Cat 17A fuel issue

[Old Magnet]

The correct injection pump originally was a 4H5238 with current replacement a 8M3137 also supplied under 7F6042, 8F2590, 8M3277 and 8M3280 part numbers.
Rack setting is 0.375".

 

[56wrench]

on the injection pump/plunger for the original bad cylinder, did you check for a stuck delivery(check) valve?

 

[hdsbc]

so here is my finding so far first picture is psi on cylinder #1 it actually was more like 325psi but by the time i ran all the way back to the house got the camera and took the picture it leaked down to what you see in the picture at 310psi. the reason for the leak is i didn't; have any thread sealant on my custom adaptor and left it for like 5 minutes so it probably was not the cylinder leaking just my joint.

Picture #2 is of Cylinder #2 the "dead Cylinder" in question it was the same psi as #1 325psi. I am not going to do cylinder 3 and 4 because its a pain since there behind the turbo i have a chance of damaging all the new gaskets i installed last year in the kit and # 3 and 4 are running fine.

will post fuel pressure #'s as the batteries charge.

 

[hdsbc]

so all 4 existing piston pump caps were 4f5019 I still had the original box from last year the new piston and cap is a 8m3280. I tried to do a fuel pressure test no go i think since i am using a long line as an adaptor is not making any pressure i will have to get a super short double female swivel made tomorrow at the parts store i think, to do it.

where do i do this Rack setting is 0.375"?

"on the injection pump/plunger for the original bad cylinder, did you check for a stuck delivery(check) valve?"
where is this check valve you speak of from what i see its a common fuel port that supplies all pistons from a 1/4 tube in the top of the pump casting.

 

[hdsbc]

 

[hdsbc]

 

[Old Magnet]

My Fuel Injection Testing Manual does not show a 4F5019 for a 5-3/4" bore.
Is it a 10mm diameter plunger?
Fuel is supplied from a common chamber within the injection pump housing.
There is a check valve built in to the individual pumps. (attached)
Pumps are designed to give a specific volume at various rack positions (0.375") would be maximum opening travel of the rack quadrant for the late 17A.

 

[hdsbc]

so i measured the old piston it is 0.3935 = 9.9949 mm so i am sure it is a 10mm piston and cap because am am sure after 60+ years of use its has a little play

 

[Old Magnet]

I'm suspect of the hose in your testing arrangement. When properly tested all connections should be rigid fittings. Even steel line is eliminated on the test apparatus but that is not absolutely required in the field.
Capsule unseating pressure range is 300 to 800 psi. Under 300 psi should be discarded.
As far as pump pressure, they are considered a positive displacement pump and could build pressure to destruction.
On the test stand pumps are run checked at 125 and 600 rpm.
Normal cranking speed on fully charge batteries is about 250 to 300 rpm so at half engine speed for the pump you should get close to meaningful readings.

 

[hdsbc]

so my findings for today are good and bad. I put everything back together today since i can't do a injection pump test i figured if the engine was rotating with the starter i should watch for pop at the injector out side of the head and low and behold finely excellent spray pattern on #2 injector, it was magic. I don't know what happened threw all the troubleshooting but it is working as it was intended. My best guess is the lifter had to be sticking and not returning fast enough to do its job properly at higher rpm ( engine running), and i come to this conclusion because after swapping all of #2 components to #3. #3 did not go dead.

Now as for the bad news it is still not fixed it still is only running on 3 cylinders of power and if i can find a way to post the 1 min video of it running you will most defiantly concur. so I did a leak down test, now i have never done one before. ( if I did something wrong please inform me so i can learn thank you)

so made a special tool will some old gauges and fittings watch a you tube video and off I was. started at cylinder #1 to get a base line. brought cylinder #1 up to TC on the compression stoke and put 30psi in found out after 20psi it moves the crank so consulted the video and changed to 10 psi like they were doing. the cylinder it failed every bit of air was coming out the exhaust turbo. so not a good sign defiantly have a valve seat problem in #1.

Next off to #2 do the same thing TC on compression 10 psi and total fail every bit of air i could hear moving around in the crank case. So definitively i have bad rings or a untrue liner.

Now i have fixed the injection pump problem definitively can say i have proper pop pressure on #2 and since all the other cylinders are firing they have to be good also. I can move on from that knowing its solved but my real question to everyone is why can i have perfectly fine compression in both cylinders both fail a leak down test and 1 will still operate fine?

All in all i very appreciative for all you good folk helping me out on this project and i really mean that, especially you old magnet for taking the time to answer a young guys questions. I know what my next steps are now tomorrow i will be ordering a new head gasket, probably 2 cylinder liners 2 sets of rings and 2 rod bearings and doing at least a lap job on the valve train in my near future. if i am going to open it up again do it all so it can move dirt for another 30 years.

 

[Old Magnet]

Well, your making good progress...but we never did get what you are calling perfectly good compression. So what exactly did you get? Even on the ragged edge these old buggers will run.
Better add at least one piston to your parts list and a closer look at rod/bearing #2.
I meant to post a procedure for leak down testing.I know I have it but I'll be damned if I can find it. Will look some more but in general I think you got the drift.

 

[hdsbc]

i had to make a a you tube account to upload the video this forum won't allow videos. so as they say "a picture is worth a thousand words" so a video has to be a million.

Got to youtube.com and in the search bar copy and paste
?v=Pp9F7djs3HE for the misfire video
?v=wf2V_wfYfyI for the blow by video

 

[hdsbc]

by perfectly fine compression i meant it was 325psi for both #1 and 2 from what i read it should be 275- 400 Psi and mostdefinatly within 10% of each other

 

[Old Magnet]

I'll check you video but before I forget, be sure to check liner projection on all cylinders when you next have the heads off.

 

[Old Magnet]

Those compression numbers are way to low, it's a wonder your making auto ignition compression temperature.
For that engine you should be in the 445-486 psi when cranking.
490 -530 psi at idle run speed. Anything below about 365 psi leads to combustion and starting problems.

Finally found the leak down procedure.... You've got one tired engine....
https://ch-part.com/i.caterpillar/gmg006940001/

My bad on your pressure readings. At first I couldn't tell if you were reading compression or fuel injector pressure.

 

[Puffie40]

Since you plan to take the head off, take a good look at the valves. Chances are they would love some refurbishing as well.

 

[Tinkerer]

 

[56wrench]

in my opinion, may be worn out rings, stuck rings or broken rings. if excessive starting fluid is used on an engine with loose rings(ring lands worn out) it can cause ring breakage. could also be a combination of issues and valve problems, but my money is on a piston/ring/cylinder problem

 

[hdsbc]

today i had a few hours to tear down the motor again. Both heads are off this time this project turned into a new top end project.
My findings are not good. #2 is the worst cylinder out of the bunch next is #1 and #3 and 4 are not terrible.

#2 the top 1inch of the liner is shot with deep pitting in the liner and lots of heat damage to the top of the piston deep popcorn like cavities i have seen this before in a lean burndown condition scenario before so I assume that #2 was starved for fuel and burnt everything up inside. and that would confirm my injection pump problems. so in the long run i think it paid off repairing the pump problem on this damaged motor before i rebuilt any internals.

#1 shows similar signs of were just not as bad. and a wet consistency on top of the piston and in the exhaust port correlates with the leak down test that exhaust valve seat is bad in that cylinder

#3 and 4 look the best and defiantly were doing most of the work with a nice dry burn over the entire piston top and no damage( so far).

tomorrow's job will include pulling all the liners and inspecting for more damage. My current plan is to get gasket kit, 2 full cylinder rebuild kits for # 1 and 2 witch consist of piston wrist pin liner and rings, if #3 and 4 pistons is ok get a ring and liner kit for them cylinders, 4 new big end connecting rod bearings ( might as well replace just to say its done ) and defiantly lap all the valves and replace ones as need be. if there is any other parts or things i am forgetting please chime in I don't want to miss something on my order because shipping to Canada from the U.S is terrible

 

[Old Magnet]

#2 & 3 piston may look ok but if the top compression ring land is worn out of spec the only choice is to cut a wider groove and use a wider ring or replace the piston.
Might as well do all four while your in there anyway.