OM 617 Balancing
OM 617 Balancing
02-08-2013, 08:51 PM
#1
Just had a 617 engine balanced that I had to change the crankshaft in due to a spun rod bearing. I was surprised at how out of balance it was. The rods were off 12 gms between high and low, pistons were off 8 gms. between high and low. I expected that Mercedes engines were machined better then this. Anyone else have the same situation.
02-10-2013, 07:28 PM
#3
(02-10-2013, 03:48 PM)RedDiesel They were probably correctly matched to the old crank. Thats why it must be rebalanced when major parts are replaced.
The rods and piston assemblies should be the same weight irrespective of the crank. Obviously manufacturing tolerances come into it so they will never be the same and performance engines are often to 1 gram or less on really expensive engines. 12 grams over the rods is a lot but then designed RPM comes into it as well. Low revving engines don't need to be as well balanced as screamers like a bike engine.
Not only should the rods be the same weight but the proper way to do it is end to end. When supported on the big end the small ends should weigh the same and vise versa. There are generally pads on both ends to for this reason.
You could spend 40 hours easy blueprinting an engine but you get diminishing returns the further you go. It all depends on what the engine is for as to how far you go. If your doing it yourself it doesn't cost anything but time though. If your getting the crank balanced (pointless doing the rest really without it) get it balanced with the flywheel and clutch assembly.
(02-10-2013, 03:48 PM)RedDiesel They were probably correctly matched to the old crank. Thats why it must be rebalanced when major parts are replaced.
The rods and piston assemblies should be the same weight irrespective of the crank. Obviously manufacturing tolerances come into it so they will never be the same and performance engines are often to 1 gram or less on really expensive engines. 12 grams over the rods is a lot but then designed RPM comes into it as well. Low revving engines don't need to be as well balanced as screamers like a bike engine.
Not only should the rods be the same weight but the proper way to do it is end to end. When supported on the big end the small ends should weigh the same and vise versa. There are generally pads on both ends to for this reason.
You could spend 40 hours easy blueprinting an engine but you get diminishing returns the further you go. It all depends on what the engine is for as to how far you go. If your doing it yourself it doesn't cost anything but time though. If your getting the crank balanced (pointless doing the rest really without it) get it balanced with the flywheel and clutch assembly.
02-10-2013, 10:17 PM
#4
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
02-10-2013, 10:17 PM #412g sounds like a lot. If you're taking the time to tear down a motor, you might as well go all out in my opinion
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
02-11-2013, 01:28 AM
#5
(02-10-2013, 10:17 PM)Simpler=Better 12g sounds like a lot. If you're taking the time to tear down a motor, you might as well go all out in my opinion
That is my feelings also, is it well worth the extra $150.00 - $200.00 to completely balance the whole rotating assembly. I was just surprised the Mercedes factory didn't balance the engines closer then this, I would expect this on a SB chevy not a Mercedes motor.
(02-10-2013, 10:17 PM)Simpler=Better 12g sounds like a lot. If you're taking the time to tear down a motor, you might as well go all out in my opinion
That is my feelings also, is it well worth the extra $150.00 - $200.00 to completely balance the whole rotating assembly. I was just surprised the Mercedes factory didn't balance the engines closer then this, I would expect this on a SB chevy not a Mercedes motor.
02-11-2013, 10:09 PM
#7
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
02-11-2013, 10:09 PM #7Around 5,300 for a 617 turbo
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
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