What gives CAT engines their distinctive "whine" noise?

Rideandrepair · Mar 31, 2019

Goodysnap said: ↑

Yup.

Straight cut geartrain and on the front of the engine out where you can hear it.

On Cat alot of people dont take the time to set the lash on the cam gear correct. I find the lash off on alot of engines that have been apart recently. It is easy to just slap parts and skip critical adjustment steps.

ISX is ussually noisy too. Especially non scissor gear engines.

Push tube engines are generally much quieter.
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I have a question, sure to make you shake your head, but here goes. If I change only the bearing on my 12.7 bull gear. Retorqe it properly, will the gear lash be affected? It’s obviously set perfect now, as it’s lasted so long. Is it possible to simply check gear lash afterwards, and if ok leave it be? Or does the idler and gear lash have to be disturbed to replace the bearing only? Never set a gear lash, on anything before, a bit intimidated about getting it wrong

Austen · Mar 31, 2019

Hey, thanks guys, wow, great group of replies here.

Thanks for affirming my inclination that the sound is in fact due to the straight cut timing gears. You can hear it in some of the smaller displacement engines they made as well such as the 3126 / C7 platforms and even the old (big) 3408 V8s have the same whine to them too. You don't however hear it in the 3160 / 3208 platforms.

Moderator 'Mack E-6' mentioned the Detroit Series 60's have the same sort of noticable whine to them and couldn't agree more.

As mentioned in my first post, many big diesel engines have a whine to some extent but the CAT engines seem to have it more apparent. The Cummins "Big Cam" engines for example don't really have any whine at all in comparison.

TPDoverTN · Mar 31, 2019

Ridlingdj said: ↑

Both of these girls will do well over 80 and feel like you are doing 55

Snapchat-823286202 by Ridlingdj posted Mar 31, 2019 at 11:09 Sir, do both of those beauties have the same make and model engine? What power plant do they have? Thanks for your reply

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TPDoverTN · Mar 31, 2019

x1Heavy said: ↑

You can kick any truck to 80, even the older two strokes from the 60's if you have enough time to get it up there. Now that does not mean you can stay at 80 on the slight upgrades and so on.

What you really want are the old time snorters with the late mechanics, about the 425 Cats, 500's and so on. Without restrictions. Sometimes there are shops that for a price will provide a variety of modifications to a semi, within the bounds of that DOT regulations regarding what you have to have on the truck did not cover whats under it in those days.

Prior to the computer engines many engines have a certain personality. I remember the cummins, when it's running in the sweet spot and nothing was bad before there was computers, it will make a form of music. But idling? the fan noise covered it. Now the detriot. You can get em going but they did not have the air to stay at top speed. What they did have was the beef at the bottom RPM to go upgrade. HERE KITTY KITTY KITTY. Enter the Cat. Step aside this kitty is coming through. First to the top buys Dinner. Cat is hungry.

Enter a word for the Mack. Their engines and transmissions make a truck that has short legs and 100 pound horseshoes. IF you are in a mountain slope on ice the kind no one can walk on.. that little mack is coming up with the stuff your store needs in the morning. Everyone else is throwing chain, falling into ditches or whatever. It's not much of a truck. But they have done things in my experience that will break any other truck that is not military.

CAT got out of the truck engine business entirely because they could never build it to comply with regulations anymore in emissions etc. Most any engine driven by computer today are weed eaters. They are all the same. Whine.

Then break and need a bigger computer to fix it. Ive got a decent computer that hooks to the OBD2 in my 350 vehicle but that's only to get at the codes, live data and erase etc without having to take it to the shop and pay 60 dollars for a computer looksee.

The engine itself is brainless with three exceptions, a pair of oxygen sensors at the exhaust side one coolant temperature sensor and another for outside air. Once the engine computer has the 4 it knows what mixture to make at the intake. Otherwise you ran it open loop rich spewing carbon over everything and smoking the town. That 350 is nothing special, 80K on the block a third engine in the vehicle with 260,000 miles on it.

Now trucks? Ive had some that were between 1.25 to 2 million original miles on them and they did the job. Older than I was by far. But they got the job done even if half the stuff was broken.

Emissions and company control of governors really strangled and casterated trucks. Took the old time possibilities right out of them. They end up being gilded cages where our young 20 something labors in a world of micromanagement, like a hamster in the wheel.

Fuel is the other. If you hold at 55, you go through a certain amount. Get to 80 you are increasing your power requirements, fuel burn, areodynamic drag, inertial rolling problems and so on by exponential factors. And you will need alot more fuel.

However you got 5 mpg of fuel 40 years ago and you are now adding about oh... 60,000 inflated dollars worth of crap all over a 18 wheeler to get what? 8 little miles to gallon? HA... what a waste. Now if you are a fleet with 1000 or 10,000 then it's cheap to spend that kind of money retail for that 8 mpg.

Show me a 18 wheeler that will do 40 miles to gallon, fuel once a month or twice if that. The Nation's need for Diesel will drop quite a bit to our benefit.

When you get a 40 ton semi up to 130 and even beyond, well... physics will decide who lives or dies doing stupid stuff like that. Ive had em up there and that's not the half of it. Ive had my doors blown off by really fast 150's on up. They are truly fast.

If you had a unlimited rig from LA to Jersey, you are not going to get there that much faster in terms of a few hours versus something in the trailer that took 2 months to make in china and a month to ship over the pacific. There is no point.

Enter the shipper and reciever. They all have to have appointments and get it yesterday. They abuse the driver a thousand ways from sunday when it does get there on time. Companies are told to pound sand if they are early or late. Don't come back for more freight. For a load of potato chips. Or perhaps mulch that will sit in the garden center rack a month in all weather.

I learned to get away from food, meat and seafood. Those are all important yes, but the time losses and financial abuses in those places is not worth it. You cannot make money doing that unless you were a bull hauler.

Medicines is my niche. A 65 mph truck will get to Detroit overnight from say Memphis in good order. No issues. A 130 mph truck will not get it to Detroit that much earlier. Maybe 3 hours. It still will be shipped from there to the hospitals around 10 am every morning so your 130 mph road burner hellraising death ride is worthless. You follow me?

What is it then that will bother me? Three things. Emissions, Micromanagement and abuse followed by the governed speeds that are excessive. If I am trying to get into Tenn tonight and have to fight 1000 trucks all trying to pass each other at 61, 62, 63 mph on a 70-75 or 80-85 mph interstate I am running late because I cannot get to legal speed limit. It's a hazard.

Eventually cars will be gagged just as bad as trucks. Then you will learn just how inadequate our two , three lane highways have become at that point.

If I need speed, there is the internet, whistle up a light jet to the local general aviation field, be at 45000 feet and at the east coast anywhere within 3 to 5 hours max and the west coast in 4 to 7 hours max depending on the jet. That kind of speed would involve a human or family issue where money is no object with the goal that you will be there asap.

There is nothing that fits into a 18 wheeler today anywhere in North America outside of war that needs to be anywhere in a hurry. And so the companies are the root of the speed problem. They brought it upon themselves.
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Mr. 1XHeavy, wow you are truly a subject matter expert, thanks for taking the time to respond. You certainly went above and beyond anything I was expecting.

Brettj3876 · Mar 31, 2019

AModelCat said: ↑

The ISX has that distinct sewing machine sound when you stand in front of it. Some seem to make that weird chugging sound when they start pulling though.

Cat seems to be the smoothest sounding engine, followed by the Series 60.
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Yea the isx sounds almost like its gonna fall apart lol. I like how they sound. The DD15s I've been around sound terribly bland. An old PLN E-7 is silky smooth, esp if running 15.3 pistons. The later Etech's sound clackty with the unit pump setup

Gambino1994 · Mar 31, 2019

swaan said: ↑

They all sound perty good in there own way. The ones that make me cringe is a lot the isx engines sound like there going to granade when pulling. Seriously sound like a rods coming through the block... they should of stayed with the N14.
.
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I thought I was the only person who thought that about the isx. Some of them sound sooo bad

swaan · Mar 31, 2019

Gambino1994 said: ↑

I thought I was the only person who thought that about the isx. Some of them sound sooo bad
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Yup and even brand new ones too. It's a real wierd wooshing/hammering sound. There just a terrible engine in my opinion. Lol.
Whenever I see a newer kw or pete on side road with hood up it seems it's always a red motor.

mtoo · Apr 1, 2019

I think all new engines sound like a vacuum cleaner. Don't know if they suck or not, never driven one. All I've ever had are old school cats. But in my opinion they sound like a vacuum cleaner.

AModelCat · Apr 1, 2019

Brettj3876 said: ↑

Yea the isx sounds almost like its gonna fall apart lol. I like how they sound. The DD15s I've been around sound terribly bland. An old PLN E-7 is silky smooth, esp if running 15.3 pistons. The later Etech's sound clackty with the unit pump setup
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My father had an '06 ISX (EGR only) and I never really noticed that chugging sound with his, either from the passenger seat or when driving past while pulling. Mostly just sounded like turbo whistle more than anything else.

My favourite engine sound has got to be the old MBN CAT when you crest a hill, back out of the power, grab a split on the button, then gradually feed back into the power. That turbo spool and engine growl gets me every time.

rollin coal · Apr 1, 2019

That's the sound of money blowing out the stacks my MBN does it too.

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