W50 Overheating Mystery

ScottC · **Joined:** 02 Jan 2011 15:51 **Posts:** 53

I just got the invoice today...it was a little more than I thought, but still much less than it could have been. But my cold beverage can come from my new fridge!

Mike · **Joined:** 09 Jul 2008 12:51 **Posts:** 251

I was getting a rise in temp above 1900RPM and set about doing a few things mentioned in previous comments.

- replaced the thermostat (the old one was completely gunked up and I suspect a major contributor to the increase in temp. The little hole on top of the thermostat was covered over with a thick sludge)
- replaced my radiator/reservoir cap (the old one, 4lb, looked like either the 2nd cap or the original. The top upper rubber seal looked like it wore away long ago. I replaced it with the 7lb cap)
- I back flushed the sea water system as described in previous posts by disconnecting the line out from the oil cooler and forcing water back towards the sea water pump outlet; hose disconnected to flow into the engine bilge. Then flush it forward, then flushed it back again.
- I took out the sea water pump and checked the impeller... one fin was missing so this was replaced.

The engine appears to be running cooler but I need to apply a rpm load on it this week to see if this worked. I can say for sure that changing the impeller really boosted the water flow. I can tell a big difference. Surprised that one fin missing could make that much difference.

From now on my yearly maintenance schedule will include:
- Flushing the FRESH water system with water and add new antifreeze
- Flushing the SEA water system
- checking the sea water pump impeller (and replacing every two years)

If anyone has installed a larger sea water pump please let me know what pump you used ?
Also, if anyone has installed a larger oil cooler, also, please let me know what cooler you used ?

Velera · **Joined:** 29 Dec 2006 09:38 **Posts:** 656

did you find the fin? Just one of those can block the pump outflow.

puffcard · **Posted:** 02 Jul 2013 18:14

Yea find the fin they DO NOT dissolve. Also add descaling to your maintenance schedule. The marine heat exchanger guy (Mr Cool) said that vinegar is ok as a descaler, but suggested something stronger like Rydlyme. The new heat exchangers from Mr Cool are much better and effective than the originals and at $300 its a pretty good deal.

http://www.rydlymemarine.com/

Mike · **Joined:** 09 Jul 2008 12:51 **Posts:** 251

good advice.. thanks

Velera · **Joined:** 29 Dec 2006 09:38 **Posts:** 656

Jim mentioned this, but the W50 WILL overheat if the heat exchanger cap is not put on correctly. You must have the little divider in the cap in just the right position to divide the two chambers in the heat exchanger or else the cooling water will bypass. I always found it a challenge to get it positioned correctly.

Mike · **Joined:** 09 Jul 2008 12:51 **Posts:** 251

Well, I've been chasing a problem with coolant missing for the last several weeks. I first thought I had an overheating problem but those symptoms were related to a bad alternator ground. The missing coolant had me convinced that I had a blown head gasket or cracked head even though I was not blowing white smoke OR had water in the oil.

Temperature: The W50 manual states on the 10 Must Always Do page - Check coolant water frequently to make sure it is AT 190 degrees or less. The thermostat is set at 180 degrees so I would expect as you reach hull speed and putting a load on the engine, you would be running between 185-190 degrees. This is normal. Temperatures ranges over 190 to 200 are not. I installed a new radiator cap and thermostat and believe that actually helped the full load operating temp a bit by a few degrees but my original full load operating temp was at or under the recommended Westerbeke temp anyway before my gauge problems. I did the back flushing thing, forwards and backwards. I even installed a new oil cooler but not because of this. It blew an oil fitting resulting in oil pouring out. While getting the fitting off the oil cooler I noticed it was in really bad shape so I purchased another one. So, after doing all this, the question is did I have a temp problem ? I think not. Ensuring a good alternator ground proved to be the problem with temp gauge readings being off and brought my readings back to normal ranges.

Lost coolant: I purchased a radiator pressure tester and pumped it up to 8lbs psi. After about one-two hours I was losing 1 psi. The first thing I checked were my hose connections and found two leaks. Both were on the hot water heater by-pass valve. This valve gets so hot you could fry and egg on it. The reason I never saw coolant directly below it while it was running is because it was evaporating. It was a small leak, maybe 3-4 oz over a 2 1/2 hour period while the engine was running; a loss not very noticeable on short trips but very evident after a 7 hour running time.

I was all set to re-power but I can't throw the old girl away so easy.

UPDATE:

I feel like the little dutch boy plugging holes.... I was still leaking coolant. I did the dirty deed and pulled off the manifold and HX so I could take the HX to a mechanic. He closed loop tested the HX and !!!! found that the sea side was leaking into the fresh water side; ordered a new one from Mr. Cool and really liked the quality; much better than the old one with TWO removable ends for cleaning. By the way the new HX did lower my running temp; it now stays at a constant 184 degrees after reaching hull speed.

So.. after a new alternator, new oil cooler, new thermostat, new radiator cap, new hoses, new HX all seems OK. I shudder to think if I had hired the work done how much it would have cost with parts. The new 7lb radiator cap was BAD. It created a vacuum once the engine cooled off and did not allow coolant to flow back down into the engine. I had saved my OLD 4lb cap, reinstalled it and all is good.

2ND UPDATE:

I purchased another coolant cap, this one from Torrensen/Toad Supply. Now my engine temp stays at a constant 180 degrees seemingly no matter what RPM I run the engine at; never run it past 2400-2500 RPM. The first "new" cap was cheaper.... I guess you get what you pay for some times. Note: After finishing a long trip running the engine for 10-12 hours a day for about 11 days I found that on about the 3-4 day the engine was actually running cooler for longer periods. I never flushed my engine coolant from the engine itself and I suspect old gunk was freed up after running the engine so long. In any case I'm now a happy camper. It was worth all the work !! I'm now a believer that this engine should run at 180 degrees; if it's not, you have a problem with the items listed above.

cseltzjr · **Joined:** 16 May 2009 08:06 **Posts:** 236

An old thread I know but I thought I would pass along some of my experience in this area. I had an overheating problem that also had the symptom of lower raw water flow with increased engine RPM. I finally found that the rubber impeller had become detached from the brass interface. The impeller looked brand new when I took it out to inspect so I put it back in and kept on looking for the problem. It was pretty much by accident that I found the problem.

Also, there was talk on this thread about increasing the water flow by reducing the pulley size on the raw water pump. That can lead to too much water pressure on the pump and it can cause the seal to fail prematurely. I went through several pump rebuilds before I realized that the PO had a 4" pulley on the pump when the original was more like 6". The boat actually came with 3 raw water pumps so they were used to rebuilding and replacing them. Since I changed the pulley back to the correct size (almost 10 years ago), I have rebuilt the pump only once.

puffcard · **Posted:** 25 Apr 2014 21:43

If your impeller is becoming detached from the brass hub, you might have another problem. I had that happen twice and even got a new impeller from West cause one was only 3 months old. What I found was blockage at the heat exchange inlet. The pump is positive displacement, the pressure can get very high and load up the pump impeller.

cseltzjr · **Joined:** 16 May 2009 08:06 **Posts:** 236

It only happened once. It was a defective impeller and Jabsco replaced it. Imagine the difficulty of tracking the problem though! I pulled the impeller out to check for wear / broken vanes and it looked brand new (which it pretty much was) so I simply put it back and continued to trouble shoot. It was a while before I stumbled on the answer. I had the pump apart and was fumbling with the impeller while I was thinking about where to look next when I found I could twist the rubber right off the brass. It was a bit over a year though before I figured out that the pulley on the pump was too small and that was leading to the failure of the shaft seal on the pump. Too much pressure on the output side. I put the bigger pulley on and haven't had to deal with it since (other than routine maintenance).

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W50 Overheating Mystery

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