Engine Pinging?? Starange Sound.

[RSchwarzli]

So, over the last few weeks I have noticed a strange noise from the motor. This is the 3rd tank of fuel that I am on and still noticing it. It almost sounds like pre-ignition like you would have in a gasser. It happens under low load (5-6 psi) and it sounds really rough. Alsmost a really laud clatter. Not just me either. Had dad ride in the truck and he noticed it very off as well.



It is load related. If I step on it and go 10 psi plus, then I cant detect it anymore. It is most noticeable while driveing about 50 mph empty.



Any thoughts? Comments?



My details are as follows during the most noticeable sound interval:



Pyro - 400-450

Boost - 5-8 psi

Tach - 1900 RPM

Temp - 170 ish

Oil pressure - 50 psi (normal for the truck)

2 stroke out ratio with fuel - 100/1



Thanks!



Robert

 

[JLEONARD]

Change in the fuel mix at the pump ie more kerosene therefore slight change in timing due to ingition characteristics of the fuel??????

 

[RSchwarzli]

Was kinda wondering the same thing... ... .



Robert

 

[TWorline]

Does it run a little ruff or have a miss when it pings? If so it is an injector, I know in a big truck it sounds almost like a rod coming loose!

 

[RSchwarzli]

It SOUNDS like it is running rough, but I do not feel/detect any roughness any other way other than by ear. if it was an injector, would it be RPM/load based like it currently is?



Is there any way to see if it is an injector without pulling it and pop testing it??



Thanks!



Robert

 

[JLEONARD]

Is there any way to see if it is an injector without pulling it and pop testing it

You can check all the cyls with a heat gun at idle... the cold one will be the one not spraying right.

But if they are so close that you can't quite tell... . don't worry about it.

 

[sdstriper]

JLEONARD, do you mean a point and shoot thermometer? Infrared type?

 

[JLEONARD]

do you mean a point and shoot thermometer? Infrared type

yes

Those gizmos have many uses and should be a part of your tool kit.

 

[cerberusiam]

do you mean a point and shoot thermometer? Infrared type

yes

Those gizmos have many uses and should be a part of your tool kit.

Yeah, everybody needs a Buzz Lightyear ray gun in their tool kit. :-laf:-laf

 

[RSchwarzli]

Ok, got one of these heat gun thingies.



Now where do I need to aim it??



Also on a side note (as I know SOMEONE will run with it), yes I tested it on my brain to check for heat from activity. It resulted in a below freezing number.



Robert

 

[JLEONARD]

 I tested it on my brain to check for heat from activity. It resulted in a below freezing number

You know what the women say so try it on the head you think with :-laf:-laf



I would try aiming at the exhaust manifold legs and the base of the injectors.

See what you get.

One thing to bear inmind... . try to get the same distance away and the same angle for each reading to get as much accuracy as possible.

 

["Mad Max"]

'Buzz Lightyear Raygun' - that's too cool a sounding gizmo not to own one... ... . darnit fellas - now I gotta go to the store #@$%! Oo.

 

[JLEONARD]

MM don't bring it out at a party:-laf

 

[Jgolden]

Cool tool for sure. I think they all have laser dot to ID spot. Got mine at Sears because I was in a hurry. Probably cheaper in other places. The closer you can get to the spot you want to measure the more consistant the reading.



Works for tire temp, wood stove chimmney temp (yep, thats a chimmney fire allright. ) brake temps, diff, on and on.

 

[RSchwarzli]

'Buzz Lightyear Raygun' - that's too cool a sounding gizmo not to own one... ... . darnit fellas - now I gotta go to the store #@$%! Oo.

:-laf:-laf:-laf:-laf



Same thing I thought!



Robert

 

[JGrefenstette]

real simple and fast way to check for a bad injector.



get a wrench and crack the injectors one by one. id start at 1 or 6 cylinder and work your way down the line. crack em just enough to get fuel to bubbly or squirt out. usually not much more than 60*. if the idle changes you got a good injector, if it stays the same, then you know its bad. if you have a bad injector you cant miss it by using this method. you may want to repeat the process a few times just to get a good feel for the tone of the idle, if you notice a change as you go. reason being, if you have a bad injector, youll be hearing 3 different tones as you go down the line an crack em. firing order is 1-5-3-6-2-4. so lets say #5 is bad. i crack #1, and i get a real bad lope in the idle, cause now im not only missing on #5 cylinder ignition, im also missing the ignition prior (#1). i then crack #2. idle changes, but much less than #1 did. next i crack #3, same as #1 i get a bad lope, because once again im not getting fuel in two cylinders one right after the other. then i crack #4, same tone as #2 gave me. then i crack #6, yep you guessed it, same tone as #2 and #4. simple as that cowboy. i probly made it sound harder than it is by trying to explain it. but you get the picture. dont take more than a few minutes. dependable old method.



have you advanced the timing of you injector pump? cause if you have, and your running a fairly 'hot' winter blend. it would make sense that the fuel being injected sooner in the compression stroke and having more kero in it, would cause it to ignite prematurely.



thats my 2 cents, hope it helps you somewhat.

 

[RSchwarzli]

OK. That did sound consuzing! Will try giving it a try though!



Timing is still factory as far as I know. I personally have never touched it.



Thanks!



Robert

 

[JGrefenstette]

haha, sorry robert. let me put it too you this way.



1. Start engine, let idle.

2. Get a wrench to fit the injector fitting.

3. Crack #1 cylinder injector fitting.

4. Listen for idle change.

5. Tighten injector fitting back.

6. Repeat steps 3 & 4 on cylinders 1-6.



if you crack any of the injectors, just enough that full spits out, and the idle does not change, bingo, thats the bad apple of the batch. once you do that, and hear the idle variation, you will start to understand what i was talkin about in the first comment i made. but id just forget that for now an go by those 6 basic steps best of luck my friend.

 

[RSchwarzli]

Ooooooh! I get it now!



Actually, it made sence after re-reading the post a few times and picturing what you were saying. Will have to give this a try.



Thanks for the clarification!



Robert

 

[Moe]

How about some part names or models. Sounds interesting. MOE