Engine water cooling not circulating

[K2MSmith]

My engine got really hot and I had to shut it down today. I noticed no water circulation. It was circulating when I left the dock. I know this is probably a common issue but can anyone give me some tips on where to start looking ? The diesel mechanic told me that I could use a “sea strainer” when he did the service. So I guess, my boat doesn’t have one. Could there be a clog somewhere ?

 

[bigd14]

Seems like a clogged intake would be most likely if it suddenly stopped flowing. Maybe a broken impeller too. You will probably have to remove the intake hose between thru hull and raw water pump to get at the clog. People have used a dowel or similar object to ream the hose/thru hull out. Let us know what you find out.

 

[K2MSmith]

Seems like a clogged intake would be most likely if it suddenly stopped flowing. Maybe a broken impeller too. You will probably have to remove the intake hose between thru hull and raw water pump to get at the clog. People have used a dowel or similar object to ream the hose/thru hull out. Let us know what you find out.

I looked up diesel impeller and online and there are some YouTube movies that show you how to check it. If I can find the thru-hull fitting on my boat, I’ll try that first in the morning. I’m wondering if there are any simpler diagnostics before I take off the impeller cover ?

 

[Frank Langer]

Sometimes a plastic bag or weeds can cover, or get sucked into the raw water intake. A quick dive with a coat hanger hook can check if there something in that thru hull. Then close the thru hull and open the impeller cover to check if all the vanes are visible, none missing, and no visible cracks in the impeller. If ok so far, open and shut the intake seacock to see if water comes thru to the impeller opening. If not, there is still a blockage there. If yes, the blockage is further up the system towards the heart exchanger.
I'm assuming you have enough coolant in the engine. Also, on our boat, and others, you can get an air lock in the cooling system, requiring bleeding thru the pet cock near the thermostat. In fact, I would check that first, and if you get air bubbles coming from the petcock, there may not be a blockage elsewhere. To check for bubbles on our boat I remove the cap on the overflow tank, then open the petcock, with a rag in hand.
Let us know how you make out.
Frank

 

[GrandpaSteve]

I had this problem recurring a couple of years ago. The impeller was fine and the seawater intake was fine. The problem was the impeller cover on the pump face was worn after 30 years , causing a problem with the pump getting suction. For me the answer was a new Oberdorfer pump.

 

[Loren Beach]

I had this problem recurring a couple of years ago. The impeller was fine and the seawater intake was fine. The problem was the impeller cover on the pump face was worn after 30 years , causing a problem with the pump getting suction. For me the answer was a new Oberdorfer pump.

Years ago, our OEM Universal diesel (with Oberdorfer pump) developed some wear grooves on the cover plate. A friend of mine machined/sanded it flat. That seemed to help it prime faster. (We do have an ongoing challenge with our Columbia River water in that it carries, along with the usual silt, glacial fine grit suspended in it. It is abrasive, altho it takes quite a bit of use to really affect pump parts. )
I finally replaced the whole pump because we could see that the chamber was pretty 'smoothed up' inside and likely not making as firm a contact with the rubber impeller as it did when newer.
Depending on the water quality and fine sand contents where you are, perhaps eventually all of these little pumps might need to be replaced, Maybe. Perhaps.

 

[K2MSmith]

Seems like a clogged intake would be most likely if it suddenly stopped flowing. Maybe a broken impeller too. You will probably have to remove the intake hose between thru hull and raw water pump to get at the clog. People have used a dowel or similar object to ream the hose/thru hull out. Let us know what you find out.

Thanks to all for your quick replies. I’m somewhat embarrassed how little I know about this stuff I’ve attached photos. It looks like the sea water pUmp with impeller is the greenish ( brass ? ) thing with the four screws on the cover . The black hose goes to a thru-hull fitting ( see 2nd picture ) . The valve turns easy. Both easy access . Wonder if I should just try to remove hose at pump side and see if water goes thru it before I take off impeller cover ?

 

[Loren Beach]

Thanks for the pix. That green-bronze color on the left (viewing the image) is the raw water pump. Other observations: is the bracket for the alternator the original one that was known to break? If so, there is a replacement kit for it.
The view thru the galley counter door seems to show both the fresh water and salt water foot pumps, and the shiny one on the the right is probably a replacement - note the later model way the center part is held together.
The thruhull fittings and ball valves look like the original RC Marine (later bought and redesigned by Forespar). I would suggest replacing all with new ones, next haul out.

 

[Frank Langer]

Hi,
Normally, one should check the impeller at least annually, and replace every few years (some say annually!), so I would still suggest you remove the impeller cover to check it's condition and see if all the vanes are there, if there are cracks, etc. Removal is easy--close the seacock, use an allen wrench to loosen and remove the four screws. It's best to have a replacement gasket for when you put the cover back on, as the existing one will likely be stuck there or tear or be otherwise not useable. Puttiing some rubber friendly grease on the inside of the cover and very lightly on the vanes will help it start up properly, and sometimes a bit of extra throttle is needed to get it primed for the water to flow.
Frank

 

[K2MSmith]

Thanks for the pix. That green-bronze color on the left (viewing the image) is the raw water pump. Other observations: is the bracket for the alternator the original one that was known to break? If so, there is a replacement kit for it.
The view thru the galley counter door seems to show both the fresh water and salt water foot pumps, and the shiny one on the the right is probably a replacement - note the later model way the center part is held together.
The thruhull fittings and ball valves look like the original RC Marine (later bought and redesigned by Forespar). I would suggest replacing all with new ones, next haul out.

Thanks Loren , I wasn’t aware of alternator bracket and original valves / fittings . I’ll put on list to replace .

 

[K2MSmith]

My setup for checking the inflow side . I connected a garden hose to it and water seems to run freely full pressure thru the thru-hull . So either it’s not clogged or I unclogged it . I did have a bucket and turned in a little at a time .. Maybe I should check impeller ? It looks tempting enough to open cover but I don’t have a spare gasket yet .

 

[K2MSmith]

Sometimes a plastic bag or weeds can cover, or get sucked into the raw water intake. A quick dive with a coat hanger hook can check if there something in that thru hull. Then close the thru hull and open the impeller cover to check if all the vanes are visible, none missing, and no visible cracks in the impeller. If ok so far, open and shut the intake seacock to see if water comes thru to the impeller opening. If not, there is still a blockage there. If yes, the blockage is further up the system towards the heart exchanger. I'm assuming you have enough coolant in the engine. Also, on our boat, and others, you can get an air lock in the cooling system, requiring bleeding thru the pet cock near the thermostat. In fact, I would check that first, and if you get air bubbles coming from the petcock, there may not be a blockage elsewhere. To check for bubbles on our boat I remove the cap on the overflow tank, then open the petcock, with a rag in hand. Let us know how you make out. Frank

 

[K2MSmith]

Where can I find the petcock /thermostat? It looks like everything is clear in inflow and impeller looks new .

 

[Frank Langer]

Where can I find the petcock /thermostat? It looks like everything is clear in inflow and impeller looks new .

Hi,
That impeller does not look new to me, but still looks ok, based on your pic. After a while cracks develop where the vanes attach, and a "set" develops where the vanes bend which impedes flexibility and affects operation.
Gaskets can be purchased on line or at a Universal/Westerbeke dealer, or you can buy gasket paper at any automotive store, but these gaskets are very thin, so don't buy thick paper or the cover won't fit tight to the impeller.
Frank

 

[Frank Langer]

Your petcock is the small wing like thing just to the left of your coolant cap at the top of the engine. Open it carefully if it hasn't been done in a while, so you don't break it off.

 

[K2MSmith]

Hi,
That impeller does not look new to me, but still looks ok, based on your pic. After a while cracks develop where the vanes attach, and a "set" develops where the vanes bend which impedes flexibility and affects operation.
Gaskets can be purchased on line or at a Universal/Westerbeke dealer, or you can buy gasket paper at any automotive store, but these gaskets are very thin, so don't buy thick paper or the cover won't fit tight to the impeller.
Frank

Mystery solved !!!
I ran engine with pump cover off and see that the shaft is spinning inside the impeller , but the impeller not turning . So I need a new impeller. I’m bringing the shaft / impeller/ photos to svendens to see if the have an impeller and right tool to remove it . Does anyone know what kind of pump is on this M25 model ? The pump has a number in it . See photo .

 

[goldenstate]

Glad you got it sorted out.

I suspect the guys at Svendsen's will be able to determine the right part based on your engine type and your photos. You could pull the old impeller out and bring it with you for comparison. I would try a pair or two of medium-sized needle nosed pliers before I bought any fancy puller tool. Or anything that can get purchase to slide the impeller off.

-Tom

 

[goldenstate]

As for why the impeller isn't spinning like it is supposed to:

 

[Alan Gomes]

As for why the impeller isn't spinning like it is supposed to:

View attachment 35576

The retainer clip is unnecessary. You could discard it altogether and it would have no effect. On my previous two Universal engines (M18 and M25XP) with Oberdorfer pumps I discarded the snap ring since it does nothing in a normal installation. It would, however, keep the shaft from sliding out the back on a pump that was removed from the engine for some reason. But in terms of the shaft sliding forward, that can't happen when the cover is in place.

The flat on the shaft that mates with the flat on the impeller is what would make the impeller turn.

 

[K2MSmith]

The retainer clip is unnecessary. You could discard it altogether and it would have no effect. On my previous two Universal engines (M18 and M25XP) with Oberdorfer pumps I discarded the snap ring since it does nothing in a normal installation. It would, however, keep the shaft from sliding out the back on a pump that was removed from the engine for some reason. But in terms of the shaft sliding forward, that can't happen when the cover is in place.

The flat on the shaft that mates with the flat on the impeller is what would make the impeller turn.

it’s a little difficult to figure out which pump I actually have. it appears to be an Oberdorfer pump or clone of one. It does not look like a Universal/Westerbeke pump as shown on their site. The shaft has one flat section. I went to West Marine and it looks like a Jabsco impeller 7273-0003P is the same outline as the original with one flat on the inside sleeve. They did not have it in stock. I took a chance and ordered one of these From a marine pump supply and I am having it fedex’d. If anyone has the same pump would appreciate any sources for the part. It doesn’t appear to be a common type of impeller as west marine and svendsens both did not have it.