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+--- Thread: Need help to solve om617a nailing... (/showthread.php?tid=3767)
Need help to solve om617a nailing... - bryant.cw - 07-02-2012
I have swapped in an om617a into my W460 G wagen. The first motor I swapped in had horrendous nailing, low power, and bad blow by. I sourced another motor and dropped it in.
It runs much better, has compression around 340-360 in all cylinders, less blow by, much less smoke from the exhaust, more power etc. Feeling better about this engine.
However, I still have nailing in 2 of the cylinders. Not tragically bad, but I can't stand it. Just grates at my nerves, not to mention it causes the engine to shake and really rattle the whole car.
I have adjusted and cleaned alda and fittings, stretched the fuel bypass spring, adjusted IP timing with millivolt method, run diesel purge, adjusted the valves, new fuel filters, new fuel lines, diesel is clean and fresh, new lift pump and primer pump, no air in the bypass line as far as I can tell, cam timing is -3 degrees (which makes no sense, but considering that mercedes allows up to +8 degrees of chain stretch, I don't think a few degrees off should matter much), 'rebuilt injectors' with monark nozzles but I can't really verify for myself they are in spec.
What should I check next?
RE: Need help to solve om617a nailing... - JustPassinThru - 07-02-2012
(07-02-2012, 06:18 AM)bryant.cw ...I have...'rebuilt injectors' with monark nozzles but I can't really verify for myself they are in spec.
What should I check next?
You just answered your own question. Buy the pop tester and shims kit from mercedessource.com, pull the injectors, disassemble them and clean thoroughly (I use Hoppe's #9 gun-cleaning liquid in an ultrasonic jewelry-cleaning machine) (also, do not mix parts from the injectors; clean them one at a time), then set the injectors to pop at precisely 131 bar = 1926 psi. Hand-file one shim if you need to (finishing with # 0000 steel wool --I wrapped a bit of this around a Dremel bit (well, actually, a variable-speed Proxxon, which is the German Dremel)-- and a thorough rinse with carb-cleaning spray to elimininate metal particles), to get the pop pressure at a dead-exact 131 on all five. I did this to mine when I installed the mercedessource Monark 261 nozzles and can, at idle, balance a nickel on the valve cover.
Or, just ship them off to Greazzer and have him do it, see this thread:
http://www.superturbodiesel.com/std/thread-3745.html
Greazzer uses a different cleaning solvent, and he does not use any abrasives. I presume he has a better shims kit than I do.
RE: Need help to solve om617a nailing... - sassparilla_kid - 07-02-2012
(07-02-2012, 09:12 AM)JustPassinThru I did this to mine when I installed the mercedessource Monark 261 nozzles and can, at idle, balance a nickel on the valve cover.
I need to see this, since I am leery of even setting a starbucks coffee on my car while its running sometimes
RE: Need help to solve om617a nailing... - bryant.cw - 07-05-2012
Vid or it didn't happen!
That sounds good, I have more pressing stuff to do at the moment, but I think I will do what you suggested. Might build my own pop tester just for the hell of it. As it stands, some times it nails, sometimes it doesn't as much, I've had to take a look at my project, a look at my wallet, and learn to get a handle on my expectations. C'est la vie.
Thanks for the advice, but you really should get a video of the nickel on the valve cover!
RE: Need help to solve om617a nailing... - Simpler=Better - 07-05-2012
(07-02-2012, 09:53 PM)sassparilla_kid(07-02-2012, 09:12 AM)JustPassinThru I did this to mine when I installed the mercedessource Monark 261 nozzles and can, at idle, balance a nickel on the valve cover.
I need to see this, since I am leery of even setting a starbucks coffee on my car while its running sometimes
Balanced injectors make an enormous difference. Check one of my videos in my build, with shot nozzles, a stretched chain, on a stand it's still pretty smooth.
RE: Need help to solve om617a nailing... - bryant.cw - 07-08-2012
Yargh, no money to procure or make pop tester. Anybody wanna rent theirs out? Sigh, living in alaska would probably make any rental + both ways shipping almost as expensive as making one. Not to mention you've got me wanting to get an ultrasonic cleaner now! I am wanting to make a fairly large one capable of doing brake calipers, cylinders, starter etc etc.
Perhaps some amount of nailing is acceptable, or at least tolerable without feeling you are going to cause damage?
RE: Need help to solve om617a nailing... - JustPassinThru - 07-08-2012
Greazzer's fee is very modest. I suggest you PM him.