Cat 973 fuel injector pump - no fuel

[Welder Dave]

I've worked with a few guys that take all the overtime they can get. Their plan is to make enough money they can retire at around 55 and do the things they always wanted to. The problem is their body isn't up to doing all the things they wanted to do in their 20's and 30's and/or they have health issues. It's nice to have a good job you like and still have time off to do some of the things you want. If you're lucky you'll get a long term job with a few weeks vacation every year and a pension to boot. My partner has been in healthcare for 42 years and her pension was maxed out a couple years ago. She's still working cause she likes her job but buying lots of RRSP's so she isn't taxed to death. She even put some RRSP's in my name. She also has so many holiday days they have to pay her out for some of them. They'd be lost if she took a month or more off on vacation. She's the staffing resources coordinator and very good at her job. There are so many jobs to fill in healthcare it's very stressful for the staffing office. She's the one that sets up all the interviews and does the pre screening of all new hires. With covid it's even more hectic. The facility she works at is getting a multi-million dollar expansion. She might be retired by the time it is finished.

 

[Cmark]

Cmart: Thanks for your thoughts and advice on various issues. Wish I could write such concise and easily understood descriptions. Are you a mechanic or a novelist ?

Thank you for that. I was encouraged to read from an early age. I left school at age 16 having been taught the same basics of grammar that everyone else was. Apart from that, I'm a pure autodidact.

Cmart: Thanks greatly for ideas for freeing up the rack and plungers. That advice alone is worth $100+ an hour for your keyboard time. I reckon you could make a good living as a Cat consultant. Is the rack accessible thru the drive gear on the front of the pump ? Can I give the rack a tap at the front after just removing the pump drive gear cover ?

I'm pretty sure you have to remove the pump from the engine to access the end of the rack.

Still wondering what sort of rack travel I can expect ? Is it about the same as the expected travel of the stem of the governor servo valve ? 1 to 1½” ?

I haven't been able to find a figure for rack travel on your "new scroll" pump. However, on the early scroll pump in my pictures the rack travel is approx. 0.800". I would be surprised if yours wasn't similar.

 

[Len220]

I haven't been able to find a figure for rack travel on your "new scroll" pump. However, on the early scroll pump in my pictures the rack travel is approx. 0.800". I would be surprised if yours wasn't similar.

That's helpful.
When I took the rear governor housing off, I was able to grab the end of the governor servo valve and give it a tug. it only moved a ¼" as if it had that much free play. I wondered whether I was putting force directly on the rack by pulling/pushing on the valve. Considering that the valve's main function is to open and closes ports, which allows oil to either side of the piston, the piston being directly connected to the rack, made me think that the valve may not be physically linked to the rack and therefore only have to move that ¼".
Then in the manual I read about adjusting the FRC and hooking the sleeve to compress the spring over the valve stem, which it says moves the rack so you can insert the rack positioning tool in the side of pump (under the pump timing access cover). This while the engine is not running. Also the end of the valve stem has to contact the lever (4W-5735), lever (B) in my photos, in a few scenarios. When the valve stem is all the way rearwards, in the situation of maximum fuel, so the FRC can limit travel if required AND all the way forward, in the situation of fuel cut-off. This range of movement on the face of the lever is 19mm (just measured). So now I'm thinking the servo valve stem physically rests against the servo piston (so that when the rack moves rearwards, pulled by the piston, the valve stem is also pushed rearward ? Or even physically linked together ? I can't tell from the schematics and cross sections.

In any case, the 19mm ... guess what ... approx. 0.8"

 

[Len220]

Another ½ day on the Cat 973

How do you get the pump elements out if the rack is stuck out of centre you ask?
A fair question, and one that in recent weeks has been much on my mind.

There's a couple of strategies.
First thing to try is to remove the bonnets from the pump elements. They are held onto the barrel with a spring steel clip. With a bit of brute force you can yank them out. This lets you see the top of the plunger. With the follower on the heel of the cam you then punch the plunger down, turn the cam to push it back up again and repeat until, hopefully, the plunger frees itself.

If that doesn't work you have to dismantle the pump so you have access to both ends of the rack and then hammer it into position.

Another ½ day on the Cat 973

Accessed the rack at the pump timing access cover. Had to take the battery out and get my head right down low to see it. The slot in the rack was at the very front of the window (cf the photo below).

Got a big screw driver in there and tried to lever the rack rearwards. Also gave the screwdriver shaft a few solid hits to see if I could jar the rack backwards. Got a few mm of movement. Tapped it forwards, with a few light taps with a hammer on the end of the governor servo valve. After a couple cycles of this, there was less movement in the rack. Next time, I’ll take the cover off over the drive gear and see if I can access the end of the rack from the front and give it a whack.

If not, I’ll be yanking the bonnets out as Cmart suggested. Forgot to check what thread was on the bonnets, so I can make up a screw-on puller to mount onto the top of the bonnets. Anyone ?

Also what is the best way to remove the bush that sit above the bonnets ? The D & A manual shows removing with a special tool, but not how they are held in place. Only when I read later, “Tighten the bushing to 140 ft.lbs” do I assume they are screwed in. Cmart, a closer view of the pump you are working on shows a thread at the top of the barrel. I'm guess the Cat tool has a hollow centre to sit over the bonnet and perhaps an external hex to engage the bushing. While degreasing and flushing the top of the pump with some diesel, I didn't notice any detail like that ? Same when I had the injector pipes off the top of the pump the other day. Just look like a tight cylinder of metal around the bonnet ?

If I yank the bonnets out, I assume I will destroy the clip (7W-1927 RING-RETAINER) that holds the bonnet and pump barrel together ?

When I yank the bonnets out of the top of the pump, what stops the pump barrel being pulled off the top of the plunger, leaving the plunger behind ?

Further reading and I found the rack travel figure - “Correct rack travel is 15.7 mm (.618 in)”. D & A manual, first point on p.26.

 

[Cmark]

You need to get used to the idea of buying the special tools because you aint getting it fixed without them. The part numbers are 8T5287 and 8S2244. The retainer has internal splines which engage with the 8T5287. 8S2244 screws onto the bonnet and acts as a support. You also use it as the handle to remove the pump elements or rive the bonnets off. As required.

I'll preempt your next question. What if the internal splines are rusted out?
Good question. You will have to weld a nut onto the retainer.

Yes you will destroy the clip.

The plunger will be held into the barrel by three things. A mild interference fit between the return spring and the barrel, an interference fit between the return spring and the plunger retainer, and rust.

There is a locating pin (mentioned earlier) which lines up with a slot in the quadrant for assembly purposes. This needs to be lined up again for removal and is the reason the pump element can't be removed with the rack in any old position. If the plunger wasn't rusted to the barrel, I suppose you could pull the barrel off the spring and leave the plunger behind but this would mean pulling on the quadrant against the pin. The pin is tiny and if you break it off then you're in a whole new world of trouble.

 

[Len220]

You need to get used to the idea of buying the special tools because you aint getting it fixed without them. The part numbers are 8T5287 and 8S2244. The retainer has internal splines which engage with the 8T5287. 8S2244 screws onto the bonnet and acts as a support. You also use it as the handle to remove the pump elements or rive the bonnets off. .....

Thanks very much. That picture of the Cat tool (8T-5287), alone, tells me so much - “picture worth a thousand words”. I know if you haven’t got the image handy on your computer it’s a rigmarole to post it in the forum. Thanks for your effort. And yes, I “aint getting it fixed without them”.

My service manual states 8S4163, but cross references to your P. No. If I had been more proactive I should have Googled that P No. and viewed a picture of the Cat tool.

Doubt whether the internal splines are rusted off the retaining bush. Climate out here isn’t as corrosive as for you poor buggers on the coast (assumption). Anyway, I now know what to do if they are gone.

In what way does tool 8S-2244 act as a support when screwed onto the bonnet ?

Yeah, I noted in the manual, the locating pin in the bore of the pump housing for locating the plunger gear teeth (and the dowel for locating the barrel). When I try to “rive” a bonnet out of the pump housing, what chance the barrel and plunger also comes out and breaks the locating pin ? AND without the pin, if the assembler was sure the gear keyed into the rack in the correct position, can the pump operate without the pin ?

New word “rive” … my education continues. I thought it was a typo, initially, then I looked it up.

Is there a kit that has all these pump special tools ?

Do you recommend a source for Cat spare parts ? My closest Cat dealer is Westrac in Dubbo. I’ve had a very helpful interaction with a young fella there, recently, regarding schematics for the hand pump to release the brakes, and many months ago regarding lubricants. Yep, this is my first Cat machine. More familiar with TD24s, very early TD9s, and more recently worked on a BTD8 (82 series).






Didn't have the heart to tell my father (now in his 90s) that I had painted his little dozer "Old Cat Yellow".

He has been an IH person all his life ... often broaching how the TD24s out performed and were more productive than the contemporary D8. Actually, I think they were D8H, 10 years younger. Bit heavier and more powerful, but they could NOT pull as well under load in a turn. I loved those 2 little leavers between my legs while Cat drivers had to pull steering clutch levers and stamp on brake pedals (from memory ?).

I’d like your (and Nige's) thoughts why I was able to start the engine 2 years ago, after sitting 10-15 years, but have these problems now ? The first time, it did go straight to high idle and the Governor control lever had no effect. Implies the rack may have been stuck, but was Ok when I re-started and weeks later.

 

[thepumpguysc]

The bonnet removal tool is a MUST HAVE.. u aren’t getting them loose without it..
The other tool is a waste of 80.00 if u ask me..
I did a 3208 on the engine for a customer awhile back.. I didn’t have the bonnet tool, and told him so.. he wanted me to do the job so he offered to buy it..
I said, Sure, if your willing to buy the tool, I’ll fix your pump..
He went to the cat dealer and they sold him BOTH those tools.
I never took the installation tool out of the package.. & he took it back.
OH, your going to need an air impact gun to loosen the bonnets..
Trying to loosen them by hand is a no-no..
Each plunger and barrel assembly has a SHIM under each one..
MAKE SURE they stay in their respective cylinders.!!!

 

[Len220]

The bonnet removal tool is a MUST HAVE.. u aren’t getting them loose without it..
The other tool is a waste of 80.00 if u ask me..
I did a 3208 on the engine for a customer awhile back.. I didn’t have the bonnet tool, and told him so.. he wanted me to do the job so he offered to buy it..
I said, Sure, if your willing to buy the tool, I’ll fix your pump..
He went to the cat dealer and they sold him BOTH those tools.
I never took the installation tool out of the package.. & he took it back.
OH, your going to need an air impact gun to loosen the bonnets..
Trying to loosen them by hand is a no-no..
Each plunger and barrel assembly has a SHIM under each one..
MAKE SURE they stay in their respective cylinders.!!!

The service manual says the spacers (shim) are the same size for each FI pump. Also there is an O-ring between them and the bonnet. For the stroke length of the plunger to be fixed, I assume the O-ring is NOT pinched between the spacer and bonnet, but sits adjacent.
However I'm a bit OCD about putting components back exactly where they came from, even bolt locations. You never know if someone has previously stretch a bolt or thread past its elastic limit.
Have a couple cordless impact drivers up to 1500 ft.lbs !

Bonnet tool - I'll need a good grip on the bonnet to "rive" it out (thanks Cmart). I'll be acquiring one. How'd you get hold of the bonnets to extract ? Fingers ? Pair of pliers ?

 

[thepumpguysc]

That’s what the other tool is for but I just wiggle it out..w my fingers.
The oring goes under the bonnet.

 

[Cmark]

In what way does tool 8S-2244 act as a support when screwed onto the bonnet ?

I have to disagree with thepumpguy. The two tools are a close sliding fit together. It prevents the extractor from rocking over and potentially damaging the splines when you're giving it the beanz trying to break the retainer loose.

AND without the pin, if the assembler was sure the gear keyed into the rack in the correct position, can the pump operate without the pin ?

Yes, AFAIK it will run without the pin. The problem is how can you be sure you have it in right. I don't think there is a documented procedure for checking rack travel to confirm it's installed correctly, unlike the "early scroll" pump.

Is there a kit that has all these pump special tools ?

I don't know. If there is, the cost will make your eyes water.

Do you recommend a source for Cat spare parts ? My closest Cat dealer is Westrac in Dubbo.

Plenty of choices for aftermarket. Closest to you will be Don Clark Tractors. Also Tillys of Toowoomba, RD Williams in Brisbane, and others.

OH, your going to need an air impact gun to loosen the bonnets.Trying to loosen them by hand is a no-no..

Again, respectfully disagree. As long as the pump is securely fastened to something (like an engine), you have less chance of collateral damage using hand tools.

Each plunger and barrel assembly has a SHIM under each one..
MAKE SURE they stay in their respective cylinders.!!!

Yes!

The service manual says the spacers (shim) are the same size for each FI pump. Also there is an O-ring between them and the bonnet.

The shims alter the timing of each individual pump and are selective. The O ring goes between the bonnet and the threaded retainer. The other internal seals are all metal-to-metal. As with all fuel system components, cleanliness is vital. If there is any doubt about the mating surfaces I will give the spacers a rub on a flat plate covered with 1200 grit paper just to be sure.

 

[Len220]

Somebody must have too much money or there were major problems with the machine. That's an expensive chunk of iron to be basically abandoned. How many hours does it show?

Just realised I hadn't answered your query while deleting notification E-mails.
Machine Hours - Don't remember the figure, but I recall thinking unremarkable. The machines has been sitting for maybe 15 years. That makes it 15 years younger, wear wise, however the exterior has been knocked about. If it came from a landfill site, it must have had an intermediate life knocking down scrub or timber.
Also the electrics are in a mess and I doubt the hour meter would run. Don't know whether that was the case when it was last running. I've had to restore electrical circuits. Fuse holders in a mess, caps missing. There was no power to the start switch and I wasn't able to locate the original wiring to and from the start switch fuse. Had to make up new wiring. I wondered whether it was a bit of sabotage by someone who coveted the machine and hoped to make a low offer ? Both water hoses to the cab heater were cut - I joined them with a ⅝" double ended brass barb.

 

[Len220]

I have to disagree with thepumpguy. The two tools are a close sliding fit together. It prevents the extractor from rocking over and potentially damaging the splines when you're giving it the beanz trying to break the retainer loose.

Good enough for me. Don't like it when a socket or spanner tips off a fastner.

Yes, AFAIK it will run without the pin. The problem is how can you be sure you have it in right. I don't think there is a documented procedure for checking rack travel to confirm it's installed correctly, unlike the "early scroll" pump.

Is the gearing so fine that you couldn't judge that the slot in the plunger gear was going down the bore close to where it should be ? No experience here, just my own perception from the service manual pictures. The manual mentions a Rack Positioning Tool to measure rack travel. "A smaller measurement is an induction of incorrect FIP installation".
I guess if it was that easy they wouldn't have designed that pin in the pump. Can't be an easy manufacture. I also get it that if 1 tooth off, the motor could race, or maybe even worse ... one cylinder is getting max. fuel while the others are being governed at a lesser fuel volume. Trying to think what that would do to a motor ?

I don't know. If there is, the cost will make your eyes water.

Looks like I'll accumulate these Cat tools from aftermarket, eBay, etc. The pump bush (8T5287) is quite cheap O/S (<$10) but shipping takes it up to $40-60. Quite a few other tools required to set the pump and tune. I'll work my way through that maze as I go. I'll be looking for advice, which ones can be fabricated and which are better purchased. 5P4814 - Collet and 6V2014 - Bracket Assembly, comes to mind.

Plenty of choices for aftermarket. Closest to you will be Don Clark Tractors. Also Tillys of Toowoomba, RD Williams in Brisbane, and others.

Thanks. I'll be making some 'phone calls.

Again, respectfully disagree. As long as the pump is securely fastened to something (like an engine), you have less chance of collateral damage using hand tools.

Convinces me to bring the machine home to take the injector pump assemblies out, rather than remove the pump.

The shims alter the timing of each individual pump and are selective. The O ring goes between the bonnet and the threaded retainer. The other internal seals are all metal-to-metal. As with all fuel system components, cleanliness is vital. If there is any doubt about the mating surfaces I will give the spacers a rub on a flat plate covered with 1200 grit paper just to be sure.

Interesting that the D & A manual says the "Spacers are the same thickness for each fuel injection pump so they can be mixed." However I'll be cautious as per my early post.

 

[Len220]

I don't know. If there is, the cost will make your eyes water.

My eyes are watering. 6V–4157 Transmission Test Group ≈ $3,000

 

[Cmark]

If you get one element off by one tooth then the issue will be obvious on startup and you can just shut it down. If you are unlucky enough to get three or four elements wrong in the fuel-on direction, then you may find yourself in a runaway situation and have to block off the air intake.

Interesting that the D & A manual says the "Spacers are the same thickness for each fuel injection pump so they can be mixed."

Oh. I may be wrong on that then. My apologies. I will have to review it and get back to you.

 

[Cmark]

Yep, sure enough it looks like the "new scroll" pump doesn't call for the individual pumps to be timed with selective spacers. Unlike the "old scroll" pump.


This is the only reference I can find that infers that the spacers on the "new scroll" pump have to be installed in their original position.

 

[Len220]

Plenty of choices for aftermarket. Closest to you will be Don Clark Tractors. Also Tillys of Toowoomba, RD Williams in Brisbane, and others.

Ordered 8T5287 - bush wrench and 8S2244 - bonnet extractor, today from DCT, Castlereagh. Not much more than ½ price of the main Cat dealer ... about $75 posted.

From this picture found on the Internet, it's apparent from the machined face, that the pump must come off the front gear housing to access the front of the rack. (Cmart right again)


I'd rather spend an hour tapping the rack back and forwards then riving out the bonnets. The rack has a tiny bit of movement, so I suspect there is a plunger(s) stuck. Let's hope I can jar them loose, so I can position the rack in the centre and remove the bonnets & plungers the normal way.

 

[Welder Dave]

Does the K not work on your computer? Cmark not Cmart. He has a wealth of knowledge that is sure nice when you need it.

 

[Len220]

Does the K not work on your computer? Cmark not Cmart. He has a wealth of knowledge that is sure nice when you need it.

Thanks for bringing that to my attention. You think you've read something accurately, then continue the error. Can't call it a typo ... keys too far apart. Oh well, least I didn't use Kmart.

 

[Bluox]

Ordered 8T5287 - bush wrench and 8S2244 - bonnet extractor, today from DCT, Castlereagh. Not much more than ½ price of the main Cat dealer ... about $75 posted.

From this picture found on the Internet, it's apparent from the machined face, that the pump must come off the front gear housing to access the front of the rack. (Cmart right again)
View attachment 241449

I'd rather spend an hour tapping the rack back and forwards then riving out the bonnets. The rack has a tiny bit of movement, so I suspect there is a plunger(s) stuck. Let's hope I can jar them loose, so I can position the rack in the centre and remove the bonnets & plungers the normal way.

You can build yourself a tool to help pull the pumps if they are stuck.
Take a fuel line nut and weld a 3 or 4" t-handle on it, a 1/4 bolt is about right.
Good luck
Bob

 

[Nige]

My eyes are watering. 6V–4157 Transmission Test Group ≈ $3,000

They will water even more when you discover 6V-4157 is only the box with the gauges in it. There is another number (could be 6V-4158 but don’t quote me) that contains all the test hoses and couplings, adapters, pressure taps, etc, required to actually connect the test box to a machine. Last time I looked that group was about half the price of a test box. I think it’s called something like a “hose & fittings group”.