Any mechanics in Phoenix Tucson? - Page 3 - PeachParts Mercedes-Benz Forum

mannys9130 · #31 09-29-2015, 07:10 PM

The old tractor engines that ran on gasoline to start and warm had an antechamber that was opened by a third valve. To start, a lever was pulled opening the chamber, the throttle butterfly was opened so that the intake drew air through a tiny single barrel carb, the ignition (spark plug in the antechamber) was switched on, the injection pump was switched off, and the engine was started. The power that the engine made using gas was not even enough to move the tractor with. It was simply to warm the engine in lieu of a glow plug system. Once the engine was nice and warm, the lever was pushed to off and the injection pump was turned on. All of the gasoline components were disabled and the antechamber was closed off raising the compression considerably. Once running on diesel, the tractor could then do serious work.

The antechamber is the key there, as is the carb. The compression dropped low enough with the extra chamber to prevent any kind of preignition. The carb made it so gasoline (which is an excellent solvent) never came in contact with the diesel (which a pale lubricating oil) fuel system. If gas is put into a diesel, it washes away lubricating diesel from critical places like IP elements. Once it gets into the injector, it does the same thing but it also melts the injector pintle and scorches the nozzle. In normal operation, diesel is sprayed slightly BTDC and a small delay occurs between vaporization and ignition. When gasoline is injected, it becomes more of a flame thrower than a fuel mister. That heats the pintle until it is flame erroded away. The internals of the injector can also seize and gall due to lack of lubrication.

Gasoline can be mixed in small amounts with diesel when very cold. Generally 20-30% is the limit and Kerosene is greatly preferred for that task. In Massachusetts we had several station that had a #1 diesel pump for those who wanted to make a diesel/kerosene blend. In Tucson, we have a station that you can buy 110 octane racing gas and even red tinted off road diesel for farmers who have farm machinery. It doesn't get cold enough here to need kero though.

It is possible that AAA tried topping it off. I actually had a customer come into my shop because the car wouldn't start. The tow driver said "The fuel pump's dead." I put a gallon of gas in and primed it, and it fired right up. I asked the customer when the last time she filled up. She felt so stupid, but her husband had just passed and it really was taking a toll on her sanity. AAA will bring you a few gallons of gas if you run out on the highway, so it isn't out of the realm of possibility.

IDK, there isn't enough evidence to diagnose the problem just yet. I'm awaiting the OP's report of how the injector swap went to make any further speculation.

leathermang · #32 09-29-2015, 07:23 PM

I was actually referring to bulldozers ...
..?

mannys9130 · #33 09-29-2015, 07:29 PM

Seriously?

The intake valve opens, the piston moves down drawing air into the cylinder. The carb is in the path from its air cleaner to the valve, so fuel is mixed just like a gas engine. There is a butterfly the closes off the carb for diesel running, and closes off the main intake for gas carb running.

mannys9130 · #34 09-29-2015, 07:34 PM

https://m.youtube.com/watch?v=Y81EUqzvbWc

leathermang · #35 09-29-2015, 07:37 PM

How do you keep that mixture from igniting way before top dead center due to air temperature ?

mannys9130 · #36 09-29-2015, 07:42 PM

The antechamber reduces compression to gasoline engine levels. That's that third valve I was explaining. At 9:1 there is no preignition. The spark plug ignites it just like normal. Once you pull the lever to switch to diesel operation, that antechamber closes and bumps the compression back up into diesel range.

That video is really good. David explains things very well.

Fattyman · #37 09-29-2015, 08:41 PM

Alrighty then.
Installed used injectors and new heat shields.
Wow, what a difference!
It's even worse

So I'm onto something here, knocking is worse and you can tell that the replacement injectors are out of balance. Now I now why these have been sitting in a bin for so long.
So it looks like a set of Greazzer injectors are in my future.
This thread will be prolonged a bit longer

mannys9130 · #38 09-29-2015, 10:09 PM

What did the nozzles of the original injectors look like? Did they look scorched (more so than normal)?

leathermang · #39 09-29-2015, 10:15 PM

So the noise changed from nailing to knocking ?

Desert Panther · #40 09-30-2015, 12:55 AM

Quote:

Originally Posted by mannys9130

In Tucson, we have a station that you can buy 110 octane racing gas and even red tinted off road diesel for farmers who have farm machinery. It doesn't get cold enough here to need kero though.

sorry for the thread hi-jack, but I really need to know the answer to this quick question....

Where, where, oh where is this mysterious station that sells red tinted off road diesel in Tucson???? I hate having to pay any extra taxes or fees when buying diesel fuel for my tractor, but I've yet to find a place that sells red diesel, although I've heard rumors about it. Please - DO TELL!

Fattyman · #41 09-30-2015, 01:29 AM

Quote:

Originally Posted by leathermang

So the noise changed from nailing to knocking ?

Yes, but not on all cylinders. Before it was annoying but drivable. Now I wouldn't drive it around the block.

cooljjay · #42 09-30-2015, 01:38 AM

Quote:

Originally Posted by Desert Panther

Where, where, oh where is this mysterious station that sells red tinted off road diesel in Tucson????

You can move to this helll hold....You can get off road diesel right on the corner gas station two blocks from me.....but just don't try to ask for fried chicken....or you'll end up strung up to the entrance of the town....Subway just sued a town not far over and won a few million bucks....never heard of a food joint suing a town till I moved here....twilight zone...every day...

Mike D · #43 09-30-2015, 11:54 AM

Quote:

Originally Posted by Desert Panther

sorry for the thread hi-jack, but I really need to know the answer to this quick question....

Where, where, oh where is this mysterious station that sells red tinted off road diesel in Tucson???? I hate having to pay any extra taxes or fees when buying diesel fuel for my tractor, but I've yet to find a place that sells red diesel, although I've heard rumors about it. Please - DO TELL!

Offroad Diesel Fuel in Marana, Arizona with Reviews & Ratings - YP.com

mannys9130 · #44 10-01-2015, 02:31 AM

Quote:

Originally Posted by Desert Panther

sorry for the thread hi-jack, but I really need to know the answer to this quick question....

Where, where, oh where is this mysterious station that sells red tinted off road diesel in Tucson???? I hate having to pay any extra taxes or fees when buying diesel fuel for my tractor, but I've yet to find a place that sells red diesel, although I've heard rumors about it. Please - DO TELL!

I PMed you shortly after you posted this. Did you get it?

Fattyman · #45 10-13-2015, 07:17 PM

OK, put in the serviced set of injectors from Greezer (nice work) and there is no change in the nailing from before. Engine runs nice and smooth but doesn't sound nice and quiet as before it was overheated. Next up, pre chambers.