Heat Exchanger Zinc Change out

[britinusa]

I just read Ron's Mainsheet Article about rebuilding the Oberdorfer Pump.

Just what I needed! Both the old and new pump have the O-ring between the cover and the pump body.

Thanks Ron.

Paul

[KWKloeber]

Paul

You are plain lucky (with the condition of the pump/impeller as you describe it.)  Wasn't it in July that I posted, "Inspect it" -- based on the condition shown in your photo!!

I removed the sender and cleaned out the housing threads with a battery post cleaner (looks like a small wire bottle brush) and reinserted the sensor.
Started the engine but still nothing reading on the gauge. I shorted the gauge to the block and got full gauge reading.

If you have continuity between the sender body and battery negative (which you previously reported that you did) -- you're chasing the wrong dog "screwing" ) with the threads.  You ALREADY convinced yourself that you have a good ground and can move on.

0.4 - obviously your engine ground is good enough for the sender to work (very low current.)

Did you remove the cap and verify that there's a thermostat in installed?

Ken

Was there a thermostat in place when you pulled the sender? And if so, pull and check whether it's stuck open (check for it being normally closed and opening when boiled.)

Realize that a diesel won't get to normal operating temp unless under load.  Before I changed the WH setup and moved my hoses up to the thermostat bypass loop, I'd run her for an hour at the dock before I got hot water. (OEM the WH was in series with the HX).   With the setup after our C30  engines, you start making hot water immediately - before the Tstat opens.

You have an Oberdorfer N202M-15 or -16 pump.  Yes they can be rebuilt - as you see in the TechWiki.  However it depends on the condition of the shaft, bearing, etc.  whether it's worth it, versus getting a new pump.  If you buy all new parts, and you have the -15 pump, it's not worth it because you can get the 1/2" (-16) pump versus the 3/8".  Turn the cover over if it is scored or worn. I doubt you have calcium (lime deposits) unless you're pumping groundwater!

Re-check the impeller before you run the engine again -- (Admiral's has good intuition) -- running it without seawater will burn up the impeller and can leave bits and pieces in the cooling train and Hx.  REMOVE it and check the vanes for damage.  Throw away the cir-clip that goes on the shaft.  The clip is useless - see the TechWiki.


The gizmo next to the pump land is the cover to the governor adjustment --- don't screw with that -- literally  
The old pump should have had a small crescent ground out of the flange so it fits around the cover -- use a Dremel, grinding wheel, or file a small notch in the pump flange.

You need a thermostat - don't run the engine cold - if in saltwater, a 160F stat; if in freshwater, a 180F stat.  
Again see the TechWiki for info I posted about the Ob pumps and Kubota (i.e., cheaper) thermostats.  Your pump guy. 

Cheers,
Ken

[britinusa]

Thanks Ken,

Will do:

• Check the impeller as it ran dry when I turned off the Raw water
• Remove the pump and grind off enough to be able to put it on without having to remove the governor nuts
• Check the thermostat (I assume that's inside the housing where the sensors are located?)

Paul.

[KWKloeber]

Thanks Ken,

Will do:

• Check the impeller as it ran dry when I turned off the Raw water
• Remove the pump and grind off enough to be able to put it on without having to remove the governor nuts
• Check the thermostat (I assume that's inside the housing where the sensors are located?)

Paul.

Paul, see your XP parts manual under the Water Flange Group, the Speed Control Plate Group shows the adjusting screw -- and the XP Service Manual p.86 for the coolant flow/thermostat.
Both manuals are on the wiki and provide a wealth of information on all the engine systems (rainy weekend reading on the boat.)  I can email copies that are searchable if you want.

Cheers,
Ken

[britinusa]

Thanks Ken, found them both 

Paul

[britinusa]

Just read the tech wiki about the circlip.

Got it!

(Dang, I just ordered the circlip tool from CD. last night. I'll call and cancel that one!)

Thanks again.

Paul

[KWKloeber]

Just read the tech wiki about the circlip.

Got it!

(Dang, I just ordered the circlip tool from CD. last night. I'll call and cancel that one!)

Thanks again.

Paul

Paul,

  The wiki and posts can be your BFF, and conceivably save a lot of $ and aggravation.  It will be a sunny day when everyone "gets it."


I think you see my M.O. here. 

PS the Harbor Freight snap ring tool is 4 bucks instead of CD's 25 bucks and comes with 4 different heads.  Onto my soapbox, this is my problem with CD -- I have no problem with anyone making a buck, so long as they know what they are selling and why, and not simply passing along crap -- or selling something that is unnecessary and arguably worse for the owner.  That's not to say that CD doesn't sell many other good products.


Cheers
Ken

[mark_53]

PS the Harbor Freight snap ring tool is 4 bucks instead of CD's 25 bucks and comes with 4 different heads. 

I just replaced my raw water impeller and had to deal with removing that circlip.  The holes on the clip are extremely small. The Harbor Freight tool was too large. I did find the right size at Sears. The pins are so small, they broke after the first use. Good to have the right size tool onboard along with the impeller replacement kit. I'm hesitant on getting rid of the circlip altogether.

[Stu Jackson]

I didn't know there were circlip tools, so I use two small flat bladed screwdrivers.  Been doing it for 17 years.

[KWKloeber]

. I'm hesitant on getting rid of the circlip altogether.

WHY?
i.e., Explain what purpose it might serve.

KK

[mark_53]

WHY?
i.e., Explain what purpose it might serve.

KK

I'm not the engineer who designed the pump, but logic tells me it restrains the impeller from traveling along the shaft. You'd have to ask the engineer.  It adds little weight so why not trust their judgement? I suppose in an emergency I would forgo installing it. Call me a perfectionist.

[KWKloeber]

WHY?
i.e., Explain what purpose it might serve.

KK

I'm not the engineer who designed the pump, but logic tells me it restrains the impeller from traveling along the shaft. You'd have to ask the engineer.  It adds little weight so why not trust their judgement? I suppose in an emergency I would forgo installing it. Call me a perfectionist.

I took the time to explain it in the TechWiki entry!  Did you read that -- all should become clear.  
Others questioning whether they need the cir clip should research the TechWiki for themselves before deciding that the recommendation is contrary to Ob judgement.

The impeller is restrained in one direction by the cover, so it can't move.  
In the other direction the impeller is restrained by the back of the pump body and can't move.  
In one direction the shaft is restrained by the shoulder on the impeller so it can't move forward.  
In the other direction the shaft is restrained by the camshaft and can't move backward.  

The cir-clip serves no purpose once the pump is installed on the engine - the TechWiki explains why it's on there.  All would become clear if you read the reply from Oberdorfer.

The only purpose it serves, is to make it harder to pull the impeller and replace it in an emergency, like overheated leaving the harbor because the sea cock was closed and had to shut down. And you're headed for a breakwall or the shallows.  
Believe me -- it serves no purpose and weight isn't the issue - safety is.  

But YB, YC!  

I too am a perfectionist    -- which is why I questioned why it's on there and the functioning of it.

kk