Topic: Valve cover gasket replacement

[zxshep]

After getting the 400F running I noticed what I thought was weeping between the valve cover and head.  Well, it's a little more than weeping as it pools on the first fin down all along the front of the engine.  I am considering replacing the valve cover o-ring gasket to take care of the leaking oil.

If I do this, is it a relatively simple job?  Pull the breather cover, pull the valve cover, clean things up, install new gasket, and install covers in reverse order using proper torques and patterns?  Or is it more involved than that?  Any gotchas or things I should be concerned about?

Thanks for your input, tips, or tricks.

[Bodi]

The rocker cover seal is a formed rubber o-ringish thing.
The old one is glued in, I don't know what glue Honda used.
So the old seal has to be removed, the groove has to be cleaned out, and the new seal glued in the groove. I used a lot of different solvents to get the glue out - lacquer thinner, acetone, gum-out, isopropanol, gasoline, varsol... I don't recall if any really worked but I did finally get it cleaned. There was a lot of scraping with wood and brass improvised tools.
I used "weatherstrip adhesive" to put the new one in. There's probably an easier way but I had the rocker shafts out anyway so I weighted the thing seal down on wax paper over a surface plate to press the seal into the groove while the glue set, then scraped off excess that had squeezed out. I had also used some 1000 grit wet/dry paper on the surface plate and flattened/smoothed the mating surface of the rocker cover, I did not see any rocking or other signs of warpage with it set on the bare surface plate.
I have heard of using superglue to hold the seal in the groove but have not tried that.
Be careful with the cover bolts. Except for the ones into the weird head stud nuts, they thread into holes in the alloy head - holes notoriously prone to stripping out their threads. I don't know how the 6mm torque spec was decided, but IMO it's far too high for that alloy. You only need to tighten enough to pull the surfaces together and then add a wee bit more to stop them vibrating out. There is upwards force on the rocker shafts but the cam "bearing" isn't ever running on the cover side - it's not at all like the main bearings where bolt torque is important.
That alloy is not friendly to helicoils (there's some metal incompatibility that rots the alloy), I've successfully used timeserts or thinserts where those won't fit.
It is common to find stripped head threads on engines that have had the cover removed.
Also the bolts are complicated as the lengths allow longer ones to work in holes expecting shorter ones, meaning the shorter ones end up in holes where only a few threads are engaged - almost guaranteeing a stripped hole with its remaining threads insufficiently engaging the longer intended bolt so the hole gets completely stripped out.

[jonda500]

To preserve those soft alloy threads, first remove all the little valve adjustment covers and loosen & back out all the valve adjustment screws so the valve springs aren't pressing up on the cover during removal and refitting. Then you will of course have to reset all the valve clearances when the cover's back on.
John 

[Bodi]

Wise advice. Even with the tappets all the way out, on mine at least (high lift cam), the rockers still hit valves before the cover sits flat so it has to be pulled down a bit via the bolts.
The problem I saw is the intention to "install covers in reverse order using proper torques and patterns". The 350/400 service manual wants 8.5-12 ft-lb torque: that's just too much and torquing to this value is extremely likely to strip out some head threads.
As well as fully loosening the tappets, the rockers should be held "up" with rubber bands or whatever across the top from intake to exhaust: although the rocker face with the tappet screwed out is unlikely to catch a valvestem, avoiding bending that valvestem if one does will make the extra work worthwhile.