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SMD fluttering at idle

D

Dan MD

Member
I have had the pump, injectors and motor all redone on my SMD. It still has a flutter on the diesel side when unloaded. I found a video on youtube that sounds like mine and I would like to know if this is how they are supposed to sound.

http://www.youtube.com/watch?v=tm5SsLqg7kw

Thanks,
Dan
 
Well with the straight pipe it sounds different than ours. It does sound a bit like an injector might be off just a little. Or the fuel leaks might be affecting the fuel supply causing it.
Notice nobody checked the oil or fuel/gas levels before starting.
 
Sounds like an injector as well, but what about the pump timing? Set it to the left as far as you can go until it misses, then set it as far to the right until it misses, and then set it in the middle. Did you get the pre cups in with the arrows up, and were they in perfect shape or did one of them have some punch marks on the end from removing them?
 
(quoted from post at 17:15:34 05/23/12) Sounds like an injector as well, but what about the pump timing? Set it to the left as far as you can go until it misses, then set it as far to the right until it misses, and then set it in the middle. Did you get the pre cups in with the arrows up, and were they in perfect shape or did one of them have some punch marks on the end from removing them?
Click to expand...

I have not maxed out the pump timing as far as advancing it for fear of cracking the head. The precups are all installed correctly, but they do have punch marks in the ends. I was told that didn't matter as long as they were cracking into pieces. I don't know.
 
I have never read about timing cracking these heads, only improper cooldown. Where did you get that info?
 
(quoted from post at 19:54:23 05/23/12) BINGO! Go find some good pre-cups and problem solved!
Click to expand...

How do you know that? Also, how would one go about finding a set that doesn't have any punch marks on them?
 
Been there and done that. If that hole is not perfectly round or has a
nick in it you will get a drift in the spray of fuel causing uneven
burning and causing a miss. If that pre-cup is good, then have the
injector checked again. You will either have to do a lot of looking to
see if a good set even exists anymore, or put up with the slight
miss at idle. Good Luck.
 
(quoted from post at 20:50:47 05/23/12) Been there and done that. If that hole is not perfectly round or has a
nick in it you will get a drift in the spray of fuel causing uneven
burning and causing a miss. If that pre-cup is good, then have the
injector checked again. You will either have to do a lot of looking to
see if a good set even exists anymore, or put up with the slight
miss at idle. Good Luck.
Click to expand...

I don't know if the center bore is out of round or not, but I know the ends are smashed up on some of them where the machine shop used a punch to drive them out. Are you talking about the end towards the cylinder being out of shape or the center bore being out of shape?
 

On the Red Power Magazine forum, there was a member who recently passed away that was trained by IH service engineers back in the 40's when these things were state of the art technology. Do a search for MB Cat, he seemed very knowledgeable about the gas starts and he warned about advanced timing causing head cracks that were different than the hot shut down cracks.

Dan
 
timing your pump won't crack your head, finding "center" for your
individual pump takes time and patience, and advancing it until it
misses won't crack the head, as you are only running it for a minute
or two. If you advanced it and plowed all day all bets are off.

Like someone says usually 2-6 degrees but everyone is a bit
different. SMD all have the same way to start, but each one also has
its quirks as well. Let us know what you find out.
 
(quoted from post at 14:11:51 05/23/12)
On the Red Power Magazine forum, there was a member who recently passed away that was trained by IH service engineers back in the 40's when these things were state of the art technology. Do a search for MB Cat, he seemed very knowledgeable about the gas starts and he warned about advanced timing causing head cracks that were different than the hot shut down cracks.

Dan
Click to expand...

Thanks Dan, I'm going to go check that out. I reread my post, I wasn't trying to jump you. I just never heard that causing cracks. We have a local guy here that was a service tech when these were brand new. He is sharp and is on YT. I am not sure if he posts or just reads. I know he reads because he will read my questions or follow what I am doing with my MD. Then I will call him and he will say something like "I figured you would call" :lol: (if you are reading this I am getting close to calling you on my rear main lead)

d282 - Can you weld up the bad spots to clean them up? I think I have enough to make a good set, but one is a little fishy.
 
(quoted from post at 23:44:51 05/23/12)
(quoted from post at 14:11:51 05/23/12)
On the Red Power Magazine forum, there was a member who recently passed away that was trained by IH service engineers back in the 40's when these things were state of the art technology. Do a search for MB Cat, he seemed very knowledgeable about the gas starts and he warned about advanced timing causing head cracks that were different than the hot shut down cracks.

Dan
Click to expand...

Thanks Dan, I'm going to go check that out. I reread my post, I wasn't trying to jump you. I just never heard that causing cracks. We have a local guy here that was a service tech when these were brand new. He is sharp and is on YT. I am not sure if he posts or just reads. I know he reads because he will read my questions or follow what I am doing with my MD. Then I will call him and he will say something like "I figured you would call" :lol: (if you are reading this I am getting close to calling you on my rear main lead)

d282 - Can you weld up the bad spots to clean them up? I think I have enough to make a good set, but one is a little fishy.
Click to expand...

I didn't think you were jumping me at all. Are you able to share who the member is? I am always looking for resources. When you say local, how close to Argyle are you?
 
(quoted from post at 22:49:27 05/23/12) timing your pump won't crack your head, finding "center" for your
individual pump takes time and patience, and advancing it until it
misses won't crack the head, as you are only running it for a minute
or two. If you advanced it and plowed all day all bets are off.

Like someone says usually 2-6 degrees but everyone is a bit
different. SMD all have the same way to start, but each one also has
its quirks as well. Let us know what you find out.
Click to expand...


UPDATE!!!

I put in the "nused" precups and it sounds better but still flutters. I played with the timing and no change. I looked closely at my injection pump gear backlash and think I found my problem. My book calls for a max spec of .013 for the idler to inj. pump gear. I crudely measured it and got .060. The idler looks way too loose to me. When I turn backwards on the inj. pump gear, the idler teeth go from flush with the inj. pump gear to protruding past flush about 1/16". When I laid a straight edge to the timing marks, I can get 5 degrees of timing slop. I think the mechanic didn't tighten the idler down enough.

How big of a job is it to get at that? It looks like a lot of stuff has to come off just to tighten a stinking idler gear.

Dan
 
I finally got the front cover off and luckily all my gears look good. The problem with the idler was it wasn't tightened to spec which is 75 ft/lbs min. When I grabbed the castle nut, it was so loose I could wiggle it up and down and spin it around. The cotter pin was still in place and all the spacer parts were there, it just never got tightened up. When I was barring the engine around to line up the timing marks, the idler was rocking back and forth between the gears. I took the whole idler assembly to a local CNH service manager who has been helping me a lot and he said everything looked good with it. He also said it was a good thing I found it before something really bad happened. Now I just have to find the time to get it all back together.

Dan
 
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