PeachParts Mercedes-Benz Forum - View Single Post - DEAD cylinder: Valve + rocker arm craziness

300SDog · #10 02-19-2008, 07:10 PM

Yep, it sounds like something weird with valve guide, seat or stem that keeps the valve from closing. Strikes me that pulling the head and camshaft carrier is next logical choice. Heck ye probly wanna eyeball the bores, wiggle-test valve guides and reconnoitre valve seats anyhow based on vehicle's sketchy history.

And pulling cyl head and cam carrier on the m110 aint that tough!

To pull the m110 camshaft carrier it's wise to have an old ice cube tray for sorting parts, keepin all rockers in exact order to their respective lobes and valves. Say one side for intake and other for exhaust marking one end of tray as "front" or #1cyl. This will be helpful since you're pulling the rockers in varied order - step 1 to camshaft carrier removal. Look for worn surfaces with core metal exposed on rocker surfaces when you do this, as I'm sure you know already.

Then TDC the engine after you've pulled the rockers - and paint mark the chain to sprocket teeth for easier reassembly. Slack the chain tensioner and entire operation can be accomplished without breaking the chain you understand. Plus you will want to wire or bungee the chain to prevent it from dropping when you use rubber hammer to knock the sprockets off the camshaft ends - yer next mechanical step after pulling rockers.

The rest will be common sense - unbolting and pulling camshaft stantions and lifting the carrier thats surprisingly light in weight. Dry gasket underneath probly doesnt even need replacing. Did this myself, it took less than couple of hours recovering junkyard m110 cam & carriers using no special tools at all.

Then with cam carrier outa the way cyl head's gonna be piece of cake - just dont drop or forget 6mm allens down in the chain gallery that oughta be packed with rags first.

And how many miles on this excellent recovery operation? At 125-150k expect chain is stretched and engine needs light head work to easily last another 150k miles at least. Reconnoitre new headgasket kit including valve seals, buncha valve guides and *maybe* a few exhaust valves is all you need assuming the bores look clean. These are sodium filled valves that should be replaced if seriously pitted and NOT reground maybe gently lapped is all. Question of exposing the core and valves gettin toasted in another 30-50k miles if ye try to regrind em. And for cryin out loud NEVER plane or shave alot of metal from cyl head unless its absolutely severely warped and flunks the simple straight-edge test. Cam carriers that require any resurfacing is entirely unheard of. Heat dispersal preventing cracked/warped alloy head chassis assembly is one reason MB went with pancake carrier arrangement on m110's. Dont let anybody shave the cyl head since it probly aint warped.

Meanwhile the M110 twincam engine is hot-ticket item in extremely high demand. Heck, it'll bolt into *any* MB chassis including coupes, convertibles and long wheelbase sedans from about 1969-80. Had one in my 4-spd Euro 280SEL and it ran like bat outa hell.

Deffinitely I'd recommend not bein scared of pulling cyl head to sort this engine out. But first I'd try what MP recommended above: basically TDC the engine, compress and remove #1 valve springs and reconnoitre valve guide wiggle and whatnot there. And then reassembling springs and rocker ye may accomplish really simple diagnosis like cracked spring, dislodged valve retainer bit, bent valve stem or seized/slipped guide before pulling the head. And as i've said: if bores look clean, no cracked pistons and nothing weird with cyl head - then light top end reconditioning and reassembly would probly not be waste of time. Under worst case scenario if nothin else, there's gotta be market for reconditioned m110 cyl heads out there.