Perkins 4.108 issues, clearly failure is imminent.

[doog]

So Thanks again, Ive worked out posting on you-tube and sharing links here to give a hearing to the engine condition. And in short, the usual clatter-bang of my Perkins was reviewed by several and considered normal but yet the transfer of sound isnt quite adequate to share the scraping/ringing quality that betrayed a more serious issue. And running the engine a bit more to fit a new alternator and test it, the sound is now much more pronounced.

Added clip of the engine running again with a beautiful, low idle and solid compression, starts instantly, but this clatter.

https://www.youtube.com/shorts/_DakweU4eXE

And I removed the injectors and the rocker arms to take all the load off the engine and turn it by hand to hear what's going on. And it makes this zipper sound with a high-pitched singing overtone that sounds like a chain on a gear rolling loosely. But the only possible source inside this engine is the oil pump drive gear which engages a sprocket on the camshaft. You can hear it in this last clip, and its clearly not in the timing gears and the oil pump is the only other possible source of the sound, which is clearly the clatter Im getting.

https://www.youtube.com/shorts/qLZMbUqh6Ek

Anyway now planning to pull the engine and pull the pan and get the oil pump out. The cam seems fine and all the rods make nice little rotating turns with each lift. Not expensive, replacement about $150. I know that bad rod bushings at the pistons is a possibility but should be able to check for that once the pan is off but the sound of this engine doesnt seem like rod knocking noise. Pulling the head off and removing a piston is a lot more critical an operation than I want to attempt in my boat's galley area.

Again, bought the engine as a low time salvage because of oil pressure loss. Had the crankshaft inspected and they found no damage and it all felt tight inside so I simply ran the engine and its been great (but noisy) for 600 hours approximately. Anyway if an engine builder has any experience similar, I'd appreciate comments. And I wanted to make this info available for any with similar sounds/symptoms in their engine.

I'll add to this as I learn more.

[Cheechako]

The first video sounds near normal running at low idle.
But the hand turning is a bit weird sounding, I have never hand turned a 4-108 more than a short spin so dont know if that is normal.
-Almost sounds like the starter is engaged and spinning with the engine...?
-Maybe something in the injector pump?

[doog]

Yes near normal but not, and rapidly increasing the clattery sound. I sent for oil analysis but must open the engine. Ive had the timing gears off and the injector pump turns with no noise or any resistance at all. You know it could be a starter gear stuck in the engaged position on the flywheel and I have an aftermarket starter which has a free wheeling drive gear that could get stuck in the engaged position and its acting weird so I will pull the starter and see. And thanks so much for the suggestion that its the starter motor. It could actually be stuck here, and I accelerated the engine and it literally sang so again this could be the starter gear spinning with the engagement lever retracted but the gear still spinning on the flywheel. So thanks so much for the suggestion. (its a nifty Smith's aftermarket starter that uses less electrical draw to crank it but it is a bit sketchy sounding on engaging as if it doesnt hit the flywheel quite right, and this is a warrantee replacement after the first one failed)

Thanks again!

[Cheechako]

Originally Posted by doog

Yes near normal but not, and rapidly increasing the clattery sound. I sent for oil analysis but must open the engine. Ive had the timing gears off and the injector pump turns with no noise or any resistance at all. You know it could be a starter gear stuck in the engaged position on the flywheel and I have an aftermarket starter which has a free wheeling drive gear that could get stuck in the engaged position and its acting weird so I will pull the starter and see. And thanks so much for the suggestion that its the starter motor. It could actually be stuck here, and I accelerated the engine and it literally sang so again this could be the starter gear spinning with the engagement lever retracted but the gear still spinning on the flywheel. So thanks so much for the suggestion. (its a nifty Smith's aftermarket starter that uses less electrical draw to crank it but it is a bit sketchy sounding on engaging as if it doesnt hit the flywheel quite right, and this is a warrantee replacement after the first one failed)

Thanks again!

You could just pull the starter or back it out and turn to see if that is it....

Another thought: Isn't there a flex plate or something in the bell housing on these? I cant remember. Maybe it's loose?

[doog]

Yes no problem removing the starter and I think that's it. This is the second starter from this supplier and it may have a compatibility issue with the Perkins engine. I already replaced the damper plate and mine was w o r n but it was not the cause of this noise. The new damper plate made little difference in the sound. Thanks again for the good suggestions.

[capt.rob]

I had a similar issue with my 4107 after replacing old style starter, the gear didn't quite disengage flywheel after starting, I had to grind gears end down about a 16th inch, also sounds like possibly dampner plate between flywheel is letting go there are 3-4 springs in it to ease torque when shifting one may be broke. easy to tell when you remove tranny. I wound up having to ut a inspection hole in my bell housing to see if the starter gear was properly engagining (easy to do with a grinder and cutoff wheel).The starter gear also relies on a light spring to keep gear from trying to go back in flywheel when starter is disengaged.It doesn't sound to me like its an enternal engine issue but starter,, Dampener, water pump( fresh water pump on front of motor not sea water), alternator etc. Have you tryied following the sound using a long screwdiver, metal rod, socket extension etc. pushed to your ear like a stethascope and follow the noise to its loudest location wile running. It should take you right to the bad part.

[Boatyarddog]

Originally Posted by doog

So Thanks again, Ive worked out posting on you-tube and sharing links here to give a hearing to the engine condition. And in short, the usual clatter-bang of my Perkins was reviewed by several and considered normal but yet the transfer of sound isnt quite adequate to share the scraping/ringing quality that betrayed a more serious issue. And running the engine a bit more to fit a new alternator and test it, the sound is now much more pronounced.

Added clip of the engine running again with a beautiful, low idle and solid compression, starts instantly, but this clatter.

https://www.youtube.com/shorts/_DakweU4eXE

And I removed the injectors and the rocker arms to take all the load off the engine and turn it by hand to hear what's going on. And it makes this zipper sound with a high-pitched singing overtone that sounds like a chain on a gear rolling loosely. But the only possible source inside this engine is the oil pump drive gear which engages a sprocket on the camshaft. You can hear it in this last clip, and its clearly not in the timing gears and the oil pump is the only other possible source of the sound, which is clearly the clatter Im getting.

https://www.youtube.com/shorts/qLZMbUqh6Ek

Anyway now planning to pull the engine and pull the pan and get the oil pump out. The cam seems fine and all the rods make nice little rotating turns with each lift. Not expensive, replacement about $150. I know that bad rod bushings at the pistons is a possibility but should be able to check for that once the pan is off but the sound of this engine doesnt seem like rod knocking noise. Pulling the head off and removing a piston is a lot more critical an operation than I want to attempt in my boat's galley area.

Again, bought the engine as a low time salvage because of oil pressure loss. Had the crankshaft inspected and they found no damage and it all felt tight inside so I simply ran the engine and its been great (but noisy) for 600 hours approximately. Anyway if an engine builder has any experience similar, I'd appreciate comments. And I wanted to make this info available for any with similar sounds/symptoms in their engine.

I'll add to this as I learn more.

Sounds like the starter bendix maybe hanging up.
As in not disengaging from the flywheel.
Possible the solenoid return spring broke, and the starter drive is still engaged.
Had you check d that yet, if not, pull the starter and recheck.
Boatyarddog

[t588143]

This sounds like a rattling damper plate, not the engine itself. Those noises sound much more ‘solid’

[doog]

Yes the damper or balance plate is new, just changed that and it was worn but the new one made little difference in operation or sound. And the starter was indeed the source of the zipping gear noise, not the oil pump and its been doing this all along.

Its an aftermarket starter and the previous one also failed dropping a part into the flywheel and causing me to have to pull the engine and remove the flywheel to fix, and I got a free replacement. But this one, too, hung up somehow and didnt retract and now that its out I can see the copper bushing is melted and this was ths singing I heard on my last engine run. So im not sure I want to replace with this same starter again. It doesnt seem to fit properly as the clearance issue mentioned.

Now I can turn the engine over and check for any knocks that might indicate a spun rod bearing which I should feel at TDC or BDC as a tiny thud in the otherwise totally (should be) smooth rotation. Anyway this was clearly the cause of that crazy gnashing sound and Im just glad I didnt end up with my flywheel destroyed and needing replaced.

Thanks much for the helpful comments!

[doog]

Performed the 360 rotation with rocker arms loose and careful attention to each cyl at tdc and bdc and its tight. No hint of any knocks. I also found the original timing marks on the fuel pump wheel made with a cold chisel and restored that setting. I think I'll just add some Lucas oil treatment to help with the well-worn condition. The rockers are a bit wobbly but fully serviceable and not making noise. And I'll consider the options in a replacement starter. And thanks Capt Rob and Boatyarddog for the starter comments and I'd never have thought of that as well as the first respondent who also nailed it!

I may get the injectors cleaned and serviced while they're out or look into cleaning them with solvent.. As others have found the injector bolts had loose nuts under the hold-down straps for the heat exchanger where somebody was in a hurry so they never got torqued, and yet there wasnt any leaking evident.

Anyway glad that I was steered toward the starter and now Im not looking at an engine rebuild but much easier stuff!

This forum is invaluable!

[Finalee]

Wow that's a great outcome. Amazing it continued to start the motor. Was the bendix shot?

[Boatyarddog]

Originally Posted by doog

Yes the damper or balance plate is new, just changed that and it was worn but the new one made little difference in operation or sound. And the starter was indeed the source of the zipping gear noise, not the oil pump and its been doing this all along.

Its an aftermarket starter and the previous one also failed dropping a part into the flywheel and causing me to have to pull the engine and remove the flywheel to fix, and I got a free replacement. But this one, too, hung up somehow and didnt retract and now that its out I can see the copper bushing is melted and this was ths singing I heard on my last engine run. So im not sure I want to replace with this same starter again. It doesnt seem to fit properly as the clearance issue mentioned.

Now I can turn the engine over and check for any knocks that might indicate a spun rod bearing which I should feel at TDC or BDC as a tiny thud in the otherwise totally (should be) smooth rotation. Anyway this was clearly the cause of that crazy gnashing sound and Im just glad I didnt end up with my flywheel destroyed and needing replaced.

Thanks much for the helpful comments!

Glad that worked out for you.
As I've mentioned in other posts, it's always important to work from the easiest to most difficult solutions.
Took me years to figure that out.
Once I did, my repair success rate climbed.
4-108s are really robust.
Thank you for helping us out and communicating so well.
Boatyarddog

[doog]

Originally Posted by Finalee

Wow that's a great outcome. Amazing it continued to start the motor. Was the bendix shot?

Yes, Im having a happy dance, as you might imagine. Good on all counts, The engine seems fine! Just an issue re the starter which I think I said was a Smith's but its a Wilson. They make racing stuff and do good work but the last time it failed it was the bendix which dropped a part into the flywheel causing sudden stoppage of the engine. So I had to remove and did a thorough clean-out of the bell housing, replaced the flex disk, which was needed anyway. And Wilson replaced the starter on warrantee terms. And no, the bendix is okay this time, but the bushing melted when the bendix jammed and held the gear engaged. And it's always had a funny chatter on starting as well. This is a gear drive starter and spinning the gear does not spin the starter motor, it has a one-way clutch. (not sure just how it works) But this was clearly the cause of my gnashing sound!
Anyway it finally retracted as I was turning the engine but clearly this was the whine that I heard on the last run. Melted the copper bushing which I was afraid was the alternator, it smelled very electrical fire hot...And I was assuming it was a low battery issue causing it not to start again but clearly this is why it stopped spinning the motor after my last run where I recorded the sound.

Anyway this round is on me! I feel very fortunate right now!

[Boatyarddog]

Originally Posted by doog

Yes, Im having a happy dance, as you might imagine. Good on all counts, The engine seems fine! Just an issue re the starter which I think I said was a Smith's but its a Wilson. They make racing stuff and do good work but the last time it failed it was the bendix which dropped a part into the flywheel causing sudden stoppage of the engine. So I had to remove and did a thorough clean-out of the bell housing, replaced the flex disk, which was needed anyway. And Wilson replaced the starter on warrantee terms. And no, the bendix is okay this time, but the bushing melted when the bendix jammed and held the gear engaged. And it's always had a funny chatter on starting as well. This is a gear drive starter and spinning the gear does not spin the starter motor, it has a one-way clutch. (not sure just how it works) But this was clearly the cause of my gnashing sound!
Anyway it finally retracted as I was turning the engine but clearly this was the whine that I heard on the last run. Melted the copper bushing which I was afraid was the alternator, it smelled very electrical fire hot...And I was assuming it was a low battery issue causing it not to start again but clearly this is why it stopped spinning the motor after my last run where I recorded the sound.

Anyway this round is on me! I feel very fortunate right now!

It is possible your starter install did not line up just right.
There are spacers involved, and need to "register" properly to not bind the gear.
Install carefully.
BYD

[clakiep]

If You are open to random amateur guesses : sounds to me clearly like a cluttering loose chain. If its not the camshaft drive...some gearboxes use chains for reverse, ZF's for instance.
Maybe they they clutter even or only if just turning and not engaged ? Good luck.

Capt. Claus - ocean tramp of the eighties