2 being lower left, 3 being lower right) remove them in this order (flange surface order is front to back). Flange 1: 1,2; Flange 2: 1,2; Flange 3: 1,2; Flange 4: 1,3. The remaining nuts are the hardest to reach and will only become progressively off as you loosen them. To finally get them off you'll need to separate the manifold entirely from the block (and becareful not to have them skitter off and lose them).

7) Get in there with cleaning tools to clean the mating surfaces. Toss old nuts and use a new copper set from Delta or JHPS. Insert new manifold gasket. Slide manifolds part way into place and set the last nuts removed. Follow up with the rest of the nuts.

If your manifold is separated out compeltely (e.g. the two parts, neither attached to the exhaust) then fit the Flange 1-4 header in first and rotate it longitudinally towards the exterior of the car. Then set the Flange 2-3 header into place, set the nuts and rotate the Flange 1-4 header back over.

8) Final steps are reverse of disassembly. When retightening the engine mounts ensute that the engine has the proper longitudinal rotation. You can test this by turning the steering wheel from lock to lock. If the upper steering knuckle does not hit the exhaust or the engine, then you're good. If it's not placed correctly that knuckle will hit up against the exhaust and motor.

It's actually not a terrible job, it's just slow, occasionally painful, and requires some interesting self-positioning.

Jody

 

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 Posted: 05-13-2010 05:41 pm
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Greg Fletcher
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If installing a new header, I've found it helpful to cut off the old one with a sawsall as close as possible to the head. This can save a few hours of torment. Of course, best to install a new unit on the engine before hand at your next engine refresh, while the engine is out of the car. I also coat the manifold gasket with Aviation Gasket Sealer to prevent blowout (not uncommon on the 907). The smaller outside diameter copper lock nuts are cheap insurance and install much easier than the original nuts.

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