The Cat 3126 Engine. Know Your Engine. Caterpillar 3126B and 3126E.

In this video we are going to talk about the old Caterpillar

3126

. Hey guys, you dress for the adaptive channel and in this video we are going to talk about my favorite small cap diesel

engine

, the 31:26, we are also going to have. a destruction of the week segment at the end of this video and before we get into the video, I would like to thank Greg Martin, Miguel, Bill, Chris Max and Jason for helping support this video if you would like to support the making of these videos. Adept api comm on paypal okay let's get into the video so Caterpillar never made a light duty diesel

engine

they made medium duty and heavy duty and medium duty are basically 31 16s 3208 c7s 31:26 es c9s the heavy duty ones ​​are to watch Thirteen are the c 15 and the 3406, things like that, so why is the

3126

my personal favorite?

Well, I think it's more reliable and easier to work on on earlier and later model engines, and we'll get into the specific details on that. throughout this video so let's get into the details of this engine the first thing we do is walk through the engine so now I walk over here and then I take the side of the engine cat 31:26 and on the back of the head you're going to have

your

fuel pressure regulator on the right, next to the lift support and then starting at the rear of the engine, you can see

your

ECM, there's the black box with the letters, your p2 connector, we have your oil pressure sensor in your oil. manifold you can also see the side covers there, we'll discuss those in a moment and you can see the oil coming out of them, a pretty common problem going up to our intake manifold, we have your boost pressure sensor, we have your intake air boost sensor. temperature we have the inlet air heater solenoid the fuel filter housing you can see the injection actuation all the Huey pressure sensor the aluminum colored item here that is your Huey pump that has the round top and you can see the timing sensors here and a little more oil leaks, of course, those are your timing sensors, there are two on your front frame, above the power steering pump, so some of these engines will have air compressors.

You can see your serpentine belt and there's also a little V belt there and let me show you where. the coolant temperature sensor is a little hard to see but it's right behind the huey pump under the fuel filter now on the exhaust side of the engine so we have the thermostat housing which uses two thermostats and this one I would have a line working. On the other side of it is an air compressor, but it is not. You can see the exhaust manifold behind the intake pipes. You have the turbocharger oil return line, the oil cooler oil filter, and another oil leak that looks like a rear frames leak here between the block and the rear. frame and that's your tour okay so you have a quick tour of the engine let's look at some of the engine specs so the 31:26 was an engine that was designed after the 31 16 and before the c7, It basically uses the same block as both engines and is an inline six-cylinder diesel engine.

It uses a Huey system for the fuel system. Huey is a hydraulic electronic unit injector. It is an engine with three valves per cylinder. It has two intake valves and one exhaust valve. has a single turbocharger the intake is on the left side of the engine the exhaust is on the right side of the engine uses a gear driven oil pump uses a belt driven water pump has two thermostats has piston cooling jets no however , has wet liners, which is a bad thing because that makes rebuilding this engine more difficult than heavy duty engines that have wet liners; you could get anywhere from seventy-five horsepower up to 330 horsepower, it had a compression ratio of 16 to one, and These engines were made from late 1997 to late 2003.

They were actually making them. They were still making them when they started making the C7, which was the engine that replaced the 3126. So why do I like this engine? rather than say 31 16 or c7, well it has the best of both worlds between 31 16 and c7 and I'm going to discuss what I mean by that, so 31 16 most of the elements in the engine were similar as far as the block , it didn't have wet liners, things like that, but it changed its very complicated internal mechanical fuel system to the Huy system. Now the Huy system is not the best fuel system ever designed, but many smaller diesel engines at the time started using this system as a way to get away from the rack or high pressure pump that older engines used to use. , so being a Huy system, the fuel system is much easier.

More simply, there is no camshaft driving the injector, it is strictly high pressure oil, so let's look at the Huy system a bit. If you're not familiar with a Huy system, basically the engine supplies normal oil pressure, you

know

it's between 30 and 70 psi of oil pressure to something called a Huy pump, the Huy pump is in place of the 3116 governor that used to be there and the Huy pump takes, say, 60 psi of oil pressure and then ramps it up sharply from about 800 psi throughout the process. up to about 3500 psi then you supply that high pressure oil to your injectors and that pressure is used to push the injector plunger internally into the injector to fire your cylinder so you're still firing fuel obviously you're just using your oil High pressure, its pressure Huey. to turn on the injectors now, the later model, the c7, which replaced the 31:26, also had a Huey system, but there are some differences between the two and I think the 31:26 was a better system.

Well what really is the difference between the c7 and 31:26 Huey Systems, at least the ones with the Huey Round Top pump. The nice thing about the Huey Round Top pumps is that they have an external controller for the Huey pump. Why is that a good thing on later models? the top squares, the drivers internal and not replaceable, the part is not available from Cat so you would have to change it if you have a problem with the Huey pump or a problem with the driver, change the pump a little and be looking, do you?

know

s? about a thousand cat dollars for that, but if you only have a problem with the driver on the round top ones, you can change this driver and your cat dealer will pay you a little less than two hundred dollars, which is obviously a lot less than the total.

Not only is the Huey pump much easier to change and if you're wondering what's under that round top of your Huey pump, there's nothing there, a lot of people think it's a filter, it's actually just an accumulator, if any maybe you'll take it. off there's nothing there it's just used to store oil in the pump to obviously help with starting because it takes a little time to fill that pump so what other issues in the Huey system make it a little better than the models later? Well, there were a lot of Huey bomb failures in both the round top and square top, but it seemed like they were more common and could be more catastrophic in the square top, but the other thing that's good about 31: 26 and its The Huey system is the injectors, what do I mean by this?

They both have expensive injectors until 31:26, the injectors are much easier to remove, change the o-ring and backup rings more like small and change the design. the c7 injectors are much more difficult to remove than the 31:26, the problem is that the 31:26 have a more original bolt design and the ball is more expensive and you are supposed to replace them when you change the injectors but they also do not have a calibration file unlike the c7, so if you own one of these 31:26 and need to change an injector yourself, you can do so. There is no ECM programming, no trim file to change. if you're doing a single injector on the c7 s you have to worry about that, that makes them a little nicer, so this engine could have two different style oil pans, there was a seven inch oil pan and a five gallons, there is also a seven-inch, five-gallon oil pan. a nine and a half inch, seven gallon oil pan design and its maintenance intervals will be approximately ten thousand miles or 250 hours of run time per engine service and then approximately every two thousand hours or one hundred thousand miles, you're going to want to get your valve clearance adjusted and the valve clearance on this is the easiest thing without valves you could do is fifteen and twenty-five thousandths 15 on the intake twenty-five thousandths on the exhaust and that's it, there's no VAT, there's no adjusting the injector, you can do a The valve opens in less than an hour, if you are familiar with these they are pretty easy to do yourself, other than that there isn't much periodic maintenance, you have to do this other than waiting for leaks and stuff like that .

Now these have a separate V Bell Drive for your water pump than the main serpentine belts, so I'd like to see sevens where the serpentine belt drives your water pump. This will have its own little v-belt that will be on your pulley outside of the crankshaft that is going to run your water pump and you will want to have it changed if you ever use your serpentine belt and that belt can be a little annoying, not necessarily the belt , but the adjuster, is not an automatic tensioner for something like your The serpentine belt is a manual tensioner, so you have to get in there, tighten it and loosen it, and it can be tricky to also get to the bolts that can come loose or break because they go in on the front structure, those can be kind of a nuisance, other than that there aren't many maintenance issues with this engine, so speaking of problems, what are the main problems that this engine tends to have?

I already mentioned that it doesn't have wet casings, so if it's starting to consume a lot of oil or you're starting to have a lot of leaks and you're thinking about rebuilding a well that's going to cost you some money because there are no casings to remove so you're going to have to get a new short block or a long one. block or remove the head, remove the pistons and install new snap sleeves into the engine, which is not very cheap. Other problems with this engine similar to the c7, the oil pump idler gear can fail and although not very common this can cause a low or no oil pressure condition so if you ever remove the oil pan to inspect it or just look for a leak, you'll want to look at the oil pump idler gear to see if it's starting to wobble, it shouldn't have much play.

It now uses a pushrod design with the camshaft in the engine block and has followers or lifters that are bolted to the side covers on the intake side of the engine and the side covers are a big source of oil leaks if oil comes out. off the intake side of the engine somewhere, most likely coming out of these side covers. Now the bushings that hold the rollers to the lifters can sometimes fail if you have a dead cylinder or a weeks owner, sometimes it's not an injector you might have had. one of your followers fails and that will damage the camshaft and follower, so you would be thinking about getting new lifters and a new camshaft.

The biggest problem with these is that it is a huy system and huy systems can fail and injectors can fail quite a bit. they are often not cheap neither the pump nor the injectors are not cheap the lighter watt models with the square pump on the c7's tend to have a lot more problems with the pump failing and clearing all the injectors and they did something It's called a Huey kit that would replace all that, it's a game and it's very expensive. Look, almost four thousand dollars in parts alone costs to replace. Other than that, there aren't many problems, but you know you have your fan. problems and issues with your injectors and can give you a real headache in monetary terms, plus being a huy system these are not the best for cold starts or difficult starting conditions, stock rails are much easier to start on general, just like older high pressure pumps and heat pumps.

They are not or the Huy systems are not very good in cold start conditions, mainly because they depend on oil pressure to fire the injectors and of course cold oil does not flow very well and they have a bad tendency to have a difficult start. most of them have intake air heaters and that can help. You may want to turn the key on and let the intake air heater warm up for about 30 seconds before starting them, but there are still no very good cold start engines if you have one. On these engines there is one thing you need to check that has hopefully already been updated for you and that is an update to the Huey oil supply line, so between the Huey pump and the cylinder head is the Huey oil supply line and I already mentioned that the Huey oil has a very high pressure, up to approximately 3500 psi.

Well, the original oil supply line was a steel braided rubber hose that ran fromthe Huey pump up to the cylinder head and over time that hose will become extremely brittle and can crack and It can leak on you now if I were to rip it off and it can become extremely brittle and over time it can crack or leak now if I blew on you it would just explode very it would quickly spray extremely high pressure oil all over the place. you know if this was in an RV you could spray the turbo through the cabin and spray the alternator all over it is a real problem well there is a solution for this and it is your Huey oil supply line .

Upgrade the kit to take it from steel braided hose and go to solid steel line and you can repair it yourself. All you're really doing is removing the line from the Huey pump and then the connector that goes to the head and them. They're quick connects and you're going to install a bow ring boss - oh ring face connector on the Huey Pompey on the cylinder head and then you're going to install that line if that hasn't been done, if you own the engine you know these engines With almost twenty years now you'll want to do it right away and any dealer could do it for you too, but it's a job you can do yourself with a few basic wrenches and some mechanical knowledge.

Okay, that's not one of those problems, they're there, they're there. Overall the motors run well, easy to work with with very few special tools needed to do anything with them. They have an ECM that you would need CAD ET to communicate with if you want to do any kind of advanced troubleshooting, but generally you can. do most things yourself, even running things overhead, things like that are pretty easy and these are metric motors, which means all the bolts are metric, you know, 13 millimeters, 16 millimeters military, things well and that is the essence of these engines. I hope you enjoyed this video. we're going to do our wreck of the week segment now this is our second wreck of the week installment and this engine came out with a lot of exhaust smoke and this is a c7 s that's a lot of oil there's a ton of oil in this one it was going in and out. a lot of smoke from the exhaust, so when I removed the intake pipe I found a lot of oil.

This is the outlet of the charge air cooler. It has about an inch of oil. You can see it was getting pretty hot too. The inlet side of the charger cooler also had about an inch of oil on it so the next thing I checked was the turbocharger and it was full of oil. The turbocharger had failed and dumped oil into the inlet and out of the exhaust now that's a real problem because this has a DPF and the DPF was totally saturated, basically garbage, so you're looking at 3000 for the turbo, about 3000 for the DPF plus CA C cleaning + labor, so you're looking at about $8,000 total in parts and labor to repair this failed turbocharger.

Great repair, hope you enjoyed the weekend destruction. I hope you enjoyed the video, thanks for watching.