https://youtu.be/HSAcN2LSqsY

Knock does not start until the engine is up to temp ~80C.

in the video you can slighly hear it at the 6:00 mark and pick up from there. Its at full knock around 10:49.

Thoughts? At this point I suspect a wrist pin, but would love some second opinions. I had to order a compression gauge so I don't have any readings to give yet.

edit: No oil in the water, and no water in the oil.

It sounds metallic, so I'm guessing a lifter.

__________________
1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

Time for the length of wood dowel on your ear trick

__________________
1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD

Very definitely a mechanical knock of some sort. The camera gives no presentation of where the sound comes from, but at the end where you look at the engine end on, it seems loudest in the video. Have you checked the vacuum pump?

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

I did get out the stethoscope and listen all over the block/head/injectors but the only time I heard a tick out of the ordinary was next to block drain plug.
Kind of leaning toward the injectors. When I ran the diesel purge through it, it didn't knock. But since it didn't really get up to temp I figured it was temperature related. And it sorta is. Here is what I just ran.
Gatorade bottle as my source of fuel with return and supply hose in it.

1/8 Diesel Clean - 7/8 Diesel = Reduced knock but still very noticeable.
Stopped it and topped off the bottle with Diesel Clean so about 30-40% diesel Clean
It ran without any knocking until the bottle got low. I then filled it 2 more times with about 30-40% Diesel Clean each time. And the knocking was practically gone for that entire 30-40 min of running. Temps @ the head were 190F/88C (may need to look at a lower fan switch). I could every now and then barely start to hear the knock, but I noticed if I grounded the fan switch and held it, the very slight knock would stop after about 20 seconds of running the fan. Could I have some sort of pre-detonation issue related to a injector? and lowering the temp helps cure it?

So the plan for tomorrow is to pull the injectors and have them rebuilt this week. I'll update next weekend. Keep the ideas rolling. Cause if that knock turns out to be injectors I'll be shocked. But I sure hope that's all it is.

loosen the injector lines one by one and see if the noise goes away. if it is an injector, the noise should stop when that injector line is cracked open. om617 does not have hydraulic lifters so shouldn't be that.

__________________
1985 Mercedes 300D bought for $400 work in progress. Video Playlist: https://www.youtube.com/playlist?list=PLeYmvdiw3Xm87mFck3FjQ12ZoTSFXZ0Rr

Ooops, 617 have solid lifters, dunno why i think every engine is OM603

__________________
1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

Since I had the injectors off I had them tested and they all tested like new. If your around Conroe TX consider this a plug for Diesel Fuel Injection Repair. Mechanical diesels only.

compression test. was not able to warm it up first. Temp in garage = 58F

Front to back
305
325
290
345
360

#3 was the slowest to build pressure, and was also the lowest. Its injector heat shield was also stuck a bit. I pulled the other heat shields out with a dental pick, but that one I had to get out my heavier duty pick to pull it loose.

Draining oil and looking for metal tomorrow :-( May be a drunk cry in my beer thanksgiving for me. If I don't find any metal, then I may just reassemble it and try again.

Do a Valve Adjustment and see if that helps.

Note that the Vacuum Pump can make a ticking sound before it falls apart. Use that wood or mechanics stethoscope to locate where the sound is coming from as other said.

Also the Air Filter Housing Bracket is noted for breaking or the rubber buffers failing.

__________________
84 300D, 82 Volvo 244Gl Diesel

There is no valve lifters. One end of the Rocker Arm rides on the Camshaft.

__________________
84 300D, 82 Volvo 244Gl Diesel

dumb question.. have you poured water over the belts to see if the noise changes?

I have had belts make some pretty scary noises before.. almost seemed louder to me at the end of the video by the front of the engine.

I'm noticing a big delay in deceleration when you let go of the throttle linkage. Maybe your video isn't quite synced up with your audio. If it is, I suspect a valve problem or lift pump.

Running on diesel clean killing the knock means it's not a rod, you're free and clear there.

Definitely kill injectors one by one and see if you can localize the knock to one or two cylinders.

If your injection timing is good, injectors are good, valves adjusted properly + reasonable compression, and cam timing is good, and lift pump is good(supplying proper pressure to your IP)................

Have you driven it? Does the noise go away above a very certain throttle setting? Do you have to drive it in kind of a binary manner to avoid the noise, either on or off?

I don't want to beat the delivery valve seals drum too hard just because that's what my issue turned out to be, but man I chased a similar noise around my engine for two years. I fixed all that stuff above(which should be done anyway), but replacing the delivery valve seals solved the issue. Wish I had known back then, five bucks in parts and well under an hour to do the job would have saved me so many headaches. Other threads here on the forum lead me to believe that this is a fairly common problem.

So yeah, throwing it out there. Nice clean swap, looking forward to seeing it drive.

__________________
617 swapped Toyota Pickup, 22-24 MPG, 50k miles on swap