Oh no!, no water going into the engine...

[TonyP]

Clay

I am going through that process now.
Two weeks ago when out for a extended weekend we had some warmer (180-190+) than usual engine temps.
Found the intake filter cage jambed with debris. Cleaned but still warmer. Looked at the impeller and 2 fins missing so replaced.
Still warmer. Removed hose from pump and flow seemed ok (about 5lt in 30 secs at idle ... normal is 20ltr/min at 2500.
So now mechanic is taking over and doing a full service. ... Here's hoping.
Tony

[Ron Hill]

Guys : When an impeller vane is missing you need to track it down!!  It's usually in the bottom elbow (exhaust of the pump).

When I had an Oberdoffer pump I stopped using the snap-ring (C clip) that holds the impeller to the stainless shaft!  After you replace the impeller and the face plate - where can that impeller go? as it's captive !!

To help lube the impeller when you first install one and need to compress the vanes to get it on the shaft (Sherwood or Oberdoffer) use some dishwashing detergent.  Slides neatly in place.  Then no grease gets in the lines or HX.

All of the C34 engines (1986 and later) have Oberdoffer pumps later than are written up in the M25/M25XP  Engine manuals.  There is NO problem if you pull the (solid) stainless shaft out.  All you have to do is reslide it back in and re-engage the slot on the shaft - simple as that!!  This has been written up many, many times.

A thought

[Kevin Henderson]

Juan,

Scary feeling discovering that no water has been running through the system and cooling the engine.  Believe me... I've been there.  See Chronicle #4

http://c34.org/bbs/index.php/topic,6686.msg44047.html#msg44047

I had a great deal of asssurances that the engine was probably still fine.  I did however, pay to have a mechanic look it over to be certain.  After that it was simply going through and doing things like changing oil, coolant, filters and the heat exchanger.  (In my case the reason for the overheaing in the first place). 

As for changing out the impeller... fear not... If I can master it.. anybody can.  There are plenty of tips and tricks in here that can steer you the right way in doing the procedure.  But.. here's a couple links that I really like to describe the basics of what needs to be done.  First is one of my heroes for all things boat maintenance related... Mainsail:

http://www.pbase.com/mainecruising/impeller

The second is a local San Diego Blog.  Both procedures graphically lay out the particulars of changing out the impeller.

http://realitycheck.me/replacing-the-oberdorfer-impeller.htm

I'll just add a little something here while I'm at it but I recently found that by using the Jabsco Impeller puller, the procedure goes by much much easier.  Have fun and don't sweat

BTW.. keeping the keys to the ignition attached to the raw water thru hull?   BRILLIANT!! 

[Stu Jackson]

There is a metal retaining ring on the inside of the impeller that holds the impeller on the pump shaft.  You will need to pry this off with a small screwdriver - be careful, as it will go flying when it comes loose.  Press the pump shaft toward the engine as you pull the old impeller off; otherwise, the pump shaft can pull out of the engine body.  

This has pictures of the "innie" and "outtie" pump shaft and inside engine ends.

http://c34.org/bbs/index.php/topic,6766.0.html

With engines older than miner (1986) you should be able to pull the entire shaft out.  No need for gymnastics with the circlip.

[Juan]

Thanks guys, this is really helpful. 

Juan

[TonyP]

What do you guys think of putting a strainer between the pump and HX? Just a thought ... Tony

[Ted Pounds]

Should have a strainer at the intake.  Beyond that I see no need for one and it could cause problems...

[Ron Hill]

Tony : As Ted said there is no reason for another strainer. 

Just inspect your impeller periodically!  My thoughts   

[TonyP]

My thoughts were a strainer to catch impeller bits and be visible. I have a strainer at the intake. It would be easier to clean out a strainer than open the pump or HX
Tony

[Ron Hill]

Tony : If you want a strainer on the output side of the raw water pump and the HX; go ahead and install one.
The line is easily accessible on you M35 engine. 

Our thoughts were that it's not necessary, but if it makes you feel better - do it!!

[Jim Hardesty]

Just getting back about my alarm.  If my memory is correct took power from the fuel pump power, it was right there.  Yes the temp sensor band is on the exhust elbo just after where the water enters.  That alarm has never gone off for me, the manufacture claims just a few seconds without cooling water will set it off.  I put the alarm panel beside the stairs on the starboard side it's small and hardly noticable.  Can hear it well from the cockpit.
I have a MKll and the install was simple.  As I rember the only problem was working one handed through the top access at the aft berth, especially the temp sensor band.  I also got a fuel vacuum gage to check the filter condition.
I haven't had a problem that activated the alarms.  So can't say that they are good for anything but just a little peace of mind.
Jim

[Ron Hill]

Jim : Not to sure who made your Hi Temp alarm?
 
The Westerbeke alarm made for the M25XP, M35, M35BC engines is a switch that screws into the thermostat housing and sounds in the engine instrument panel.

There was another variation for the M25XP that used the temp gage and when the analog gage hit 200F it cause a digital alarm to sound - also in the engine instrument panel.

A few thoughts

[Ted Pounds]

My thoughts were a strainer to catch impeller bits and be visible. I have a strainer at the intake. It would be easier to clean out a strainer than open the pump or HX
Tony

Actually an interesting idea...   

Ted

[Stu Jackson]

My thoughts were a strainer to catch impeller bits and be visible. I have a strainer at the intake. It would be easier to clean out a strainer than open the pump or HX
Tony

Actually an interesting idea...   

Ted

Unless one forgets to open the raw water intake thru hull on a "regular" basis, wouldn't simply changing the impeller every year or so do it?  Many of mine have lasted for two years.

[Jim Hardesty]

Ron,
The alarm I was refering to is a exhust overtemp alarm ie not enough raw water to cool exhust.  Make by Borel.  The idea is that this alarm will go off well before the engine starts to overheat.

http://www.borelmfg.com/products_alarm.htm

Jim