# 1987 Ford 3910 diesel - rotary injector pump leak



## Harry-P (Aug 11, 2021)

Hi All,

Although I have read posts on this site for years, I am a new member, so thanks for hosting this great forum. My 1987 Ford 3910 3 cylinder diesel tractor has just developed a leak in the CAV rotary injector pump. The leak is on the underside, where the piston and housing assembly attaches to the pump body, just below the name tag. Is this assembly something that can be easily removed to replace the gasket, without removing the whole pump? Looking at the parts breakdown, it looks as though the whole unit is held in place with one nut on a stud. Are there any special precautions to take when removing this assembly? Thanks, Harry


----------



## pogobill (Jan 31, 2012)

Harry-P said:


> Hi All,
> 
> Although I have read posts on this site for years, I am a new member, so thanks for hosting this great forum. My 1987 Ford 3910 3 cylinder diesel tractor has just developed a leak in the CAV rotary injector pump. The leak is on the underside, where the piston and housing assembly attaches to the pump body, just below the name tag. Is this assembly something that can be easily removed to replace the gasket, without removing the whole pump? Looking at the parts breakdown, it looks as though the whole unit is held in place with one nut on a stud. Are there any special precautions to take when removing this assembly? Thanks, Harry
> View attachment 74080
> View attachment 74080


Welcome to the forum. I can't offer much advice, but there are plenty of knowledgeable members here that would be more than happy to help you out.


----------



## Harry-P (Aug 11, 2021)

pogobill said:


> Welcome to the forum. I can't offer much advice, but there are plenty of knowledgeable members here that would be more than happy to help you out.


Thanks, I know from my research on this site how helpful this forum is. It's great that people can share the knowledge and experience they've gotten over the years!


----------



## Hacke (Feb 22, 2011)

Are you absolutely sure about the location of the leak? The pump looks fairly wet all over. Clean the pump and when it is dry, look for leaks. Often the fuel ends up at the position you mention, but the leak is further up. Use a mirror and check the backside as well.

Hopefully, the expert (user thepumpguy) will help you later on. He use to have a tip to help to locate leaks: When the pump is clean and dry, sprinkle some baby powder all over it. A leak will be more visible then.


----------



## Harry-P (Aug 11, 2021)

Hacke said:


> Are you absolutely sure about the location of the leak? The pump looks fairly wet all over. Clean the pump and when it is dry, look for leaks. Often the fuel ends up at the position you mention, but the leak is further up. Use a mirror and check the backside as well.
> 
> Hopefully, the expert (user thepumpguy) will help you later on. He use to have a tip to help to locate leaks: When the pump is clean and dry, sprinkle some baby powder all over it. A leak will be more visible then.


I dried the area around the leak well, and used a magnifying glass, and a mirror to watch the back side, and this is where it appears to be leaking. That is a good idea, to use baby powder, so I will dry it again, and see if it still seems to be the spot.


----------



## thepumpguysc (Jan 25, 2015)

Good lookin out, Hacke.!!


----------



## thepumpguysc (Jan 25, 2015)

Whatever you do, don’t try to make a gasket.!!!
Contact me and I’ll help you out..


----------



## Harry-P (Aug 11, 2021)

Hacke said:


> Are you absolutely sure about the location of the leak? The pump looks fairly wet all over. Clean the pump and when it is dry, look for leaks. Often the fuel ends up at the position you mention, but the leak is further up. Use a mirror and check the backside as well.
> 
> Hopefully, the expert (user thepumpguy) will help you later on. He use to have a tip to help to locate leaks: When the pump is clean and dry, sprinkle some baby powder all over it. A leak will be more visible then.


Sorry for the slow reply. My wife died a few months ago, and I had just thrown out all her baby powder and stuff, so I had to get out to get some more. 

The baby powder was a great idea, and I was able to spot the real location of the leak. It's actually leaking from where the head and rotor assembly fits into the housing, right next to where I thought the leak was. On the parts diagram, I don't see a seal inside there, but I'm sure one of you knows where the leak starts. Thanks!


----------



## Hacke (Feb 22, 2011)

Harry-P said:


> Sorry for the slow reply. My wife died a few months ago, and I had just thrown out all her baby powder and stuff, so I had to get out to get some more.
> 
> The baby powder was a great idea, and I was able to spot the real location of the leak. It's actually leaking from where the head and rotor assembly fits into the housing, right next to where I thought the leak was. On the parts diagram, I don't see a seal inside there, but I'm sure one of you knows where the leak starts. Thanks!


There is a seal, look at #23 in the attached diagram.


----------



## Harry-P (Aug 11, 2021)

Hacke said:


> There is a seal, look at #23 in the attached diagram.


Thanks Hacke & pumpguy,

Of course you would expect a seal there, but my Ford Tractor Parts Catalog doesn't show one! That's a screwup on Ford's part. What are your recommendations?

Harry


----------



## thepumpguysc (Jan 25, 2015)

Take the pump off and send it to me..
That’s my recommended course of action..


----------



## Harry-P (Aug 11, 2021)

thepumpguysc said:


> Take the pump off and send it to me..
> That’s my recommended course of action..


OK, how can I contact you for details?


----------



## thepumpguysc (Jan 25, 2015)

I’ll send u a prvt msg..


----------

