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To Do A Dyno or Not


alan0043

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Hi Everyone,

 

I might be opening a can of worms here. I can understand that a buyer would like to see a engine run on a dyno to know it's condition. If I am seller do I want to put my engine to this abuse. I can understand that there is pro and con's about this subject. I would like to hear your opinion about this subject. All corrective criticism is welcomed. Think about this engine as your own engine.

 

Al

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Shows condition of engine by power output, compression bow by, turbo output. All this is a headache or at least a pocket book headache. We generally buy trucks with half or less of life left. Many get them in the 600k to 750k mileage. I did not get a dyno. But my truck was very clean, no rust, ran great. Price was good. Mine does have a lot of blow by. I intend to have it overhauled. If I had bought a truck with less miles but it would be lot more cost and I would not have been ahead. I can have it rebuilt and still be in good cost. If it had been in the 30k price I would definitely dynoed. Used trucks are a crap shoot. If you have all the maintenance records that would tell tons. Now if I was selling and someone wanted it, it comes down to your word. If you two are strangers I would expect a dyno. But again the price you are asking depends a lot.

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Hi Everyone,

 

The following is a quote that I read from a past post on the HDT forum. Talking about a dyno.

 

Posted 18 March 2016 - 09:21 AM

It can often make something break that was about to break...and that's a good thing.

 

That sounds like the dyno test can be excessive or maybe even a zealous test.

 

Posted Today, 12:32 PM

What abuse? It's a simulation of a run down the road, with sensors attached to record engine conditions.

 

Thinking about the first quote, " It can often make something break that was about to break...and that's a good thing" that sounds more than just a drive down the road to me. That is where the word abuse would come to mind for me.

 

Most of the comments are coming from the buyers point of view. If you are a seller, how do you feel about a dyno ?

 

Please keep the comments coming,

Al

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So who is responsible if there is damage done to the truck dealer or buyer. .Could not find a dealer out here that was willing to take that risk. Had to rely on ecm read out and oil analysis and maintenance records. So far so good. Had another repair shop check it out and called previous owner to find out why they sold it to the truck lot. We found out who previously owned the truck buy looking where the old company logos where on the side of truck . It leaves a ghost image on the side or door if it has not been buffed out. Called the old owner and they where more than glad to tell me the history of that truck.

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The first quote may have been a little generous in it's assesment, and mine may have been an over-simplification. The idea is to have an engine preform against known parameters to gauge it's health. If the engine is rated for 500 Hp, but is maxing out at 375 at the wheels, you can expect troubles ahead. With extra sensors hooked up, the lost power can be tracked to their origine, wheathe that's massive blow-by, failing turbo, or cracked boots.

Essentially, the whole drivetrain will be run up to, but not over, factory limits to see what shakes loose.

The answer to who pays for damage incurred depends on the agreement between buyer and seller.

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Hi Everyone,

 

Are the diesel engines in the trucks rated at the flywheel or the rear wheels ? My understanding that there is about a 20% difference between the flywheel to the rear wheels when you are rating horsepower. The drivetrain can take up to 20% of the horsepower.

 

Please keep the input coming in,

Al

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Could not find a dealer out here that was willing to take that risk. Had to rely on ecm read out and oil analysis and maintenance records.

I asked my selling dealer (GATR Volvo in Minnesota, I am in Texas) for a dyno.

They said they did not have a dyno machine.....BUT, the Pete dealer down the road did. They said if I arranged payment with that dealer, they would take it over and get it done.

 

Once I received the printout, I took it to my local Volvo dealer to translate it for me.

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I asked my selling dealer (GATR Volvo in Minnesota, I am in Texas) for a dyno.

They said they did not have a dyno machine.....BUT, the Pete dealer down the road did. They said if I arranged payment with that dealer, they would take it over and get it done.

 

Once I received the printout, I took it to my local Volvo dealer to translate it for me.

 

And, the translation was??? Inquiring minds want to know!

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The dealer down here, who had no dog in the hunt, was super nice (coulda been the uniform or the gun) and extremely helpful. Since it was 6 years ago, I do not recall the exact details but they advised the engine was well within tolerances and actually said it was a little on the high side of that for a truck with 500,000 miles. After hearing their opinion of the dyno, the conversation I had with the inspector from Truck Remarketing and the dealer, plus looking at the photographs from the dealer and the inspector I flew from Texas to Minnesota with cash in hand and drove it home.

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I chose to "limit" my truck buying budget and I am not afraid of old (I rebuilt and flew 50 year old aircraft). My price limit put me into 750,000 miles truck or older. I used a broker who dealt in trucks like that and he suggested a truck 5 years old (2000) with 836,000 miles, for just around $30K. With that kind of mileage I wanted to know how good the truck was and how good the engine and trany was. That meant independent inspection (by a Volvo dealer) and dyno. I sent a small deposit on the truck and funds for pre-paid inspection and the dyno. The understanding I had with the broker was, if the dyno failed we move on to another truck. Dyno came back good inspection revealed approximately $3,000 of repairs, half were essential half were somewhat of a "fluff". The seller and I agreed on the $1,500, he lowered the price by that much and I had the dealer do it. So in my instance of acquiring an HDT, dyno was the major decision item. Inspection was number two.

Since then the truck nipped me for close to $20 grands in age and mileage related repairs, I expected that, welcome to HDT ownership. I still think I am ahead since I bought it cheap and still had the use of the truck for all these years.

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I have been watching this topic with interest. We have a 2015 Sportchassis with a Cummins ISL 9. Rocky Mountain Cummins has s dyno service they offer in conjunction with annual service. They say they dyno the rig and check all engine parameters and adjust for maximum performance. We tow about 15k a year and felt it might be a good "investment" of about $400. The truck runs great and is getting about 9mpg when towing our 21000 lb fifth wheel. Should I save my money or dyno?? Thanks in Advance, Dick

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Dick, it sounds like you have had the truck for long enough now to know your mpg and amount of annual mileage.

 

A Dyno test is usually used to make sure a potential truck has not been "overworked" prior to purchase. Yours sounds in pretty good shape with what you are reporting.

 

Now I understand the testing facility selling you on the "possibility" of gaining better mpg, but I dought that it would change enough (if at all) to make that investment worth it! Now if your mpg starts dropping off, then you might want to reconsider.

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Hi Everyone,

 

I was able to stop by the dealership that does dyno work in my area. I talked to the fellow that does the testing. He told me that the test is like driving your truck up a grade with a load in the trailer. He said most runs are done in 9th gear. Some where around 1500 rpm's. He also told me that the test can take a little bit of time. He didn't say how long it takes. We talked a little more about testing. I said to him that the only dyno I have seen done is on a gas engine, where they are pouring the coals to the engine. He said that is not the way they dyno a diesel engine. Hearing that makes me feel better about a dyno run.

 

Al

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Phil, bit off topic but I used Truck Remarketing to look at a truck for me. I was pleased with their inspection, were you?

Carl, I was extremely happy with them. The report was very detailed and every item covered by a photo. I think I got 87 photos. They also had the inspector call me personally and let me ask him questions. He was a fellow RV'er, a retired diesel mechanic who hauls his tools in a trailer behind his MH. He and the wife traveled several states up there and he went to do inspections when they called him.

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Has anyone with a "singled" truck been successful in having a Dyno run?

 

I can't imagine an issue with dynoing a singled truck. When I was dyno-ing my truck (well, YOUR truck now!) we actually had an issue with the diverter axle. The Peterbuilt dealer I used dyno only had one roller, and the ABS proximity switches were not happy on the diverter axle not rotating

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