Adjusted valves and broke valve cover bolts, advice on replacing?


#1

I have a 2003 Honda cr-v with the k24 series engine. I recently adjusted the valves back to within spec (two exhaust were way too tight). After buttoning everything up I was on my last task of putting the acorn nuts back on the valve cover studs and as fate would have it I became distracted and snapped a couple and over tightened a couple. My question is this; these bolts serve a dual purpose in that they also help hold the camshaft caps on.(bottom half of bolt). I know that when removing the camshaft caps there is a pattern to loosen and tighten each bolt so do I need to follow the pattern when replacing the bolts or can I just pull them out individually. There are 20+ camshaft cap bolts total and I need to replace six of them, two being on the same cap.K20_head


#2

I would not loosen any of the cam bearing bolts except the ones being replaced and only one at a time. Those caps are machined after assembly, I think, and if they slip because you loosened all 4 in line, they will never again be in the right position and will destroy the cams.


#3

That thought had crossed my mind, I am also worried about warping too…Thanks for your input!


#4

I would do what @Mustangman suggests. Remove and replace/torque up one at a time. But that’s just me.


#5

Yea I think its probably my best course of action…


#6

I understand the issue of warping but I think the one-at-a-time approach will minimize any issues with that.


#7

See if you can measure the torque of the exisiting bolt, before removing it for replacement. If you can, as posted above do one at a time, and just torque the new one to the same torque, then move to the next one. An alternative, a new threaded section could probably be easily welded to the broken off stud. By easily, I mean if somebody who knew how and had the right equipment did it, like an auto machine shop.

I expect you may have another problem tho, a warped valve cover. Those valve cover fasteners usually have pretty low torque value recommendations, much, much lower than would be required to shear off the stud. Be mindful of that possibility, and be on the lookout for a used valve cover that fits this engine.


#8

Sounds not so easy, and there’d be lots of heat put into the cam area. I’d avoid it.


#9

That might pull the threads out of the cylinder head, the break-away torque necessary to loosen the bolts could be twice the proper torque. Use the manufactures specifications.

I have removed and installed hundreds of camshafts during repairs, there will be no problem replacing one bolt at a time.


#10

I have a few questions (points…) not related to stripped bolts.

You state some exhaust valves were tight. How tight and do you have any idea how long they were like that?

What can happen with tight exhaust valves (even by a measly half a thousandth too tight) is that exhaust gas can be forced past the valve face and seat when closed. This can etch the valve and valve face.

This means, depending upon tightness and time, that there can be cylinder leakage immediately or it may surface at some point in the future; say 5k, 10k, or 20k miles. It’s anybody’s guess.

Before reinstalling the head you might close the valves on the affected cylinders, add a little gas, alcohol, or mineral spirits to the combustion chamber, and allow it to sit for 15 minutes. If you see gas in the exhaust ports it’s pointless to install the head.
That takes care of the immediate but it doesn’t answer the long term question though.


#11

I suspect the cylinder head is still on the engine, I don’t believe it is necessary to remove the cylinder head to adjust the valves.


#12

A silent prayer and hope for the best because a compression test or leakdown test won’t show the minute type of damage I described.


#13

The cr-v was a one owner until I bought it and it was serviced always by the same Honda dealership on schedule. Honda recommends checking valve clearance at 110,000 miles (seems like a long interval to me) and after that only when they become noisy, some Honda techs recommends every 30,000. That being said, I have to assume that the last time they were adjusted was around 110,000 when it was serviced. Its got 194,xxx on the clock and runs like a top. The valvetrain was a little noisy so I made the adjustments.
Intake side calls for .08-0.10 (all were on the loose side, 0.11-0.14) I adjusted to 0.09
Exhaust side calls for 0.11-0.13 (two was around 0.07) I adjusted to 0.12


#14

Correct the cylinder head is still on the vehicle.


#15

Thanks for the info, the cr-v runs excellent. I will keep it in mind…


#16

A lot of people break these studs. Typical torque spec for these is low, about 8-10 ft-lbs, and most people overtorque them.


#17

What I’d do to minimize the chances for that happening, I’d make some witness marks on the bolt & seating surface, then I’d loosen the bolt a little first, then retighten it to the same position, and read the torque at that point. I expect Nevada’s recommendation to just torque to the manufacturer’s spec would work as well.


#18

I hope you mean .008-.010 inches (and similar for the other numbers).

;-]


#19

Will do, thank you!


#20

baha…yes yes…lol