26 Command Bridge '91

[Phrancus]

Thanks for that article! I did hear of the name change but not in so much detail.

True, don't need to bring it back to the state it was in 30 years ago, it's more that I'd like to know where the various - and sometimes curious - modifications originated from.

Mostly I'll be simplifying things, like you say: a lot has changed and we don't use the boat in the way it was designed for anyway.

[Phrancus]

Here's a happy update.

We had a short winter here: all of a sudden predictions showed a temperature drop to -15 and snow for a week. So I had to winterize in a hurry. I did so and when doing so I found two pieces of an impeller in the suction (sea water) tube, blocking the flow to the impeller. The impeller itself was/is like new and the engine had been running hot quicker and quicker.
Removed the pieces and after the winter week started the engine. Heating up took a lot longer but in the end the hightemp alarm went off like before.
So I figured the third piece (I found one and a half impeller vane) went up the intake and blocked the impeller like the other parts did earlier. And I suspected problems at the thermostats as this all happens around the time these should open up.
So I planned to take out the impeller and the tube/hose to the heckdrive and to open the thermostat housing to have a peek in there.
Didn't quite get to it right away so we took off for a short trip around the local waters and to my big surprise: the engine did not overheat at all. In fact, it didn't heat up either! Not even to operating temperature.

So here's what I think happened in the past: The impeller was damaged, two vanes almost came off and the engine showed cooling problems. At that point they removed the impeller and dropped two vanes in three pieces down the suction line of it. (very stupid not to check that tube and hose as it's easy to remove and flush) and mounted a new impeller. This helped a bit but not enough as the engine would run hot an higher revs (mentioned by the seller). More revs, more flow, movement of the vane-remnants towards the impeller.
Maybe they suspected faulty thermostats and removed them for a flow as if they were in the open position. I found two thermostats in the boat when I bought it. Assumed that they were replaced but didn't think a mechanic would simply not replace but remove. I tested them in a pan of water and they open and close fine.
The third remnant (half or a third of a vane) may have blocked the passage the first day and popped through and out through the system. Or it sunk in the tube/hose where I will find it next time I flush it.

I have two new thermostats ready but not the gasket holding the plate that holds both thermostats in place. Nevertheless I will put them in without the gasket (getting them will take some time) as this plate is inside the housing so no leaking system outside the engine. This will be sub-optimal and increase warm-up time but not as much as it is now without any flow restriction. So I expect the engine to be running near operating temperature.

During the overhaul in a few weeks I'll have the gaskets and replace the impellers, I prefer a good start and do regular service rather than every other moment another time consuming job when there is little time to do it right.

[km1125]

Sounds like you're on the right track. Also sounds like you're getting the weather we had a week ago!!

Those lost impeller vanes are always a problem eventually. Once I went to change impellers (that really weren't that old) and found several missing. Backflushed with a hose and got a few of them, but several were still unaccounted for. I ended up taking off the combination oil/trans cooler and bringing it home so I could backflush it with some good pressure, and I got the rest of the vanes, but a couple must have been stuck in there really good.

I always thought it would be good to have some kind of screen between the output of the raw water pump and the rest of the engine to catch this kind of junk.

[Cooler]

Those remaining impeller pieces will obstruct water flow very easily. They bump up against the oil cooler screens, and then create a cavitation in flow. Like KM said, if you can remove the hoses easily, do it. Otherwise, just keep back flushing over and over with low pressure. Sooner or later, any remaining pieces should loosen up. I had an impeller disintegrate, with a bunch of little pieces flow through. Took a number of back flushes to get all of it. Some of the pieces were as small as sand. It only takes a small piece of rubber to create that cavitation. Yep, your assumptions with a previous owner replacing bad impellers without accounting for the remaining pieces is accurate, then removing the t stats was his remedy for hot running. Some people should not own boats. er

[Phrancus]

Thanks for the information,

Source of the post
I always thought it would be good to have some kind of screen between the output of the raw water pump and the rest of the engine to catch this kind of junk.

on my (diesel) engines the flow is: heckdrive, transom with valve, hose to under engine, pipe going straight up to impeller pump, then up to the weed-filter, then tube to heat exchanger, intercooler, turbo, exit into exhaust through heckdrive.

So the weed-filter should catch impeller remnants.

what happened here is that I found some gunk after. removing the impeller on the intake of that pump. So the impeller was not getting enough intake. After prodding around I pulled out one impeller vane and the other one dropped down into the sea water intake pipe. Then I removed the hose at the heckdrive under the engine and the other parts flushed out.

I therefore have good hope that the parts were quite big and the last third of a vane either are still in the hose (didn't come out the first time) or are blocking but not so much as before or went through the impeller after blocking it for a while. So it might even be in the weed-filter.

Or it did flush out but was faster than my eye could see and it's now in the bilge-nasty-mix and I'll find it in due time.

[km1125]

Interesting that your weed filter is after the raw water pump. On this side of the pond, that kind of stuff goes before the raw water pump to (help) protect the impeller too.

I'm assuming 'heckdrive' is the same as 'sterndrive'? EDIT - just looked it up and yes, 'heck' translates to 'rear', 'tail' or 'stern'! Learn something new every day!

[Phrancus]

now you've got me doubting my own writings....

what the heck is a heck drive... I made a writing error I think. A 'Hekdrive' or Z-drive or Stern-drive. No Heck here. My mistake, sorry.

I may have made another mistake with the weed filter: this is the Sea water filter in the exploded-view as I notice now. In Dutch its a weed (seaweed) filter.

Now that you mention it, it is indeed strange to have the strainer AFTER the pump. Perhaps the Sterndrives tiny holes serve as a rough filter and the pump is supposed to be able to handle the rest. It's a pretty wide-channeled flow through the heat-exchangers so sand and such can get through. And pre-filtering might just add another point of failure when it gets filled with dirt too soon. To have that thing in a reachable (for maintenance) location may be a challenge.

Perhaps this is why the impeller is tough rubber: it will flex when needed and let things through to be held in de strainer rather than blocking completely. In my case not true as the inlet of the pump was blocked but this was by manual error: dropping the remnants in the vertical pipe when removing the damaged impeller. Having remnants pick up by the filter would be logical when it got damaged while pumping. My luck in this case that it did not desintegrate into small pieces that went past the filter like Cooler mentions.

I'll install the thermostats tomorrow and have a test run and report findings.

[Phrancus]

Well, here is another happy update: Today I opened the thermostat housing and there was:

https://i.postimg.cc/1tTQk6bq/Whats-App ... -49-21.jpg

No thermostats! So that explains the cold engine at all times. So I put in the new ones:



And we took it for a trip and both engines nicely kept their temperature around 80degrees Celcius.

Powered them up and reached a comfy 25mph on flat water. On the return run, however, the cap of the expansion tank popped off and it spit out a gallon of coolant....
Fixed the cap, filled the coolant (lucky I had that aboard) and calmly went home. No further problems.

Happy that the problems with the port engine turn out to be much smaller than we thought. Time for some maintenance: all filters and fluids replaced. Change fuel to synthetic diesel and get rid of the smell from a diesel spill around the fuel tank in the past.

Must move the bilge pick-up some day, I want it more empty than it is now.

[Phrancus]

Two days of gasonline (diesel) horror: smelly business. Someone in the past probably had problems with the diesel (bacteria growth probably) and cut access holes in the tank. After the work they sealed them off with fluid-gasket. Which is dissolved by diesel (fumes) and make removing the covers a terrible job.

But it had to be done as I could see new bacteria growth in the tank. So attacked them with some violence, knife, chisel and finally got them off. took half a day to get rid of the gasket. Pumped out the dirty diesel (will be left to sink and the filter the diesel) and cleaned the tank as far as possible with a bunch of cloths. Unfortunately they cut the holes in the wrong places: could not acces the part where the fuel sender is mounted.....

Anyway, flush, rags, and so on and the tank was quite clean.
made gaskets from cork and mounted it all with stainless rings and bolts. Hopefully it will all be sealed off enough now.
Then took 3 trips to the local gas station to fill it up with approx 150 liters of diesel (40 gallons), pumped it in and closed it all off.

Seems that the fuel sender/meter does work after all. Albeit that it shows approximately 75% full with 150 liters and 400 would be max. However, the boat is now a bit nose-light as the anchor and chain are not in. And I don't mind much as long as it moves when using fuel I'll figure out how much fuel that represents over time.

Next job is to change the fuel filters. A bit of a job too as the original Racors are corroded and their bowls very dirty. So have to take them apart and will replace the housings as well.

All this must be done and engines running in a few days as I have to move marina for the season.

Had a quick shot at polishing the polyester and that was a great moment. To see the flat, powdery surface turn into a smooth hard surface, ready for sealant plus wax.

One pretty big job done, enough more to go......

[km1125]

Sounds like some good progress!!

Lucky that you can do that safely with the diesel in the tanks. Us guys with the gasoline don't have that luxury!!