Cat 3126 Rebuild Odyssey

Topic: Cat 3126 Rebuild Odyssey (Read 3559 times) previous topic - next topic

Cat 3126 Rebuild Odyssey

August 28, 2018, 08:02:37 pm

Hello All
Been a while. This is how I spent my summer, besides racing.
Never imagined in my wildest dreams, I would be this deep into our coach.
Two trips south, and it starts smoking like Cheech and Chong out the blow by pipe. Didn't spit any oil out, just lots of blue smoke, but zero out the tail pipe.
We could have lived with that, but 1 qt of oil every 75 miles was a bit too much.
So down to the nitty gritty. The Caterpillar 3126 2 valve engine was a one year only motor in 1996/1997. They had a tendency to break piston rings. Many were fixed under warranty back when they were new.That is what happened to our motor. At 115K, it broke # 6 oil ring.
It scared the cylinder wall so bad, it was beyond repair. May have been this way for a while, but just got worse. Who knows.
So out comes the block to get sleeved. Sad, because the motor is perfect inside. Looks brand new. No codes, no loss of HP, no loss of boost. Just smoke and oil consumption.
The head also had a minor crack, but wasn't causing any issue. So rebuilt turbo, new rings, bearings one new piston skirt (they are 2 piece) and a good donor head which was rebuilt. We will now be as good as new (or better). Also replacing all the hoses, coolant & belts.
Head is done, block has new sleeve. Waiting on machine shop to finish the boring of the sleeve, and honing all the cylinders with the honing plate in place.Then a hot tank job.
I am a freak when it comes to engine detail, so every part has been cleaned and painted.Engine bay is cleaner since I took the pic shown.
More news and pictures later when she is back together running.
Chris

Re: Cat 3126 Fail

Reply #1 – August 28, 2018, 08:28:00 pm

Looks good.

Re: Cat 3126 Fail

Reply #2 – August 28, 2018, 08:28:50 pm

Cat, the gift that keeps on giving. It's looking good. 👍

Re: Cat 3126 Fail

Reply #3 – August 28, 2018, 08:33:53 pm

So, you did have the block (cylinder #6) bored and then an insert/sleeve installed. So, back to OE spec (vs something like .030 or .040" over)?

Good job.

Re: Cat 3126 Fail

Reply #4 – August 28, 2018, 08:36:15 pm

Good for you! If the coach was a SOB, most of us would tow it to some vacant lot and rent it out. Not with a FT!

Re: Cat 3126 Fail

Reply #5 – August 28, 2018, 08:46:38 pm

Quote from: wolfe10 – August 28, 2018, 08:33:53 pm

So, you did have the block (cylinder #6) bored and then an insert/sleeve installed. So, back to OE spec (vs something like .030 or .040" over)?

Good job.

Yes. I could have had it bored in the coach. It would have taken a 50 thou piston, and that was cutting it close (pun intended). But only 40 thou max piston is available. Couldn't even get one made.
It will be right now.
Chris

Re: Cat 3126 Fail

Reply #6 – August 28, 2018, 08:49:36 pm

Quote from: mike leary – August 28, 2018, 08:36:15 pm

Good for you! If the coach was a SOB, most of us would tow it to some vacant lot and rent it out. Not with a FT!

Even at that, I considered a nice river property, for it to live out it's life. LOL....So many people said trade it off. But I would never do that to anyone.
Told my wife, "We can't sell it this way, and we can't use it, so we need to fix it"
The people I bought it from, stopped by this summer in their new FT, and it bummed them out. It wasn't their fault. 1st trip south it was fine.
We'll be all in at 3K for everything, and we'll have a fresh engine. Cat wanted 20K. Going to spiff my buddy a few hun for helping. But we have been trading work anyway
Best part is, it's so easy to work on. Lots of bolts and parts, but not really rocket science.
Seeing the motor inside, it's pretty basic, and well thought out. With it's roller lifters etc.

Chris

Re: Cat 3126 Fail

Reply #7 – August 28, 2018, 08:58:03 pm

Quote from: bbeane – August 28, 2018, 08:28:50 pm

Cat, the gift that keeps on giving. It's looking good. 👍

Cummings have their issues too. Many have cracked blocks and heads. Not un-common....
Remember, if you have a motor home, you have a problem, you just don't know what it is yet!

Re: Cat 3126 Fail

Reply #8 – August 28, 2018, 09:10:32 pm

Quote from: gracerace – August 28, 2018, 08:58:03 pm

Cummings have their issues too. Many have cracked blocks and heads. Not un-common....
Remember, if you have a motor home, you have a problem, you just don't know what it is yet!

Yep you are correct. It's all fun and games till you get tired of the negative cash flow😬😎

Re: Cat 3126 Fail

Reply #9 – August 28, 2018, 10:17:13 pm

Comp cam, a little port work, bigger turbo, methanol injection and give Barbie a run for the money!

Re: Cat 3126 Fail

Reply #10 – August 28, 2018, 10:29:26 pm

Quote from: Racedad – August 28, 2018, 10:17:13 pm

Comp cam, a little port work, bigger turbo, methanol injection and give Barbie a run for the money!

LOL...Great minds think alike!
And a bigger converter,some deeper gears and a transbrake!

Re: Cat 3126 Fail

Reply #11 – August 28, 2018, 10:31:11 pm

Quote from: bbeane – August 28, 2018, 09:10:32 pm

Yep you are correct. It's all fun and games till you get tired of the negative cash flow😬😎

Life IS a negative cash flow....

There are NO pockets in caskets.

Re: Cat 3126 Fail

Reply #12 – August 28, 2018, 10:49:49 pm

Those baby cats are trouble. I wish they used 3406's in our RVs.

Re: Cat 3126 Fail

Reply #13 – August 28, 2018, 11:00:18 pm

3406 might be a bit too heavy.

Re: Cat 3126 Fail

Reply #14 – August 28, 2018, 11:45:54 pm

Quote from: bbeane – August 28, 2018, 11:00:18 pm

3406 might be a bit too heavy.

About 1000 lbs more than a M-11

Re: Cat 3126 Fail

Reply #15 – August 29, 2018, 09:39:21 am

Great. With my coach # being only 2 newer than yours, our engines were probably delivered to FT in the same shipment. I just passed 100k miles so your story & pics give me something new to worry about for a while. You had mentioned to me in the past that you had this issue but I didn't realize it took that much tear-down to fix it. I don't think I could attempt the repairs myself so I hope I never have to make that decision. Hat's off to you for tackling it.

Re: Cat 3126 Fail

Reply #16 – August 29, 2018, 10:11:24 am

Quote from: bdale – August 29, 2018, 09:39:21 am

Great. With my coach # being only 2 newer than yours, our engines were probably delivered to FT in the same shipment. I just passed 100k miles so your story & pics give me something new to worry about for a while. You had mentioned to me in the past that you had this issue but I didn't realize it took that much tear-down to fix it. I don't think I could attempt the repairs myself so I hope I never have to make that decision. Hat's off to you for tackling it.

I wouldn't worry. As many people that don't like the Cat, there are plenty that do. The 3126 engine is a good durable engine if maintained properly.Oil changes are most important because of the Heui pump.
They got a bad rap, and are called "Throw away motor's" because they don't have cylinder liners. If they did, it would have been easier to do the repair.Easier to rebuild for truckers.That doesn't make them throw away, it just means they have to be bored or sleeved out of the coach or truck.
I don't run it hard,service the heck out of it. It pushes the MoHo fine.
Like I said, the engine looked like new inside, it was just a broken ring.Just a bad deal.
Chris

Re: Cat 3126 Fail

Reply #17 – August 29, 2018, 10:46:15 am

The PO might have used ether on a warm engine, easy way to break a ring. After changing fuel filters, many are tempted if it does not start right away. Ring land wear is greater on engines with few oil changes and can allow the rings to flex beyond the breaking point with ether.

Pierce

Re: Cat 3126 Fail

Reply #18 – August 29, 2018, 10:51:42 am

Did you have to remove the rear cap? I think mine will come out the bottom if I dig a hole.

Re: Cat 3126 Fail

Reply #19 – August 29, 2018, 11:19:56 am

Quote from: Old phart phred – August 29, 2018, 10:51:42 am

Did you have to remove the rear cap? I think mine will come out the bottom if I dig a hole.

I'm about to experiment with our U300 and make a cut on both sides next to the engine door and right underneath (where you can't see it) the aluminum strip that goes around the corner. I will lay some glass over a 1/8" flat bar that will also go from the engine door and then around the corner. The bumper (everything below the engine door can then be removed and then everything taken out of the way so the engine can be worked on or removed. Screws under the trim will partially keep it in place and the existing screws on each side also making it very secure. Pretty easy modification.

Pierce

Re: Cat 3126 Fail

Reply #20 – August 29, 2018, 11:28:00 am

Quote from: Pierce & Gaylie Stewart – August 29, 2018, 11:19:56 am

I'm about to experiment...

You will, of course, post photos!

Re: Cat 3126 Fail

Reply #21 – August 29, 2018, 09:54:41 pm

Quote from: Old phart phred – August 29, 2018, 10:51:42 am

Did you have to remove the rear cap? I think mine will come out the bottom if I dig a hole.

Came right out the back, plenty of room with the head off, made a custom cradle. Took the oil pan and oil pump off 1st. Going to completely assemble the engine, turbo and all, just no pan or pump. Installing with a fork lift. We measured it, plenty of room.
I converted a place on the back of my car hoist with a platform, to assemble it.
Crank in, roll on side, piston's/rods in, stand straight up complete assembly. Then put the bell housing on, hanging off the end of lift
The crank is flush with the bottom of the block
Chris

Re: Cat 3126 Fail

Reply #22 – August 29, 2018, 10:00:55 pm

Quote from: Pierce & Gaylie Stewart – August 29, 2018, 10:46:15 am

The PO might have used ether on a warm engine, easy way to break a ring. After changing fuel filters, many are tempted if it does not start right away. Ring land wear is greater on engines with few oil changes and can allow the rings to flex beyond the breaking point with ether.

Pierce

You never know, but it has a great fuel primer, so that is never a problem. It has been a southern coach, Texas and California all it's life. Always starts easy in sub zero here
PO owner has 50 tractors, he is pretty smart about diesels on his farm.
Chris

Re: Cat 3126 Fail

Reply #23 – August 29, 2018, 11:35:03 pm

My 3208 cat was only a little grumpy, when i had to fire it up in an emergency, block heater not plugged in, no ether, 15 outside. It's going to be in a 40+ heated insulated coach house from now on.

Re: Cat 3126 Fail

Reply #24 – August 30, 2018, 02:10:14 pm

Quote from: Old phart phred – August 29, 2018, 11:35:03 pm

My 3208 cat was only a little grumpy, when i had to fire it up in an emergency, block heater not plugged in, no ether, 15 outside. It's going to be in a 40+ heated insulated coach house from now on.

The 1st winter after our purchase, we sold our old coach. Part of the deal was they got to store it inside our heated shop.We leave at Christmas anyway.
I find if I use the block heater, it actually starts harder. The block heater warms the engine enough the "wait to start" feature turns off (plenum heater). So then it's a bugger to get running.

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