# Checking compression



## 5pntslw (Sep 20, 2018)

Hey everyone! So I have a 1958 Ford 861 Diesel tractor and I want to check the compression on it. I pulled one of the injector lines off the head to pull an injector but I have NO clue HOW or even IF they can be removed... this is the only picture I currently have if you need another tell me what and I will get it to help out. I am a mechanic for a living but this is my first old diesel I've ever had the privilege to work on haha. Thanks for any help! It is appreciated!


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## Guest (Sep 22, 2018)

Did you get your service manual yet? In lieu of that, I recommend you hold tight until one of the diesel guys can advise you. I do know the compression on a diesel is MUCH higher than on a gas engine and requires a totally different pressure gauge setup.


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## 5pntslw (Sep 20, 2018)

No unfortunately still waiting on my manuals to come in the mail. Yeah they do, I have the tools to be able do ALMOST anything I want lol i just cant seem to figure this one out yet haha


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## RC Wells (Dec 26, 2008)

Take a look at the engine and fuel system here: https://partstore.agriculture.newholland.com/us/parts-search.html#epc::mr62720ag21519

The parts diagrams will point you in the right direction, and once you have the repair manual you will be ready to go.


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## thepumpguysc (Jan 25, 2015)

May I suggest removing the RETURN LINE from the injection pump top cover & trying to start it.. THAT pump sits "down" into a drive, normally they're horizontal.. so your top cover is actually to the left.. its the "long cover" w/ 3 screws.. just pull the hose & remove any fitting on the top cover & try to start it..
YOU HAVE TO HAVE a GOOD battery.. A diesel starts from heat build up in the cylinders.. you have to get it spinning fast enough for the fuel to ignite.


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## thepumpguysc (Jan 25, 2015)

The injectors are in the head under the valve cover.. you can see how they're connected in the Ford link.. Its VERY COMMON for the connection to leak & get fuel in the oil.. so BE CAREFUL w/ that.. get the appropriate orings & seals..
A diesel will only start w/ around 300 psi of compression.. a GAS compr. tester will explode at those pressures.. U will also need a compression adaptor to go down into the hole.. Its not like a gas motor where u can hold the gauge in the hole.. u need all sorts of special tools.. or RENT them.??


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## Guest (Sep 22, 2018)

Just to let you know again, I'm out of my comfort zone here. But, I just checked my IT shop manual (its for my 2000) and it has no compression check procedure, only what compression should test at. I recalled overnight that my test procedure was included with my compression gauge test kit. With my gas engine, it instructed that I disconnect air intake hose at the closest point to the engine (at the carburetor for my gas engine) and fully open the throttle (probably not applicable to your diesel). Gathering info from other posts, I recall that the injectors can be hard to break free and that they are torqued in.


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## 5pntslw (Sep 20, 2018)

Thanks for the info guys! Looks like I'm gonna have to find the adapter for my guage to check the compression. But since I'm gonna have to pull the valve cover it might be a couple/few weeks to get the time to dig into it that far haha.


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## Guest (Sep 24, 2018)

That's the way things work here......everything costs 2 x what I thought and takes 5 times as long!


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## thepumpguysc (Jan 25, 2015)

WHY are u chasing compression?? THATS kinda the last resort.. simply because it requires a lot of work & special tools the "home owner" doesn't have..
Does it start w/ ether? is the injection pump even pumping?? have u tried to bleed the air from the system?? We need some "background"..


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## thepumpguysc (Jan 25, 2015)

Most Auto Zone stores rent tools.. just take an injector with you to match up..
You just have to leave a deposit & when u bring it back, the rental is free..


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## 5pntslw (Sep 20, 2018)

I wanted to check compression because it will only start if I spray it and while it is running it smokes more then I feel is a normal amount. The injection pump has been bleed but it is also leaking externally at the gaskets but not bad just enough that you see it is wet. I've fixed the wiring so now the glow plugs work etc. It has a 12v conversion and it does crank at a decent speed and I feel it should start without a problem with that crank speed. While it is running it runs great just smokes and wont start without giving it spray


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## RC Wells (Dec 26, 2008)

This is where more information turned out to be critical.

If the injection pump is leaking, it will be pulling air into the injection pump and make the tractor very hard to start without ether. Microscopic air being sucked into the fuel as it runs will interfere with the injector fuel pattern, and cause incomplete combustion and excessive smoke, usually blue tinted.

Testing compression looking for the cause of smoke when the injection pump is leaking is, in my opinion, premature.

I recommend the obvious fuel pump leakage problem be corrected, then the tractor worked reasonably hard with new engine oil, and then assess the smoking once the engine is fully warm and been run under load.

If the engine remains hard to start and has excessive smoke after the injection system is repaired, then it would be time for a compression test.

Low compression on these diesels usually leads to white tinted smoke when the injection system is sound.


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## 5pntslw (Sep 20, 2018)

RC Wells said:


> This is where more information turned out to be critical.
> 
> If the injection pump is leaking, it will be pulling air into the injection pump and make the tractor very hard to start without ether. Microscopic air being sucked into the fuel as it runs will interfere with the injector fuel pattern, and cause incomplete combustion and excessive smoke, usually tinted.


It is blue tinted and smells like unburned fuel.. hopefully I get the repair manual in the mail soon! I've rebuilt truck injection pumps in the past I hear/read to reseal these is fairly simple with a manual. Anyone on here ever rebuilt/resealed a DBG Roosa Master pump that could confirm? I found a kit for around $30 I believe it's the Stanadyne 24371 kit


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## Guest (Sep 24, 2018)

IDK about RCWells, but I would bet ThePumpGuy will be chiming in.


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## 5pntslw (Sep 20, 2018)

This is my pump... it looks like the leak is coming from maybe a cover on the right side and the big cover on the left


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## thepumpguysc (Jan 25, 2015)

The 24371 kit is correct BUT.. that pump is SO OLD that they discontinued the orings to reseal the advance block in the kit & u have to buy them separate. The advance block is the piece to the right in the pic.. it has an oring on the bottom & 2 orings for the caps.
You'll need a book to rebuild that pump.. There is a hidden glass check ball & spring under 1 of the screws.


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## 5pntslw (Sep 20, 2018)

thepumpguysc said:


> The 24371 kit is correct BUT.. that pump is SO OLD that they discontinued the orings to reseal the advance block in the kit & u have to buy them separate. The advance block is the piece to the right in the pic.. it has an oring on the bottom & 2 orings for the caps.
> You'll need a book to rebuild that pump.. There is a hidden glass check ball & spring under 1 of the screws.


Ok so I got a chance this evening to clean the pump up REALLY good so i can see where any leaks are coming from. I found the one i knew of (the return line flare is damaged) and i found that it is also leaking around the back side from the throttle linkage assembly. So I guess I'm gonna have to remove the pump to regardless to replace those seals?


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## thepumpguysc (Jan 25, 2015)

Yeah, it looks like theres no room to pull the throttle shaft.. The pump removal is simple.. It would probably be smart to time it before u pull it..
Shut off the fuel, remove the side cover.. its gonna be full of fuel so have a pan ready.
Under the cover you'll see a stationary line, rotate the pump until another line lines up w/ the stationary one & stop.. Then the rest is self explanatory.


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## 5pntslw (Sep 20, 2018)

Ok cool thank you thepumpguysc I'll order the kit and get that taken care of sooner then later


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## thepumpguysc (Jan 25, 2015)

I just re-read my post.. I MEANT.. rotate the ENGINE until the other line comes up..
NOT THE PUMP.. sorry..


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## 5pntslw (Sep 20, 2018)

thepumpguysc said:


> I just re-read my post.. I MEANT.. rotate the ENGINE until the other line comes up..
> NOT THE PUMP.. sorry..


Haha not a problem I knew what you meant.


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