"Blow by" question

[bludev]

Thanks for all the input guys.

It is a 743b ... I did check the voltage on the wire which goes to the glow plugs ... it was around 6 volts with the key turned to the left (ie heating position) ... does anyone know if that is correct ... the voltage on the battery was right at 12 (the battery is getting weak and I have had to jump start it since the weather has turned cooler combined with the hard starting)

Thanks for all the help

Is this in a 743?

Before you start changing anything, a little time with a meter, or for that matter a test light will go a long way.

Make sure you are getting full power too the glow plugs first so you know which side to start looking.

The glow plug closest to the back of the machine is a bugger to do.

 

[Eagleview]

It should have 12 volts @ the glow plugs , it sounds like your battery is on the way out . Even though it is showing 12 volts with the meter , i think if you put a load tester on it you would find the battery would fall on it's face .

 

[AlanB]

6 Volts is a problem.

Off the cuff guess, bad connection, or bad solenoid.

Start chasing voltage back and see where it is dropping off at.

In my 743 it was the solenoid towards the back of the machine, on the left hand engine compartment side.

There is a skidsteer forum, that is extremely helpful as well, and those guys know the SS inside and out. I don't remember the exact name but something like Skidsteer forum should find it.

 

[Terra Firma Scott]

Not sure of the glow plug set-up on your bobcat but i had an issue with my caterpillar awhile ago....

the shorting bar (Battery voltage)which secures to the top of all four glow plugs had vibrated loose the nuts at the top of 3 plugs!!!

im sure if you checked voltage that you would have seen or felt if it was loose but just a thought.....

 

[skidsteer.ca]

6 Volts is a problem.

There is a skidsteer forum, that is extremely helpful as well, and those guys know the SS inside and out. I don't remember the exact name but something like Skidsteer forum should find it.

www.skidsteerforum.com
Ken

 

[EddieWalker]

Looks like you found your problem with the low voltage on the wire and the battery. Winter is the killer of batteries. If a battery is close to the end of it's life, the cold will make it happen instantly. With just 12 volts, I think you are very close to having to buy a new battery.

For the glow plugs, follow the wire until you find where it changes voltage. It could be just about anything, and the only way to know for sure it to follow it.

Testing compression on a diesel engine requires removing the injectors and a special compression tool. You can't do it with the same thing you test compression on a gas engine. Instead of doing this, look at the air that's coming out of the crankcase. There should be a vent tube someplace, but your dipstick to check the oil will work too. Does any oil come out of these tubes? If you are getting oil to spray out of there, you have too much blowby and need to rebuild the engine. Like mentioned previously, in winter, it might look like allot of blowby because the air is colder and you will see it more then you would in the summer.

Constant black smoke and a loss of engine oil are other signs that the rings are worn.

Did it start good in the summer?

Has it lost power?

Eddie

 

[skidsteer.ca]

The voltage at the plus should be almost the same as the battery. You have a bad conection on the the glow plug circuit somewhere. This cause the voltage drop that is preventing your plugs from glowing properly.

Also common is to have some of the glow plugs burn out. Remove the wire/strap conecting the 4 glow plugs, hook you test light to the pos on the battery and attempt to get a ground through each indevidual glow plug by touching the prob on the wire terminal. If the glow plug is burnt out it will have a open circuit through the element and the test light won't iluminate
Ken