1hz making a weird noise (1 Viewer)

[pickelltree]

Hey. In the video at the 12 sec point my 93 1hz out of a coaster bus does a burp. I’m not sure what or where this pressure is being released and why it is happening.

Today we timed the injection pump. 1.09
Compression is all about 375 psi

I am in Ecuador and they don’t know too much about this engine. The plan for tomorrow is to take the head off again and adjust the valves.

I would rather not do this but not sure what else.

It seems like when underload. Like going up a hill. It rattles then will make this burp It will do it more then once if it’s a long uphill.

This has happened after they rebuilt he engine. I’m pretty sure they used th correct parts because we shipped in from Peru. But don’t want to rule that out.

Today we drove it with an extended hose off th valve cover to th ground to make sure there was no blockage with it returning to th intake pipe. But it still made the burp

Hopefully someone can understand what I’m trying to explain. Thanks for any input

 

[ozarkmud]

I'm not seeing the video that you mentioned.

 

[pickelltree]

Video won’t load. s***

I'm not seeing the video that you mentioned.

 

[pickelltree]

Video won’t load. s***

 

[TonyP]

How was the compression taken? Per FSM? Min compression for a 1HZ is 384 psi on a warm engine with >71 psi across all six.

 

[pickelltree]

I can’t see the extension that can be used on this forum to post videos. Anyone can help me so I. Can send the video here

 

[pickelltree]

 

[pickelltree]

Thank you for your patience. Here is the video. What is happening at 12 sec seem to happen often

 

[mudgudgeon]

Really hard to judge anything from that video.
Idle sounds solid.

Describe what happens when driving it? Do you feel it in the east the engine performs?
Or just a noise?

 

[sunrk]

The idling of the motor sounds basically identical to the 1hz in my 80 that's currently done just over 693 k km's, The valvetrain noise doesn't seem of concern.

Is the motor warm/hot or just started from cold when the video was taken?

If you've been able to capture the same thing occuring again, has there been any odd pulse either in change of exhaust note, or a puff of black/blue/white smoke?

How many km's on the motor? Have the shims been checked/corrected in the last 100 k km's or so?

With my 80's 1hz I often when the motor is fully cold on startup get it behaving like 1 or more of the injectors haven't opened and sometimes that can last up to 10 or 15 seconds if the motor is really cold. But then it's fine apart from the idle revs never being spot-on the same all the time.

 

[DivByZero]

I don't have anything of much use to add, other than to say I hear the sound you're worried about, and it definitely doesn't sound normal. Never heard my 1HZ make that noise.

Do you know where the sound is coming from? Maybe try an engine stethoscope to narrow down the source?

 

[pickelltree]

Happens when engine is warm and cold. Usually under load. Seems like the engine makes a rattling noise as I’m driving. This this burp releases that pressure. I. Or sure exactly where it releases but it could be through the air intake.

The engine was just rebuilt. So the shims could be incorrect. The mechanic here thinks that is the issue.

Because of the box on the back I can’t see if there is a puff of smoke

When I climb hills there is a lack of power in general. When it burps like this the power doesn’t change much but it does shake the engine/truck

 

[pickelltree]

They are changing the valve guides. Could that be the issue? I think they believe that the valves are not opening enough and pressure is escaping when the valve are closed.

For me- escapes where. I am not following their thoughts

 

[mudgudgeon]

I think they believe that the valves are not opening enough and pressure is escaping when the valve are closed.

This doesn't make sense to me.

If the valves aren't opening fully you'll be down on maximum power, but it shouldn't prevent them sealing.

 

[pickelltree]

Seems like the rattle noise was this thing a bit loose. The holes are a bit oval now but not to bad. As long as they get this to hold firm it should be ok?

The changed the shims on all the exhaust valves they said and changed the valve guides to some copper ones. Not sure if they are a different size or just a different material. Any thoughts on this change?

 

[pickelltree]

Ok. I think it was the valves. They readjust them and it’s stopped. I also discovered that it was running rough due to being in Quito. Almost 3000 meters. Since then I e driven to bogota and at 700 m. It was quiet and strong. Now in bogota it is louder and less power. I’m better when I go down in altitude it will run good again

Another noise was the clutch disk. It wasn’t worn. Was new actually but it wasn’t heavy duty. I changed it with a beafier one and now there is no noise crime the clutch