General 617 Questions

[BradenFinney]

Hey. I've just purchased a 1983 300 Turbo Diesel. I bought it with the intention of dropping my running and functional 240D engine into the good frame of this new car.

Before I do that, I wanted to see the extent of work needed on the 617 engine. I was told that it needed piston rings. Before I pronounce the engine alive or dead, I first wanted to get a status check on what all I may be missing from the engine bay.

The first image shows my engine. The battery is undersized, the air intake system is disconnected, the egr is disconnected, the cooling system is in pieces, and the fuel system is disconnected. I believe I have all the parts, though. Can anyone see anything odd from this bad overall picture?

In the second picture, I go through parts that were included in the car. Looks like I have old fuel return line, a new "spool" of return line, a handmade repair for the vacuum diverter in the brake booster feed line, the original (broken diverter) booster line, and fuel injectors. For the injectors, one zip lock has 5 (315's) which I presume are the ones last in the car. There are three other 315's and one 345. Are the 315's original to the specs of the car? Are the unknown cores I have good for anything?

The third picture is an assortment of coolant hoses, vacuum lines, etc. My thermostat housing has two sensors that I am not sure where their plugs are in the car. One sensor/switch has a male connection and the other looks like its either a female plug or missing two wires coming from it. What are the purposes of these switches/sensors, was this the original housing to my car, and where should I look for the wires at?. Also in this picture is a small black gizmo that looks like a washer fluid pump not meant for this car? Additionally, anything I should be looking at w/r/t the ignition switch? The one in the car does not spring back when its turned to the "crank" position. Additionally, it is generally cranky to turn. I presume the new switch was meant to replace this but I don't have any supporting evidence.

Image four has bracketry that I'm unsure of. I think I've found the right spot for the black bar as being part of the throttle linkage shenanigans. What are the two other brackets? I think one may be a turbo heat shield?

Image five has the air cleaner. I think I'm missing a section to connect the top of the valve cover breather to the top of the housing. I've got the oil seperator inside of the cleaner. Where does the discharge of this cleaner go to? I think there's a hole somewhere down near the turbo inlet for this line?

[BradenFinney]

From picture one, What connects to the rear end of the turbo? Looks like its probably a vacuum line?

Picture two shows the fuel injection side. I think all of these hard lines mostly match what the car came with. The original 5th is disconnected from the others and I have an additional two other hard lines. Anything special with these hard lines other than if they fits they sits?

Lastly, in picture three, I assume the "hole" on all cylinders around the prechamber is normal? Looks like this may be how the prechambers are keyed into the head? I noticed not all of the locking collars are oriented in the same direction, so I imagine that if this engine ever runs again I may need some tightening with these guys...

Thanks for any and all help you all can provide!

[shadetreemechan]

From your second post, picture one is the boost sensor that goes to an overboost valve on the firewall next to the brake booster. Hard lines look fine and prechambers too.
I would do a valve adjustment and then a compression test on it since the injectors are already out. That will tell you what you have without trying to figure out how to reassemble it from the get go.

[BradenFinney]

Originally Posted by shadetreemechan

From your second post, picture one is the boost sensor that goes to an overboost valve on the firewall next to the brake booster. Hard lines look fine and prechambers too.
I would do a valve adjustment and then a compression test on it since the injectors are already out. That will tell you what you have without trying to figure out how to reassemble it from the get go.

Gotcha, thanks for that info! I think my engine picture shows a small black line coming from a doodad near the brake booster. I assume that's the boost valve. I'll confirm tomorrow.

I agree on the compression test. Will need to get a kit and some feeler gauges for the valve adjustment. Just didn't want to get too excited and realize I was missing substantial engine components. Glass half empty type I guess lol!

[SonnyMorrow]

I second the above post, doesn't seem like many parts are missing if any at all. So you should totally check the compression and if the compression is low or not evenly distributed then you know the seller was correct in saying that the rings are shot.

Usually, the only reason these engines get retired is when they burn so much oil or lose so much oil that one of the main bearings dies and the engine is toast (given a few thousand miles it will lock up). If you get some okay compression readings I still wouldn't put all your eggs into one basket until you can confirm that the engine runs without any knocking. In my experience, people often try to pass these cars on when there is a rod knock of some sort.

Just make sure to have a very strong battery that is meant for a diesel engine when testing the compression. Then reassemble the engine get her running and see how she runs and if there are any concerning noises.

[shadetreemechan]

Just make sure you do the valve adjustment! Tight valves can make a fine engine look shot.

[BillGrissom]

Agreed. If the compression is >350 psig in all cylinders, don't pull the head. Around 400 psig is "like new". The engine should run at least another 200K miles. If <300 psig, it may not have long. My 1985 engine was showing 250 psig in all and needing a block heater to start on 40 F mornings. Within a year it seized at 330K miles. Teardown found chunks missing at several piston ring grooves, scored cylinders in a few, and something round left marks from bouncing around in cyl 1.

[vwnate1]

Cool ! .

Don't rush, do all the little things mentioned in the proper order .

I used the Harbor Freight Diesel compression tester, it's crude but does the job well .

[BillGrissom]

Originally Posted by vwnate1

... I used the Harbor Freight Diesel compression tester, it's crude but does the job well .

I own it too and find it suitably designed, and has proper fittings for my OM617.952 engine. I've only used it thru the injector holes when the injectors were out for refurb. I also have a pop-tester I fabb'ed. A couple things to note, for all compression testers:

They must replace exactly the same volume of the part removed to give a valid absolute reading. This is especially true in a diesel since half the TDC air volume as a gas engine. If using the small glow-plug hole, this is less critical. In gas engines, they often don't spec absolute readings, but rather just variation between cylinders, though <100 psig would be bad regardless. I think this is because the cranking pressure can depend on the camshaft installed, particularly racing cams with much overlap between intake and exhaust valves. In a diesel, you care most about absolute reading.

Another critical thing is that the tiny check-valve is at the very tip of the fittings, to avoid the volume of air in the tubing. Testers use a Schrader valve as the check-valve, but a special one with a very weak spring. Most I've seen have a white plastic seal to distinguish. You can buy replacements at specialty auto tool shops (ebay today?). I have a package from long ago. If you replace w/ a regular one from a bicycle or car, the stronger spring will give more pressure drop and falsely low reading.

[vwnate1]

Just so Bill ;

I remember when any F.L.P.S. stocked those white Schrader valves, the tiny pin that stocks out if ever so easy to get bent in your tool box...

For me, the most important thing is relatively equal compression .

I've had a few OM617's that had decidedly less than 300 P.S.I. yet I was able to make them start easily and run very well with minimal oil leakage .

Once my 240D's #1 exhaust valve began to 'tulip' I had barely 200# and it ran fine but didn't fire at all at idle .

All this goes to show that unless you like to tinker or are rich, German cars are not for you .

[BradenFinney]

Well I've got these valves adjusted. First time doing a valve adjustment of any kind. My first valve I was too scared I was doing something wrong because I could only spin the entire valve retainer and spring assembly in circles. Once I took a break and came back, things went much more smoothly. The main trick was really talking out loud on what I was trying to accomplish and which wrench to hold versus which one to break (and what direction) to get my adjustments done.

From radiator to windshield, these are the values I had. I got them all adjusted to spec (0.004 and 0.012) and triple checked them all before calling that good enough.

E I I E E I I E E I
0.002 0.004 0.003 0.016 0.012 0.002 0.014 0.014 0.003

Cylinder 3 intake had a super loose valve. All others seemed reasonably decent.

I am now ready to do my compression test. Since the engine can't run right now, it's going to be a cold test. Should I remove the glow plug relay to not energize the glow plugs? I am doing an injector test. If I want all things to be equal, I should be doing as much as possible to keep the battery charge up and engine conditions identical, correct?

[BradenFinney]

Well, it looks like I've gotten to the point where the previous owner left of.

With a brand new H8 (900CCA) fully charged battery, a disconnected glow plug relay (pulled the cord to the plugs), and all fuel injectors removed, I get 0 PSIG across all 5 cylinders. I am not overly tightening the test plug in the hole. I would think that I should get any value even if my plug was too loose. When cranking, there is sufficient pressure to blow out all my injector hole napkins. There is enough pressure to bobble the needle on the tester gauge. The gauge never climbs, though.

I would think bad gauge if the PO hadn't had the problem I am seeing right now. The engine is holding oil, so I very much don't think I lost a piece of something out the engine. The oil is pretty tainted (haven't changed it yet, probably a mix of oil, diesel, and whatever lubricants PO originally put in the engine to try and increase compression). The water jacket is pretty rusty as well as the water pump discharge hose. I could suppose there to be a head gasket issue, though I don't really have any clear evidence of that. My only other clue right now is a failing starter? When I first tried to crank the engine, the start spun freely without engaging the flywheel. It took me a few rounds before it engaged. Once engaged, it proceeded to blow out the napkins so I would think that that is sufficient turning speed? I haven't dropped anything down the throat of the prechamber yet to try and lubricate the piston rings. Looking for advice on what to try next.

The engine turned over quite well by hand the ~4 revolutions I made adjusting the valves.

[BradenFinney]

Originally Posted by BillGrissom

I own it too and find it suitably designed, and has proper fittings for my OM617.952 engine. I've only used it thru the injector holes when the injectors were out for refurb. I also have a pop-tester I fabb'ed. A couple things to note, for all compression testers:

They must replace exactly the same volume of the part removed to give a valid absolute reading. This is especially true in a diesel since half the TDC air volume as a gas engine. If using the small glow-plug hole, this is less critical. In gas engines, they often don't spec absolute readings, but rather just variation between cylinders, though <100 psig would be bad regardless. I think this is because the cranking pressure can depend on the camshaft installed, particularly racing cams with much overlap between intake and exhaust valves. In a diesel, you care most about absolute reading.

Another critical thing is that the tiny check-valve is at the very tip of the fittings, to avoid the volume of air in the tubing. Testers use a Schrader valve as the check-valve, but a special one with a very weak spring. Most I've seen have a white plastic seal to distinguish. You can buy replacements at specialty auto tool shops (ebay today?). I have a package from long ago. If you replace w/ a regular one from a bicycle or car, the stronger spring will give more pressure drop and falsely low reading.

Took apart my "https://www.harborfreight.com/diesel-compression-tester-set-63726.html" tester. No check valve to be found at either side of the 90. Can't really tell from the quick connect fitting, but I don't think there will be one there. Any guru advice for getting one installed? I doubt any hardware store near me will have a random check valve...

[vwnate1]

I was wondering because you said the gauge 'bobbled' ~ it must not do this ~ with each compression stroke the needle should raise up a bit more, keep cranking until the needle stops rising .

I have no idea where to buy the correct WHITE BANDED Schrader valve but yes, I'd try Harbor Freight first, then maybe your local NAPA store...

[BradenFinney]

I appreciate the input! I'm going to have to find an entire check assembly. I don't see any way for a Schrader to fit period inside of the default contraption.