Universal M 15 Problems

[RobbyBobby]

Hi,

I recently become a happy owner of the young (30 years young) Catalina 27. She has problems and quirks, I have no experience with DIY so we learn as we go.

I have M15 that give me two problems; one is overheating the other is fuel leaking on the injectors. Please let me explain.

1. Under load engine keeps proper (145 F) temperature for first 45-50 minutes, next starts overheating, so what I do is to clamp feedback raw water line forcing water pump to drink only fresh and cold Bay water.
This resolves the problem. I read that some owners of the M15 put an extra ball valve on this lane to do exactly this. Kind of strange mod. BTW I did descale the cooling system with Rydlyme (BTW it works miracles)

Now I have no idea why this might be happening? I checked the thermostat (boiling it in a pan at home) and it works . For some reason my temperature reading system is not working and I cannot figure why. This probably will need to wait. Mainly because even I tried to order new temp sender none of the suggested two by Torrensen did not fit. However I use laser temp reader as temporary solution.

2. My fuel return lines from injectors are leaking, 1-2 drops every 30 seconds and this dripping starts after 30 minutes of engine running. I changed the lines and tightened the clamps as much as I can but it does not help. As you can see on the photos those lines even bulge a bit.
As a side effect since injector temperature gets around 185 F the leaked fuel starts to burn and smoke.

Please see attached photos. Thank you very much for your suggestions and help.

Happy sailing!

[daddle]

Your fuel return line is somehow blocked between the injectors and tank. Try running it from the engine into a jar. Does the leak stop?

Ball valve for water recirculation? What? Only the coolant recirculates. The rawwater goes out the exhaust. There should not be any tees in the raw water line.

[Chief Engineer]

Return line hose looks like it is the wrong size (unless the camera lies) the line is low pressure and very small.

What temperature do you get at overheating?

Do you have water coming out the exhaust when the thermostat opens?

Is there a water heater plumbed into the engine?

[Boracay]

These are more questions for our experienced engineers...

Would it be possible to remove the thermostat completely for a test run? If the problem is overheating then running the engine too cool for a while should not do too much damage and it would certainly settle any questions about correct thermostat.

Also would it be possible to change the oil to a full synthetic? This could have less friction and run more freely through the engine, maybe cooling it a little more. Should be OK on an older engine?

[daddle]

Originally Posted by Boracay

These are more questions for our experienced engineers...

Would it be possible to remove the thermostat completely for a test run? If the problem is overheating then running the engine too cool for a while should not do too much damage and it would certainly settle any questions about correct thermostat.

Also would it be possible to change the oil to a full synthetic? This could have less friction and run more freely through the engine, maybe cooling it a little more. Should be OK on an older engine?

It's unlikely the thermostat. You saw it working. It's that goofy recirculation of the raw water. That cannot work as intended...makes no sense...even with your explanation...

Those hoses are old. Perhaps some other coolant-side hose collapses while running....after it heats up. Replace all the hoses. Get rid of the recirculation hose.

[Chief Engineer]

I just don't like the intermittent water supply to the exhaust line

Can you supply answers to post #3?

[RobbyBobby]

Gentlemen,

First thank you very much to all of you who took time to reply.
Please let me clarify some things. I did not modify anything ..yet.
This particular engine cooling system is set up like that (with water recirculation) from the beginning. I remember reading some post when the gentlemen who owns M15 always laugh when he starts the engine and there is no water coming out of the boat and good intentional passer by are yelling at him "no water, no water, cut the engine" and he just stoically replies; "it is OK it is supposed to be like that". Well, he is right, idea is to warm up the engine as soon as possible (as we all know cold engine is as bad as too hot). I did not like the idea that the engine does not spit water immediately as much as you dont like it. But it is how it is supposed to be working.
What bothers me is that now I need to clamp the recirculation line, it should be the task for the thermostat.

As a side note good folks made a lot of mod to this engine (which by the way is kept in high respect by owners). Ball Valve being one of them. Next one is connecting sink line to the very same T and running engine on either fresh water or coolant alone before shooting it off, purging the cooling system from salt water. Others yet add fresh water cooling system because as they said they hate the idea of salt water eating innards of their beloved 5411. Also if the engine is fresh water cooled it can be run on higher temperature whereas raw water cooled has to run at lower temperature to avoid excessive scaling.

1. Return line hose looks like it is the wrong size (unless the camera lies) the line is low pressure and very small.

--You are very right, there were replaced by professional diesel mechanic (what I mean is that I paid him) He stated that the old one were old and new one should be better. It was leaking before the change and it is leaking after the change

2. What temperature do you get at overheating?

158 F measured at cylinder head. When I get this high I clamp mixing tee and this very quickly (1 minute max) cool the engine to 140 F. Operational temp according to manual should be 135 to 150

3. Do you have water coming out the exhaust when the thermostat opens?

Yes, more then before and more if I put the engine to work (that is put it in gear)

4. Is there a water heater plumbed into the engine?

No

I will try to find the obstruction on fuel return lines as suggested by Daddle tomorrow.

Again, thank you very much Guys for your thoughts and suggestions. Good night!

[daddle]

Hmmm. Really. I assumed the Universal M-15 is fresh water cooled with a heat exchanger...as the datasheet I have so states. Am I confused?

In that case quick warm-up is obtained just like in an automobile: by the thermostat bypass on the freshwater coolant. Raw water only cools heated coolant. I wouldn't think there is a need for raw water regulation of any kind.

We once had a ballcock on the raw water cooled Atomic 4 because the thermostat gave such problems. But that just restricted flow a bit upon tweaking.

I think your valve setup will be difficult to regulate given changing flow conditions.

Flushing freshwater thru the raw water system is maybe a good thing, but better done some other way. Perhaps backflush via a 2-way valve near the exhaust elbow tube.

As a side note: I had a new M4-30 (similar to your M-15) that had an intermittent raw water pump shaft. The pump tang had been cut too short to fully engage the injector shaft. Sometimes it spun, sometimes not. A bit of a trick to diagnose. And the clowns at Universal maintained it was "impossible" until I sent it in.