Engine water cooling not circulating

[Geoff W.]

Looks identical to mine, which is an oberdorfer style raw water pump. I replaced mine with this one. I think a few others have done it too - Globe 815 Run Dry Impeller.

Globe 815 Run-Dry Impeller - 01-12-1540

All Globe Run-Dry™ Impellers are made from elastomers giving them the combined characteristics and multiple properties of rubber, nitrile, viton and neoprene. Features: Will not swell Will not shrink Solvent-resistant Self-lub

www.defender.com

I had an interesting heating issue today where I started my engine and could hear my exhaust very loudly, and noticed the engine temp creeping up. I throttled down, it shot a ton of steam out, and almost immediately the temperature dropped back down. It was very strange, though now reading this I think there may have been something blocking the raw water intake.

 

[clayton]

Looks like an Oberdorfer M202-15 pump. Most places do not carry the impellers and paper (thin) gaskets. If I remember correctly from a (very) old thread, the shaft can be pulled out just enough that it won't engage with the engine "cog" that drives it, and it doesn't have to be pulled much, a 1/4 inch or less. Hopefully I'm not talking out of my arse and giving you bad info on the shaft alignment, sure I remember this from years ago.

 

[Loren Beach]

Our mechanic always advised to be very gentle when re-inserting that shaft. Helps to slightly 'round' the end edge radius too. There is a hidden rubber seal that seals off (cordons off) the inner oil from the outer water, and you do not want to force the shaft to the extent that you nick that seal.
Not 'rocket science' but just another of those little techniques that you learn when doing maintenance and saving yourself $100. plus, per hour.
While it's not always apparent at first glance, these engine assemblies and parts actually respond to a more gentle approach for a lot of maintenance procedures.

 

[K2MSmith]

Looks identical to mine, which is an oberdorfer style raw water pump. I replaced mine with this one. I think a few others have done it too - Globe 815 Run Dry Impeller.

Globe 815 Run-Dry Impeller - 01-12-1540

All Globe Run-Dry™ Impellers are made from elastomers giving them the combined characteristics and multiple properties of rubber, nitrile, viton and neoprene. Features: Will not swell Will not shrink Solvent-resistant Self-lub

www.defender.com

I had an interesting heating issue today where I started my engine and could hear my exhaust very loudly, and noticed the engine temp creeping up. I throttled down, it shot a ton of steam out, and almost immediately the temperature dropped back down. It was very strange, though now reading this I think there may have been something blocking the raw water intake.

Thanks Geoff, I have ordered one of these (as well as the Jabsco) it won't hurt to have a spare.

 

[K2MSmith]

it was a little difficult to debug this problem. the inflow and outflow was not clogged and the impeller looked pretty good. A rigger friend of mine suggested that the impeller can spin on it's shaft without the blades turning. So I ran the engine for a minute with the pump cover off. Shaft spinning but blades not moving. Took me half a day to figure out, but saved some money in the process and it gave me a feeling of confidence that I can actually do something mechanical myself

 

[Frank Langer]

it was a little difficult to debug this problem. the inflow and outflow was not clogged and the impeller looked pretty good. A rigger friend of mine suggested that the impeller can spin on it's shaft without the blades turning. So I ran the engine for a minute with the pump cover off. Shaft spinning but blades not moving. Took me half a day to figure out, but saved some money in the process and it gave me a feeling of confidence that I can actually do something mechanical myself

You know, we've all gone thru this process of gradually learning the intracicies of the various systems on our boats, and the engine stuff is usually the most challenging. Keep learning, use your problem solving skills, ask lots of questions on this site, and you'll be fine.
Frank

 

[Rocinante33]

it was a little difficult to debug this problem. the inflow and outflow was not clogged and the impeller looked pretty good. A rigger friend of mine suggested that the impeller can spin on it's shaft without the blades turning. So I ran the engine for a minute with the pump cover off. Shaft spinning but blades not moving. Took me half a day to figure out, but saved some money in the process and it gave me a feeling of confidence that I can actually do something mechanical myself

So the rigger correctly diagnosed a mechanical problem? Good man! Not his usual area of expertise, but he guessed it correctly nonetheless.

what color was that bad impeller? Was it a blue Globe brand or did it have black vanes?

 

[Rocinante33]

So the rigger correctly diagnosed a mechanical problem? Good man! Not his usual area of expertise, but he guessed it correctly nonetheless.

what color was that bad impeller? Was it a blue Globe brand or did it have black vanes?

Good job to you, also Kevin. Not straightforward to diagnose.

 

[K2MSmith]

Good job to you, also Kevin. Not straightforward to diagnose.

Keith , the impeller has black blades . Not sure how the brass bushing is attached to the vanes , but I can easily rotate the blades , while holding the shaft ( with it removed of course ) . It seems the center hub is slipping . I could probably fix it with epoxy , but a new one is relatively inexpensive. I ordered a black one from jabsco, but since then someone posted a source for the blue global ones so I ordered one of those too . Should I wait for the blue one ?

 

[footrope]

Your pump is an Oberdorfer. Clayton is probably correct about the model number. You can use a paper gasket but they cost $10 each around here. I've made one from a brown paper bag, and it works fine. It looks like there is also a groove for an o-ring in that body, which is a newer body than mine (I have a -7). The o-rings are available from marine stores and marine engine shops which will take away any guess work about finding the right fit. The cover should compress the o-ring so the cover mates to the body without leaving a gap. There is probably a part number on that cover that you can look up and see what pumps it fits.

I've used both black rubber impellers and the blue Globe, but prefer the black rubber. Get a new one. They really aren't repairable. Check the impeller at least at the beginning of every season, or more often - get spare gaskets or o-rings. There are plenty of stories of cracked and broken vanes when the impeller isn't replaced often enough. When the vanes break off they can plug the raw water line and may get into the heat exchanger. Either situation can cause overheating.

Hope it all works out for you.

 

[K2MSmith]

The pump has what looks like a “1105” stamped on it if that is any help in identifying the model ( see photo ). I was thinking why not just buy another one as a spare but they are expensive ! ( maybe 400-450 US ) - so just ordered impellers.

 

[Brad Johnson]

I installed a run dry impel and had problems all the time , I replaced with a tradition impel and no troubles in two years.

 

[Alan Gomes]

Keith , the impeller has black blades . Not sure how the brass bushing is attached to the vanes , but I can easily rotate the blades , while holding the shaft ( with it removed of course ) . It seems the center hub is slipping . I could probably fix it with epoxy , but a new one is relatively inexpensive. I ordered a black one from jabsco, but since then someone posted a source for the blue global ones so I ordered one of those too . Should I wait for the blue one ?

There have been past reports of Globe impellers in particular manifesting this problem, i.e., the hub spins but not the blades. Check the archives on different sailing fora for this.

 

[Kenneth K]

When I was researching impellers on this site a few years ago, I did see some complaints about the Globe run dry impellers separating at the hubs. But the complaints were lacking in details-- I.e., how many hours, how many seasons on the impeller, was a raw water strainer installed, etc?

The failure mode of the standard impeller (black rubber blades with brass hubs), on the other hand, seems to be that the hub stays intact but the blades shred.

Which is worse? As long as the blades stay intact and a spare is on hand, an old impeller can be replaced in about 20 minutes. However if a blade(s) is shed, it could take hours or days to find &remove all the bits of rubber from throughout the cooling system---every elbow, every hose , the pump, the heat exchanger--and your engine is down for the count (or at least prone to overheat). That's something to consider in regards to your intended use of the boat and engine.

I use Globe 815s and put a fresh one in at the start of every season. Never had a problem. And, it also gives you insurance in case of a run-dry event.

 

[debonAir]

You should put a new impeller in every few years at least, depending on how much you motor.

You also should get a raw-water strainer between the thru-hull and the pump since bits of ocean life and gargbage are getting sucked in to the pump and pushed through the heat-exchanger and you don't want build-up or clogs in there.

I tried the run-dry but went back to the black. The run-drys are polyurethane (vs neoprene) and don't flex as well and were harder to install. I might put one back in since that's all I have for spares now but for some reason I can't explain the softer rubber ones seem better. It doesn't take much wear on the inside face of the water pump cover to make the pump unable to prime itself so you want to check that.

The newer Oberdorfers have an o-ring on the face plate vs the paper gasket which is a big improvement since the gaskets are hard to find and get messy, and the newer plate is reversible meaning you can flip it over if the inside gets scored. You should be able to get a new pump for about $300 from pumpsandpartsonline (where I got my replacement, they were really great to deal with) https://www.pumpsandpartsonline.com/shop/oberdorfer-pumps/rubber-impeller/rubberimpellerpumps/N202M

Moyer Marine also makes a drop-in replacement that has (handy) thumb-screws for getting at the impeller. https://moyermarine.com/product/mmi-502-flange-pump-csob_00_365/ and ball-bearings inside.

Note that the Moyer (and the N202M) have a 2-bolt flange. You need to have the little adapter plate between the timing gear cover (the big metal cover that is the front of the engine) and the pump to use that style. You can get that adapter from Moyer also.

Looking at your pictures, it looks like you have the "other" style pump that mounts directly on the timing gear cover studs you need the other flange style:

N202M-15 -- Rubber Impeller Pump

www.pumpsandpartsonline.com

This style has the advantage of not needing the little shaft extender that sits inside the adapter plate (don't loose that if you have one!!) but either is fine.

 

[Sean Engle]

Just as an aside, whenever you flush or pull a hose off, etc. You also get air pockets in your system which have to be burped out else you will impede water flow. Squeeze your hoses - they should be silent. If they're not, you've got air in them.

And...another source of this is when your heat exchanger rots out - and your coolant escapes through it. You should be checking your exchanger for growth/blockages/rotting and change the zinc in a regular basis...

 

[Kenneth K]

debonAir said...."You should put a new impeller in every few years at least, depending on how much you motor"

I wonder sometimes if NOT using the engine, say for a few months over the winter, is harder on impellers than regular use. One of the blades has to stay bent and misshapen for the whole time the engine is not in use.

If I can remember, sometimes I'll hand-turn the engine just a bit over the winter. It rotates the impeller blades and internal engine parts. A freshwater or antifreeze flush is probably helpful too if the engine is going to be left sitting unused for awhile.

 

[Filkee]

After I run antifreeze through the engine each fall, I pull the impeller and slather it in unpetroleum. I take it home and put it in a cupboard and visit it every few weeks to make sure it’s happy. Picking the crumbs out of the system once was enough (okay, maybe twice). And I have like three spares on board. Don’t like overheating.

 

[K2MSmith]

The long story has a happy ending:

thank you all !

 

[footrope]

In salt water, this can happen if the engine isn't run frequently enough. This is the result of one season of use and two consecutive seasons of sitting at the dock. The impeller is a Globe 815.