M-18 Universal Running Hot!!

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B

Bob

Yeah, good ole Lake Lanier........... Water came up a whopping five feet over the last four months but is still 10 feet down! Water is deep enough to get out, but caution is the word. Memorial Day was a perfect time to get the gal out of the dock after a long years rest. My M-18 has 495 hours logged and has always been dependable. It started right up, maintained idle, temperature and good charging til I got out in open water! Lots of steam at the exhaust and temperature ran pretty quickly to 195 degrees at 3/4 throttle. Fluid check (oil and coolant) before leaving the dock was up to standard, new Racor fuel filter viewing glass showed no particulate and intake clear. It only got hot beyond 1/2 throttle position, so I kept it at 1500-1700 rpm mostof the day (no wind mind you) and it stayed steady at 160-170 degrees. I am stumped............any ideas or checks I can make? Thanks Bob 30 Catalina Mark II
 
Jun 7, 2007
875
Pearson- 323- Mobile,Al
Impellers????

Sometimes the impeller blades break on my boat. This can cause less water flow from clogging and less pump efficency. Another cause might be a stuck thermostat!!!! My volvo chronically runs hot. It was converted to freshwater and I think that there is not enough water going through the heat exchanger. I am considering going back to raw water cooled.
 

RichH

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Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
How do you store the engine for winter?

How old is the engine?" If you always store the engine 'dry' - removing all the cooling water, instead of filling it with antifreeze with rust inhibiter, the possibility exists that youve started to form 'slab rust' in the exhaust manifold. Universal manifolds are quite famous for forming slab rust - huge platletts of rust that come off the internal casting and either fully or partly block the flow channels in the manifold. First thing to do is check the water output at the exhaust port at the back of the boat with a bucket and stopwatch and with the engine running at 'cruising' rpm. In your owners manual you will find the specified exhaust water flowrate at a specified rpm. If the flow is less than spec. at the spec. rpm you have a blockage: piece of broken pump impeller, broken impeller, slab rust in the manifold, junk in the inlet strainer, ..... with 'steam' coming out there is something that is partly blocking the raw water circuit, etc. Many times slab rust that is blocking the flow channel will fall to the bottom of the casting when the engine is shut down, sometimes you can 'reverse flow' the cooling water circuit (with a garden hose) to 'release' such slab rust, sometimes you have to remove the manifold turn it upside down and reach in with a stiff wire to break up the 'slabs'. BTW - the 'best' way to 'store' a marine diesel is to fill the engine with 50:50 antifreeze. Prevents the formation of destructive red (ferric) slab rust and keeps the black/protective (ferrous) rust intact which is protective to cast iron. US Navy ships always keeps their engines running to prevent destructive ferric rust from forming. Anyway, once you get your problem straightened out, be sure to **run the hell out of the engine for several hours** so that you restore the protective layers of blue/black ferrous rust inside the block and inside the exhaust manifold. An engine that is developing red/ferric rust in the internals will usually have the telltale 'red streaks' at the exhaust outlet. Running the hell out of a marine engine will greatly retard 'red' rust formation; high engine temperatures promote the formation of protective ferrous (black) rust. If you always drain the engine cooling water for winter, my bet is that you formed slab rust probably inside the exhaust manifold as the worst case scenario.
 
Dec 3, 2003
2,101
Hunter Legend 37 Portsmouth, RI
My Friend's Universal...

...in an O'Day used to break impeller vanes until one got clogged in the engine. Then he had to install a new engine. Best Bet? - remove the impeller when storing the engine for the winter. And "pickle" the impeller in olive oil in a jar over the winter in case it can still be used next season!
 

RichH

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Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
Id avoid olive oil .....

Impellers are made either from neoprene or BUNA. Olive oil when it oxidizes (becomes rancid) forms very potent organic acids (Oleic acid, etc.) and these acids make Neoprene/Buna soften and swell. Its a good idea to remove the impeller to prevent a permanent 'set' in the vanes .... but storing it DRY is preferable. This is the very same reason that you shouldnt use so-called 'bio-diesel' made with 'reclaim' (old cooking oils) without changing all the rubber components in your fuel system from Neoprene to EPDM, etc.: Filter gaskets, diaphragm in the lift/priming pumps,seals in the injection pump, etc. etc. etc. etc. etc. etc.
 
Feb 6, 1998
11,759
Canadian Sailcraft 36T Casco Bay, ME
My methodology for overheating..

#1 Check and clean engine intake thru-hull/seacock. #2 Check and clean hose from intake seacock to strainer and any elbows that may be in this path. Large (very large) zip ties work well for this. #3 Remove strainer basket and snake both inlet and outlet ports. #4 Remove hose from strainer to water pump and check/clean #5 Remove and check or replace impeller and also check the old one for broken vanes. If vanes are broken you NEED to find the pieces. #6 Test run engine make sure you have good water flow. If you are still over heating move on. #7 Using an infrared thermometer (you can't effectively trouble shoot a cooling system without knowing actual temps!) measure the temperature at the sending unit, on the thermostat housing, and compare that reading with your temp gauge. Also, measure the temperature differential between the inlet and outlet sides of the HX and write down the differential. If the gauge and infrared are close and high remove and replace the thermostat. If you must, and are of the overly cheap mentality, remove and test the stat in a pot of water using the infrared to confirm opening temp and re-install. #8 Make sure "sealed" side of the system is not air bound and use the air purge valve to check for any trapped air. #9 If still overheating check the temperature of exhaust elbow (on the engine side) and about 6-8 inches from the exhaust elbow on outlet side for a large temp differential. If you have a large temp differential you may have a blockage at the exhaust elbow. Fix this before moving on and re-check engine. #10 If exhaust elbow checks out open up the heat exchanger and look for "gunk" if junk, corrosion, pieces or crap are present remove the HX and bring it to a radiator shop for an acid bath cleaning. #9 Re-install HX and check engine. #10 If still overheating check for flow and then if it seems restricted purge and clean the "sealed" anti-freeze system side. It's possible the journals and pathways are loaded with rust and corrosion and you have a partial blockage. When the engine is finally fixed and running well use your new infrared thermometer to record the following numbers in a notebook. This will save LOTS of time when you have a cooling system issue in the future.. Incoming water temp at seacock HX Temp differential between inlet and outlet sides. T-Stat housing temp Exhaust elbow - both sides Exhaust hose temp Various points of the cooling system It's best to mark every one of your infrared thermometers "laser" measuring spots with a Sharpie marker so you can repeat these numbers and readings accurately by always measuring the same exact location. With an incoming water temp similar to your baseline and similar warm up and run times all should be similar to your benchmark. P.S. On the M-25 Universal increased the diameter of the HX to a 3" model because the original was grossly undersized. You may check to see if they recommend this on the M-18 as well..
 
B

Bob

I do not "winterize"

Great info. My engine is an 1988 model and has always been in fresh water. Low hours (under 500) for 10 years of age. As Lake Lanier suffered from the drought last year and still continues to remain low, venturing out and risking hitting a submerged stump or obstacle was not in my plan. I went out into open water for the first time this past monday. I did visit the boat during the winter several times to check dock lines, bilge pump operation and to start the engine and warm it up, but never under gear at the dock. Operating temps were normal at throttle up in neutral. Interesting......... Down here in Dixie I never "winterize" my diesel for the winter as that is not a common practice here. Actually, my perferred season for sailing here is the winter! The lake never freezes, the boats stay at the docks and even my fresh water supply is left alone in the tanks without adding anti-freeze. This is the only benefit of sailing in a southern lake, but I would trade anyday with you folks near the ICW to avoid this rediculous Army Corp impoundment and the politics of "water levels"! I will check the impeller as suggested and follow several of the recommended procedures. One tank of diesel can keep me going for several seasons down here and I do add bio-cides. Thanks for the great replies Bob
 
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