That HEUI oil supply line update is CAT part # 2413782 for the 3126B and is around $60

Another place I enjoy listening is when I’m driving. I think being a good truck driver, more so for owner ops, is to know Diesel engines. Even if I drive a Detriot , I wanna understand the ins and the outs of the engines. These types of videos should be mandatory to get a Cdl. Just my 2 unsolicited cents. No refunds and the complaint department is closed...forever.

I love the Destruction of the week segment you put in your videos. Very intresting

I like the destruction of the week segment in the videos... kinda cool seeing the different kind of repairs you run into.

Thank you for taking the time to post of these videos sharing your knowledge. I have a Freightliner m2 106 with a cat 3126B. It died on me driving down the freeway. I figured it was the Huei system but it ended up being the ECM. I had the codes read since mine didn’t show any codes on the dash and I had all 6 injector codes. One of your videos said if I had those codes it was most likely the ecm. I pulled the ecm and took it to cat for them to test it. It was bad. After the testing old and programming the new ecm it was just under $5,000. I installed it today and my truck fired right up!! Thanks again!!!

Your channel kicks ass. Just bought my first dump truck and it has a 3126. Don’t know crap about engines but I’m sure you’ll help.

Good job,you are here to help people thank you for that :)

Oooo, awesome to have this overview of the 3126! I only wish mine was as easy to access as the one you show in the video. Very cool, man

Makes me happy I retired from the field in the 90's. I understand the hi pressure systems but not this newer stuff. But cool to learn something new.

Thanks for the very basic info on the engines and quite educative

Only recently my Cat dealer installed the "HEUI oil supply line update" to my Safari Zanzibar motor home with 3126B engine during some routine maintenance I had it in the shop for. Glad to know that is done now!

I just saw a GMC Topkick for sale with one of these engines in it. So if I decide to go check out the truck, now I know what to look for. Many thanks. 👍

That helps a great deal in understanding the components and sensors. What was especially critical was the possible turbo oil line failure. I have seen a number of RV's that had engine fires. This is very important to check. Thank you.

I like the way you explain things brother. Very professional , and matter of fact. Thank you for reminding us about the oil tube steel tube.

Good video. It's nice to know about an engine that I haven't had any experience with. There's one engine that really impressed me that I got to run for 3 days. The 3176. If you have a video on that, please point me to it. If not, you should do one if you get the chance. What impressed me was that the transmission stuck on the high side on my last trip with that truck, and the engine had very little trouble starting up a hill with a full load. It pulled like an electric motor. While it wasn't ever gonna win any races, I found it amazing that the engine was able to get the truck moving without burning the clutch to ashes.

I really like this video I’ve recently discovered I have a 3126 on one of my fleet freightliners thanks for telling me a lot of the problems that I may be facing

hey josh. my boyfriend and i recently purchased a school bus in order to convert it into a livable rv type situation. the bus is a 2004 freightliner thomas built with a 7.2l inline 6cyl 3126 connected to a 6spd allison tranny. ill cut to the chase, i know nothing about automotive anything. my boyfriend on the other hand is well adept in many skills. one of those being automotive. however, this is his first diesel engine. upon purchasing the bus, it had no noticable engine issues or electrical issues. since owning the bus (4 months in) we began having minor issues such as radiator leak at the top where the inlet hose is located, alternator charging issue and now electrical. my bf was able to find and replace the alternator. we are still having electrical issues i.e. strobe lights blown out, rear tail lights and reverse lights not working and also a dull front right side head light. my bf checked all the fuses, replaced the ones that blew and also replaced some relays and bulbs for good measure. he has been chasing wires and is starting to "loose his shit" his words, not mine. he has been trying to find wiring diagrams as well as anything refering to a 3126 school bus. he has continued to run into roads blocks. we are located in los angeles (which is not diesel friendly). if there is any way you can help us, that would be amazing.

EXcellent Info really needed this Thanks

Destruction of the week is kind of depressing ! Great video thank you for these I am planning on purchasing a 1999 freightliner with on of these in it

Thank you for the education! I’m about to buy a 2001 Thomas bus with the Cat3126 and AT455 transmission.

Thanks for sharing the info on the 3126 ! We have one that has some " blow by " and power loss and trying to decide on rebuilding it .

Hey buddy thanks for this video that’s the same engine I have on my truck and I love it and I totally agree with you is easy to work all the way around before this truck I have a 1994 International with a navistar engine it was my first truck and I was getting crazy with it every time I have to fixed. Now I got this 2002 kenworth T300 with a Cat 3126 and it became my favorite engine I would never go back. Cat engine 💪👍.

Great info. Subscribed.

I would have to say the biggest pain with the water pump v belt on a 3126 is getting it over the balancer. The belt is smaller then the balancer and you have to stretch it around it. Not much room to work between the front balancer​ and the radiator in an 03 GMC topkick C7500 with a 3126 shoe horned into it. Great videos keep them coming

Great Sound !

The 3126A was a MUI system... Not HEUI. It was in equipment. But yes, it was a stop-gap between the 3116 and 3126B. Also... run a quality synthetic oil. Cold start issues are much less. -35°F at 5900 foot elevation starts are possible if the intake heater is working and your batteries are good. Same applies for a 7.3L Powerstroke/ t444e International

I believe you said up to 330 hp. All literature says the 3126B engines in my 2002 Cabo boat are 450 hp. Early years, I cursed them some, such as when on a trip I had to replace a failed HEUI pump. However, during the past 15 years I leave North Florida running the boat far down the Abaco chain and home with hardly ever any problem, often logging over 1000 miles per trip. In past 15 Engines are meticulously maintained by one skilled diesel mechanic I settled on and no one else has touched my engine in the past 15 years.

great video, thanks

Very good as I consider buying a 9-98 built Freightliner bus with a 3126 and AT545. Thanks.

I use to think the Heui system was sketchy until I bought my 99 7.3 Powerstroke 1 ton dually. The Ford system came from the Cat design. This year (2023) the HPOP started leaking oil very bad and I was forced to fix it. I did all the work myself including new o-rings for the turbo pedestal and turbo and new oil lines and I've got to say the Heui is not that hard to work on after all. My 99 now runs like brand new. It did have a slight miss prior to doing the work and now its fixed. The Hpop wasn't bad by the way, it only need to be removed cleaned and resealed. The Injection Pressure Regulator was also re o-ringed and this stuff is all original parts. The system is damn good in my opinion but it helps to understand how it works. Clean oil and oil changes are very important in these systems. The reason I watched this video is that I'm looking at a motor home with the 3126 motor.

Great videos keep it up.

Hi @Adept Ape, Your video on Caterpillar 3125 engine was a breath of fresh air. In fact your channel is just what I was searching for. I own a 15 tonne 2003 Ford F750 truck with Caterpillar 3126B engine. In where I live it is not a common engine, so getting local mechanics and advice on problems is a nightmare. Please I need your advice urgently. Normally my engine comes on and steams fine without problems. But then I had some nozzle problem and had to "snuff" with petrol to start it. Later I had an accident in which the truck fell on its side. After setting it upright I noticed that after filling up the radiator with water it vanishes without any outward sign of leakage. We started it but it would not steam if I took my feet off the pedal. Also the oil was whitish, as if mixed with water. I was told by mechanics that it was either a top cylinder or gasket fracture. And oil had flowed on top the pistons. We have since replaced the gasket after checking that no visible sign of fracture is in the top cylinder. Fixed, cleaned and coupled the cylinder, nozzles and valves back in place but here's the situation am facing: 1. My engine is starting and steaming very well, but bringing out a steady stream of light steam via the breather when it is switched on. 2. The water slowly vanishes from the radiator after switching off even if it was just filled up fully. 3. When I gauge the oil. I find it is whitish again. Although I don't notice any drop or increase in the oil level. Can you please advice me on probable cause? A mechanic suggested that there's a minor leak due to missing gasket oil seals. What do you say about that.

Great content! I’m doing Engines right now.. Caterpillar C7

I just bought one of these engines and I am totally stoked to hear you have a good opinion of it. Allegedly it has 200k kms and it was in a fire when the car next to it burnt. Looked bad at first but as I clean stuff i't starting to look better and I now think I might get it running! Looking for a wiring diagram to see what pins need power and ground on the computer...

Good stuff!

Thanks for the video man

First off, great video! Love when I see a new video post. Second, is there any way we can see more 'nuts and bolts' videos. I dont know if I missed anything in regards to it. I know its probably harder to do it while working. Again thanks for the videos, keep up the good work!

Very good

Great video. Have you ever known anyone using sea foam in the oil 100 miles before a oil change to clean the oil&heui system?

Goodday are you able to give the correct difference between the 3126-B and the 3126-E and what's needed to change so it can work? Kind regards.

Would you happen to know where I can find the high pressure ac sensor on my 3126b freighliner FL70 totor home. The Collings fan is stuck on and I am trying to trouble shoot all possible causes

I ve the 3126 in a 2002 bus. 385000kms. been very good engine. change oil every two months 3000kms. wish i could buy a brand new one.

Get a block heater or diesel heater (webasto) to for cold starts. Can pull Webastos off of school buses at scrap yard. Will heat the entire block and your interior within a few minutes in freezing temps. Nice hot start ups.

How to avoid destruction of the week in vids would be lit 🔥

and i love Destruction of the week

Great Video, however I have marine application of the 3126 model, do you have any videos on marine uses. There are slight differences.

How hard is it to change the dry liners in the 3126? Did not realize that this had the dry and have started rebuilding yesterday. Do you have a video on removing and installing the dry liner?

That engine with the blocked DPF should have been throwing a heap of codes long before it got to that bad I would have thought. Any chance the DPF blocked first and the increased back pressure blew the turbo oil seal so the problem went from bad to worse. Cheers mate🍻

Anybody else go to the gym and listen to apes videos ? Getting an education and working out at the same time.

I have a round to on my 3126 1998 it the first engine 3126 so it's different. I put a new huhi pump less than 100 hours ago. It was running fine except for surging when idleing.. this morning it was below freezing and it's not starting. It was 24 degrees so hopefully start after it warms up.

What do you think or know about the International dt 466E heui engine?

I was wondering if you have any info on converting the 3126 to run on vegetable oil?

Josh I have a 3126 in a beaver motorhome. What is the critical heat range that would hurt the engine? It's been up to 212 degrees pulling hills.

I have a 99 3126B I think it’s the 275hp engine. Is it better to chip them or program more hp in these? Thanks

Brother Man U have a lot of knowledge on a lot of diesel.

Thanks for your video! Looking to add more power to my pre-1998 3126 RV. Any advice?

I am looking to buy a FL80 with the 3126 engine. Of the 2 models of the 3126 is there a big difference between a B or E motor?

Cool video. I was wondering what is the BIGGEST engine cat ever put in a over the road truck/ heavy haul? Do you have a video on KZfaq for this subject? Thanks Ray

loved my 03 frieghtliner fl-80 with the 3126 at 1800 rpm running 63 mph got 11 mpg out of it wish i still had that old truck only problem is letting it idle 5+ hours when you start going again it would blow tons of whitish blue smoke for abought a mile till it burned off was pulled over in VA once the officer thought i was on fire told em naa its just smoke it'll clear up in a minute he let me go but followed me till it cleared

My brother inlaw has this engine in is motor home recently it got washed at a truck wash in canada where they sprayed high pressure water underneath the vihecle, ever since then he has been having electrical issues including an engine stall when he shift it to reverse any ideas?

Great video! I learned a lot. I am a new owner of a Cruisers 39 and it has two Caterpillar 3116TA engines. I have tow basic questions: the first is, where can I locate the dipsticks? The second question is: where do I add oil, if needed? The previous owner always used 15W - 40. I assume that is a good weight of oil for North Carolina. What are your thoughts?

How would I go about bypassing the breather catch can on a 2006 c7

I enjoyed it alot i just bought a 1998 chevy 6500 rollback towtruck with the cat 3126 looking for a little more power and any fuel saving tips if there is any i watched about 7 of your videos your very good at explaining things thanku again

Hey can you post a 3126b uprate ability and comparison chart for the 8YL?

I have a problem with my cat 3126 I was changing the injector # 4 and one of the bolt falls in to engine and any help with any suggestions

Hey hey @Adept Ape! Love your videos! Very informative & we appreciate you! QUESTION: We have a CAT 3126 on our '97 Thomas Saf-T-Liner bus and the engine wouldn't start the other day in freezing conditions. The lights on the dash light up like normal, but when turning the ignition to start, it didn't even sound like it wanted to turn over. We took the batteries to Napa Auto Parts to get tested and they were both at 12.2 volts (the tech said they needed to be at 12.6V, so we bought a 10A battery charger, which we're waiting to arrive next week.) Do you think the COLD is the main culprit? Or do you think the alternator could be an issue? What do you think we should check to diagnose the main issue? Once we get the battery charger, we'll charge the batteries indoors where it's warmer and then put them back in to see if it starts. We're not running the engine much since we are still doing our school bus conversion. We searched your channel for alternator diagnosis but didn't find any video on it (if you do have a video, could you please drop a link here in the comments for us? Any tips are much appreciated! Thanks so much! - Brian + Erin

I'm considering buying a 1986 Ford L-8000. It has a CAT 3208. If a had catastrophic failure with the 3208 would the 3126 be a reasonable candidate for a swap?

Do they make a power steering rebuild kit for 3126 e

I have a 01 Thomas bus with a 3126b210. Can i rerate it up a little or is 210 the highest I can go? Thanks for the great videos

What's the difference in the 3126 and 3126B, it's a 2001 in a 38ft sportfish. Thanks

Are the 1996 model engines an actual 3126, or are they a "cross-over" engine? I've got a 96 Motorhome with a 3126 in it and am curious.

"HUEY" (SP) System. What does Huey stand for? At 130,000 mikes of light load driving, what mentioned problems are likely? Thanks.

How about sharing what makes the air cooling fan clutch go on and off there is a switch on the firewall but how does it get the signal from a temp sensor or from the ecm. Thanks you real do nice videos

Are there any scan tools that will read the huei PIds? Or do I need the cat scan tool

Great videos Josh. Wonder why Cat has not O ringed (in place of gaskets) the places where oil leaks are most prevalent? This would solve all of these issues.

Have you had trouble with #5 cylinder breaking rings?

Hi i got C12 i just fully rebuilt that Eng but oil pressure is stay 15-18 psi @600 rpms when water temp is 185 is this normal oil pressure?

Good video. Wonder how long the guy drove pumping oil out the exhaust before he noticed?

Thanks for sharing your knowledge...have a question..recently bought a 2003 fl70 with the 3126, noticed there's a bit of oil in the coolant, thinking it might be the oil cooler however am in little bit of doubt ( also thinking it could be the head gasket) reason being on higher speeds the temperature increases to the point where the fan kicks quite frequently. At lower speeds 70 kph and under seems to be okay. Your thoughts?

I've seen a 330hp 3126 melt the exhaust brake butterfly valve nearly shut in a motor home application. Had low power/Smokey complaint.

i have a 2001 Chevy C6500 with a cat 3126. it has 470k miles and runs like a champ. sucks on power, but it runs good. being with so many miles i am cautious about bumping the hp tune up. i found a 3126 locally for $500 and i am thinking about doing a 350hp turbo build. not sure exactly what hp i have now

I have a question I have a 2003 Freightliner fl-70 and it has a Caterpillar 3126e and I found a caterpillar caterpillar 3126b can I use the b engine in place of the 3126e or can I use the block or head what is usable and what is different any help would be appreciated thank you very much

I have a customer with a 2000 3126b 210 hp. They found a school bus with a 2001 3126e with adv. 190 hp and a max of 246 hp. Without knowing the engine family of one of the engines is there a way to tell if the 3126e is interchangeable to they're truck with the 3126B ?

C7 engine runs good when it starts. Will not start if oil pressure does not show on dash gauge. After a few times trying to start the engine the oil pressure will finally show on the gauge and the engine will start. Any ideas???

what cause fuel knock on first start up on 3126??

My topkick c7500 with this motor in has started to loose power going up steep grades, no engine light, no rough idle, just spits and sputters a little bit when going up hill... any ideas guys ?

Is the Heui oil supply line update harder to install on a square top Heui pump. Our 2003 Newmar MH has a 3126E HEP08621 with the sq. Heui pump. If the pump should fail can it be replaced with the round top. Thanks.

Oh LORD you are a wealth of knowledge. Can someone help. I have a 2002 Thomas built 3126 cat it was idling rough with white smoke and the next day it would not start, I opened the dog house to hear the motor while cranking it, I heard a clicking when cranking and when I turned the key off it made a ding noise. Any help is surely appreciated.. Thank you

Lucky that engine didn't run away on him with that much oil going in! Seems the 3126 always needs its oil cooler o-rings (and subsequent gaskets) replaced around 100K. I actually liked the little water pump v-belts cause I could keep on going if the fan/ac/or tensioner pulley/belt failed......just don't stop and idle, or run the batteries dead! My Louisville rollback put 250K miles on its 3126 before the coolant started to pump out the de-gas bottle......suspected a headgasket or maybe cylinder cavitation pitting?......paid nothing for her and sold her for nothing, but got many years of reliable running with only a bad lift pump and oil cooler leaks for repairs.

Great video. I’m looking at a motorhome with this engine. The owner said the engine has larger injectors and has been tuned to 390 horsepower. This makes me want to walk away from it. I get nervous when engines are TUNED. Is this a common upgrade in the 3126? Again Thanks for the great information

How do you change the oil pump in a 3126 cat engine adept ape?

Hello, I have a 1999 Chevy C6500 Cat 3126 Engine. Having a issues with lost of power when check engine comes on, also ruff idle, any suggestions.

My cat deal parts department has no clue about the line update.do u have a part#

@Adept Ape what would cause coolent in oil and exhaust in a early 3126

Currently stuck in the desert with an overheating 3126 due to the fan not kicking on high at 220F. Spoke to several people and the consensus was stuck thermostats. Found some several hours from where we’re at and replaced them today. Took it for a test drive and now our coolant gauge on the cluster isn’t working. Please help!

Do you have any thoughts on the 3176?

Hello, i changed the injectors on a 3126b all was ok and after a week when is hot it whount start i must wait until is cold then starts quick, can you tell me what to do next

Great video dude. Correct me if I'm wrong, but I believe it wasn't 175 HP as low hole, it was 170HP. 330 was right as high end Apps.

How do is trouble shoot no crank maybe neutral safety gone bad or even ecm?

I have to say, I really dislike the HEUI injection system. On two occasions in 3 years (in different trucks, but same make/model), I've had problems with this system. The situation was: 1. I got a low oil pressure light and buzzer (but no rough running, misfires or check engine light); and 2. the engine shut down 30 seconds later (on a busy highway, no less - thankfully I got to the shoulder just as it quit.) Got a tech to come and take a look - no sign of leaks, no oil in the exhaust or intake, nothing in the radiator, no problems with turbo seals, not blowing smoke...but the crankcase was definitely empty. He put about 7 gallons in the engine and sent me on my way. 20 minutes down the road, the same problem - all the oil was gone again. Got it towed this time. The result: next day, the tech at the workshop told me it was the high pressure oil getting past an injector seal and being pumped down the return line into the fuel tank to mix with the diesel. Maybe I'm just unlucky...but I find I'm a bit leery of the HEUI system these days because of these experiences. PS: Great videos, mate - love how you bring a good amount of detail to the table, instead of the usual youtube overviews. Awesome work. :-)