Knocking after replacing fuel injectors

Tin Kicker

Member III
Sounds like progress in eliminaition of things it is not.

It's pretty hard to change the timing on these motors unintentionally, plus this started just after you changed injectors. Are the new injectors the same numbers as the old ones?

The copper washers should be pretty standard. If your local car parts stores don't carry the size, try pulling a map up on your phone and search on diesel truck repair.
 

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
Unfortunately the new injectors I have don't have a 4-digit number stamped on them like the pic. Calling Oregon Injectors confirmed the part number is 15271-53020, which are NOT the ones I ordered, so I'm probably eating humble pie on this. I ordered three new ones with the correct number and am crossing my fingers here.

I guess even if the form factor is the same, the part number could indicate the internals are calibrated to slightly different compression specs?

You always hope it wasn't your own error, but 90% of the time...
 

Tin Kicker

Member III
Ouch. That's an expensive call for a set of new ones but then the new ones are pretty close to the price of an overhaul.

I have overhauled a very similar tractor set, but just been lucky on re-installation to find the cleaning was enough to make an improvement. You need to ABSOLUTELY keep the same parts in the same injectors and I could not test them because they need a lot of pressure to open them.

Hope the new set does the trick.
 

Christian Williams

E381 - Los Angeles
Moderator
Blogs Author
I had my original injectors tested, the spray pattern was still correct, and new heads were put on for $50 each.

Replacement with new injectors might not be the first option for many of us, and there are many outfits that will test and bid on a rebuild by mail order.
 

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
Set of new 15271-53020 (3 injectors) currently runs about $110 on Amazon... not the most expensive mistake to make, but a good reminder to do better due diligence next time. Still hoping this is it, not something else.

I also repainted the engine, feeling like I need to make sure I didn't overpaint electrical connections or something too.
 

1911tex

Member III
Set of new 15271-53020 (3 injectors) currently runs about $110 on Amazon... not the most expensive mistake to make, but a good reminder to do better due diligence next time. Still hoping this is it, not something else.
Geoff W.: Get a quote from www.rockauto.com before ordering from Amazon...I saved over 50% on my injectors...same numbers. Fast delivery and no problems. FWIW
 

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
Ok, got the new injectors in via mail, but forgot the washers at my girlfriend's place, so while I wait for a round trip ferry ride perhaps y'all could indulge me..

I ran the engine on Wednesday to go race and didn't notice a bunch of fuel on the water, or extra exhaust. I just fired up the engine again to see if I was crazy or not, it started okay, ran and idled just fine, put it in gear at the slip and revved up to max. At first it only hit 2800 and then went up to 3k.

As far as I can tell it's not spitting a ton of fuel or gray smoke. but, now I can't remember how the engine used to sound, so I'm not sure if it's more clicky than it used to be or if it sounds fine. I recorded it for a few seconds so you can hear it. Does this still sound off to you? That sound like a rattling spray paint can seems off to me.

 

Christian Williams

E381 - Los Angeles
Moderator
Blogs Author
To my ear they all sound like that. Old engines, every tolerance a bit worn, engine good only for another 10,000 hours.

My solution was sound deadening insulation and an acoustic blanket. Huge "improvement to the engine."

You could always change the oil. It has no effect whatever on anything, but is a known psychological palliative that works for me.

I am really, really, not a diesel mechanic. Also, I think your diesel magically repaired itself, which they are known to do.
 

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
I am really, really, not a diesel mechanic. Also, I think your diesel magically repaired itself, which they are known to do.
Maybe so. I know the knocking I was hearing was distinctly painful to hear and sounded very wrong, but I don't THINK I'm hearing it now.

I found a video from when I was doing who-knows-what before the injectors and it sounds about the same.


Maybe I'm just panicking and grossly underestimated how long the effects of a Racor full of Seafoam would take to pass. I have a real mechanic still scheduled for 7/3 and he'll probably shrug and say the same thing - old engine, seems fine.

I'll try cleaning my electrical connections, maybe overspray from the new engine paint is having an effect on the tach somehow.

Thanks to all for the support on this journey through this cardiac stress test of a maintenance job.
 

Kenneth K

Sustaining Member
Blogs Author
Sounds just like mine.

I used to think I heard a "slapping" sound that I convinced myself was from the belt being too loose. I ether got the tension right eventually, or I just got used to the sound. I can see your belt wobbles a bit between the alternator and crankshaft pulley, too--just like mine.

If you had knocking, and it went away, I'd guess you had air trapped in the lines somewhere that eventually worked its way out.
 
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Kenneth K

Sustaining Member
Blogs Author
Last year when I changed fuel filters, I filled the secondary filter with Seafoam before re-installing. I did NOT get any knocking from the Seafoam, but I can't say the engine ran any better afterward, either. Seafoam showed a demo on You-tube of filling the fuel filter with their product on a DIESEL truck engine. I basically just mimicked what they did in their video. Says right on the can that Seafoam is for diesel engines, too.
 

1911tex

Member III
Sounds like my M25......without the insulated panels in place. Once in place...makes a huge livable difference. Quit worrying and go have fun!
 

Tin Kicker

Member III
While I applaud you for trying with the video, the microphone just isn't good enough for us to be able to do much with over the internet. Even so and on the up side, everything sounds fairly evenly timed.

Let us know what your diesel mechanic says next Friday. You might also share his view on Seafoam with us.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Regarding the sound in the video - sounds like a normal small diesel to me. That "clatter" is predetonation, and normal at idle. My old Universal did that, and the new Beta does so also, but is quieter.

Take this with a grain of salt, since I am not a mechanic.
 
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Kenneth K

Sustaining Member
Blogs Author
Regarding the sound in the video - sounds like a normal small diesel to me. That "clatter" is predetonation, and normal at idle. My old Universal did that, and the new Beta does so also, but is quieter.

Take with grain of salt, since I am not a mechanic.
How does a diesel pre-detonate? It can't ignite until the fuel is injected. Wouldn't that be the same thing as knocking, and caused by errant fuel timing?
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Ken, I recall a mechanic friend telling me that on older or well used diesel's, there is always a bit of carbon residue in the chambers and that can hold enough heat or glow to randomly pre-ignite the incoming fuel/air charge. At idle the engine makes a "popping" sort of rattling noise. When I asked him about it, on our high-hour engine, he would nod and say that he could hear it 'popping' at idle and that was normal and acceptable.
As the guy said in that movie: "that's all that I know about that!"
:)
 

Kenneth K

Sustaining Member
Blogs Author
Although, in thinking it over, I still have the same confusion--even with glowing carbon deposits in the cylinder, there is nothing to ignite until the fuel is injected, which is when the combustion should occur anyway.
 
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1911tex

Member III
Ken, I recall a mechanic friend telling me that on older or well used diesel's, there is always a bit of carbon residue in the chambers and that can hold enough heat or glow to randomly pre-ignite the incoming fuel/air charge. At idle the engine makes a "popping" sort of rattling noise. When I asked him about it, on our high-hour engine, he would nod and say that he could hear it 'popping' at idle and that was normal and acceptable.
As the guy said in that movie: "that's all that I know about that!"
:)
Thanks Loren: I thought I was due for a valve adjustment with the clatter at idle. Above idle...not a problem.
 

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
Although, in thinking it over, I still have the same confusion--even with glowing carbon deposits in the cylinder, there is nothing to ignite until the fuel is injected, which is when the combustion should occur anyway.
Ken, as I have recently half-watched a youtube video about diesels vs gasoline engines, I am now a certified online diesel mechanic. It could be that if something in the cylinder is already hot enough to start the combustion earlier than desirable, the very very first fuel coming out of the injectors might light before the entire spurt of fuel has been injected, is compressed, and ready to go. this would probably create a noisier/rougher shockwave than if everything was sub-second perfectly running.

anyways, that'll be $.02 an hour for the speculation. bill is in the mail. i've got to get back to patting my head and rubbing my belly at the same time.

project note: I ran the engine a while this weekend. Still putting out a lot more exhaust then it should, and at one point it began intermittently knocking. It stopped after stopping the engine for a while and restarting it. I can smell some diesel when i open the lazarette lid, so something is leaking. I should have already done this, but will now replace the fuel lines with new ones. All this leads me to think there is probably an air issue somewhere, or something isn't as screwed in as tightly as it should be. maybe i went overboard on the anti-seize when putting them back in.

this is all sunday speculation, I'm not going to do much else til the mechanic comes on Friday.
 
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