Tapping sound at cold start. Am I worried for no reason?

[big orng]

I bought a used Mx5100 in Nov (128 hrs). Great tractor!
We had a could snap(low 30's) I went to start it after letting the glow plug engage for about a minute. There's a fast tapping sound near the front of the engine. After about 2 minutes it clears up. Doesn't do it at all when it's 50* or warmer. I've changed the oil but it's still doing it.
Should I be worried?
Thanks for any advice.
Here's a link to YouTube with the sound.
Sorry I'm moving it so much. I'm trying to get different vantage points.
http://youtu.be/lEfjnxNbY68

 

[85Hokie]

I bought a used Mx5100 in Nov (128 hrs). Great tractor!
We had a could snap(low 30's) I went to start it after letting the glow plug engage for about a minute. There's a fast tapping sound near the front of the engine. After about 2 minutes it clears up. Doesn't do it at all when it's 50* or warmer. I've changed the oil but it's still doing it.
Should I be worried?
Thanks for any advice.

Can you describe the tapping sound a little better? I know that is asking a lot , where is it coming from ? Top of engine? Bottom of engine? Does the tapping change with engine RPM's?

Right now my guess - would be valve train? valve lash?

 

[Tooljunkie]

Most diesel cold starts usually make a hammering for a couple seconds,at least all the ones i hear start. But up here everything does it at startup when its well below freezing.

 

[mickeyd]

Welcome to OTT big orng from Alabama.

 

[Tooljunkie]

Most diesel cold starts usually make a hammering for a couple seconds,at least all the ones i hear start. But up here everything does it at startup when its well below freezing.
128 hours for excessive valve lash is a little low. Best to open hood, have someone start it while you listen for noise. Better yet, make a recording and place it on the youtube for all to hear. Just a suggestion.

 

[big orng]

I was thinking about the recording. Thanks I'll try that.

 

[big orng]

Can you describe the tapping sound a little better? I know that is asking a lot , where is it coming from ? Top of engine? Bottom of engine? Does the tapping change with engine RPM's?

Right now my guess - would be valve train? valve lash?

I first thought is was something like a stick against the coolant fan. Real fast and it does change with the RPM's. Its near the front, as best as I can tell, and somewhat more noticeable on the oil filter side. That's why at first I thought the oil was just getting thick so I changed it.

 

[85Hokie]

Most diesel cold starts usually make a hammering for a couple seconds,at least all the ones i hear start. But up here everything does it at startup when its well below freezing.
128 hours for excessive valve lash is a little low. Best to open hood, have someone start it while you listen for noise. Better yet, make a recording and place it on the youtube for all to hear. Just a suggestion.

A valve train that has lash at 128 hours would be a bad thing! Only thing that popped into my head other than something else that is expanding as it gets warm.

Mine will grumble a bit when cold - but gets smooth quickly, never more than 10 seconds or so ......I am at 105 hours.

 

[North Idaho Wolfman]

Make a recording and post it, it's probably nothing to worry about as most diesels will have knocks, ticks, clatters, and such till they get warm.
A fuel treatment like Stanadyne will help bring the cetane levels (similar to gasoline octane) up and that might eliminate the knocking issue.

 

[Dave_eng]

I find with my M7040 that after it starts in cold weather, even using the block heater, it needs to run at 1,500 rpm for things to smooth out and quiet down. Kubota recommends leaving the tractor at a fast idle for up to 20 minutes to warm up the hydraulic system.
If you are running it at a slow idle after a cold start I would expect a lot of concerning noises.
Dave M7040