Dyno test cost??

Hi I'm looking for advice I'm looking to buy a 2012 volvo vnl 780 with 960k miles automatic transmission for $13000 is my first semi truck

 

I would start by making a new thread in the correct sub forum, instead of necroing a thread that has nothing to do with your question.

 

I find this dyno thing really interesting....reminds me of when the first dealer scanners came out...no one would touch or look at anything till you diaged the car for 150$ plus.

I dont see how a dyno will tell you much unless you have previous runs to compare it too....geeze, if your interested in buying a truck do what its designed to do, plug it into a loaded trailer and drive it....if the seller said "no you cannot" i'd walk.

If the dyno is used properly a diag tool, so as one item in the game.....ok maybe....but i can throw alot of parts at something for a few grand that some places charge to run it and basically say "no fault found"

 

The main purpose is to see what HP number the engine is laying down to the tires. If it's not within a certain parameter, then something is wrong. Also, you can test blow by at the same time.

If we all tried to get the seller to let us use the truck to pull a loaded trailer, we'd never get to buy a truck. If someone wanted to buy my truck, and a stipulation was they wanted to see how it pulled loaded, I know exactly what I'd tell them, and "F" is going to be a prominent letter in my language.

 

I understand fully why they use a dyno, been around this stuff all my life and have an engineering back ground in racing along with being a mechanic.

I find it interesting that you wouldnt let me hook your truck to a load and drive it (with you along of course) but you'd trust me to put it on a dyno? Either one could wreck your truck and i could actually do it on the dyno faster......oh well to each their own as they say.

 

A Dyno results gives you two things, one is it can show up sensor failure or ECM failure of fueling issue, and it shows percentage of rated horsepower of the engine. This gives an overall health check of the engine, the lower percentage the less chance the engine will survive heavy work. An additional test that is done is called a blowby test, which is a measurement of crankcase pressure and it indicates under a full load the condition of the rings and/or cylinders.

the comparisons are made when the numbers of the engine being tested are within established specifications from the manufacturer.

 

As i said, i know exactly what its for and how its used......(been used in the industry that im in for over 30 years already and my buddy is a dyno engineer for the military) but i just wanted people to know that its not the end all and be all when i comes to diaging things. If you've got a problem with a truck a good mechanic will be your best defence along with every tool at his disposal...if you are buying a used $150k truck, use every possible means to get the info needed before making that purchase, dont rely solely on a dyno sheet.

 

Personally, I know of NOBODY in real life who has taken a potential truck purchase in for a dyno run. Oil samples and maintenance records are usually the absolute most that are ever asked for.

Anyone with half a brain and basic mechanical knowledge can climb around under a truck and inspect it. Doesn't take 15 years of being a full time mechanic to see oil leaks, worn brakes, damaged air lines, loose u-joints, hacked up wiring etc.

 

Actually a dyno report is the brst tool to use when buying a used truck you know nothing about.

Taking a truck out bobtail or even pulling a load won't tell you half of what a dyno report will. You will never work the truck hard enough to bring potential issues to the surface like a dyno can.

Early stages of headgasket problems will not show till worked hard. Presurizing the cooling system or overheating will be pronounced on the rollers.

HP and blowby are only part of the equation. Strange vibrations and fan on/off time , cooling ability , cracked head ,ect ect...

I would never buy a used , unknown truck without a clean dyno report.
You want to save $800 on a dyno report but the truck could potentially have serious issues that could cost thousands to fix. Doesn't make sence to me.

 

I spent $1500 at Cummins putting my old girl (named Veruca Salt) on the treadmill. I had them bump the Torque up. She was on and pulling hard for close to a half hour.