Thermostat Issues

While changing the oil in my Nereus I was watching the temperature gauge and noticed that the engine temperature would warm up to 95 degrees before the thermostat would open, once open the temperature dropped markedly to 80 degrees before finally settling at about 85 degrees. It was quite clear that the thermostat was faulty if not on the way out. There was no way I could leave it like that.

Since this boat has a heat exhanger the thermostat is the same as a car so replacement parts shouldn’t be hard to get from the auto parts store. The thermostat is hidden behind the usual cover at the front of the engine;

It also looked like the gasket was not sealing well with evidence of a small leak having occurred at some point. The downside of replacing the thermostat it would require the coolant to be drained, so it’s was also time to also service the heat exchanger and kill two birds with the one stone. Note to self I need to find out what’s required here.

The first surprise upon pulling the bolts out of the old thermostat cover was the bolt on the port side was mild steel and was only being held by three turns. It was a little short. The other starboard side bolt was stainless and much longer (32mm cf 25mm). A quick confirmation with a set of vernier calipers told me the right length was 32mm. Now this engine is from the period where metric and imperial co-existed in Australia. So it was highly likely the bolt as 5/16 imperial and not 8mm metric. So a quick measurement with a thread gauge confirmed it was a 5/16 UNC 1 1/2″ long bolt that also required a split washer, so off to the bolt shop we go I don’t have much in the way of imperial bolts in my workshop.

The thermostat housing was a little pitted, so that was duly rubbed on the concrete with a circular motion to grind away some of the surface material (easier than sandpaper and a sheet of glass if you don’t have it) and all traces of the gasket were removed with a utility knife.

The thermostat also came with a paper gasket, which was duly coated in Hilomar M (I prefer the aerosol) to ensure a good seal and then re-assembled. The thermostat housing was also a little pitted on its face so before being coated with Hilomar it was ground flat again on a concrete surface, an old trick a mechanic once taught me.

Doesn’t look much different that before, except the keen observer will see the bolts have changed just a little and there’s no sign of that coolant leak. The proof in the pudding will be that it doesn’t leak.

The last task was to get the coolant out of the bilge, so to the pumps… well the bilge pump at least. Before I threw the coolant all over the driveway the outlet was redirected into a bucket and fresh water used to dilute the coolant sufficiently until no more Green was observed in the bilge.

Time to move onto the Heat Exchanger before re-filling with coolant.

Marinised Ford 6-Cylinder Engine

There is surprisingly little about marinising car engines and putting them in boats.

Manufacturers like Mercuiser, OMC, Pleasurecraft and others have being doing this under their own brands for many years and it was quite common in the early 70’s through to the mid 90’s that various companies were doing it themselves in a workshop. My new boat is one of the later.

So after having owned my Nereus for a while now I thought I’d detail what I’ve learnt about it so far about the marinised Ford 6-cylinder engine that is in it;

  • Ford 250 pre-crossflow inline 6-cylinder (donor either Ford Falcon XA or XB)
  • Strongberg 1-bbl down draft carburettor
  • Delco Alternator (10SI body) with external regulator (RE55)
  • Bosch starter motor
  • Standard Kettering Ignition with Bosch GM573 points (!!!) and 12V coil
  • Borg Warner Velvet Drive Gearbox
  • Savage MK1 Compact Heat Exchanger
  • Fynspray 3/4″ Raw Water Pump
  • Marinised Wet Exhaust – Unknown

So the only unidentified part on this engine is the wet exhaust manifold, I’m hoping that at some point I’ll work out who made it. There may be a plate or a marking that I’ve not found yet that will give me a clue.

From the list above it is quite clear that this is a “car engine in a boat” which has not yet been completely marinised. Many of the accessories and ancillary parts are still automotive grade parts which are not intrinsically safe in a marine environment. To properly marinise any engine and make it safe one has to reduce the chance of a spark from igniting fuel vapour in the bilge and/or prevent fuel vapour from being released into the bilge in the first place.

With anything that I rely on to get me home safely the engine in this boat is certainly right up there on my list of things to pay attention too. So as I go through the boat doing my usual checks and maintenance I’ll be upgrading various parts to improve safety where necessary. Since this boat was made in the mid to late 1980’s there is no immediate need to rush out and replace the engine and all of it’s accessories, since it has lasted this long already without them.

More to come.

Changing the Oil in a boat

One of the more interesting jobs with an inboard boat is changing the oil. Unlike a car it’s a little challenging to get under the boat and drain the oil into a pan. When purchasing the boat one thing I noticed was someone had installed a manual oil pump, you should be able to see the shiny thing in the middle there with a handle.

So the first step was to get the engine oil warmed up before we pump it out. Since this was the first oil change I decided to use some engine flush to make sure it’s as clean as we can. Once the engine was good and hot the oil was a doddle to pump into a bucket and remove. Then it was a simple matter to replace the oil filter and re-fill.

I’ve so far been happy with the Penrite Oil I put in my Hilux, so once again I’ve gone with the same brand. Using the Penrite product selector it suggested a standard mineral oil with plenty of zinc, so 5L of Penrite HPR30 was purchased. I’m thankful these older engines only requrie 4 and a bit litres of oil, so only a 5L bottle is required.

I was happy to find that the oil filter used is the same as my old Hilux, that will save some confusion in the future.

Now to get in and start degreasing the engine and bilge.

The Nereus

For many years I’ve been wanting to purchase a Nereus inboard fishing boat. These boats were made in South Australia from the early 1970’s until the early Naughties. They are a very popular fishing boat that has a wide beam and is well known for it’s excellent handling in rough seas.

Finally after a 12 month search a Nereus came onto the market that ticked all my boxes. In a nutshell I wanted a boat 16-18′ in length, with a good hull, on a good trailer with an inboard engine and gearbox. If it came with a heat exchanger that was a bonus.

Well here’s a picture of our new purchase on the trailer at Port Wakefield on our way home from Yorke Penninsula. It certainly doesn’t look like a boat built in the mid 1980’s.

While the Nereus is common in SA that doesn’t mean they come up for sale often, it also means that when they do come up they hold their price. So to offset the cost and ensure it doesn’t sit on a trailer for extended periods I’ve gone halves with my Parents. Between my father and I we should able to get her in the water and out fishing as often as we can.

Here’s a few pics of the inboard engine;

The engine in this Nereus is a Ford 250 cubic inch pre-crossflow log head inline six cylinder. Being the pre-cross flow engine this inline six is the American designed log head which was used in a heap of different vehicles. Of note you can find them in Mustangs and F100’s in the states, or Ford Falcon XA/XB/XW/XY and some Cortinas from the 1970’s. The block numbers suggest the doner car was a 1972 Ford XA Falcon This should make it fairly straight forward to get spare parts.

Anyway that’s the Nereus in a nutshell. I’ve already started making a list of the “jobs to do” and I’m looking forward to getting cracking.