B7100: Injector type?

[edfortmiller]

I have a 1997 B7100 HSD. I'd like to test the injectors: POP and spray pattern. My friend has a injector tester but needs to know what type of injector the tractor has in it so he knows what kind of adapter needs to be purchased. We would also like to run a compression test and the same info is needed so he knows what type of adapter to get for the compression guage. I looked on the injectors but don't see any information. He said typically an injector has a number on it (externally).

Just trying to chase down the rough idling problem I mentioned in a different thread.

 

[BobinCols]

I doubt if you have a compression problem on a 1997 tractor. If the injectors are still in the engine and it is runable do this if you haven't already. Warm up engine and let idle. Loosen injector line nut at the injector nozzle one at a time with the engine idleing. If you loosen the injector line nut on a cylinder and the engine runs rougher, you know that that cylinder is firing good. If you loosen the injector line on an injector and the idle does not change, that cylinder is the problem. Take that injector to a diesel injection shop and have it repaired. You could also have a bad delivery valve in the injection pump (one for each cylinder). You would probably have to purchase the items you wanted thru a dealer. Also check easy things like a loose fuel line getting air in the fuel system.

 

[Kelvin]

Hopefully this is obvious to you, but don't try to use an automotive compression tester to test the compression.

I don't have my B7100 manual with me right now to give an accurate compression value, but it is significantly higher than gas engines. If you are able to measure the compression on an automotive compression tester, then you will have found your defective cylinder. My B7100 had one cylinder that had bad compression rings (engine had overheated at some point because of the previous owner's lack of understanding of the B7100's thermosiphon cooling system). I was able to measure that cylinder's compression on my automotive guage before I destroyed it testing the other two cylinders.

It was back in 1997 when I went through all of this, but seems like I gave up on trying to find a shop that had the proper equipment to check a diesel engine's compression. Rumor had it that if I could have found a shop to perform the compression test, it would have been very expensive. Some of the diesel mechanics may be able to explain that statement, because I don't know why it would be that costly.

Kelvin

 

[edfortmiller]

The injectors are still in the engine and the engine seems to run fine except at the lowest idle. I figured if I'm yanking the injectors I figured I might as well run a compression test at the same time.

 

[edfortmiller]

I'm aware of a diesel engine having a much higher compression than a gas engine. If you have a chance and could look up what the compression spec is I would appreciate it. And would the compression spec be when the engine is cold or hot? Also while you are in the manual if it has the injector break pressure (POP) I would be interested in that information as well. My buddy has been maintaining his diesel VWs for years so he is quite knowledgeable about diesel engines.

 

[Kelvin]

I looked all over for my the binder that keeps all of my manuals. Finally found it setting next to me and the computer with the newspaper over it.

The informaion from the I&T Service Shop Manual for the B7100D, B7100 HST-E, and B7100 HST-D tractors are as follows:

Compression Pressure: 398-454 psi. Allowable minimum pressure is 341 psi.

No mention of engine temperature during compression test.

Injection Timing: 25 degrees BTDC
Injection pressure: 1988psi
Compression Ratio: 22:1
Slow Idle Speed: 750-800 RPM
High Idle / Rated Speed: 2800 RPM

If "injector break pressure (POP)" is the same thing as "OPENING PRESSURE (mentioned in the TESTING section), then the pressure you are looking for is 1988 psi. The only other value given is in the sentence "SEAT LEAKAGE. Nozzle tip should not leak at a pressure less than 1846 psi."

There are about 2 pages of instructions about injection pump removal, replacement, testing, and overhaul. There is a caution about the procedures requiring special tools, and...

"Unless necessary special tools are available, service on injectors and injection pumps should be limited to removal, installation and exchange of complete assemblies. It is impossible to recalibrate an injection pump or reset an injector without proper specifications, equipment and training."

Kelvin