I know all of Mr. Gee’s loyal fan base will be disappointed but this is likely the second to last episode in the Low Oil Pressure Season of As Mr. Gee Turns. Have no fear however as I am already cueing up the next Season where Mr. Gee will be living up to the series title as he turns his crankshaft round and round with ease to similarly powers Möbius’ CPP propeller to spin as we go round and round this awemazing world of ours.
Those of you who are waiting on the edge of your seats for the final outcome of this season’s mystery thriller to find out who it is that is finally found guilty of murdering poor Mr. Gee will be glad to know that the jury is finally back with its definitive verdict! The title of this week’s update will give you a clue but you’ll have to read on to find out who turned out to be the dastardly killer on that ill fated maiden sea trial.
With that baited opening, let’s jump right in and pick up where we left off last week.
Circumstantial Evidence is Suspect for Good Reason!
In typical TV Series fashion, here is a quick summary of “as seen in previous episodes” …………
All of you who have been following along so closely (thanks!) will recall that from the very beginning the prime suspect in this murder mystery has been “Nick”, this mysterious dent in the steel oil pipe inside the crankshaft that carries the vital pressurized oil from the main bearings up to the connecting rod bearings.
It will likely remain a mystery as to what/how/who could have inflicted this dent in the oil pipe to begin with but the suspicion has been that Nick created a hole or a thin crack in the oil pipe at cylinder #1 and when Mr. Gee got up to operating temperature and loads, the oil sprayed out of the oil tube causing the deadly loss of oil pressure and the subsequent destruction of the main and connecting rod bearings.
When I did the first full factory level rebuild of Mr. Gee las year and found Nick hiding in the recess of the lightening hole at Cylinder #1 my conclusion after doing some preliminary testing was that it was “just” a nick and that the walls of the oil pipe had not been breached and did not leak.
However, after the sudden loss of oil pressure during the first sea trial and the subsequent discovery upon tearing down Mr. Gee of this catastrophic failure of the main and connecting rod bearings you can see here, all the evidence pointed to me having been wrong about the oil tube and I immediately gave myself a good kick in the a$$ and pleaded guilty of letting Mr. Gee and the whole Gardner engine family down by not living up to the highest level of Gardner standards for 100% confidence inspiring quality of workmanship.
In that first rebuild, I took what I thought at the time was more than enough of a “belt & suspenders” approach when I silver soldered Nick for an extra measure of security just in case there was a hole or a crack in the oil tube. However, as the evidence accumulated as I stripped poor Mr. Gee naked, it all pointed to ME having screwed up by not replacing the crankshaft of at least replacing the oil tube with a new one.
Circumstantial Evidence Just Won’t Do
When I removed the crankshaft and was able to inspect it even more carefully, it still did not appear that there was any hole or crack in the oil tube BUT this time I was going to leave nothing to chance and so I had a whole new crankshaft along with a lot of other parts, gaskets, filters, etc. shipped from Gardner Marine Diesel in Canterbury England and they all arrived just in time last week.
However, I was just not going to be able to SWAN or Sleep Well At Night just putting Humpty Dumpty aka Mr. Gee back together again with just all this circumstantial evidence. I had to know for sure what had caused the oil pressure to drop and the bearings to fail.
First, I threaded one end of the oil tube and screwed in a SS set screw coated with sealing compound.
Next, I taped the other end of the oil tube where it exited out of the main bearing journal with an M6 thread.
This kind of rigorous laboratory testing does not come cheap and unfortunately two innocent bicycle tubes paid the ultimate price and gave their lives to the cause.
They contributed these two valve stems, which were the key to this test by allowing me to pressurize the oil tube to a known level and keep it there.
I carry a full set of Imperial, Metric, British Standard and Whitworth taps and dies (the tools that cut male/female threads in metal) and so I quickly cut some M6 threads on the valve stem I liked the most.
And screwed it into the open end of the oil tube which I had previously tapped above with matching M6 threads.
I removed the valve from the stem and poured 10W40 engine oil to fill up the oil tube and put the valve back in.
Out came my trusty hand pump which also has a gauge at its base and I pumped it up to about 120PSI, which is more than three times the normal 38 PSI oil pressure of a Gardner 6LXB.
I had my hands full so didn’t get any photos, but I then used my industrial heat gun to heat up the oil tube and the surrounding area of the crankshaft to about 70C / 160F which is higher than the normal operating temperature of oil in a 6LXB which is about 60C.
Having replicated all the conditions the oil tube would have been under when Mr. Gee was spinning away on that fateful day, this test would tell me once and for all if there was the least bit of leakage of oil from this oil tube.
Prior to testing, I had scrubbed the whole area around the oil tube surgically clean so even a drop of oil would be easy to see.
It was with very mixed emotions that after repeated tests, not a single drop or dribble of oil emerged!
Nice to be vindicated and have proved that either the dent or Nick had not penetrated the walls of the tube and/or my silver solder patch had done the job.
Nick was immediately released from custody with the sincere apologies of this kangaroo court, but I was now left back where I started, not knowing what the source of the problem was!
So I did what you do in such situations, you“go to the mattresses” and call in the experts. In this case I reached out to my two best experts in such areas; Michael Harrison who is “Mr. Gardner” and owns/runs Gardner Marine in Canterbury and Greg, one of my longest running best friends from back in the days when we were both working nights and weekends as heavy duty mechanics at a large lumber trucking company in Vancouver BC while we were both going to a combination of UBC the University of British Columbia and BCIT the British Columbia Institute of Technology, to become Industrial Education teachers aka “Shop Teachers”.
I had been in touch with Michael and Greg since the low oil pressure fiasco had begun and was sharing lots of photos online and daily updates as I worked on Mr. Gee. Michael, who has worked on hundreds of Gardner powered boats all over the world, came up with the key when he posited that we/me were thinking about this backwards. It was not that the wear on the bearings was caused by low oil pressure, it was the other way around! The low oil pressure was CAUSED BY the wearing of the bearing material which allowed more and more oil to escape out the growing space as the bearing material wore away.
OK you might ask, but then what caused the wear in the fist place?!?!?!
If you really want to know the answer to this question, please keep reading but there are no photos to go with this so it will just be my text based explanation to walk you through it. You will be fully forgiven if you want to skip down to where we resume our normal photo based programming!
After walking through the events more thoroughly and with Michael’s vast experience with Gardner engines and Greg’s decades of experience with diesel truck engines of all kinds and then my notes and recollection of the events leading up to the failure, we were able to figure out the TWO contributing factors that caused to the rapid wearing of the bearings and the subsequent loss of oil pressure.
Factor #1 is that I had reused Mr. Gee’s original crankshaft “as is”. That is to say I did not replace it or send it out to have all the journal surfaces reground.
I have rebuilt a LOT of engines over the past 50 years and what you/I normally do is completely inspect the crankshaft of the engine you are rebuilding. You use very accurate micrometers to measure the diameter and concentricity of all the journals and compare these to the factory specifications to determine what amount of wear had taken place over the life of that engine/crankshaft. Then you also carefully inspect all the surfaces of the old bearings and the crankshaft journals with a magnifying glass for any wear, grooves, scratches, etc. If the crankshaft is within specs, not worn and all the journal surfaces are still like new, then you can reuse that crankshaft. If not you most often send it out to have all the journals ground down smooth and use oversize bearings to make up for the material that has been ground off.
Factor #2, is that one of the two captains who had been hired to take Möbius out on sea trials prior to Christine and I accepting the boat from the builder and taking full possession and responsibility of the boat, did not have any experience or knowledge of CPP or Controllable Pitch Propellers. It did not seem like a major issue at the time as I explained how they worked and showed him how to slowly move the Pitch lever at the Helm forward to increase the Pitch angle and cause the CPP prop to “bite” or grab the water more and more to pick up boat speed through the water. I showed him the Pitch gauge and explained that he needed to increase the pitch very slowly and not to take it past half way during this first test while we were “breaking” everything in.
With the engine being brand new and coming up to temperature for the fist time, there was some smoke coming off the engine from all the new paint and left over bits of grease and oil from working on the engine so I had left the Helm and gone back to keep a close eye on Mr. Gee as he went through his paces. While I was there I tell from the sound that the engine was under a lot of load and I saw that the oil pressure gauge had dropped to just below 20 PSI and I immediately pulled Mr. Gee’s shutoff lever and shut him down. But it was too late, the damage as it turns out had already been done!
What had happened was that the Pitch lever had been pushed all the way forward which dialed in the maximum pitch angle on the four massive prop blades and with Mr. Gee running at lower RPM of about 1100 this massive sustained load had caused the brand new bearing surfaces to rapidly wear under the load as the original crankshaft journal surfaces labored over them. For those of you who have driven a standard shift car or truck, this would be like trying to climb a steep hill in high gear with the “pedal to the metal”. You get the idea!
Now the puzzle pieces all fell into place; the huge loads on the new bearing surfaces had worn rapidly which increased the microscopic space where the oil normally keeps the two surfaces from touching and so as this space increased with the ongoing wear, more and more oil was able to escape or “leak” out the sides and fall back into the oil sump. A vicious cycle then repeats itself with more wear leading to lower oil pressure which leads to more wear which leads to ………… where we are today!
While disappointing to say the least, at least I was now confident that we had found the true cause of the wear and the low oil pressure and Michael added that he had seen this exact same scenario play out on several Gardner powered boats over the past 20+ years so I can at least SWAN and get on with putting Mr. Gee back together again with his all new crankshaft, bearings and even more TLC than I already lavish upon him.
OK, back to our regular Show & Tell programming!
In Go the Pistons
When I left off last week, I had installed the new crankshaft and main bearings so now it was time to install the pistons and their con rod bearings which you see here as they come out of the Gardner factory box.
Here are two of the six pistons as I prep them to be installed. Yes they are massive, each piston displaces a volume of 1750cc on each power stroke. NO! that is not a typo, that means that the volume of each one of these six cylinders is larger than most 4 cylinder engines in the cars you drive!
Each cylinder has been freshly honed to create the Goldilocks surface finish for the new rings to all seat in just right.
This original Gardner illustration out of one of the manuals I have will help show the relationship between the pistons, crankshaft, connecting rods, etc..
Each piston is liberally coated with clean engine oil and then very gently lowered into its cylinder.
Each of the three rings are then compressed so that they fit inside the cylinder and when the last ring is in the piston slides down the last bit to where the top con rod bearing rests on the awaiting con rod journal.
Next I rotate the crankshaft 90 degrees to put the con rod at its lowest position so I can install the bearing caps. The coloured plastic tubes are there to make sure that the four con rod bolts can never Nick (remember him??) the journal surfaces as it is lowered in place. Now I can slide each con rod bearing cap in place over those four bolts and cinch down the nuts in stages to the Gardner specified torque.
Here is the last Piston/Con Rod on Cylinder #6 with the protective cardboard wrapper still on the journal which I now remove, turn the crank 90 degrees to put the journal up at Top Dead Center or TDC and lower Piston #6 in place.
A classic example of just how and why Gardner engines are so robust and long lasting is this added feature that creates one of the most solid “bottom ends” of any engine I know. In addition to the massive aluminium caps that hold the main bearings in place, these two cross rods run through each of those caps and create a super solid main bearing system to keep that crankshaft rotating merrily for many many years.
Once all 12 of those cross rods are torqued down and all the pistons have been installed and their caps fully torqued down the “Bottom End” as it is called is now all assembled and the last remaining item is to install the external pipework assembly that takes the pressurized oil to those holes you see in the flat oval bosses with 2 bolts in them here.
Main Bearing Lube Oil Pipework Assembly
Here is that lubricating oil pipework’s all disassembled ready for final cleaning and then installation of the sealing O rings that go inside each of the cast iron junctions that bolt to the main bearing caps you see in the photo above.
Five of the seven main bearing fittings are assembled here and then …….
…… they slide into this T junction where the oil comes in from the oil pump and filter and get distributed fore and aft to all 7 of the main bearings.
BTW, for those wondering why the wear on the bearings #1 and 2 up at the front was the most and then became a bit less as you went aft, you can now see why as bearing on Cylinder #1 is at “the end of the line” or furthest away from the source of the oil pressure. So as the wear began and the oil leaked out, the pressure drop became progressively greater as it worked its way back from this T joint.
Piston Head Clearance
I won’t bore you with the full installation but there are lots of critical dimensions that need to be measured as you assemble a new engine and one of these you see here which is measuring the exact distance from the top of the piston to the top freshly ground surface of the surrounding cylinder block. I set up my dial indicator on top of the piston and move the piston to exactly Top Dead Center TDC and set the dial to Zero at this position.
Then I rotate the dial indicator so that the pointer now rests on the cylinder block surface and check how much higher this is.
If you look at the photo above you can see that the difference is 0.015 or 15 thousandths of an inch and the factory specification is that it must be between 0.012 and 0.020 so this is Goldilocks “just right”.
Heads Go On
With the Bottom End all now fully assembled it is time to move up top and put the two heads back on. Freshly cleaned studs are all installed with Loctite to keep them properly torqued for the next 50 years.
Wondering what all the black “donut holes” surrounding each cylinder are?? These allow the coolant (water + antifreeze) to circulate between the lower cylinder block and the upper heads to keep everything at just the right operating temperature which in the case of a 6LXB is quite low at about 60C / 140F whereas modern engines run at about 80 – 95C.
Obviously that coolant needs to say where it belongs and not lead out into the cylinders so this is the smart simple way Gardner seals each connection.
The silver ferrules slide through the fat O-ring and them you press fit this assembly into each hole in the cylinder block. When the head is bolted down it squishes each rubber O-ring to form a permanent watertight seal.
Thin steel head gaskets go on next to create the extremely critical seal that keeps all the huge pressures created when each cylinder fires to stay inside and provide the massive “push” of each piston as it travels downward creating all the HP and especially so the massive torque or “twisting power” that Gardner engines are so renowned for.
Everything all done in the Engine Room and now time to prep the cylinder heads to be installed.
I’d estimate that Mr. Gee had a total run time so far of less than 5 hours so it was pretty quick and easy to clean up each head and the valves of the carbon deposits from that run time.
My best guesstimate is that each head weighs about 70kg/155lb so hoisting the off my workbench and up on top of all those studs and lining them all up so the head slides down onto the cylinder block is some eXtremely good eXercise!
Front head goes on first as I have to slide in the ground shafts that each valve rocker arm rotates on so I install all the rocker arms, push rods and decompression levers first and then hoist the aft cylinder head into place and do the same valve assembly to it.
One of the last steps before I can lower Mr. Gee back in place and attach him to his buddy “Normy”, the Nogva CPP gear box, is to lift that humungous flywheel back up and slide it onto those 6 big studs you can see sticking out of the aft end of the crankshaft in the bottom Right.
I’m in fairly good shape and so is Christine but this flywheel is about 125mm/5” thick solid steel and weighs in at a svelte 120Kg / 265lbs so I used my brains instead of my “brawn” and rigged up some of our triple blocks that we will use to hoist our Tender Davit up and down and rigged them with some stronger than steel Dyneema line to make it eXtremely easy to lift the flywheel back up in place and line it up with all those bolts.
Once I had torqued down the six bolts that hold the flywheel solidly onto the end of the crankshaft I could lift the other half of the flywheel housing in place and bolt those two halves together.
This solid pair of housing create the big flat surface for the two rear engine mounting brackets to bolt to so they go on next. I custom designed these last year and we fabricated them out of 25mm / 1” thick AL plate that is TIG welded together and then each of these have the vibration dampening engine “feet” or mounts bolted to them and these feet are then bolted to the 25mm thick engine beds below.
This is where I left Mr. Gee hanging a few hours ago and while it was Fathers Day today, it felt appropriate that as Mr. Gee’s “Dad” I should be giving him all this TLC and attention today.
I hope all you Dads out there had a fabulous Father’s Day that was just right, just for you!
So this is where I will also leave all of you “hanging” for this episode of As Mr. Gee Turns and I hope to have him fully mounted and possibly running again in time to bring you perhaps the final episode of the season!
Thanks for your time to join me here today for this latest Möbius Show & Tell, and please come join me again next week to find out how this season ends and I do hope you will add your comments and questions in the “Join the Discussion” box below.