Operating temperature for Universal 25

[David Brownlee]

What operating temperatures do people see running their Universal 25's?

In our newly acquired CD 31, we found that 2300 rpm (what we understand to be a good operating speed) pushed the temp over 190 (what the manual calls the top of the safe range) to about 200. So we've slowed down and now, in the heat of early summer on the Chesapeake, find that we have to keep the speed down to 2000. Mind you, the previous owner installed a three bladed prop (no, I don't know the diameter and pitch--those markings are illegible) that keeps the engine from turning more than about 3100, and that may impose additional load.

Just curious to see what other people experience before calling the mechanic.

David Brownlee
CD31 #1 WINDRUSH
Havre de Grace, MD



dbrownle@sas.upenn.edu

[len]

dave

i have the same engine - i usually cruise at just under 2000 RPM and the temp was 180 until this year when i had to put in a new fresh-water pump and raw water pump, now the temp is 170 - for short bursts i'll go up over 2000 RPM

if you haven't done it already, changing the water/antifreeze mix is probably a good idea, it could be very old

len



md.frel@nwh.org

[John Sill]

My Universal 25 runs at 160. I'm told that the ideal is 180 for these small diesels, but a new thermostat is an expensive proposition on these engines. I like to cruise at or below 2000 rpm in reasonable sea conditions. Even at high revs, temperatures don't approach yours.

The most common failure is the impeller on the sea water side. Frequently a broken vane will lodge in the heat exchanger. It's not too difficult to take the exchanger off and back flush it. You also need to replace the pencil zinc in the exchanger frequently.

Good Sailing,
John - CD31
Beholder's Eye



jesill@erols.com

[Tom]

David, It sounds like you may be over propped. I have a three blade on mine and when up to a 13 inch diameter. At 1800 rpm it was running around 145 which I didn't think was hot enough so I started cruising at 2000 which brings it up to 155. I'm sure I couldn't get it to 190 even pedal to the metal. Check your impeller as a previous post suggested, make sure you're intake strainer has the holes drilled out and isn't clogged with bottom paint. You have to do this every year with a drill bit. Then check your prop. The first number is just the diameter in inches which you can measure with a ruler. To find the pitch you have to take it to a prop shop if you can't read the number stamped on it. They have a gauge that they run over one blade that reads it out for you. They do this for free. The rule of thumb is that in perfectly calm water with no current you should be able to reach the rpms that the engine is rated at. Thus if your engine is rated at 21 hp @ 3200 rpm you should be able to reach 3200 rpm if your prop is pitched correctly.

Checking your impeller is easy on these engines. Remove the three little screws and lift the cover off carefully being careful not to damage the paper gasket. When the impeller blades go bad they usually tear at the bottom first. Once they break off they jam in the hose bibb on the exhaust side (i.e. port). Out here in the West they only sell the impeller as a kit with the shaft seals and gasket and it's over $ 40. Ouch. Check to make sure the cam isn't scored because if it is, it will tear the new impeller up right away. You can usually see score marks on the impeller blades if the cam is rough. You also may know that you have to sand the scoring off the inside of the impeller cover if you replace the impeller. Put a piece of wet and dry sandpaper and a little water on a flat surface and sand the cover smooth or it can tear up the new impeller also. Don't forget to put soapy water on the new impeller when you install it so it won't grab when you first start it and don't start the engine until you remove the bleed screw on the top and have water running freely out of it before you button it up to start. Any of these things can damage your new impeller and you're in for another $40.

I agree with the other posts that there is something wrong if you're running at 190 degrees even up at 2300 rpm. Check the impeller and change the coolant, if that doesn't do it have the prop pitch checked the next time you're out. JMHO

What operating temperatures do people see running their Universal 25's?

In our newly acquired CD 31, we found that 2300 rpm (what we understand to be a good operating speed) pushed the temp over 190 (what the manual calls the top of the safe range) to about 200. So we've slowed down and now, in the heat of early summer on the Chesapeake, find that we have to keep the speed down to 2000. Mind you, the previous owner installed a three bladed prop (no, I don't know the diameter and pitch--those markings are illegible) that keeps the engine from turning more than about 3100, and that may impose additional load.

Just curious to see what other people experience before calling the mechanic.

David Brownlee
CD31 #1 WINDRUSH
Havre de Grace, MD

TomCambria@mindspring.com

[Jack Chamberlain]

We have a Universal Atomic 25 diesel on our CD 33, Maggie Rose. Cruising temp about 150. Should be hotter, but I'm happy it's not overheating. Overheated once when fresh water got too low and it air locked, or something. Had to bleed, and keep enough water in overflow tank. No problems since. Jack



jchamber@crosslink.net

[Jerry]

What operating temperatures do people see running their Universal 25's?

In our newly acquired CD 31, we found that 2300 rpm (what we understand to be a good operating speed) pushed the temp over 190 (what the manual calls the top of the safe range) to about 200. So we've slowed down and now, in the heat of early summer on the Chesapeake, find that we have to keep the speed down to 2000. Mind you, the previous owner installed a three bladed prop (no, I don't know the diameter and pitch--those markings are illegible) that keeps the engine from turning more than about 3100, and that may impose additional load.

Just curious to see what other people experience before calling the mechanic.

David Brownlee
CD31 #1 WINDRUSH
Havre de Grace,

A friend of mine has a CD31 and we were taking it from Maine to Fla and had to restrict the RPM do to over heeating.
He called the factory and they advised him that the Heat exchanger was to small and they had a change out package for a larger heat exchanger. No more heating problems with a three blade prop. They also have an alternator bracket mod, The original mounting on the front gear case can crack the case. The gear case cover was $300 about five years ago. The mod was about $80 as I recall.
Give the factory a call and discuss it with them.

Jerry




jlecocq@milehigh.net

[Stan]

According to the owner's manual, the Universal 25 (21 hp) normal op temperature is 165 to 190 deg F. I'm sure that sea water temp. will affect this op temp.
The maximum rpm is 3000. In the "break-in and general running" section, they recommend that an average cruising speed for a sail boat installation is about 80% of the maximum engine speed attainable, to achieve hull speed (0.8 x 3000 = 2400 RPM). The standard prop was a 13 x 13 2 blade Michigan.
Also, the water pump, if equipped with a grease cup, should be lubricated every 30 hrs. by turning the grease cup 1/2 turn.
Let me know if you need more info., I can send you a copy of the User's manual if need be.

Fair winds
Ker'and Stan
s/v Nomad
cd31 #008



skuhlman@sprynet.com