Making Connections

The day our engines arrived Ray and I were working on removing the mechanical fuel shut-off cables that were used to turn off the Perkins engines.  We understood that the Cummins had an electrical fuel shut-off for turning off the engines, so these wouldn't be needed.  We stopped to watch the engines being unloaded, and looking at the fuel injector pumps we noticed two control levers, not one.  Although there was an electric solenoid shut-off, there was also a mechanical lever.  We hadn't pulled those control cables out completely, so just put them back where they were. 

The cables came over the front of the engines on the Perkins, while the Cummins brackets were designed for the cables to come from the rear.  We weren't sure if our cable length would work or not, but with a lazy S route under the engines it turned out just right.  We were short by one double cable housing clip, and that thing was nearly $20.  After a few fruitless excursions to the Second Wave marine consignment store and some forays on Ebay I conceded defeat and bought one at Fisheries. We needed a longer bracket to accommodate the length from the end of the cable housing to the connector, so Ray fashioned a pair of those in his shop.  We also removed the control levers for the fuel shut-off so Ray could weld on an offset extension for a better connection.  We ended up with this nice looking installation.

The boat has exhaust pipes running from the engine room all the way back to the stern – these pipes are in excellent shape, as we replaced them a few years back with fiberglass and hose connecters.  The new engines have exhaust water injection elbows which we need to connect to these existing exhaust pipes.  The new elbows are 5” in diameter, while the boat’s exhaust system is 4.5” in diameter, so some adjustment is necessary.  There are some commercially made “reducers” available, but the only ones we saw are straight, which would introduce some complications with a bit too much length.  Also, it would then require purchasing a couple of additional 5” elbows to route the exhaust from the engine to the pipes.  We decided we would build our own reducers, by enlarging one end of the existing 4.5” elbows we have now.  I purchased a one foot section of 5” fiberglass pipe that we could cut in two to make our modifications.  As I was hoping, the store had a 3’ long remnant and just handed that over for the price of 1’ – a little extra material in case we need it.

  We also purchased a quart can of fiberglass resin and a small bottle of catalyst, as well as about 10’ of 4” wide fiberglass cloth.  With one end of our 4 1/2" elbow cleaned and sanded, Ray added an O ring he made from some tubing to prevent the resin from running down the elbow.  Our plan was to wrap the fiberglass cloth around one end of our elbow to bring its diameter up to where the 5” extension would just fit over it.  The directions for the resin/catalyst ratio were for a full quart, way more than we needed, so we used syringes to extract 4 oz. of resin and 3 or 4 ml of catalyst.  The syringe used for the catalyst scaled down to only 5 ml, so that was a bit of a guess, plus the ratio changes quite a bit with the ambient room temperature.

 We decided about 3 wraps around the cylinder would be about right, cut off the proper length of cloth, mixed our resin and went right to work, as we knew we’d have a limited working life with the resin.  We were just finishing up the 3^rd wrap when the remainder, about half of what we started with, solidified in our cup.  It quickly generated enough heat that we couldn’t hold it by the bottom – we set it outside away from the house just in case it was going to burst into flame.  It didn’t.  When the cloth set up we tried the 5” tube over it and decided a couple more wraps would make for a good tight fit.  With our next session working with the resin we used a bit less catalyst, applied the extra wraps and overlaid the 5” tube onto the piece just before we had our next lump of solid leftover resin.  We had used most of the 10’ of cloth, so purchased some more for the second elbow.  With even less catalyst this time, we got the entire wrap plus the 5” tube on the second elbow in one session.  Our new elbows provided for the 90 degree turn to the bulkhead on each side, as well as the reduction in diameter.

On the deck you can see the old 4.5" plug that kept water from entering the boat while the exhaust is disconnected, and clamped to our new reducer elbow via a length of hose is the new 5" wood plug that serves the same purpose.  Both sets of plugs will remain on the boat in case they're needed during some future exhaust work.

Some of you may be wondering what the heck we’re doing using fiberglass for exhaust piping.  Although the exhaust directly out of the engine can run up to 850 degrees, this is quickly cooled when the raw cooling water is injected into the exhaust at the water injection elbow.  This is now a common material to use for marine water-cooled exhaust – much cheaper than copper (the previous pipes on the Potentate) or even hose, and with a much longer lifespan.

I had also purchased some 5" diameter stainless steel exhaust elbows on Ebay, thinking they would come in handy for routing the exhaust from the engine.  Using one of the stainless elbows and short lengths of hose for connecting, I hooked up the starboard exhaust from the water injection elbow all the way to the bulkhead.  I didn't like the looks of it at all.  It just didn't look like very much slope.  The raw water used for cooling exits through the exhaust, and with this slight of a slope I was concerned that water could backwash up the exhaust into the engine if the boat were rocked the wrong way.  This would be a very bad thing, especially with salt water. 

I did some research and read somewhere that the exhaust elbow should be at least 12" above the waterline.  By sighting a nearby thru-hull fitting from the outside and inside we estimated that we had just around half that elevation.  I took the connection apart and put the wooden plug back in.  We took a trip to Broomfield's Marine Exhaust in Ballard to see what sort of riser might be available.  He had a couple of 90 degree elbows designed for Cummins, and we borrowed those to better estimate what we'd need.  I bolted them together with a 90 degree offset, then clamped on our exhaust elbow with some vicegrips for a visualization. 

We could see that we could do another two or three inches of elevation, and that we'd also need the riser to extend away from the turbocharger another 3 inches so as to clear the raw water outlet pipe from the heat exchanger.  We ordered two risers made from elbows with a straight piece welded in.  They were ready in a week or so.  I put them in the trunk and made the next stop at Ballard Insulation, where I had heat shields made for them.  These aren't water cooled, so can get up to 800 degrees depending on the load on the engines.  The small threaded fittings are for the pyrometer sensors.  These riser were not cheap, but are a lot less expensive than having salt water inside your engine.

We also got some pieces of high temperature gasket material while at Broomfield's, and Ray cut out a couple of gaskets for the risers with his scroll saw.  Here they are sandwiched between a couple pieces of wood to prevent the material from fraying.

In yet more Ebay shopping I had acquired a box of stainless steel T-bar clamps and a couple of high temp silicone exhaust hose couplings, so we were ready to assemble our exhaust system and see how it all fit together.  We had the steel exhaust gaskets that came with the engines, and we used those between the turbochargers and the new risers.  The gaskets Ray made we used between the risers and the water injection elbows. 

We put a thin layer of white lithium grease on the joining surfaces as well.  I had learned earlier from Broomfield's how that helps with the seal while we were working on the Perkins exhaust system.  The extra 2 feet of 5" fiberglass pipe we had was just the right length for the port side run from the injection elbow to our newly made reduction elbow.  The insulating pads are held on with stainless steel wire, laced together not unlike a boot. 

We found it was easier to put the pads on before connecting the raw water hose from the heat exchanger to the elbow.  The starboard side went together in a similar fashion, with a shorter run to the reduction elbow.  The hose from the heat exchanger to the elbow is wire reinforced, and also repurposed.  It's from sections of the hose I removed from the raw water through-hull fittings to the engines and replaced with new.

In between our steps of getting the exhaust parts fabricated and aligned to our satisfaction, we’ve also been doing some other necessary stuff, like connecting fuel input and return lines, raw water hose, battery cables, painting the new stringer blocks, filling the engines with coolant (the coolant that was in the engines didn’t have much anti-freeze in it – a result of having engines shipped up from Florida!), and reinstalling the boat’s hot water tank, which is now plumbed into the starboard engine’s coolant system for heating our water while cruising.  The tank fit back in its original spot, with about an inch or two of clearance from the starboard engine’s crankshaft pulley.  

  Despite all that we’ve done to date it seems like there’s just as much stuff left to do as ever, but we’ll eventually be to the point where we’re ready to turn the key(s) and push start(s) to see what happens.  After that comes another list of tasks, including fixing that big hole in the ceiling!

We have been enjoying our short work days, with equal amounts of pondering to go with the actual work – and with occasional lunch breaks at Voula’s or the Salmon Bay Café as well.

In the photo above you can also see the raw water pump below the control cables, with no pipe attached.  Sea water is pumped through a heat exchanger to cool the engine’s coolant, similar to a radiator cooling a car engine – we just use water instead of air blowing through the grill.  In addition to the engine coolant, we also have to cool the transmission fluid and reduction gear oil as well.  The engines came equipped with transmission coolers, but we opted to use the old ones that cooled the transmissions when the Perkins were driving them.  They are larger and serviceable – Ray had previously disassembled and cleaned them, so they were ready for duty.
 

With the additional circuit for cooling the reduction gear, we had some rerouting to do on the raw water plumbing.  In addition, one of the pipes that came attached to the starboard engine’s raw water pump was smaller than the port side, as well as a bit shopworn.  The pipe on the other engine was PVC, and we decided to go that route on the starboard side as well.  We acquired some various universal flex hose lengths at an auto supply store, as well as a couple of preformed elbows that were 1 ¾ inches in diameter – the size needed to fit onto the transmission and gear coolers.  The outside diameter of the PVC pipe is an odd size not intended for clamping hose to – so we fixed that by getting some PVC couplers, which Ray cut in half and turned down to the proper outside diameter on his lathe.  He also formed a ridge at one end to better hold the hose. 

Once we cut the PVC sections to the proper length we used PVC cement to attach and bond our custom fittings to the ends of the pipe.  The raw water is now routed across the back of the engine under the turbocharger into the transmission cooler, then to the reduction gear box (which has its own water jacket), and from there to the heat exchanger, where it cools the engine’s internal coolant.  From there the raw water is injected into the exhaust elbow coming out of the turbocharger where it cools the exhaust and then exits with the exhaust out through the transom.

With the plumbing completed we turned our attention to the electrical connections.  Earlier I mentioned that I had located and acquired a pair of brand new Cummins gauge panels complete with 30’ wiring harnesses.  Ray had made a new mahogany panel from an old cabinet door of mine that I’d set aside nearly 40 years ago for this purpose, and I augmented the gauge set with additional VDO gauges for turbo boost, pyrometer (exhaust temp) and transmission pressure.  We installed these on the helm a few months ago, but we’re now ready to make the connections to light them up.

The turbo/boost gauge is mechanical – no sending unit, just a small air hose from the intake manifold is all that’s needed to actuate it.  I had a length of plastic hose left over from repairing the ice maker connection some time ago, and Ray had a length of similar sized hose that he’d previously used for compressed air in his shop.  With that supply and some compression fittings we were able to make connections, thread the hoses through the rear bulkhead and up the closet wall to the gauge panel. 

Next came the pyrometer gauge.  When we had the exhaust risers fabricated we had a threaded hole put in each one, to which we could insert a temperature sensor.  This sensor can detect temperatures up to 1500 degrees, although the exhaust coming directly from the turbocharger should never exceed about 850 degrees at wide open throttle.  The sensor has an electrical pigtail which attaches to a length of double wire that we also routed through the firewall and up to the helm.  These additional gauges are also illuminated, as are the original panel gauges.  We tapped into the power and ground connections of one of those gauges to connect the lights of the new gauges.  The gauges have small clear bulbs, but also came with green and red sleeves which could be put over the bulbs.  I used the red to match the other gauges.  The transmission oil pressure gauges we’ll hook up later, using a pair of unused wires that are in the harness.

Once this was done we decided to turn on the battery switch for each engine so we could turn on the ignition key to see if all the lights worked and if the gauge needles would set to zero.  I was at the helm and Ray was in the engine room to flip the switch.  He did starboard first, and the engine started cranking, even though the key was off and I definitely wasn’t leaning on the starter button.  That was a bit unexpected and exciting, but Ray turned it back off pronto.  I thought something must be messed up between the gauge panel and the wiring harness, so we disconnected the gauge panel completely from the engine and tried it again – with the same result.  We left starboard off and turned our attention to the port side.  We did not get that result there, which was a bit reassuring.  No sounds, smoke or smells occurred when the battery switch was powered on, and when I turned on the key for the port engine all the gauges lit up, and the low oil pressure light came on, as well as the warning buzzer.

We were about to leave the starboard snafu for the next day when we encountered Randy Rice as we were leaving.  He is another tenant at the marina who repowered his boat several years ago using these same model engines.  He came to take a look at it, and surmised that maybe one of the wires from the relay below the starter was crossed up.  He disconnected it, then did some testing with my voltmeter at several contacts.  All was as it should have been, and the wire he disconnected had belonged where it was.  He put it back to the same terminal; we turned on the battery switch and … nothing.  It behaved itself and when I subsequently turned on the key for the starboard engine the gauges lit up, the buzzer sounded, etc.  A light tap of the starter button engaged the starter so all seemed okay.  We could only surmise that the load of spray paint that was put on the engine after it was rebuilt had somehow been conductive, or something was making contact that resolved itself with the removal and replacement of that wire.  We weren’t quite ready to start the engines then – still haven’t opened the seacocks for the raw water inlet and there are some additional witnesses who may want to see what happens when we turn the key for real.