Valve Seal Replacement? - Mercedes-Benz Forum
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#1 (permalink) Old 11-04-2012, 06:50 AM
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Valve Seal Replacement?

I ordered a full set of intake and exhaust valve seals from EuroTruck and have had them for...oh, maybe a year now.

How big a deal is it to swap these out? I've done a LOT of mechanical and engine work just not on these. I would speculate pulling injectors, pressurizing cylinder, spring compressor, pull keepers, pull old (hopefully old and cracked or otherwise poor condition) seals, replace...then start going back together. I'm not sure if my manuals have valve lash specs.

Anyone with any input would be greatly appreciated! The 'mog-stink' is pretty bad. If I'm on the trails it'll kill any mosquito in a wide radius, after a road trip it seems better but only for a short time. Engine runs very well otherwise.

I have my fuel turned up to prolly 100hp and a pyrometer, and bumped the timing ahead 3* or 4* when I did it. I wrote it down, I'll have to check exactly. I made a scale on AutoCAD from center of pump where it would pivot up to bolt to tell the degrees of movement. I may just need more timing but I think she's pulling some oil too. The exhaust is really nasty. Truck only has 17,000miles.

Any input or suggestions, again, is greatly appreciated!

My 406: XM-47's, hydraulic driven Garwood 10,000lb pin-on front winch, custom bumper, small jib for front or rear, PTO driven 20,000lb Garwood rear winch w/ level wind, (super secret) forward-N-reversing unit for rear winch/PTO operation, 8 speed 2x4 conversion...+2, front 3pt hitch, HT11-A1 backhoe.

"I was just walking down the hallways of a high-school while kids were changing classes. Believe me, the world may not have ended today, but the future doesn't look so bright. -Trev"
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#2 (permalink) Old 11-05-2012, 12:10 AM
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Hi Spicergear, Changing valve seals is an easy job don't worry about using compressed air, remove rocker/valve cover, rocker shaft and injectors, get a socket or ring spanner on the front pulley nut so as you can turn the engine over, start with #1 cylinder turn the engine over so as the piston moves down most of the way to BDC and get about one metre or 3 feet of nylon rope that will fit down into the cylinder through the injector hole, about 10mm diameter will fit through the injector hole,make sure you hold onto the end of it, now with your socket turn the engine over and the piston will jam the rope up against the valves and keeps them closed, using a piece of 1 inch angle iron about one foot long with two holes drilled in the right place you can compress the spring and remove the collets, remove your bar the spring and old seal, fit new seal replace the spring and collets release your bar turn the engine backwards to release the rope pull it out of the cylinder and repeat the procedure on the other cylinders. Once you get into the swing of it it's very quick you will want to change the seals on all your mates engines. Cheers Gary
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#3 (permalink) Old 11-05-2012, 12:23 AM
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Drill the first hole in the one inch angle iron in a position nearer one end of the bar and screw one of the rocker shaft bolts into the rocker shaft bolt hole in the head and the other hole is drilled very close to the end of the bar then file out the side of the hole so you have a U shape in the end of the bar which will line up on the top of the valve spring giving you enough room to remove the collets, the bar is levered up to compress the spring to remove the collets. I've changed the seals on my SBU 352 without raising the cab.

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#4 (permalink) Old 11-05-2012, 05:03 AM
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Awesome! I've used the rope trick before through a spark plug hole on a gas engine.

I understand the angle iron tool perfectly as well! I really hope this helps clean up the exhaust.

Thanks Gary!!!

My 406: XM-47's, hydraulic driven Garwood 10,000lb pin-on front winch, custom bumper, small jib for front or rear, PTO driven 20,000lb Garwood rear winch w/ level wind, (super secret) forward-N-reversing unit for rear winch/PTO operation, 8 speed 2x4 conversion...+2, front 3pt hitch, HT11-A1 backhoe.

"I was just walking down the hallways of a high-school while kids were changing classes. Believe me, the world may not have ended today, but the future doesn't look so bright. -Trev"
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#5 (permalink) Old 11-12-2012, 01:23 AM
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What causes the seals to go bad? I have a great running OM352a but she stinks and causes a plume everywhere I go, I have been thinking injectors but it just runs to well to be them.
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#6 (permalink) Old 11-12-2012, 05:29 AM
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Age.

If the engine has been sat for any time then the seals dry out. Or they can just wear if it's high hours.
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#7 (permalink) Old 11-12-2012, 11:35 AM
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Question

My 352a does the same I have done the injectors,pump and seals to no avail, engine has traveled 137000ks,compression test good,engine does not use any oil and it doesn't smoke black or blue on hills or under load, only smokes on start up, I have wondered if the oil that pools around the injector recess in the head is seeping past the copper seals under the injectors? or is being pumped through the turbo? I have also removed the breather pipe that goes from the rocker cover to the aircleaner.
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#8 (permalink) Old 11-12-2012, 11:46 AM
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It's mogstink!

Someone told me once that the fuel in Europe is a bit different, and if you adjust the timing and such for our fuel, it makes a difference, but will still stink and smoke a bit. Can't say for sure, but I could see it.

I use kleenflo additive, and it make a world of difference in the mogstink. Mine will still smoke at startup in cold (-5 or colder) but the warm day stink/smoke is greatly improved with the additive.

The OM366a seems to smoke/stink a hell of a lot less than the OM352 as well. Just observation.

-Trev
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#9 (permalink) Old 11-12-2012, 11:55 AM
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352 smokes and stinks new or old.

Cold startup it's pretty bad. If you still smoke after running then your engine is running to cool. Try to get to 190*F or higher to reduce or eliminate running stink.

FOR SALE: 1985 U1300L 200HP $50,000
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#10 (permalink) Old 11-12-2012, 01:12 PM
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Mine will clean up a bit after running on the road for a while and getting some good heat into it but as soon as it idles for a bit, it's back to the Mog-stink. I'm only like 17,000 kilometers on it and the hours seem to match up. I was also thinking that since it's an industrial engine they have the timing pulled way back so it will last forever even though it's not running as efficient as it could.

I'll see if I can find that additive and maybe bump the timing ahead a little more.

I wonder if the additive I'm adding to put back in what the low sulfer fuel is missing could have something to do with it also??

Thanks!

My 406: XM-47's, hydraulic driven Garwood 10,000lb pin-on front winch, custom bumper, small jib for front or rear, PTO driven 20,000lb Garwood rear winch w/ level wind, (super secret) forward-N-reversing unit for rear winch/PTO operation, 8 speed 2x4 conversion...+2, front 3pt hitch, HT11-A1 backhoe.

"I was just walking down the hallways of a high-school while kids were changing classes. Believe me, the world may not have ended today, but the future doesn't look so bright. -Trev"
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