The case of the intermittent water cooling system

[SkiprJohn]

I've seen the ball valve trick on many old Albin and Volvos. It works but you have to work it.

The black particulates very well could be any hose in the system that is breaking down internally. I've seen a hose that looks just fine on the outside but the inside is collapsing into pieces and clogging the rest of the system.

Have you changed hoses? Is there a filter screen on the outside of the boat to keep plastic bags and jellyfish from getting sucked up into your system?

Good luck on this one.

[brownoarsman]

Thanks for the continued advice! It sounds like some other 5411 owners are running their engines cold, so maybe I should never have fiddled! There was a bit of white smoke which seemed to be unburned diesel, this is why I was trying to increase temp, that and to avoid excessive buildup. Though no one with this engine seems to be having that problem even when running cold.
I should note that when the temp got to 160 and up, I shut it down as soon as I noticed it which was pretty quick; it certainly didn't run for more than five minutes at those high temps.
I was at OceanFest today in the keys (got to support the reefs afterall), but will take a look inside the hoses tomorrow (they all look good on the outside).
Sailorchic may have it right. A weak pump may explain why the engine runs after clearing the water passages. Since I refill the block from the top before reattaching the hoses, the priming is accomplished this way. I had assumed since the pump was pushing water it was all okay, but it may not have the needed pressure. That, a small drip from the weep hole, and a supposed to be temporary face plate screw might be the culprit. (That last one was me-I dropped the OEM screw in the bilge when I was checking the impeller the first time the engine clogged when I opened the recirculating valve, and solved it by putting a nut in front of the head of a longer machine screw. It kept the plate under tension, and there's no leaking around the face plate or anything, but maybe it's not exactly perfect).
Thanks again for the help and I look forward to reporting back with good news


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[brownoarsman]

Oh yes, and I have a clear outside filter screen and a clear strainer.


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[Terra Nova]

Originally Posted by Terra Nova

The black particles that smudge are pieces of broken water pump impeller...

This, not hoses. Some of your passages might be blocked by larger chunks. Did you actually remove the impeller to check it?

[DeepFrz]

Also be sure to check your water injection elbow at the end of your exhaust manifold. They can get pretty clogged up and may have trapped some impeller bits over the years.

[Rick Williams]

I was plagued with the same problem on my 1YGM Yanmar. I followed the logical steps until I was reduced to disassembling and replacing anything that looked suspect starting with the entire water pump. What I found was a small fish that must have come through the strainer as an egg and grown up in the water filter as it was too large to come through the strainer but big enough to clog the incoming elbow when the engine was running hard.
The other clog was a tiny mussel that had lodged in the outgoing elbow of the water strainer. When we were loafing along enough water got by but when we throttled up to get under a bridge against a tide we'd invariably overheat because we were getting water flow suitable for low speed but not enough for high speed.
I use high speed figuratively.
Good luck.
Read the manual.

[SkiprJohn]

I've also seen a hose that has deteriorated where the inner liner has come away from the outer liner and only closes itself off when there is suction on the hose. That was a hard one to find. If all hoses are good then disregard what I'm telling you but don't ignore the fact that they could be breaking down in an old engine installation.

[brownoarsman]

Mystery solved! Thanks for the discussion here, as it made me realise my assumptions were wrong. Because the impeller was pumping water but the outflow from the top of the block was weak, and the strainer was clear, I had assumed the pump was weak or the block was clogged.
After reading your replies, I stripped off all the plumbing from the seacock to the thermostat housing (was planning to do this before ordering new pump parts, but since I was away from the boat on land, wanted to get everyone's knowledge first ) Turns out that there was a big clog in the hoses between the strainer and the pump. I imagine it came from the recirc valve when I opened it to raise the engine temp, and it would just flow back up that hose sometimes, and other times would clog my system. Only took five hours this morning to inspect the impellers, blow the block again, and take everyhing off
Thanks awfully for the help, I'm very glad to have a working engine, which I'm about to pit against the currents of Bahia Honda.
For those of you with raw water cooled engines that fresh water flush after use; how do you put the freshwater in? My pump is mounted below the waterline so is filled automatically, but I tried to feed it water from a bucket to see if the pump was working, and it wouldn't prime against gravity. I suppose the simplest thing is a gravity drain into the pump.
The front plate is also showing some wear, so I will still add those parts to my replacement kit Good thing to have dealt with before the trip to the Bahamas!


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[MarkSF]

Do you know what they call an automatically-self-adjusting ball valve? A thermostat.

[bailsout]

I have a pvc tee between the filter and the pump. The tee is upside down with a male hose bib and a screw on cap. I also have a 6' piece of garden hose with a female hose bib on each end. I attach a garden hose and flush until I only taste fresh water out the exhaust. If you don't have a fresh warter pressure source you can install a male hose bib to the bottom of a bucket and gravity feed.
If your cooling system is working well measure the amount of water coming out at a specific rpm over a specific time. Check it from time to time or when you suspect a lower flow.

[Terra Nova]

Originally Posted by brownoarsman

...My pump is mounted below the waterline so is filled automatically, but I tried to feed it water from a bucket to see if the pump was working, and it wouldn't prime against gravity...The front plate is also showing some wear...

Your pump is bad.

[brownoarsman]

Yes, the thermostat is definitely on my list of things to do. Voyaging while repairing, well, the ugliest itches get scratched first and this engine is approaching eczema levels, while before it was more of a mosquito bite.
It seems I posted too soon about success. While I did clear out the lines between strainer and pump, and the pump is now very forcefully jetting water, about 8 inches forward at a 60 degree grade, and the whole system was working earlier today, it again failed to get water to the exhaust outlet when I started it to go into Bahia Honda. The upstream pump obstruction was seemingly only one part of the problem. Blew out the water passages but there didn't seem to be any obstruction.
Thinking air was easier to push against than water, I cleared the water passages and let the pump push water through the block (versus what I usually do after clearing the passages, which is to fill the block from the top of the engine); this seemed to work as it is running now. However, I don't believe that logic. I will order a new pump and try that as well, after disassembling the system from the thermostat housing back.
If I had liquid gasket on board, I'd go ahead and put the thermostat in at the same time.
So many new things to learn, so little time, and too many false triumphs!


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[brownoarsman]

Also I don't know what I'd do if I wasn't using run-dry impellers. Highly recommended to anyone who may have to do a lot of start/stop while they are testing their engines. That raw water obstruction may have fried an ordinary impeller, and I would have gone through half a dozen until I found the clog!


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[brownoarsman]

Terra nova - I haven't found any more burnt up black bits. My impeller is okay, no cracking or any loss of flexibility. These run dry ones are blue so, while they may crisp to a hard black, I think that black stuff may have been from many impellers ago.

The plus side of ordering a new pump, as you suggest, is that the new oberdorfer from depco doesn't use grease cups I only ran the impeller dry from the bucket for 20 seconds before I feared burning the impeller. I imagine given the force of it when it's pumping water, however, that this should have been enough to prime the system. So, like you said, bad pump?


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[brownoarsman]

So in today's installment of making things worse by trying to make them better; the engine would crank but not start this morning. Started it three times for five seconds max, with a little more glow plug each time. Still not starting. Bleed system, try again for a five second spin. Still spins, but no start. Add diesel in the event the fuel gauge is wrong and it's fuel starved. Thud

Starter just makes a clunk. Odd. I'll turn off all the loads on the batteries. Thud. Weird. I'll disconnect the alternator. Thud.

Oh ****. My mind goes back to Asa 101-3; turn off seacock before multiple starts. I would not have thought that 4 5-second starts would flood my cylinders, but there it is. Crank shaft wouldn't turn by hand. Luckily I had my Calder with me, shut off the seacock and engaged the decompression lever and spun the shaft, and there were some difficult turns. Did that for a while, just to be sure, until it spun freely by hand with the decompression lever on and off. Then I engaged the shut off on the throttle, engaged the decom lever and ran the starter motor a couple of times in one second bursts and then did the same with the decom lever in operating position. It spins again, and even starts for short moments! And luckily, my dipstick came up black with no milkyness in the oil. I'll check again once I can get the motor running for longer than a few seconds. Still, how much damage may I have done?

Changing filters now to see if that will solve my fuel sending issue.


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