Diesel or GAS!!!!???????

Ron Musgraves

Exterior Restoration Specialist
Staff member
Diesel or GAS!!!!???????


I talked with a small engine diesel mechanic the other day while waiting for my cell phone to be updated.

We where discussing how small gas motors if your lucky only run about 1500 hours and many times only a 1000.

Then he told me about a brand name I didn’t remember that is warranted for 20,000 hours and only cost about 3000.00. I want to find out if the cage my equipment in will fit this motor in it.

At this cost I would buy about ten gas motor or more to just one diesel. I was aware that diesel motors on pressure washer would run longer I just didn’t realize how long they would last.

I saw a post from mark @ easy clean. Diesel Kubota Mark maybe you could offer some help as to the hour specs on this diesel diesel unit?


Nice machine I would like to hear from others with diesel units…. please. tell us how long they are really lasting???
 

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Diesel

Ron as soon as you find out I'd like to know. I've got a Vanguard in one of my trucks that's on its last legs and Scott's got me all excited about changing to diesel. Was getting ready to buy a 20hp Honda until I talked to him so it's still up in the air.

I buy new engines every 18 to 24 months so the prospect of one lasting 20,000 hours is pretty cool.
 
Some small Diesel engine names:
1. Kubota, The one in the picture is water cooled. Probably better for our neck of the woods.
2. Yanmar, They have a lot of small marine diesels.
3. Lombardini, A lot of availability, but I don't know a lot oabout them.
4. Ruggieri, Same deal, except that Delco offers a machine with this brand of diesel. Maybe Larry can step in with an honest opinion of what to expect from it.

As for me, I anticipate that all my machines will be diesel powered from here on out. I am tired of the Honda and Vanguard warranties not being honored because the motor "got to hot". Good grief, I have to run my machines when it is a weathermans 112-115. That means we are actually working in close to 130 degree heat, yes they are going to get hot. The diesels love the heat and are actually more efficient the hotter they get, to a point. I think that more exploration is going to be needed.

Scott
 
Scott,

I do not have the information available at this time
however I will look in to it on Tuesday and post more data
on the diesel powered units later this week.
Kubota Engines Link

Another Kubota Engines Link

pho482.gif


More Kubota info

Still did not find the life expectancy info yet will keep looking.

Have A Great Day!
 
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To be fair how about a side by side comparision on gas vs. diesel?

All things, oil changes, run times, temp. repair cost etc.

Also just wondering if they make a gas engine for pressure washers that has a raditor for cooling, seems that would solve a few of the heating problems.

My reasons being all the diesels have raditors for cooling so why not the gas engines too?


Jon
 
Good points Jon....That's what I'm looking for, someone to tell me what the down side to a diesel engine in a pressure washer is, and if they've ever seen one run for a few days.
 
Mark,

Do your suppliers offer a comparrision?

Gas vs. diesel

air cooled vs. water cooled?

Run time between service?

Run time before they expire?

The cost factor is appox. $3000 to $4000 more for diesel so that we all know.

It is the questions above we would like to see answers to.
 
a negative thing that I heard about a diesel engine in a pressure washer was the vibration factor. I heard at one time that they really vibrating and broke a lot of parts. Maybe by now they have taken care of that situation.


You can run off road diesel which is a lot less than regular diesel at the pump. the only difference is the red dye which is placed in the off-road diesel for road tax purposes. Totally legal to run in any pressure washer or anything that is not used on highways.

a gasoline engine runs right at 14.7 parts air to one part gasoline. and the diesel is somewhere around 40 to 1 ratio. the person does not have to be a serious mathematician to figure out real quick the reason why a diesel is more fuel-efficient. also, the diesel engine makes real great low rpm horsepower. air or water cooled would be okay. Need to figure out the governor system.

I think I would do the diesel somehow some way. New, used or slightly abused...........Dan Swiderski ( not Dan S )
 
Regardless of which engine you choose to use they should ONLY be used at Wide Open Throttle at all times. ALL small industrial engines are designed and rated to operate at this level.

In a given situation a compression ignition engine (Diesel cycle) WILL outlast a internal combustion (Otto cycle) engine by at least a factor of 4. This is due to a couple of things; diesel engines have heavier blocks and cylinders (compression ignition typically is from 15 to 25-1 compression at TDC where a gasoline engine is from 7 to 10-1 compression at TDC) and the fuel acts as a coolant barring the fact that most of the diesel engines used over 10 hp include liquid radiators.

A cooler engine WILL outlast an air-cooled engine any time. That is why Kohler has released their new series of Aegis engines. They are 2 times the cost of a comparable air-cooled engine.

By the way engines create power from stored fuel, motors require external energy (electric motors).

Typically a diesel engine will have a 10,000 hour life cycle. At an average work year of 2200 hours you are looking at ~5 years of life. Seasonal use will lower the total to closer to 1000 hours per year, so ~10 years of life, MINIMUM.

In either case you will have most likely replaced the coil, pump and other parts. Kind of like the 100 year old axe you have that your grandfather replaced the head and your father replaced the handle on.

Brake specific fuel consupmtion for an 18.8 hp Kubota D-722E is ~0.44#/hour at 3600 RPM. The Honda GX620 20hp is ~0.51#/hr at 3600 RPM. However, traditionally, a 14 hp diesel has been used as the equivalent to a 20 hp gas; therefore a 18.8 hp diesel is approximately the same as 27 hp gas. (GX 670 24 hp bsfc. is ~0.58#/hr or 31% less efficient)

As both engines operate at the same RPM it stands to reason that they should vibrate the same. Actually the Kubota is a three cylinder which is smoother than the V-twin Honda. Like a triplex pump being smoother than a duplex pump.

Cost becomes a factor though. A 20 hp Honda will cost ~$1500 while a diesel will cost ~$5000. (These are illustrative numbers only!)

Oil change intervals are similar based on hours of operation.

Dyed diesel fuel may plug injectors and/or fuel nozzles causing problems. Yes it is cheaper but may not work as well. Offroad injectors are larger and more forgiving than onroad ones.

Just a brief primer. Hope this helps? Cheers.
 
We run a 14 HP Kubota Diesel on a Hydro Tech skid unit. Bought it in 94' and it is still running strong. The only repairs to the engine have been injectors cleaned, a new gasket, and now I need a muffler. A little pricey but well worth it.
 
Diesel engines

I have two diesel Kubota engines that will outlive me! They run forever, just change the oil and filters every 200 hours. Quiet water cooled etc. They are a 28 hp and 31 hp, we run dump guns and 8-12 gpm depending on the job requirements and water supply. Used to use honda's but noisy and they break after time. Check out the diesel, you can buy off road diesel fuel cheap also. Jim T.
 
diesel or gas

The City of San Francisco uses Alto Kew Technologies brand of pressure-washer. A 16 HP diesel motor. I do not like the brand because it is not American made and it takes time to get parts. This unit is too loud, so if you are cleaning in a residential neighborhood, you are going to receive complaints. Kew Technologies quick disconnect couplings look fancy but are a inconvenience when needing servicing. It is too much work to fix couplings if they leak internally. We only have 200 hours on this particular unit and it has been in the shop several times. One suggestion that I have for everyone is to make sure the fuel tank and filter is clean at all times. This machine is real sensitive to dirt in the fuel system. The bonus to this machine is that everthing is ran by diesel, so you do not have to buy unleaded. We have 19 gallon fuel tank and we can run the machine for over 9 hours straight without depleting the fuel. I believe this is considerably better then a gas motor. As we continue to use this particular unit, I will update you with the problems that might occur. I like diesel but not this unit because of the reasons above.

Thank you
 
I sure learned alot from this thread and can't wait to get my hands on one of those babys. Thanks you guys.
 
I BUY ONAN 20 HP , 2 MORE HP THEN I NEED , THEY DONT RUN AS HARD AS 18 HP WOULD HAVE TO. ONE IS 4 YEARS OLD THE OTHER 2, BOTH WILL STILL RUN ALL DAY LONG. KNOK ON WOOD!

THIS WOULD NOT HELP A WASHER WITH A GEAR BOX, MINE ARE PULLEY , I HAVE CHANGED THE PULLUY SIZES TO LOWER RPM.
 
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The money you spend is merely your own.

There are advantages to using a single fuel preventing mixups and simplifying purchasing. Service will cost more as well as parts. Nooise is comparable or even lower due to liquid cooling.

Gasoline is easier to find at odd times of day ( I know because I have a diesel Jetta). Parts and service are also more readily available and often less costly.

IMHO I would go for an LP only set up like Dave Olson uses and barring the expense of a Genset I would get a belt-drive version of our model 5530K16 (5.2 @ 3000) Kohler Triad LP engine and 345,500 Btu. LP burner. The rules for transporting LP fuel over the road are consistent and well understood (look at LP fuelled RV's, service/government vehicles, busses etcetera).

Hope this helps? Cheers.
 
The major disadvantage of LP in my area is that you annot fill up after the sun sets. I don't know why, that is just the way the law is written. I do have ready access to diesel, 24/7. I can think of a 24 hour diesel station within about a mile of every direction of travel I take when I am going to work., and usually there are two or three.
As for Dave Olson's set up, I would take one like that, but talk about capital intensive. That is a ton of money to have tied up in a single rig. I am sure that it would pay for itself, but I think that the chances of it paying for itself are a lot better in a small market like Dave lives in VS. a Large market with a ton of competition like where I live. Good grief the distributors here put an average of 5-6 new rigs on the road a week for just the new contractors.
Anyway, I prefer Diesel to LP, although LP would definitely have some advantages.

Scott
 
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