Engine Knock??? Or Not???

[Anonymous Poster]

As a mechanic I've heard rod knocks a thousand times and seen what can happen if not taken care of quickly. But most of my experiance has been with gasoline engines, not diesels. Obviously they rattle quite a bit, but this noise coming from my 1500d has me concered. It knocks louder than i think it should when first started and slowly goes away as it warms up, and does not do it at all rpms, however it never really goes away completly. The oil pressure checks good at around 35 -40 psi and I pulled the pan and the bottom end seems tight.

I read though some old posts and found that it may be something in the fuel system, dirty injectors or fuel or maybe the timing. A couple posts said that 2cyl motors make more noise then most and that its normal and not to worry about it. Each time a start it when I'm showing it off to friends they all ask about this noise.

Well it does have me worried and I need some help from some of you that have played around with these machines. What should I look for or try to do first, or is it normal? Thank you all very much /forums/images/graemlins/confused.gif

 

[gbirky]

Mike,
Most of the 2cyl Yanmar diesels have that knock. Its commonly known as the Yammer-Hammer. Of course, without hearing it, nobody can tell you for sure whether it is the normal knock. It is normally most noticable when first starting and running at slow speeds. It is normally ALMOST un-noticable at operating speed. The operating speed should be marked with a red mark on the tach. At that engine speed, the pto turns at approximately 540rpm when the pto is in the lowest gear.

 

[Tractors4u]

It sounds like it sounds just like my 1500D.

 

[Anonymous Poster]

Anyone know if DetroitMike can record the sound and attach it so that those who know what a 1500 sounds like can listen and see if they think anything is wrong.

 

[SteveM]

I am on my third 2cyl diesel, and while they do knock a bit, I think you may have something wrong. No friend has ever asked or noticed about my machines idling- it just isnt that loud of a knock (1 yanmar, 1 kubota, 1 hinomoto in my experience)

I would have it checked by someone familiar with old 2cyl diesels.

 

[TBone]

If you check the archives I think you'll see that this question has been raised before. I have a friend who has a 2 cyl Yanmar and the first time I heard it I thought it was coming all to pieces. /forums/images/graemlins/shocked.gif He said everybody thought the same thing but it had been running like that for the 4 years he owned it and was still going strong. /forums/images/graemlins/laugh.gif I don't think you have anything to worry about but I wouldn't like it either.

TBone

 

[Anonymous Poster]

Thanks for the help guys. From these posts and the old ones I read, it seems like most folks say this is normal. I think I'm going to look for a diesel pro around here to take a listen just to be sure though. The last thing I wanna do is smoke the motor after only having it a couple months.

I'm curious though, Greg, I noticed on your web site that you have had at least one Yanmar engine torn down. How difficult was it to get rebuild parts are were did you get them. Hopefully I won't need to worry about that right now, but it never hurts to be prepared. Thanks All

 

[EFC]

On diesels, if it is a rod knocking, then it will get louder as the oil gets hotter. Normal diesel knock will get quieter, as the oil gets hotter. Sounds like your 1500 is running perfectly, more knock=more compression (or dirty injectors but a dirty injector never quiets down).

 

[gbirky]

Mike,
I have now torn down two Yanmar 2T72 engines. I believe the YM1500 has a 2T90 engine. Both are common engines used in applications other than tractors. I have not had any problems getting engine parts. The first one I replaced every bearing, seal, and gasket, as well as piston rings. This one I'm just replacing a sleeve and rings on one cylinder. I haven't had trouble getting parts. Most of them were from Lawn Care Equipment - a Yanmar dealer near Lancaster, PA and Sheaffer's Town and Country Tractor - another Yanmar dealer in Illinois.

 

[normde2001]

"What should I look for or try to do first"

I would look for, and install, a good pair of ear protectors. They do wonders for the "Yammer hammer" /forums/images/graemlins/grin.gif