The internal lubrication of the delivery valves is diesel fuel, other components use engine oil.


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In the context of this thread, will cranking the engine to do a compression test while the fuel inlet to the lift pump is disconnected damage the delivery valves?

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I just used a Mighty-Mite type vacuum pump on the stop valve. Just a few pumps is enough (~10" vacuum?). That lets you test the stop valve at the same time.

I also have the Harbor Freight Diesel Compression set (~$20), and it works fine. You probably aren't latching the coupler right. It is just a standard air-tool quick-connect. Insure you push it in fully and pull the collar forward, if the spring doesn't.

On a virgin NEW injection pump, not enough to matter.

On a used injection pump of unknown history, (the issue is not common) it has happened to me.

My point is why take unnecessary risk.

Loosening the steel line nuts on all of the injectors, will prevent:
* Unwanted fuel entering the cylinder during testing.
* Excess wasted labor.
* Potential damage.

There will be minor external fuel drooling, to be cleaned later.

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Yep it's popping off at the quick coupler. It is a different quick coupler than the one used for the glow plugs, so I'm guessing it is the quick coupler that is causing the problem. I definitely have it fastened as solidly as it will go ... I tried several times, but each time it would pop off. I think maybe I could rent a tester from Pep Boys and see if it works any better.
Injector pics ... the oil was all over the tips. Some of it was fuel (those droplets on the cardboard were partly fuel that dripped out):

__________________
1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)

There is only one quick coupler (the brass thing at the hose with a spring loaded collar). The part that goes on the injector adapter is a fitting. Check the shape of that fitting compared to the ones for the glow plugs to see if it is different. Also check the quick coupler o-ring to make sure it has not unseated itself. If it has, lube it with some oil then pop it back in. Also lube the collar with light oil to make it work smoother.

There shouldn't be oil on injectors in a good running engine. What you have maybe fuel from your compression test with the fuel not shut off completely + soot which together look like oil. One way to find out is put the injectors back in, run the engine till fully hot and take the injectors out. They should be dry with just a thin layer of soot.

While your injectors are out, might as well get them pop tested for opening pressure and spray pattern and correct it if there are problems before putting them back in. Don't forget new sealing washers (heat shields) every time an injector is R&R'ed. You gotta plan what to do when pulling injectors and do as much as possible and not use up too many sets of heat shields which add up and gets expensive.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Ah, I was using the wrong terminology. I think it's the fitting that's bad (but it is the quick coupler that's popping off). I'll inspect the fittings and the inside of the coupler.
The engine was fully hot before I took the injectors out. After the first test attempt, I put the GPs back in, started it up and drove it around the neighborhood until full temp. Then I removed the lines and injectors. So something must be amiss ... I guess that should not surprise me by now. I will take them to my mechanic and see if he can pop test (or recommend a shop to do it). I do have one set of heat shields I planned to install after the compression test, but now I need another set if I want to try the compression test again.
At the moment my project for the day is removing the mouse that has ended up in my home office ... fun ...

__________________
1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)

Update: I took the injectors to show my mechanic. He could not find his pop tester ... he said he never uses it anymore because he finds it more cost/time-effective to replace the injector than rebuild it. He did not think the oil on the body of my injectors was a concern, but that the fuel leaking from the nozzles was. His advice was get remanufactured ones, install them with new heat sheilds, forget about the compression test for now and see how it goes. I.e., if it runs smoother, the problem was the leaking injectors. He had a set of injectors in his store room he said he could give me for a good price but when we checked the numbers, they were for a 602.
I have to admit I'm kind of confused by what injectors to buy or not buy, even though there have been a ton of threads on it. The dealer searched for remanufactured and new ... the former showed none in stock and the latter showed 15 in Germany. But, the ones listed as new in Germany also said "remanufactured" under them. I've heard mixed reviews on the Bosch remanufactured units, but I've also read a couple posts saying the ones from the dealer are a safe bet? My indy also thought the Bosch units from the dealer were the best route. I know I could try to rebuild them myself with Bosios or Monarks, but I don't have a shop to balance them, and I don't have a ton of time. I.e., IF the Bosch units from the dealer are dependable, I'd rather go that route, but if they're going to be off-balance or stream I guess I have to come up with a different plan.
I kind of hijacked my own thread ...

__________________
1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)

He can't find his pop tester and don't use it anymore? See if you can buy it from him cheap! It'd be a cool tool for you to have.

If you send me your injectors I can pop test them for you. I can shoot video of the pattern. I can also rebuild them if needed (if you supply the nozzles).

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Unfortunately, he couldn't find it. I suppose I could mention to him that I'm interested in it if it ever turns up.
If I send them up for pop-testing and possible rebuild, how long would that probably take? I suppose I'm not in any huge hurry, but just curious as I weigh my options.

__________________
1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)

You should be able to find a local shop to check your injectors. Do a search for "diesel injection". Ask them if you can see it while they pop test them. If there are none by you, I can pop test them in a day or 2. Rebuild in about a week if you supply the nozzles.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked