• FIRST AND LAST NAMES ARE REQUIRED WHEN REGISTERING

M18 Inspection

IH Cub Cadet Tractor Forum

Help Support IH Cub Cadet Tractor Forum:

jchamberlin

Well-known member
Joined
Jul 19, 2010
Messages
1,842
Location
Farmville, North Carolina
displayname
Jeremiah Chamberlin
Pic 24 Split Ball Gage set
253844.jpg


If you’re like me, you had never heard of one of these instruments until the Kohler Service Manual mentions them at p. 10.7 under the heading “Valve Guides” where it reads, “To check valve guide to stem clearance, thoroughly clean the valve guide and, using a split-ball gauge, measure the inside diameter.” (emphasis added)

Valve Guide Dimensions
Specifications in Manual for M18, p. 1.9
M18 Ream to 0.3125"
M18 I.D. Max Wear Limit Exhaust 0.007"
M18 I.D. Max Wear Limit Intake 0.005"

Found, Max Wear Exh: 0.0061" on #1
Found, Max Wear Int: N/A

Valve Guide Dimensions 2/8/13
Side #1 Inches
Exhaust, Top 0.3119
Exhaust, 1/2" Up 0.3159
Exhaust, Bot 0.3186

Intake, Top 0.3113
Intake, Bot 0.3113

Side #2 Inches
Exhaust, Top 0.3104
Exhaust, 1/2" Up 0.3104
Exhaust, Bot 0.3104

Intake, Top 0.3123
Intake, Bot 0.3123

All but one of the guides are within specification. The guide for the exhaust valve on cylinder #1 is fairly wallowed out on the bottom, a result, I expect, of carbon buildup on the valve stem. The crust of oil emanating from the combustion chamber around the guide was quite evident in valve spring “galley.”

Pic 25 Exhaust Valve #1 (Dirty)
253845.jpg


Pic 26 Exhaust Valve #1 (Dirty, rotated 90 degrees)
253846.jpg


Pic 27 Exhaust Valve #1 Clean
253847.jpg



Valve Dimensions
Specifications in Manual for M18, p. 1.9
M18 Exhaust Valve Minimum Stem O.D. 0.3088"
M18 Intake Valve Minimum Stem O.D. 0.3103"

Valve Dimensions 2/8/13
Minimum Maximum Clearances
Side #1 Inches Inches Top Mid Bottom
O.D. Exhaust 0.3094 0.3094 0.0025 0.0065 0.0092
O.D. Intake 0.3108 0.3109 0.0004 0.0004 0.0004

Side #2 Inches
O.D. Exhaust 0.3094 0.3094 0.0010 0.0010 0.0010
O.D. Intake 0.3107 0.3108 0.0015 0.0015 0.0015

The manual tells us to calculate the clearance using the largest O.D. of the valve stem, and if the valve stems are within specification, to replace the guide. All the valve stems are within specification.

It is important to clean the valve stems, and if possible the guides to get a valid measurement. Although, in the case of Exhaust Valve #1, the wear was evident before the jug was cleaned up.

Conclusion: So where does this leave us?

I found the greatest wear at:
1. Main Bearings (Taper out of spec)
2. Connecting Rod Journal at the Piston Pin (out of spec)
3. Cylinder Bore (Taper for #1 was out of spec)
4. Valve Guides (Exhaust #1 out of spec)

Everything was within or at specified tolerances. I expected to find much greater wear at the “Big End” of the connection rod, not the small end. I also would have expected the rod’s journals to wear out well before the main bearings, but such was not the case. I guess the taper n the cylinder and the wallowed-out valve guide are things to be expected. I would have thought that each side would wear evenly, but I suppose differences in carburetion are to be expected, there also may have been some cooling issues on Side #1 of which we are not aware.

I’m not sure where I will go from here. A large part of me wants to touch a hone (just touch it), replace the rings, the valve guide for #1 Exhaust valve, the main bearings, throw it back together and call it a day.

I’m interested in confirming or opposing opinions.
smile.gif
 

jchamberlin

Well-known member
Joined
Jul 19, 2010
Messages
1,842
Location
Farmville, North Carolina
displayname
Jeremiah Chamberlin
Pic 20 Bore for Cylinder #1
253853.jpg


Pic 21 Bore for Cylinder #2
253854.jpg


Cylinder Bore Dimensions
Specifications in Manual for M18, p. 1.8
M18 I.D. Max Wear Limit 3.128"
M18 I.D. Max Out-of-Round 0.002"
M18 I.D. Max Taper 0.0015"

Found, Max Wear: 3.1267" #1 Top
Found, Max O-O-R: 0.002" #2 Mid
Found, Max Taper: 0.0019 #1 Side

Bore Dimensions
Side #1 Inches
B-Top E-F2R 3.1248
B-Top E-T2B 3.1248

B-Mid E-F2R 3.1244
B-Mid E-T2B 3.1254

B-Bot E-F2R 3.1262
B-Bot E-T2B 3.1267

Side #2 Inches
B-Top E-F2R 3.1245
B-Top E-T2B 3.1256

B-Mid E-F2R 3.1253
B-Mid E-T2B 3.1233

B-Bot E-F2R 3.1253
B-Bot E-T2B 3.1239

Most of the measurements are within specification, the exception being taper on cylinder #1, which is 0.0004” over the limit. The bores are not “worn out,” although the top of cylinder #1 is getting close to the limit (3.1267” vs. 3.128” specified); and the out-of-round dimension for the middle of cylinder #2 is right at the limit 0.0015”. I’m afraid that if I try to hone them, I might make them worse, and by the time the –new– rings break in, the cylinders will be out of spec. Yet it seems premature to go to 0.0010” over for the pistons and the bores, not to mention the expense of the machining and all that could go wrong on that score.

Pic 22 Snap Gage Set 01
253855.jpg


Pic 23 Snap Gage Set 02
253856.jpg


A word about the instrument used for this measurement. I discovered that there is a “trick” to using the “snap (or telescoping) gage. This instrument was used to get the larger the internal dimensions given in this inspection which the feeler gage or Plastigage couldn’t capture. Theoretically, one should be able to place it in the bore at 90 degrees at the longest span and remove it and take the measurement with a micrometer. However, try as I might, I could not lock in a measurement using this method. Almost every time I would tweak the instrument in the barrel while tightening it down, and the snap gage would wind up with an extension slightly less than the maximum span. Very frustrating.

I hit upon the following method, implementing some advice from an experienced machinist to “tip it in.”
1. Set the gage in the barrel at 5 to 15 degrees angle from vertical
2. Preload the gauge so that it will “take a set” by tightening the stem slightly
3. Bring the gage to vertical and continue “over center” until the point at which it frees itself and can be removed from the barrel.
4. With the gauge out of the barrel, finish tightening the stem
5. Return to the barrel at 5 degrees from vertical and repeat motion through vertical: the gage should retain its “set” or “repeatability” and can now be measured (outside the barrel) with the micrometer to the same level of “feel” achieved in the barrel.
6. In the course of measuring, if any doubt occurs as to whether the “set” is lost (as when over-tightening the micrometer), the gage can be returned to the barrel and the “feel” confirmed.
I don’t know if this the “correct” way to use a snap gauge, but it worked for me. I felt more confident in my measurements, and they were easier to make once I pre-loaded the gauge.
 

jchamberlin

Well-known member
Joined
Jul 19, 2010
Messages
1,842
Location
Farmville, North Carolina
displayname
Jeremiah Chamberlin
Pic 12 Mahle piston
253866.jpg


Pic 13 Made in “Brasil”
253867.jpg


Pictured above is the Kohler “D” Style piston used in the Magnum engines and NOT identical to the pistons or rods used the KT twins. See Service manual for details.

Piston Dimensions at Pin (Not Specified)
Piston Dimensions at Pin 02/07/13 (Not Specified)
Checking for Clearance, Out-of-Round, and Taper

Piston #1 Average
Side #1 (Flywheel) Inches Side #2 (PTO) Inches Clearance
Perp-Outer 0.6256 Para-Outer 0.6266 0.0010
Perp-Inner 0.6256 Para-Inner 0.6266

Piston #1 Average
Side #1 (Flywheel) Inches Side #2 (PTO) Inches Clearance
Perp-Outer 0.6264 Para-Outer 0.6265 0.0010
Perp-Inner 0.6254 Para-Inner 0.6265

Found: Piston dimensions at the pin were significantly Out-of-Round (especially Piston #1); wear evident upon visual inspection as shown by discoloration on the sides, bare metal top-and-bottom. Dimensions for Piston #2 were fairly symmetrical, Piston #1 were more oblong.

(Note: Given the mix-up in Rod ID that occurred during disassembly, the Pistons could also be mis-identified, but they were kept with respective pins and rings.)

Pic 14 Top of Piston after hand cleaning using wire brush after a night’s soaking in kerosene
253868.jpg


Pic 15 Side of Piston after assiduous hand cleaning
253869.jpg


Piston Specifications at D1 (per Manual, p. 1.10)
Piston Specifications in Manual for M18, p. 1.9
Thrust Face O. D. @ D1 --New 3.1203 to 3.1210"
Thrust Face O. D. @ D1 Max Wear Limit 3.1181"
Thrust Face to Bore Clearance @ D1 –New 0.035 to 0.052"

Piston #1 Inches
Side2Side @ D1 3.1185

Piston #2 Inches
Side2Side @ D1 3.1181
Piston Dimensions are within specification

Pic 16 Top of piston cleaned on bench wheel
253870.jpg


I tried to clean these pistons up using the used bench grinder my son had given me for Christmas. I hit it with a coarse wire wheel. As you can see, it obliterated any “Fly” marks. I tried to inscribe a “V” pointed in the proper direction and add an “F” but I wasn’t holding the letters precisely vertical and was only able to make partial impression.

Pic 17 Groove cleaner from Top
253871.jpg


I also tried to clean the grooves thoroughly with a tool made for the purpose. I had difficulty getting the tool started, and I got a good amount of aluminum shavings in my lap. So the unit certainly cleans the grooves up.

Pic 18
253872.jpg


I had the most trouble keeping it steady in the oil groove because the tool was too narrow to seat properly in the groove opposite the cutting edge. I had better luck in the two upper grooves in which the “V” in the tool could be reliably placed in the groove and guide the cutter without as much side-to-side movement.

Pic 19 Side view of machine-cleaned piston
253873.jpg


While the piston certainly looks good, I’m not sure how it will spec out upon reassembly. I left the other piston alone.
I probably won’t go near another piston with a bench grinder, and I won’t touch it with a ring-groove cleaner either, until or unless I know that I will be re-using the piston. I had no idea these things absorb the energy they do or that they are exposed to so much wear.
 

jchamberlin

Well-known member
Joined
Jul 19, 2010
Messages
1,842
Location
Farmville, North Carolina
displayname
Jeremiah Chamberlin
Crank’s Connecting Rod Journal Specifications and Measurements
Connecting Journal Specifications, see Service Manual p. 1.7
Crankpin Max O. D. Wear Limit" 1.3728 Inches
New Crankpin O. D. 1.3733/12738 Inches
Crankpin O. D. Max Out-of-Round 0.0005 Inches
Crankpin O. D. Max Taper 0.001 Inches

Crank Dimensions
Side #1 Inches Inches
F-Perp 1.3734 F-Para 1.3734
R-Perp 1.3734 R-Para 1.3734

Side #2 Inches Inches
F-Perp 1.3734 F-Para 1.3734
R-Perp 1.3734 R-Para 1.3734

Found: Crank’s Connecting Rod Journals are within their wear limits.

I had more luck getting readings on the rod’s journals, since the Plastigage was designed for such readings.

Pic 08 Plastigage on Rod #2 Journal
253879.jpg


Reading shows less than 0.051mm (or less than 0.02”); note that if the Plastigage is compressed beyond the indicator, the clearance is SMALLER than the mark.
In this case, the reading on the Plastigage is between 0.038mm and 0.051mm, or between 0.0015” and 0.0020” or about 0.0018” by my reading. The snap gage and micrometer peg the largest gap at 0.0020” –so by any measure, the rod journal clearances are within the 0.0029” specification.

Pic 09 Rod Side-to-Side Measurement
253880.jpg


Connecting Rod Journal Specifications and Measurements
Posi-Lock Connecting Rod Specifications in Manual for M18, p. 1.7
Rod to Crankpin Running Clearance -New 0.0012" to 0.0024"
Rod to Crankpin Max Wear Limit 0.0029"
Rod Side Play on Crankpin 0.005 to 0.016"

Rod Dimensions 02/04/13 Rod Clearances 02/05/13
Side #1 Inches Side #1 Inches
Big-Perp 1.3746 Under Cap 0.017
Big-Para 1.3746
Rod #1 Side Clearance 0.011" at Rod 2/12/13
Rod #1 Side Clearance 0.012" at Cap

Side #2 Inches Side #2 Inches
Big-Perp 1.3753 Under Cap 0.018
Big-Para 1.3754
Rod #2 Side Clearance 0.009" at Rod
Rod #2 Side Clearance 0.010" at Cap Sticky 2/12/13

Found: Connecting Rod Journals and side clearances are within specification, although I wasn’t quite sure how to get a side-to-side measurement. I just kept sticking the feeler gauge in between the rod and the crank until I felt resistance. The re seemed to be more “room” between cap and crank than between rod and crank –0.0001” give-or-take.

Pic 10lastigage on Rod #2 Cap
253881.jpg


Pic 11Big End of Rod #2
253882.jpg


Additional Note: The big end of connecting rod #2 seems to have been slightly deformed by its impact with the governor/block. There seemed to be some slight “stickiness” to the rod on the crank when it was approximately parallel to its “throw” on the crank. This coincidently was about its position upon impact!

Also, rod #2 is VERY tight on crank journal #1 (ask me how I know,  The same “stickiness,” 180 degrees apart, was evident when the #2 rod was installed on journal #1, so what all these facts indicate, to me, is that the journal on Rod #2 has been “egged out” from the impact. The wear is indicated by the discoloration on the rod and cap at approximately the point measured as “Parallel” to the beam above. Even though the measurements are within specification, a large part of me would like to have a new rod with which to reassemble this motor.
Another “casualty” to Rod #2, if I haven’t mentioned it, is the rod stud. The impact froze the nut to the stud, so I would at least like to at least replace the stud and nut, although they are not available separately from Kohler, I would like to think they could be procured from 3rd party sources.

Pin Dimensions and Piston Clearance Specifications
Piston Pin Specifications in Manual for M18, p. 1.9
New Pin O.D. 0.6247"/0.6249"

Pin Dimensions 02/07/13
Pin #1 Inches
OD 0.6251

Pin Dimensions 02/07/13
Pin #2 Inches
OD 0.6252
Found: Piston pins are within specification.
Connecting Rod “Little End” Dimensions and Specifications
Connecting Rod (Little End) Specifications in Manual for M18, 1.7
Rod to Piston Pin Running Clearance --New 0.0006 to 0.0011"

Rod Dimensions 02/07/13
Side #1 Inches Side #1 Inches
Perp-Front 0.6262 (-) Perp-Front 0.6262 (-)
Para-Rear 0.6262 Para-Rear 0.6262

Side #2 Inches Side #2 Inches
Perp-Front 0.6262 Perp-Front 0.6262
Para-Rear 0.6262 Para-Rear 0.6262

Found: Connecting Rod to Piston Pin Clearances are within or at specification: 0.0010” for Rod #1, 0.0011” for Rod #2. Rod #1 was slightly Out-of-Round, but not enough to measure with current instrument. That is, the snap gage felt tighter in the journal when place perpendicular to the rod beam, but it retained its feel when transferred back to a parallel reading. By the same token, Rod #2 was just slightly larger than Rod #1, but again, not enough to measure with current instruments.
 

jchamberlin

Well-known member
Joined
Jul 19, 2010
Messages
1,842
Location
Farmville, North Carolina
displayname
Jeremiah Chamberlin
Pic 02 Micrometer set 01
253890.jpg


Pic 03 Micrometer set 02
253891.jpg


Yes, these are a cheap set of micrometers from China, not top-of-the-line instruments from Starrett or Mitutoyo, but they seem to get the job done. The two more important pieces in the box are the instruction sheet on how to take a reading and the standards for checking the five gages that can’t be zeroed on themselves (like the 0-1” unit). The standards are helpful to check the instrument’s accuracy, but to verify one’s “feel” for the proper measurement before taking it in hand to make measurements. All the external dimensions were taken using these micrometers, and many of the internal dimensions were also taken using “snap” (or “telescoping”) and split-ball gages, see more below.

Crank's Main Journal Specifications, see Service Manual p. 1.7 2/15/13
Main Journal Max Wear Limit 1.7407 Inches

Front Main (Flywheel) Inches Inches
Front Perp 1.7413 Front Para 1.7413
Rear Perp 1.7413 Rear Para 1.7413

Rear Main (PTO) Inches Rear Main
Front Perp 1.7415 Front Para 1.7415
Rear Perp 1.7415 Rear Para 1.7415

Found: Crank’s Main Journals are within their wear limits. I wasn’t sure if the O-O-R and Taper was specified for just the bearing or the journal, so I measured them both. Note that it takes eight separate readings to check for O-O-R and Taper, at least the way I did it the first few times. I finally settled on taking a reading at one point and then tried to see if it “transferred” first for Taper and then Out-of-Round. If this is “cheating” so be it, but the whole trick to measuring with a micrometer (besides learning how to read it), is to develop a good, consistent “feel” for each measurement. I found that the difference between my “feel” between “tight” and “light” on a measurement was about 0.0001” so unless two reading rendered a significant difference in “feel” I took them to be identical for present purposes. I am guided by my 8th grade math teacher, an exceptional fellow, who first taught me that all measurements are approximations; but in machining the goal is to identify and remove as much as possible any ambiguity.

Pic 04 Plastigage package
253892.jpg


The measurements are given in SAE units on one side of the package, and in Metric units on the opposite side, although the dimension does not change from side to side.

Pic 05 Plastigage Interior shot (Marked Up)
253893.jpg


The Plastigage itself appears to be no more than a sophisticated, calibrated, thin strand of wax. The way it works is (1) snip off a length appropriate for the journal being measured, (2) place on journal or cap (slight pressure to make it “stick” is OK, then (3) tighten cap down to specifications. (4) Remove and examine by comparing the width of the compressed Plastigage to the gage marks on the paper sheath package: simple and effective. Not only can you get a good idea about the clearance, but any taper will be evident by varying width in the compressed wax.

Pic 06 Main Bearing from “2459” installed in “3822” Block
253894.jpg


Unfortunately, I couldn’t figure out a way to insert the Plastigage in the main bearing either before or after installing the crankshaft.

Pic 07 Plastigage on Main
253895.jpg


I was able to wiggle a bit into one end on the Flywheel end, which measured out to 0.060” –right at the 0.059” specification. All the measurements below were taken with the snap gage and micrometer.

Main Bearing Specifications and Measurements
Main Bearing Specifications in Manual for M18
Sleeve Bearing Max Out-of-Round .0005 Inches
Sleeve Bearing Max Taper .001 Inches
New Bearing Running Clearance .0049 Inches
Sleeve Running Max Wear .0059 Inches
New Sleeve Bearing I.D. (Installed) 1.7439 to 1.7461 Inches

Main Bearing Readings 02/06/2013
Front (Flywheel)
N/S Front 1.7464 E/W Front 1.7440
N/S Rear 1.7465 E/W Rear 1.7443

Rear (PTO)
N/S Front 1.7465 E/W Front 1.7455
N/S Rear 1.7466 E/W Rear 1.7460

Found: Front side of Side #1 is Out-of-Round 0.0025” well beyond the 0.0005” specification.
Note: MAX reading on sleeve is only 0.0005” out for tolerance for a NEW bearing.

Personally, I don’t see how you can keep this bearing from quickly going O-O-R both because of how it is made, and because of the way it is mounted between two halves of the crankcase. I would be happier if the engine were designed with a “pillow block” of some kind –i.e., a solid piece of cast iron or steel alloy that was bolted to the crankcase, more along the lines of the Kubota diesels that Bernie Pientka has documented on the Forum (although it need not be quite so complex as the Kubota design to satisfy me).

At any rate, it looks like I will need new main bearings fore and aft.
 

jchamberlin

Well-known member
Joined
Jul 19, 2010
Messages
1,842
Location
Farmville, North Carolina
displayname
Jeremiah Chamberlin
The purpose of this inspection is to assess the current state of engine wear and thus determine which parts will need replacing and what parts will require machining. In the process I will identify which measuring devices I used and how I used them. The engine was previously diagnosed with internal damage in my post “M18 Starting problems” in the “CCC and MTD Machines & Equipment” section of the IH Cub Cadet Forum, and the “fresh” view of the motor’s internals can be found in the “M18 Teardown” post in the same section.

Pic 01 Replacement Block scribed under closure plate “3822” cf. to original block scribe “2459”
253898.jpg


I think these marks are factory, but they were found on only Side #2.

This Do-It-Yourself approach is offered in place of my more customary “pack it in a box and take it to the machine shop” method of engine repair. As will soon become evident, I don’t claim to have any more knowledge about engine building than the average high school student enrolled in shop class. The trouble is, I was never able to take shop class even though I dearly wanted to (I was in the college prep course track).

The goal of the entire rebuilding effort is an engine that, while it may not be “right” (or perfect) in every respect, it is “good enough” to provide trouble-free service. I’m not going for an all-out performance modification, I’m not after the tightest tolerances, I don’t even mind a little smoking on start-up and moderate oil consumption; but I don’t want any oil leaks, and I don’t want to be tearing it all down again in 6 months. I have no way of knowing how many hours are on the engine, but unless someone can show or tell my different, I’m hoping that the engine has about half of its useful life left. That is, if it is true, as some say, that the engine is designed to run 1000 hours or so between re-builds, I’m hoping to get about 500 hours out of it after I put it back in service. Many of the key parts (like the rods) are no longer available (technically the rods are on Back Order, but nobody is holding their breath). The parts that are available are frightfully expensive, for instance, the main bearings (at standard dimensions) are $60.00 a piece (on the Kohler web site), a set of pistons with rings runs about $150.00 –if they are available (at the time of writing, I’m still checking in availability). So if the engine cannot be returned to service pretty much as-is, then the end result will be a sadder, but wiser “old geezer” of a mechanic with a bunch of parts in the “OEM used parts bin.”

We will look first at the crank and rods, wrist-pins, and pistons, before turning to the cylinder bores, and finally the valves and guides. We will reserve examination of the rings until the call is made on the pistons, whether to replace them or not.

To keep track of all the measurements required it is necessary to orient them in the engine:
• The Sides are called out in Fig 9-12 of the Service Manual, Disassembly chapter, on p. 9.4.
• Cylinder/Side #1 toward the Flywheel (for Kohler the Flywheel is at the Front).
• The breather is on Side #1; to the left as you face the PTO, to the right from the Flywheel.
• The governor, the oil pump, and the oil filter are all on Side #1

Best Practice
Best engineering practice calls for considering what one expects to find before attempting a test or measurement. For any engine, this newbie expected to find greatest wear in the components in the following order:
1. Cylinder Bore
2. Rings
3. Valve Guides
4. Connecting Rod Journal on Crankshaft
5. Main Bearing Journals on Crankshaft
6. Valves
7. Pistons

This was not what I found.

My reasoning before taking measurements was that cylinder walls would surely take a beating, and the valve guides are replaceable for a reason. I thought too, that the rod journal would seize/wear long before the main bearings. I never really considered the piston itself as a point of wear. Again, I was wrong on most of my assumptions.

Crank Teardown
I’m actually concerned more about the crank than I am about either the cylinders or the valves. I have ventured into “hopping up” engines before, only to be bitterly disappointed when they failed. My “take-away” was that oil control was far more important than compression ratios, valve lift, duration, or timing. If oil is an engine’s life blood, the crank and block are its skeleton. It doesn’t make much sense to build up an engine’s “muscle mass” by flowing the head, increasing compression, and extending duration and overlap if the “skeleton” of block and crank can’t hold up under the stress of increased torque and higher RPMs. Bottom line: I want the crank to be as “right” as I can get it.

The crankshaft in an internal combustion engine converts the angular force from the piston on its power stroke into a (relatively) constant rotating force at the crank shaft. I expected to find the crank experiencing the most wear at the rod journals when the piston’s rod reaches its greatest moment of force (or torque), at an angle perpendicular to the crank’s throw. I thought the force of the power stroke would be communicated to the main bearings fore and aft, but that the crank, in flexing slightly would absorb some of the energy. I found instead, that the crank’s main bearing journal bore the brunt of the burden of converting the reciprocating mass into rotary action.
 

jchamberlin

Well-known member
Joined
Jul 19, 2010
Messages
1,842
Location
Farmville, North Carolina
displayname
Jeremiah Chamberlin
After reviewing my post I would like to make the following corrections and observations.

1. Clearances at Piston Pins were within specifications.
Explanation: I had mis-read the micrometer, corrected the reading during the editing process, and failed to update my conclusions.

2. I think the pistons were mis-identified, so the readings for Piston #1 should be for Piston #2 and vis-versa.

I still want to put this motor back together basically as-is. I need to replace the main bearings -For What Its Worth, and I would like to replace Rod #2 and re-use the pistons while buying new (STD) rings; but I don't think the crank needs to be ground, and I THINK I can get away without boring the cylinders out 0.010". However, if I have to bore the cylinders out, I might as well get new pistons; and --all things considered-- getting new pistons might be a good idea anyway. I'm really interested to hear from folks who have tried what I'm suggesting, that is, going on the cheap.

Is it worth it, or is going all the way the only way?

What do you think?
smile.gif
 

nbartee

Well-known member
Joined
Feb 12, 2002
Messages
607
displayname
Norm Bartee
Jeremiah,
I know when I rebuilt my M18, I didn't like the readings I was getting on the cylinders. The pistons were fine. BTW, I always use a broken piston ring to clean the grooves. Anyway, I didn't want to pay for a rebore so I bought used jugs off EBay. I took a chance, I know, and had to buy two sets before I was satisfied, but didn't pay much for them anyway. It was a lot cheaper than reboring cylinders and buying pistons.
 

jchamberlin

Well-known member
Joined
Jul 19, 2010
Messages
1,842
Location
Farmville, North Carolina
displayname
Jeremiah Chamberlin
Norm: Thanks for stopping by and taking the time to respond. I had never thought of replacing the jugs separately.

What criteria did you use to reject the first set of replacement jugs and caused you to accept the second set?
 

nbartee

Well-known member
Joined
Feb 12, 2002
Messages
607
displayname
Norm Bartee
Jeremiah,
There was a broken chip out of the skirt. It didn't affect function because the piston doesn't travel down that far, and I was thinking nothing better would show up so I bought them. Well, right after that, a better pair did show up at a price I wanted to pay. I wasn't in a hurry.
 

jdiederichs

Well-known member
Joined
Nov 9, 2004
Messages
659
displayname
Jim Diederichs
Nice detailed write-up Jeremiah! I like the use of Plasti-gage, back in the '70s I started using it and still do. It still has it's place in an engine builder's tool chest.

You documented things very well and provided good pictures to illustrate your written steps. Nice work!
beerchug.gif
 

jchamberlin

Well-known member
Joined
Jul 19, 2010
Messages
1,842
Location
Farmville, North Carolina
displayname
Jeremiah Chamberlin
Jim: Thanks for stopping by and for the words of praise. I'm not sure if the rebuild will work, but I'm going to give it a try.

Sorry to hear about the layoff at Kohler. As Tom Hoffman has said, finding another gig is tough. I'm three months away from my 60th birthday, and I've been looking for work for 6 months. After being "loyal" to several employers, I find it difficult to explain my "varied resume" to a complete stranger. All I want to say is that I did whatever it took to get the job done wherever I worked. It seems that "those of this world" have the upper hand in these matters. Everyone seems to want to sit in judgement. I wish I had studied harder for the rewards in this world instead of the next.
smile.gif
(No, I don't) It just s**ks being me right now.
 

Latest posts

Top