YM1700 - Engine Reassembly questions

[SailorBob]

Some of you may have seem my thread on the Parts/Repairs Forum ("Overheated Tractor - Where to start?").

I am picking up the head today from the machine shop. I had the head magnafluxed, pressure tested, and resurfaced. I also replaced the valves, springs, and steam seals with new ones. I have all of the rest of the rebuild parts as well. Anyway, I am getting ready to put the engine back together and I have a few questions:

1). I have the shop manual for the YM195. It has torque specs for the head (assuming they are applicable for the 1700) but, I cannot find the tightening order for the head bolts.

2). The shop manual does not call for any sealent on the head gasket. There was a small amount used on the previous installation. Should I use any and if so on which side(s) of the head gasket?

3) I am also installing new rod bearings, pistons, rings, piston pins, and bushings. (not cylinder liners since I believe they are still good) On the rod bearing cap end one end has a notch. I am not sure which side the notch should be on? I am thinking the notch probably helps to funnel oil into the bearing. So, I would think that the notch would be on the same side as the direction that the crank turns.

4). What type of oil should I use for the break in period. It is still very hot here and will be so for a couple of months. I was thinking about either Rotella 15W40 or Delo400 straight 40 weight.

5) How should I run the engine during break in period?

I did not intend to write a novella here. I have never rebuilt a diesel engine before and want it to get it right. Any experience insight will be greatly appreciated.

Thanks, Bob

 

[svcguy]

1) I would ensure the torque for your model, unless the engine is exactly the same as a 195. Don't worry about a sequence if there isn't one, simply start in the middle and work outward equally side by side from the middle. I like to torque in three steps with cleaned, lightly oiled bolts, but many feel it's totally unnecessary.
2) Permatex (or equiv) head gasket sealer is favored by many rebuilders, but isn't critical. Often it is thought to help seal the head against failure, especially where a scratch or slight pitting is evident. A tacky spray, you simply follow the directions on the can. A resurfaced head should pose no problems as long as the block surface has been cleaned well and you have good surfaces.
3) Ensure you run a ridge reamer around your cylinder prior to overhaul, even if it doesn't seem necessary. Pistons often have a mark on them for front. Not being familiar with your particular engine, I would think your crank is pressurized, but you are asking a very important question. Pistons and rods are directional. Assuming you have lightly honed your cylinders for the rings to seat. Always wash your cylinders after honing with ATF until rags come out clean.
4) I would definately use 15w40.
5) Different theories on break in will abound, but many have a common thread. As soon as you start the engine, try and vary engine speed as much as possible during the first few minutes without running at flat out or low idle to seat the new rings. Avoid having the engine sit at the same speed for any extended periods early in it's new life. Don't run heavy loads flat out for the first 10 hours if possible. New bearing surfaces need to run in. Close initial tolerances create heat that will subside fairly quickly. Running the engine up to 85% for the first part of it's life without full loads will probably result in a longer lasting engine. Avoid low idle and lugging an engine.

My thoughts.

 

[SailorBob]

svcguy,

I will contact Hoye about the torque specs for the head since I bought the parts from them.

The machine shop guy loaned me a nice ridge reamer. I definitely intend to use it. I will also hone the cylinders as well. The ATF fluid is a nice tip too.

I will have to study the manual and look at the pistons a little more closely. Hopefully, I can determine the front of the pistons. It could also be that the rod caps will only go on one way anyway.

I am a little nervous about putting it back together. I don't want to make any mistakes. I have a good bit of money invested in this rebuild.

I really need to get this tractor going again soon. Hurricane season is heating up and I will need the tractor for the cleanup of the aftermath if we get hit again not to mention all of the grass that needs to be cut.

Thanks for the reply.

 

[svcguy]

You don't need to be nervous. Engine overhauls are simple and straight forward, but need close attention. Torques are best done in a couple of steps to ensure an even torque to specification. Assembly needs to be carefully done so you don't knick crankshaft journals or scratch bearing surfaces. Clean, careful reassembly is within the reach of any thoughtful mechanic, professional or home. Coat all bearing surfaces with clean oil during assembly. I have had many years of experience to draw from and can assure you that if you follow the directions and give your attention to the job, you will be happy with the result. Take your time, check everything twice and relax. One word of advice, hone cylinders lightly and don't take too much out of the cylinder. You simply need a new surface to seat the rings.

Some of the finest work I have seen has been done on a persons first engine.

 

[SailorBob]

This weekend I started working on putting it back together and decided that I should go ahead and replace the cylinder liners too. The ridges were larger than I thought they were. I forget that we are dealing with tolerances in thounds of an inch. I hate to spend all the money on this tractor but, at least it should be like new when I get done. I will be back at it this weekend.

Svcguy,

Thanks for your encouragement.