Mystery Part

[Mike]

Just curious as to what the square box in front of the fuel injector unit on a thermodyne 673 is ? I have a line coming from inside the cab that says throttle hold and the line comes out but my truck does not have this square unit. The site that I saw this on is www.supermotors.net/registry/media/576224. The line that I have feeds no where.

Thanks

mike

[Rob]

Just curious as to what the square box in front of the fuel injector unit on a thermodyne 673 is ? I have a line coming from inside the cab that says throttle hold and the line comes out but my truck does not have this square unit. The site that I saw this on is www.supermotors.net/registry/media/576224. The line that I have feeds no where.

Thanks

mike

Post a photo of your injection pump. I think you have a Woodward governor setup on your pump but want to verify first.

What did your truck do in it's prior life?

Rob

[Mike]

Post a photo of your injection pump. I think you have a Woodward governor setup on your pump but want to verify first.

What did your truck do in it's prior life?

Rob

Rob,

I'll have to get back later in the week for the photo, but otherdog knows how to talk to the bulldogs and ask anything from them. He's the Bulldog Whisperer. I bet he carries a big themometer with him inorder to get them big dogs a talkin.

I do know that it's a Robert Bosch pump and did not look as if anything had been mounted for the cable to hook to. It would be nice to use this setup when going any distance.

Thx

mike

[HK Trucking]

That sounds like one of those old "oil pressure activated" governors which required oil pressure in order to do it's thing.

When the engine got tired and oil pressure was slow to build at start up, the engine would not fire because the oil pressure was insufficient at cranking speed to activate the governor.

Some guys hooked a cable to the end of the rack, and this enabled them to pull the rack open manually when starting.

A side effect of this home brewed setup was that on a hard pull, you could also pull the rack all the way open manually!!!!!

.

[Rob]

That sounds like one of those old "oil pressure activated" governors which required oil pressure in order to do it's thing.

When the engine got tired and oil pressure was slow to build at start up, the engine would not fire because the oil pressure was insufficient at cranking speed to activate the governor.

Some guys hooked a cable to the end of the rack, and this enabled them to pull the rack open manually when starting.

A side effect of this home brewed setup was that on a hard pull, you could also pull the rack all the way open manually!!!!!

.

Yeah, Woodward made them. Great when they did not leak, or the linkage was not worn internally. They would hold a steady rpm within the horsepower range of the engine very well until aged. I did away with them on gensets almost 20 years ago due to difficulty obtaining parts. Up until a couple of months ago I'd never seen one on a motor vehicle, (except fire apparatus) and lately several have shown up. They were great for running a stationary pump but as Herb mentioned if the oil pressure doesn't rise with the engine cranking, they don't like to start, or idle correctly.

Rob

[theakerstwo]

That sounds like one of those old "oil pressure activated" governors which required oil pressure in order to do it's thing.

When the engine got tired and oil pressure was slow to build at start up, the engine would not fire because the oil pressure was insufficient at cranking speed to activate the governor.

Some guys hooked a cable to the end of the rack, and this enabled them to pull the rack open manually when starting.

A side effect of this home brewed setup was that on a hard pull, you could also pull the rack all the way open manually!!!!!

.

that used to be common around here but many years ago.

[theakerstwo]

Yeah, Woodward made them. Great when they did not leak, or the linkage was not worn internally. They would hold a steady rpm within the horsepower range of the engine very well until aged. I did away with them on gensets almost 20 years ago due to difficulty obtaining parts. Up until a couple of months ago I'd never seen one on a motor vehicle, (except fire apparatus) and lately several have shown up. They were great for running a stationary pump but as Herb mentioned if the oil pressure doesn't rise with the engine cranking, they don't like to start, or idle correctly.

Rob

Rob on some of the DD 149 engines with the woodward governors i remenber they had a small oil can for a reservoir just for start ups that was left full of oilafter shut downs and that was but a few seconds then the engine better get to pumping oil or it would shut down.

[Rob]

Rob on some of the DD 149 engines with the woodward governors i remenber they had a small oil can for a reservoir just for start ups that was left full of oilafter shut downs and that was but a few seconds then the engine better get to pumping oil or it would shut down.

That is true Glenn. They also used them on the 12V-71 series. My Detroit used that type but also had a "Tuthill" gear pump driven from the left engine camshaft and the governor operated independent of the engine oil pressure. As they wore they were more and more "sloppy", (mainly ripple and droop) as the wear became worse. One of mine got to the point the frequency would shift almost 5% when a sizeable load was applied. I changed it to an American Bosch unit with a magnetic pickup and the same shift went to about 1/2% with the new governor. The response was instantaneous with no surge, or hunting, and stability never drifted.

Some electronics are good and work as they should.

Rob

[Mike]

That is true Glenn. They also used them on the 12V-71 series. My Detroit used that type but also had a "Tuthill" gear pump driven from the left engine camshaft and the governor operated independent of the engine oil pressure. As they wore they were more and more "sloppy", (mainly ripple and droop) as the wear became worse. One of mine got to the point the frequency would shift almost 5% when a sizeable load was applied. I changed it to an American Bosch unit with a magnetic pickup and the same shift went to about 1/2% with the new governor. The response was instantaneous with no surge, or hunting, and stability never drifted.

Some electronics are good and work as they should.

Rob

I looked at the pump last night and it is an American Bosch without the provision of the throttle hold as I can see. I will post a picture asap when I learn how again. Also, what makes the fuel in the tanks want to expel out while on a level surface? Its coming out of the caps on both sides. I know that its expansion during this hot weather but it is enough to get my attention.

mike

[Rob]

I looked at the pump last night and it is an American Bosch without the provision of the throttle hold as I can see. I will post a picture asap when I learn how again. Also, what makes the fuel in the tanks want to expel out while on a level surface? Its coming out of the caps on both sides. I know that its expansion during this hot weather but it is enough to get my attention.

mike

Newer vehicles have vented fuel caps for this purpose. Does at least one of your fuel tanks have a vent? If it does and is clogged you could have the symptoms you do now. I'm assuming both tanks are full to be pushing out both sides. Only one vent is required if the crossover tube and valves are open.

Rob

[Mike]

Newer vehicles have vented fuel caps for this purpose. Does at least one of your fuel tanks have a vent? If it does and is clogged you could have the symptoms you do now. I'm assuming both tanks are full to be pushing out both sides. Only one vent is required if the crossover tube and valves are open.

Rob

Rob,

The tanks are three quarters full. And not sure where to look for a vent. I would guess that it's not on the tank but higher up toward the engine.

mike

[Freightrain]

The typical vent is in the center of the tank, under the cab, in the rear. Usually a coiled up piece of copper tubing.

Mine has RB pump, but the throttle hooks to the rearend(if I recall?)as the govenor is on the back side. I have the manual throttle, but it's a twist/lock cable style. It hooks into the throttle linkage, and I do use it for long trips on the highway.

[Mike]

The typical vent is in the center of the tank, under the cab, in the rear. Usually a coiled up piece of copper tubing.

Mine has RB pump, but the throttle hooks to the rearend(if I recall?)as the govenor is on the back side. I have the manual throttle, but it's a twist/lock cable style. It hooks into the throttle linkage, and I do use it for long trips on the highway.

Mornin Larry,

Looks like they would have ran the vent pipe up toward the higher elevation.....firewall maybe. I have plenty to look for at this time. Seems one thing leads to another..... got another question.......the air governor on the firewall....does the allen head nuts act as a filter and have to be unscrewed to clean out the governor area? Also, the unit beside the air governor is closed off from getting air. It is supposed to have a special lube for the shutterstat to work. Is this fluid suppoed to be oil, or hydralic fluid or antifreeze> My books all five of them do not tell me what this fluid is. Can you shed some light on this?

THX

mike

[Freightrain]

Umm, no idea, no idea, and no idea. Never messed with the air govenor. Don't know anything about special lube for shutterstat. Mine picks up air from the firewall(can't recall what it picks off from memory), goes to thermostat control and then to shutters. No lube that I know it needs? I've had my shutter piston apart and cleaned all the old oil/gunk from the piston/seal. Works like a charm.

[Mike]

Umm, no idea, no idea, and no idea. Never messed with the air govenor. Don't know anything about special lube for shutterstat. Mine picks up air from the firewall(can't recall what it picks off from memory), goes to thermostat control and then to shutters. No lube that I know it needs? I've had my shutter piston apart and cleaned all the old oil/gunk from the piston/seal. Works like a charm.

The valve was closed off at the firewall and when I opened it up while building air, running the truck and the pressure gauge inside would not get above 60lbs.. Now that I have closed it off again, the pressure builds up to 120lbs. and governor cuts out and back to 90lbs. it goes thru it's cycle. But the shutterstat still does not close the shutters.

mike

[Freightrain]

There is suppose to be a thermostat valve in the water manifold on the drivers side that allows the air to operate the shutters. Valve might be stuck? Does it get air to valve? Air on the other side when motor is cold? Air to shutters? Mine lines were also clogged with dried up crap and I finally replaced both and also cleaned out control. Works like a charm.

I can get some pics tonight showing how it's all plumbed.

[Mike]

There is suppose to be a thermostat valve in the water manifold on the drivers side that allows the air to operate the shutters. Valve might be stuck? Does it get air to valve? Air on the other side when motor is cold? Air to shutters? Mine lines were also clogged with dried up crap and I finally replaced both and also cleaned out control. Works like a charm.

I can get some pics tonight showing how it's all plumbed.

Something tells me that i'll be replacing lines also. It has to be stopped up somewhere from firewall to shutter control small unit next to the radiator. I'm not sweating this. I like asking questions so others can build interest in the threads here.

THX

mike

[HK Trucking]

Mike, those allen head things are 1/8 pipe thread plugs used to plug off unused ports in the air governor.

On the American Bosch pumps with the "oil pressure" (Woodward) governor, the governor is at the front of the pump, instead of at the rear like the mechanical governors.

[Mike]

Mike, those allen head things are 1/8 pipe thread plugs used to plug off unused ports in the air governor.

On the American Bosch pumps with the "oil pressure" (Woodward) governor, the governor is at the front of the pump, instead of at the rear like the mechanical governors.

Herb,

Sorry for getting back to you so late. My D2 Governor is on the fiewall and I was wondering if it was possible to clean it out also? Or necessary. Since i'm checking air lines. What would cause the air pressure to drop so much when I opened up the valve on the shutterstat air filter mounted on the firewall next to the D2 governor?

mike

[Mike]

Post a photo of your injection pump. I think you have a Woodward governor setup on your pump but want to verify first.

What did your truck do in it's prior life?

Rob

[Rob]

Just re-read your original post and now see you were not referring to your pump. The one in the linked photo is a Woodward setup where yours' is not.

I don't know if a jackshaft of some sort was on your throttle linkage to set the high speed idle via mechanical linkage but that cable/ring had to go someplace.

Rob

[HK Trucking]

That unused cable probably was connected at one time to an emergency shut off valve, as that is where an emergency shut off valve would be located, right where the fuel line from the secondary filter connects to the pump gallery.

Mike, if you have determined that the air pressure governor is defective, don't even bother trying to clean it. New governors are pretty cheap, it's not worth messing with.

[HK Trucking]

What would cause the air pressure to drop so much when I opened up the valve on the shutterstat air filter mounted on the firewall next to the D2 governor?

mike

Sounds like there must be a good sized leak somwhere between that valve you opened, and the shutter cylinder, possibly in the lines, the shutterstat, or the shutter cylinder itself.

.

[Freightrain]

Like mentioned, my lines were crudded up pretty bad as the shutters worked/then didn't. A coat hanger thru them finally got the crap out and worked fairly well. I've since replaced the lines.

[Mike]

Sounds like there must be a good sized leak somwhere between that valve you opened, and the shutter cylinder, possibly in the lines, the shutterstat, or the shutter cylinder itself.

.

Herb,

I was just wondering if the small air governor on the firewall had provision to clean out, maybe where the allen head screws were located? I did not bother it, because for $10.00 bucks they can be bought reasonable. But from the shutter filter, which mine is located on the firewall beside the air governor, found the long airline defective with substantial size hole leading to the shutterstat. So last night both air hoses came off and i'm ready to buy new ones. I also took off the shutter cylinder and have cleaned it up, got off all paint, dirt and am ready to repaint it back to original color and leave the other parts their natural finish with a coat of clear over the top. I will assemble tonight when I get off from work here. And also check it for leaks by submerging it into a bath of water with 90 lbs. of air following. I'll keep ya'll informed and hopefully take some pictures along the way. Whats going to be funny to me is, the rest of the engine bay is old and grimmy looking and will have one part that will look new, which will be the shutter cylinder unit.

Thanks for the replys guys!

mike