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  #16  
Old 01-17-2022, 07:48 AM
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Which of the Hong Kong Freight testers did you buy? Unless you bought the diesel one you just wasted your money. The standard ones claim to read up to 300 P.S.I. but that is a B.S. claim. A diesel engine will blow them up in a heartbeat.


(https://www.harborfreight.com/diesel-compression-tester-set-63726.html)



The HF testers are good for comparative tests only. I've never found one to be anywhere accurate to within 80% of the true reading.

Just my personal experience, YMMV.

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  #17  
Old 01-17-2022, 08:29 PM
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Quote:
Originally Posted by Mike D View Post
Which of the Hong Kong Freight testers did you buy? Unless you bought the diesel one you just wasted your money. The standard ones claim to read up to 300 P.S.I. but that is a B.S. claim. A diesel engine will blow them up in a heartbeat.


(https://www.harborfreight.com/diesel-compression-tester-set-63726.html)



The HF testers are good for comparative tests only. I've never found one to be anywhere accurate to within 80% of the true reading.

Just my personal experience, YMMV.
Bought this one. Now on a quest to get an inline check valve rigged up... Compression test only for comparison, yes. Looking for some sort of ballpark metric to pronounce the engine viable or not.
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  #18  
Old 01-18-2022, 12:05 AM
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Post Compression Test Evauation

Remember : this is a new to you engine so make it run and adjust everything on it you can then RUN IT as often the compression will rise as a dormant engine comes back to life .

As much as I love my 240D, they're slow and a nice OM617 will provide more driving enjoyment .
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1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

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  #19  
Old 01-18-2022, 12:33 AM
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Quote:
Originally Posted by vwnate1 View Post
Remember : this is a new to you engine so make it run and adjust everything on it you can then RUN IT as often the compression will rise as a dormant engine comes back to life .

As much as I love my 240D, they're slow and a nice OM617 will provide more driving enjoyment .
All good advice. I loved my 240 and then I was an ass and wrecked it. Really do miss driving it. Rode great, ran 80 mph just fine down the highway. Best case scenario (I think) at this point is get this 617 viable and then swap as many parts as make sense from the 240...

That being said, if the 617 is viable... I would be tempted to find another donor body for the 240 and get 2 running and driving cars
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  #20  
Old 01-18-2022, 10:58 AM
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Wink My Free Advice

...Is based on 50 + years of experience with mostly older vehicles .

Of course one should always triple check against other ideas but few will ever put the hard and long miles on older vehicles like I do ~ I especially love long distance driving to remote places so how it runs is more important than how it looks to me .

If it isn't fun why bother ? .
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1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better
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  #21  
Old 01-22-2022, 03:33 PM
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Where to go next?

Well good news and expected (bad) news. My brand new compression tester had no check valve and was giving erroneous results. https://www.harborfreight.com/diesel-compression-tester-set-63726.html

I was able to find an inline check that was a thread-in-and play solution. Just add pipe dope.
https://www.grainger.com/product/GRAINGER-APPROVED-Check-Valve-4DHR7

I wasn't too crazy about eliminating all air leaks. With the check valve connected and the quick connect fitting off, the gauge leaks down very slowly (could be leaking from the one fitting I did not remove from factory or where the rubber hose meets the metal threads). With the quick connect on, the injector side fitting screwed a little more than finger tight (with an old heat shield installed), the unit leaks down quicker than before. Probably leaking from the same points as before, but the higher pressure causes the leak to be faster. I video taped my gauge since I was doing this solo from the ignition to get my max value.

With the glow plugs disconnected, all injector holes open (sans the one getting tested) the following results were obtained:

100 psi, 200, 200, 220, 260 Dry compression. It was about 38F outside, battery was fresh, engine was definitely stone cold.

Added 5ml of some ATF I had laying around (ATF to penetrate some as well as provide general lubrication) down each prechamber. Spun the engine over for 10 seconds or so with all injector holes open. Repeated compression test over and got the following:

180,280,290,300,300.

So... The good news is the engine has some sort of compression. The bad news is that cylinder 1 (the one closest to the radiator) is hurting. And all 5 cylinders definitely appear to have worn rings since all saw a ~80 psi increase. The question now is which direction should I proceed. I have read that just running the engine (with fresh oil) can help to revitalize bad numbers. Is 180 psi enough compression at face value to allow the cylinder to even fire?

In order for me to try and crank the engine over, I would need to rebuild all 5 injectors. The previous owner said he tested them and they were not to spec. Is it worth it to get 5 decent injectors (I have 13 injectors to play with) and try and get this engine running? My original purpose behind the car was to drop my 616 from my wrecked 240 into it. So I guess even if the 617 is "dead" I still haven't lost. Problem is I'm now kind of fond of the 617 engine and want to give it a fighting chance.
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  #22  
Old 01-22-2022, 10:34 PM
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Thumbs up Don't Stop Now !

Send those injectors off to Greezer and install them, get the car running, then fix the brakes and drive it, get a feeling for it as you sort out the various things .
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1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better
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  #23  
Old 01-22-2022, 11:15 PM
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Quote:
Originally Posted by vwnate1 View Post
Send those injectors off to Greezer and install them, get the car running, then fix the brakes and drive it, get a feeling for it as you sort out the various things .
Looks like he just rebuilds (demo's, cleans, maybe shims?) with existing nozzles? I can't imagine he supplies new nozzles for the listed price I see on his website. I'd probably be more inclined to buy a pop tester and DIY.

Definitely want to get the engine to run... Just nervous about being out $170 on nozzles, $90 on pop tester, xxx on fluids if the compression numbers obtained seem to indicate imminent issues even having a "driving" car.
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  #24  
Old 01-22-2022, 11:24 PM
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Thumbs up Fair Question

You should ask him .

I know from my own trying that getting a full set of injectors to all pop at within 5 P.S.I. of each other isn't going to happen the first several times you try it .

The smoothness and increased power and fuel economy won me over the first set I tried .

They've been in my 204D for years now and still no smoke .

I understand the need for economy here but the quality is more important than the original output of $ .
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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better
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  #25  
Old 01-22-2022, 11:35 PM
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Quote:
Originally Posted by vwnate1 View Post
You should ask him .

I know from my own trying that getting a full set of injectors to all pop at within 5 P.S.I. of each other isn't going to happen the first several times you try it .

The smoothness and increased power and fuel economy won me over the first set I tried .

They've been in my 204D for years now and still no smoke .

I understand the need for economy here but the quality is more important than the original output of $ .
Solid point. I'm all for optimization... getting all the seasoning right if the base is solid. Seems like (after doing a leak down test for the heck of it), I just need to "risk" it and see if the engine will resurrect itself without too much hassle. Then beat it/treat it until it kablooeys and do the engine swap.

Good news is my 240D engine (aside from running and driving) has had no work done on it... So its injectors most likely need work. Thereby justifying a pop tester if I want to continue down the road of driving one of these old hunks of metal.
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  #26  
Old 01-23-2022, 12:46 AM
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Home Pop Testing

I bought a junk homemade pop tester from a member here, then I bought the exact copy of the original BOSCH pop tester from India and it's been trouble free and works well .

When I ordered it I asked for a larger liquid filled gauge that has more precise on it, they gladly provided .

I dropped it and broke the clear plastic resivoir and they sold me a new piece cheaply and quickly .

Most of the folks I know who tried bottle jack pop testers had problems with them over time .

I think a home pop tester make$ good sense but I wasn't god at home adjusting and neither were the nice guys here who invited me to their homes to show me how simple it is to pop test and adjust .

One made injectors match within 10# for my '78 NA 300CD, sadly he didn't quite grasp why tiny fire hose squirts of Diesel fuel isn't a good thing, certainly my car started easily down to 40* F and didn't smoke but...
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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better
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  #27  
Old 01-27-2022, 12:02 AM
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I was under the same discovery after a poor purchase on an 82 300cd , one cylinder with poor compression . Theirs 3 things you can try , the 1 mentioned with trying to get it started and driving it is great if it will bring a start . The second is soak the cylinder with 6 oz of marvel mystery oil for a week on that one weak cylinder and see if you can find any new improved numbers . Don’t forget to purge out the marvel with turning the motor over . Carbon around the ring area is why this may work . Third may seem far fetched but it will work on a poor compression numbers motor , one cylinder is the same issue I had . It’s rislone compression repair , it’s a very thick additive . I wasn’t sure what would happened on this old motor , wasn’t expecting it to work and yet it was running and ran for 2 yrs . Search hear for the thread which I wrote about the whole ordeal by searching rislone .
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  #28  
Old 01-27-2022, 08:28 AM
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It seems wise to me (if it will start) to drive it for awhile. Like several weeks or more. Then see if it performs reasonably well. You may find that you need to do nothing at all.
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  #29  
Old 01-27-2022, 12:26 PM
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Got me wondering. My HF diesel tester is Model 93644 and has less fittings than shown in link. I know it has a check valve since you must press the relief valve to vent the collected pressure. It is likely inside the 90 deg fitting at the end of the gage hose, but can't see it. It may not be a Schraeder valve like on my gas compression tester. Those you can see since threaded into the end with the stem almost protruding. A poor-man's test is the turn the engine over by hand and feel for each cylinder resisting you like an air-spring, over 2 crank rev's (chalk mark crank pulley). I use the nut on the power steering pulley (22 mm wrench recall). If you must wait several seconds for each cylinder to hiss-down, you have excellent compression regardless of what the tester says (many ways to mess up the test).

Re valve adjustment. It is tricky to tighten the jam nut in my OM617.952 without the adjustment nut rotating. Might be easier if used the proper bent wrenches, but I manage to work between the injector tubes. After tightening, re-check the gap since it might have changed. The trick is to hold the adjustment-nut wrench fixed while turning the jam-nut wrench, but still can take a few tries.

Re pop-testing, I think people get hung-up too on getting exact pop-pressure. First time I tested by 1984 300D, I found that 2 of the 5 injectors were lower pressure (1600 psig pop) for a non-turbo engine, rather than the correct 1950 pop pressure, and marked thus on the side (bar units). I swapped in a set of 5 turbo injectors from my failed 1985 engine, but didn't notice the engine ran any different. I think more important is to verify spray pattern. That is tough visually and subjective. Try judging how the spray hits the liquid surface in the collection jar. I've thought of making a video recorder or better, since I did academic research in liquid sprays long ago and made such instruments. My pop-tester is made from a Porta-power type of long hydraulic pump cylinder, rather than a bottle-jack. I bought it on ebay ($80 I recall), made for testing Ford Euro diesel components. Ones I've seen that look similar cost $750. Besides a liquid-filled gage, I use an electronic pressure sensor, so record a trace to post-test analyze closely the peak pressures as it pops like a machine-gun (if you press the handle correctly). I have another pop-tester in-work, based on an Italian hand pump which you bolt to a table. If similarly rolling-your-own, the trick part is a metric fitting that mates to a M-B injection tube, I bought at McMaster-Carr (<$10), along with other steel fittings (don't use brass). PN's have been posted here many times.
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  #30  
Old 08-01-2022, 09:17 PM
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Well... Many months later, the engine on the 300 lives! Exciting business. I've got to reinstall the shroud and fan and then let it idle for a while and truly evaluate how it runs... but so far I'm optimistic!

Questions: Do injector body halves ever seal themselves without external effort? Or injector to prechamber connections? I've got one of each leaking.

Also, how warm should an alternator be compared to the rest of the engine? Mine seemed warmer than ideal and I only read 12.5 or 13 volts depending on when I measured. Alt was said to be good by parts store... But its trying to feed an AGM which may be too much?


Copying my random notes for the fun of it:

Wiper bottle pump gasket replacement
Engine vacuum system repairs (Epoxied brake booster hose using reducer. May present vacuum quantity issues)
Replaced 5 glow plugs w/ Bosch
Repaired glow plug harness with dodgy solder job. Evaluate for heat issues
Replaced battery with AGM
Degreased + Cleaned Engine
Switch over line replumbing + banjo bolt cleaning
Thermostat housing pitting repair (JB weld + copious sanding)
Thermostat replacement
New Short Hose
Wastegate signal line replacement
Valve Adjustment
Linkage replacement (Throttle to pump and throttle to cruise control) and lubrication
EGR Delete (Block off plate + vacuum elimination). Still connected to exhaust for appearance sake
Alternator adjustment bolt re"die"ing and bracket adjustment. Consider replacing both belts w/ matched set
Rebuilt Starter (New solenoid, new throwout assembly, new brushes)
Replaced fuel strainer and fuel strainer hose
Rebuilt Injectors installed (firad nozzles)

Interior Removal (all seats and readily removalable carpet. Trunk linining)
Ignition Switch/Lock R/R (Replaced switch with donor unit. Screwed and epoxied steering lock to be permanently disabled. Column alignment pin will still work
Dash cluster removal
Clock Fix (Replaced both capacitors, had 2 100uF 16V units. One was tested open, one still good)
Dash Pot Fix (Contacts were nasty and corroded. Resistor coil still 100% intact. Cleaned and left in operation
Painted all gauge needles
Verified all cluster + climate control +interior bulbs work (except for cigarette)
Replaced tach cluster unit capacitors
Power mirror Revival (Cleaned internals and lubed. One motor weak and may go out)
Drivers mirror Revival (Cleaned and lubed)
Power Antenna repair (Cleaned, lubed. Last 4 inches of tail broken. Mast straightened. Won't be 100% perfect but good enough for now).
Central Lock Revival (Verified all units actuate and hold vacuum. Removed fuel door inop unit and bypassed)
Central Air Vacuum Check (Held Vacuum via green tube in engine w/ 0 inside components activated)
Vacuum Reservoir Check (Held Vacuum)
Hood Spring Reattaching
Fixed Center Console Light (Took light apart; added solder material to each "hub". Wheel is a little trigger happy now but all functions work. Have to be careful plugging back in because plug can push the circuit board off of the ground)
Lubed all four power windows and door latch assemblies (silicon spray)
Removed, cleaned, and new o-ring for fuel sender unit

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