Partial overhaul on Yanmar 3TNE88

[Mechanos]

Good thread. Sorry for your troubles. Sure would like to know who and what did whatever to that engine. Do you think they ran it low on coolant and overheated it and ran it hot for lengthy periods.

Looks to me like it's just plain worn out. Probably several thousand hours of use.

[techwrtr2]

It'll be a beast when you're done.

[Mechanos]

Finally got the block and head back from the machine shop today. If you look really close, you can just barely make out the line between the sleeves and the block. Now I have nice fresh round and straight bores and I can begin the re-assembly.

[Henri88]

Can't wait to see how this rebuilt turns out. A video of your first start-up would be cool.

[Mechanos]

Perhaps it's still a little premature, but I'm starting to turn my thoughts to proper break-in. Having never had one of these new, I've never dealt with that. I've read a little... very little... about break-in oil, etc. Exactly what is the difference between break-in oil and regular oil? Also, some poeple say you should baby the engine for a while, and others say to use it hard. I do understand the importance of varying the RPM instead of just setting the throttle and running it at the same RPM all the time. Of course, that is a little more difficult with an HST tractor... or when running implements off the PTO. I do have some wood to split and my splitter is powered off the tractor's hydraulics which would require some extended run times at higher RPM.

So, chime in with your experiences and advice on breaking in a rebuilt engine. Thanks

[kuboman]

Oh man you stepped in it now.
My opinion/experience. Run it very gentle for maybe the first hour then gradually bring up the load. Varying load is more important than rpm but make sure you keep it at operating temperature. Minimal idling. One thing you need to keep in mind is that it is heat and pressure that seats the rings. If you can keep that as your aim in how you use it you will have no problem. Once you have a few hours on it don't be afraid to work it.

[Tx Jim]

John Deere engine engineers think break-in oil is very important because every new tractor has BI oil in the crankcase when it leaves the factory. Monitoring the operating temp is very important more than load.

[ThomasH]

I would urge a bit of caution here - today's diesel engines are not designed with the same operational characteristics as ones of ones that are 10+ years ago. One area they are different is tighter clearances, and differing oil requirements. Older engines typically depended more on sulfur lubricants in the fuel plus zinc compounds (ZDDP) in oil, which is not in use as much any more.

So for your startup oil, make sure you use a diesel rated oil (which will contain more ZDDP or similar compounds), and a *DIESEL RATED* break in oil is good (but not necessary) as it will typically come with more (up to 2% ZDDP).

Also, you don't want the engine to idle for the first 30 minutes, and you want to vary the RPMS, and after that do some moderate work with it for several hours. At 50 hours, change the oil and filter. Some people will carefully cut the filter open and look for metal shavings (not a good thing) but I have never bothered, and rebuilt about 100 engines with good results.

Good luck!

[Mechanos]

Well, I finally got a chance to start re-assembling the engine today. Between bitter cold weather, fighting off the flu, and longer hours at work due to two of my guys that went out on unexpected long-term medical leave within a week of each other, and emergency situations popping up at work... I just haven't had time to do anything with it. I got the speedi-sleeves installed on the crankshaft main seal and the crank pulley. I had to chuck the crank pulley up in the lathe for some minor modification to get the sleeve to sit down on the seal surface far enough.

With the crank ready to go, I got the block mounted back on the engine stand and the crank set in place and torqued down the main caps. Next to go on was the front plate that the gear case bolts to. This plate gets sealed onto the block with RTV and many of the bolts that clamp it down are the gear case bolts. So, I set the case in place and snugged it down to allow the sealant to cure overnight. Next to go in is the camshaft, but I can't put that in with the gear case in place, that's as far as I got on the block.

Spent some more time cleaning some parts and prepping them for install, straightening dents in the oil pan, pressing new piston pin bushings in the rods. It felt good to finally be making progress. Tomorrow, I hope to get the lifters and camshaft installed, install the new pistons & piston pins on the rods and get the pistons/rods installed in the block.

[Henri88]

Nice! Thanks for the up-date!