Prepping the new Cummins engines

Hey, look at those nice shiny engines.  When we returned from delivering the Perkins to the freight terminal, they had already been moved over to where the Perkins had been sitting the past couple of months.  We covered them up with the same tarps and contemplated our next steps.

 

Initially, we were loosely scheduled to have these engines placed into the boat sometime during the week following Seafair, which would be sometime around mid-August.  One of the tasks before then was to make sure we could line up and connect to our transmissions via the adapter plates.  We also needed to acquire torsion drive plates with a spline center to match the shafts of our transmissions.  We had ordered Cummins to Borg-Warner adapter plates when we ordered the engines, but at first glance it looked like the plates already on the transmissions for attaching to the Perkins were the same size.  I held one of the new plates up against an existing one, and visually they appeared to be a match, and had the same bolt hole pattern as well.  Ray brought some very large calipers to confirm they were a match, and indeed they were.  This was great!  It meant we didn't have to remove the existing ones from the transmissions, which would be quite an undertaking. 

Through research and also advice from advisors on the boatdiesel.com website forum, we also knew we should get torsion drive plates with a high degree of deflection.  This is the amount of "give" between the thrust of the engine and the transmission shaft.  The standard drive plates with tightly coiled springs in them typically had only 2 or 3 degrees of flex in them.  We chose plates with polyurethane couplings that would flex up to 10 degrees.  This not only lessens the impact of the engine's torque, it also is much kinder to our transmissions, which will need that treatment since we chose not to rebuild or replace them.  Here's one of the plates pictured on the left.  The larger diameter piece bolts directly to the flywheel, while the raised center section with the spline center slides over the transmission shaft.  The white pie shaped pieces that hold the two discs together are a special polyurethane that will allow the flexing.

It's also critical that the transmission shaft engages a majority of the spline in the hub, but without coming into contact with the engine's flywheel.  We measured how deep the flywheel was recessed from the bell housing on the engine, then positioned one of the drive plates on one of the transmission shafts with the outer plate that same distance from our adapter plate (which would bolt to the bell housing).  We could then see how far into the spline the transmission shaft would enter.  It actually engaged about a quarter inch more than it had on the Perkins, but didn't come through to where it could contact the flywheel.  We were in business as far as that was concerned.  I purchased high strength T8 bolts to attach the drive plates to the flywheel, and we torqued them down to a specified 35 foot pounds, using Trav's click-release torque wrench. Once the engines are connected to the transmissions, these bolts are no longer accessible, so they need to be right.

The hose/pipe combination you see to the left crossing the flywheel is part of the raw water cooling system.  The pipe portion is the transmission cooler.  Transmission fluid is routed through the two threaded fittings and passes between a series of tubes which the raw water flows through on the way to the heat exchanger. In an early conversation on the boatdiesel.com forum, a seasoned mechanic had told me that the Perkins used E.J. Bowman coolers, and that they were much better than these.  He always retained those coolers whenever he did a repower from Perkins. 

That seemed reasonable to me, plus the Bowman units were serviceable - you could take them apart for cleaning whereas the Cummins units were pressed together and didn't have nearly the service life.  I had retained those coolers when we sold the engines, as they were really a component of our transmissions.  Ray took them home and disassembled them for cleaning.  Here you can see the housing, tube bundle and end caps.  The raw water passes through the tubes while the ATF flows around them to be cooled before returning to the transmission.  The line you see on the end of the tube bundle is not a crack; it's a mark Ray made so he'd know when he'd come full circle while cleaning out each tube.  They were in surprisingly good shape inside after 40 years of service.

  I wrote to the E.J. Bowman Company seeking the correct replacement O rings for the coolers, but after a few exchanges where I'd emailed them photos of the coolers showing the casting number, tube bundle diameter and length and the end caps I decided we'd do better to find some O rings locally.  We found our way to a shop in Ballard that had a warehouse full of any kind of O ring you could imagine, and selected a couple sets of a special neoprene that would do very well resisting salt water.  Ray cleaned the housings and end caps with his sand blaster, gave them a fresh coat of paint and reassembled them.  Next he used some pieces of steel to fashion cradles for each one and welded them together.  They also received a coat of paint. These will bolt to a bracket that is on top of each transmission, and we'll secure the heat exchangers to the brackets with steel hose clamps.

The O rings are all that seal the end caps and separate the water from the ATF, so we decided a pressure test was in order to make sure we wouldn’t be getting any seawater into our transmissions – that would be a very bad thing.  Using a couple old hoses, clamps, a pressure gauge, a couple plugs and a ball valve, Ray cobbled together a pressure testing apparatus, and we took it outside to the garden hose for the test.  In the photo to the left Ray is opening the ball valve to run water under pressure into the cooler.  The gauge on the other end got up to about 45 pounds or so when the clamp where the garden hose was connected gave way.  

Ray was in the line of fire as the pressurized water came flying out, but the good news was there were no leaks in the cooler.  The clamp that failed was also broken, so we replaced it with the only one remaining.  We then decided that the seawater running through here would be under no more than 25 lbs of pressure and closed the ball valve when that pressure was reached.  We left each cooler under pressure for several minutes and both passed the test.  The only water not where it was supposed to be was on us – and mostly Ray!

One more task to complete before hoisting the new engines in was to remove the one motor mount that wouldn't come out when the Perkins were removed. The head of the lag bolt was rounded off, and at the time of removal they just cut the upright bolt with a saws all to get it out.  We cut, sawed and ground off the head of the bolt until we could pry the mount off over it.  Then we used a pipe wrench with a length of pipe on the handle for additional leverage to turn the bolt.  It was in solid for sure, but I eventually got it to move, inch by inch.  I can vouch that there was no bad wood in the stringer - it had an iron grip on that bolt.