336D injectors

[Vern]

Being i was so close to getting it running I decided to go ahead and start it up. Ran good, middle cylinder firing and running smooth. After about 30 mins running it developed a knock in low RPM . I tried taking a video bu having trouble getting put on the site. the knock goes away with increased rpm. Seems to have a lot of pressure in the radiator but the pump is working and water is circulating, I did install a thermostat- it did not have one.

I'll keep trying the video

 

[Vern]

Try this

Feb 26, 2012 1:14pm | Facebook

 

[California]

Thanks for posting that.

It almost sounds like the Yanmar fuel knock in my YM240. You can hear mine if you click on my sig at the bottom of this post, scroll to the bottom of my web page, and play my recording. (especially the second half).

The way your knock fluctuates could be a variance in the quantity of fuel injected, or even early/late timing variance if such a thing is possible.

FWIW I don't see how a rod knock could fluctuate like that - but anything's possible.

 

[Neat 1500]

Mmmm it is quite random, not continuous. i wonder if the fuel delivery on one cylinder is not exact at every injection pulse?

 

[Car Doc]

I would re-check the compression after running it for an hour at 1500 rpm let the rings get started seating before condemning anything yet.

The knock to me sounds like fuel or lack of it it is like the knock you get when cracking injectors to find a miss but videos are misleading usually. The fact it didn't have a lot compression in #2 could also be the comp release out of adjustment.

 

[Domush]

The only time I've ever heard varied knocking like that was caused by poor oil delivery, in my cases caused by worn rod bearings. My butt puckered just hearing that noise again. No engine I've owned ever lived beyond that noise. granted, that is more a reflection of me than the engine

I'd love to be with car doc on this, but I just don't see how rings not being seated could cause knocking. The compression difference, yes, but knocking?

 

[Car Doc]

I have built a lot of engines and most start and run perfect if I did my part but occasionally there is a noise or something that seems out of place that goes away after a brief run in.

If it was carbon/dirt/rust like Bruce said earlier something stuck under a valve is very possible even on a clean new assembly. Air cleaner tubing etc can release this stuff anything before the valve and sometimes takes a bit of running to clear it out.

I hope thats what it turns out to be this is frustrating I have been there done it.

 

[Vern]

I used platicgage when I installed the new connecting rod bearings - measured .004 on all three. If I increase the rpm the knocking goes away and the engine runs smooth. I do not have an oil gage, just an idot light and the wiring had been bastardized so not sure that is working.

 

[Car Doc]

If it was the bottom end the knock would probably not go away low compression or lack of or excessive fuel causes knock in diesels from my experience.

Like I said to me it seems like a fuel knock but I am not a diesel expert by no means so take what I say on fuel issues with salt. Recheck the compression after a good run in and get back with us on that and I believe we will be able to determine where to look next.

fwtw My engine is pretty noisy (not that bad but...) until it gets fully warmed up and by that I mean an hour tilling etc up until then its noisy but once its warm it has no noise whatsoever and purrs like a kitten.

 

[Car Doc]

Vern, here I found you a Jeep diesel that has a knock but its got a cyl down if you listen to him crank it the hitch in its get a long will be noticeable now I mentioned it and its knocking different than yours once it fires off.

I am going to keep looking for just the right way to audibly diagnose a fuel knock and hopefully I will find something and post it.

[ame=http://www.youtube.com/watch?v=Ux9mR-hmguU&feature=player_detailpage]More Jeep noise - YouTube[/ame]