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Cat 17A fuel issue

hdsbc

Active Member
Joined
Jul 3, 2020
Messages
37
Location
Ontario Canada
So its been a long time that i have been chasing down this fuel issue and i am utterly stumped at this point. first I will give you the specs. threw my research I believe its a 1960 model year Cat 17A D7 Turbo.
I bought the machine about 3 years ago and love it since day one strong like bull and dumb like one too ( nothing electric controlled). last summer, I had a sudden engine nock and loss of power and blew the dip stick clean out of the machine. I immediately shut her down and investigated. turns out I lost fuel pressure to #2 cylinder, dead cylinder. apon digging deeper I noticed the front half of the engine filling up with anti- freeze, I suspect when #2 went dead the compression had to go somewhere and it blew the dipstick out of the machine and across the yard about 15 feet and destroying the head gasket seal. Ok so simple fix I thought.

All new head set all new gaskets everywhere tore it all down and solved that problem, re-lashed the valve train put in a new push rod and lifter because someone's jimmy rig fix from years ago in my opinion was Ludacris, did regular maintance rebuilt all the hydraulic cylinders up front with brand new rods and seals what not and then it was off to the fuel system to fix the misfire.

Now this is where my Delma is I am at a loss I have replaced the injector nozzle and body, the line has no kinks or obstructions, I put a brand new piston pump on #2 high pressure pumps spot, the yoke was in spec so didn't change it, took apart the whole fuel system no contamination in the passage ports in the filter assembly transfer pump primary filter and both secondary filters are brand new, drained the entire fuel tank cleaned it no rust or dirt. played flip flop between a known firing cylinders injectors pump and injectors the problem always stays ay #2.

So with all that I figured it has to be the cam shaft or lifter. so I follow the book bring #2 up to compression at TC bought a brand new micrometer for measuring depth, set the lifter up to spec of 1.733 " from deck to yoke that dose not solve the problem do the same test to #1 cylinder the values are equal. so then I measure the lift at full rise thinking the cam lobe is worn down, nope it is exactly the same amount to lift as #1 so then I do the measurement to see if at TC the lift is right for that duration on the lobe matches exactly to known working cylinder #1.

When the engine is running it defiantly has a loud fuel nock and if you crack the injector lines will its running #1,3,4 all affect the engine idle negatively obviously bc its a no fuel scenario but when you crack #2 it dose not react like its running on only 3 cylinders of power currently.
When you take the fuel lines off the Piston pump caps you can watch a steady fuel stream like a guizzer shooting up about 6 inches on #1,3,4 but #2 barely will squirt 3" and at the injector tip it will only dribble fuel barely no atomization.

so now i am grasping at straws I get an idea maybe the lifter spring is broken and it works fine at slow speeds with the micrometer but as the RPM increases at engine running I get a "Valve Float" scenario like racecars at High RPM. causing my problems, so tonight I took the cam and lifters out of #2 and #1 no ware no scrapes nothing then springs feel identical resistance rollers are smooth the parts look brand new.

So to sum it all up everything on that cylinders fuel system is either replaced or in spec the cam is fine the lifter looks good it has the right amount of lift and duration, the piston pump is brand new and if you swap in old one it dose not change the line is clear the injector tip and body is new. and I still have a dead cylinder.

What could it possibly be left to investigate?
 

Coaldust

Senior Member
Joined
May 9, 2011
Messages
3,292
Location
North of the 60
Occupation
Cargo Tanks, ULSD, RUG, Methanol, LPG
You could swap #2 pump and capsule with #3 to double check. But, it probably has a low compression problem on #2. Maybe a bent rod from the previous failure? When it hydro-locked with water.
You could do a compression test or a leak down test. Use the old fuel capsule to make a custom adapter for your compression tester.

Guaranteed to find the issue.
 

Coaldust

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Cargo Tanks, ULSD, RUG, Methanol, LPG
You can check for a bent rod by measuring piston height a TDC and compare to #3 running mate.
 

Old Magnet

Senior Member
Joined
May 11, 2010
Messages
2,003
Location
Corralitos, California
Yes, start by moving #2 capsule then #2 pump to another cylinder to check operation.
Are you getting bubble free fuel flow when bleeding pumps and at the injectors?
 

hdsbc

Active Member
Joined
Jul 3, 2020
Messages
37
Location
Ontario Canada
ok so i have though about those scenario also, I did do a compression test in the cylinders last year to see if there was a bent rod or mechanical failure since yes it could have been hydro locked. I can't remember the exact psi but the values I do remember were within 10% from the problematic cylinder #2 to known working cylinder #3. I have played flip flop between all the cylinders cap pistons at this point now the problem always remains at cylinder #2 never moving the issue to another cylinder even with brand new cap and piston or used matched pair.

I didn't check for bent rod Hight compared to #3 but when I had the head off last year I also had the inspection covers off to check the cam and crank shaft areas there was no obvious bend in the rod by looking at it no when I ran my hand up in side didn't feel like it was bent but obviously your eye and hand is not very scientific.

lastly even if the root of my problem is the #2 cylinder has a engine failure of bent rod or something similar ( witch has not been fully ruled out as the main problem) it would not explain the poor fuel pressure always being a constant on #2 high pressure pump the High pressure pump and its fuel rack are completely independent of the engine its like its own motor in its own right.

I wouldn't say there is bubbles in the line i would describe it more like that it is erratic. To describe this as best as i can when the starter is turning over the engine #1,3,4 cylinders pump and cap create a steady stream of fuel jumping up to a Hight of 6" with the line to the injector removed where as #2 cylinders pump and cap with either a brand new or used pump and cap always produces a stop and start like of stream never rising more then 3".
 

thepumpguysc

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Mar 18, 2010
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7,445
Location
Sunny South Carolina
Occupation
Master Inj.Pump rebuilder
Always do your parts swapping w the FARTHEST away cyl. from your suspect cyl.
If it’s 2.. swap w 4.. NOT 1 or 3.
Just incase the problem has leeched to either cyl. beside it..
Is this injection pump the kind 1 that has single pump for each cyl.?? It sound like it..
Do u know that there is a TIMING SHIM below the pump.?? It’s possible that the shim stuck to the bottom of the old one and u didn’t notice it..?? It’s worth a glance..
I sure hope that’s ur problem..
 

Bluox

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Jun 19, 2010
Messages
1,960
Location
WA state
Always do your parts swapping w the FARTHEST away cyl. from your suspect cyl.
If it’s 2.. swap w 4.. NOT 1 or 3.
Just incase the problem has leeched to either cyl. beside it..
Is this injection pump the kind 1 that has single pump for each cyl.?? It sound like it..
Do u know that there is a TIMING SHIM below the pump.?? It’s possible that the shim stuck to the bottom of the old one and u didn’t notice it..?? It’s worth a glance..
I sure hope that’s ur problem..
These old pumps use an adjustable yoke to set pump stroke ,no shims.
Bob
 

hdsbc

Active Member
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Jul 3, 2020
Messages
37
Location
Ontario Canada
i have swapped piston cup 1, 3, 4 all on to the dead cylinder #2 never changes anything I just used #1 in my explanation because it is the easiest one to swap since #3, 4 are behind the turbo and are kind of a pain to remove unlike switching 1 and 2.
and yes this is a piston and yoke style old set up very simple adjustability is done with a set nut and a depth finding micrometer set to TC on that cylinders compression stroke measurement of 1.733 +- 4 thou
 

hdsbc

Active Member
Joined
Jul 3, 2020
Messages
37
Location
Ontario Canada
also today i made a custom engine compression tester and custom fuel pressure tester with and little machining and an old injectors. if it stops snowing tomorrow i am going to put the pump back together retime all the cylinders and do a compression test on all cylinders again and now a fuel pressure test on all cylinders just before the injector at line pressure then i will know the exact values for everything and cross the next bridge. Just wanna make this old girl move some dirt again on all 4 cylinders of power.
 

epirbalex

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Aug 5, 2017
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Akitio
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peasant
I can't see it being a fuel issue , blowing the dipstick out means it had a sudden rise in pressure in the crankcase , I would think it would be a piston failed . With a head off and the plate for the third cylinder removed to give access to the bigend you can check the conrod after removing the rod and piston . I have seen a hole in the side of one of these motors near big enough to put your head where a broken rod came out the side .
 

Coaldust

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I’m not convinced there is a problem with the #2 P&B or the capsule. I don’t think it possible to look at the squirt and quantitatively determine if it’s good or bad. The NOP is like 700 psi. The injection pressure is so low, the fuel doesn’t even really “atomize” on these antiques. The Op has done due diligence with the fuel system. I admire his persistent.

The blown head gasket didn’t send the dipstick to orbit. It’s got a piston/liner/ring issue. Let’s just do a leak down test and settle this. Let’s stop talking about it and be about it. Pidder Padder, let’s get at er’.
 

Puffie40

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Apr 5, 2010
Messages
208
Location
Southeastern B.C.
I can't see it being a fuel issue , blowing the dipstick out means it had a sudden rise in pressure in the crankcase , I would think it would be a piston failed . With a head off and the plate for the third cylinder removed to give access to the bigend you can check the conrod after removing the rod and piston . I have seen a hole in the side of one of these motors near big enough to put your head where a broken rod came out the side .

I’m not convinced there is a problem with the #2 P&B or the capsule. I don’t think it possible to look at the squirt and quantitatively determine if it’s good or bad. The NOP is like 700 psi. The injection pressure is so low, the fuel doesn’t even really “atomize” on these antiques. The Op has done due diligence with the fuel system. I admire his persistent.

The blown head gasket didn’t send the dipstick to orbit. It’s got a piston/liner/ring issue. Let’s just do a leak down test and settle this. Let’s stop talking about it and be about it. Pidder Padder, let’s get at er’.

If I understand hdsbc correctly, he had done a compression test, and #2 was within 10% of the others. He also had the head off, and a bad piston or liner would have been pretty obvious while the head was off.

We haven't heard what those compression test numbers were. That might help us determine if the cyilinders are tired.
 

TomA

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Aug 17, 2012
Messages
143
Location
Mariposa, CA
If it is direct start as a down and dirty compression test, you should hear a definite skip when it is turning over. A somewhat trained ear could hear/feel under pony start.

That business of the dipstick shooting across the yard is worrisome. Changing the head gasket is not going to fix whatever caused that.
 

epirbalex

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548
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Akitio
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peasant
If I understand hdsbc correctly, he had done a compression test, and #2 was within 10% of the others. He also had the head off, and a bad piston or liner would have been pretty obvious while the head was off.

We haven't heard what those compression test numbers were. That might help us determine if the cyilinders are tired.
The motor has serious blow by issues , if it could be called that firing a dip stick across a yard . Spending time and money on the fuel problem could be a waste . Can't say I've ever heard of a dip stick being fired out . Breather on the motor might need a clean out .
 

hdsbc

Active Member
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Jul 3, 2020
Messages
37
Location
Ontario Canada
to answer everyone's responses
1st: i have checked the yoke it was still 1 thou within the books spec of tolerance not much but still there plus i tried to purchases an new one and come up unable to find.

2ed: yes i aligned the mark on the rack to the piston's rack gear thought of that also one cylinder could have been advanced or retarded fuel. But no this is not the case each piston plunger has a mark on the 5th tooth counting from the left that mates with the governor long rack indicator mark.

3rd: lets forget about the engine problem for a moment. yes i know we have not ruled out definitively that there is not a bent connecting rod i get it but that dose not explain why i have a problem with #2 pump injector system. Today is a much nicer day i am going to reassemble the pump and do another compression test on the motor to get the exact values this year compared to last year since i can't not remember the numbers.

4th: i also will be doing a all cylinders fuel pressure test today made a custom adaptor yesterday to do so.

5th" where would i look for a internal crack on the pump housing i have the cam out now and the lifter the are no physical sings of damage and i measured each lobe lift of the cam they are all the exact same the cam looks brand new for being 60 + years of service and the lifters are the same length from the roller to the top but that dose not matter since its on adjustable threaded yoke anyhow.

6th: yes when the engine is running it sounds like a misfire and you can watch the smoke out the pipe poof poof miss poof over and over again and a auditable knock like a dead cylinder.

7th: i do not have the original pony start motor when i purchased the machine someone had already removed it and installed an electric starter.

8th: i know the motor had a problem yes the dipstick blew out but it only did it 1 time, since then the engine has run for about a hours time like this trying to diagnose problems and having mechanics stop by and give there personal input. but again since then i have take the head off checked the piston rings and cylinder liner for physical damage, had the inspection cover off the cam shaft area and replaced a lifter and push rod, had the cover off the bottom and and looked for damage to the rod and crank if there was a hole in the liner or block i most likely would have seen it by now and that cylinder would be seriously low on compression. the motor still turns over and runs fine every time i start it there is no anit-freeze in the front cylinders anymore it had to be a fluke scenario were #2 lost fuel because the pump failed over pressurized the cylinder blew the head gasket and that compression had to go somewhere strait past the rings into the crank case and shot the dipstick out. i know its worry some thing but i have to fix one thing at a time nonsense of trying to remedy 7 things at the same time or else your never going to find the root of the problem to begin with.

To sum up I have to get #2 injector pump working properly to the specs of the adjacent cylinders to definitively rule out fuel is not the issue. once i know this for sure no doubt then it will be time to do an engine overhaul. In my mind this machine is paid for what i have done with in 3 years and i will never get another one in this good of shape for the money i have into it so if have have to cross that bridge i will. to me saving something this old and easy to work on is worth keeping rather then turning to scrap metal.
 
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