This just don't look right

[Briankinley2004]

I have been chasing a temperature creep problem on my starboard engine that appeared after I fixed it on my port engine. Had heat exchangers cleaned and tested last year with new coolant and port was fixed but starboard started creeping. I think it already was but was happening slower than the port. Anyway I decided to change the impellers as they are nearing two years old. When I opened the cover on both of them the picture below is what I found. I know I installed them with all the vanes pointing in the same direction and always heard they "right themselves" once you crank the engine. I'm not sure what is going on here but unless my mind is fading (could be) they all are supposed to go in the same direction. If it is wrong in the pictures it seems odd both engines would do the same thing.

 

[SEVEN]

The veins are getting weak. I changed mine out every year whether they needed it or not it’s just a safety issue.

 

[SKYCHENEY]

The engine can roll back at shutdown. Its not an installation problem.

 

[Captain Ralph]

Don't over think this.
When that engine stops, those impellers are still subject to every last movement of the cam shaft and water pressures.
There is nothing wrong on what you found and if you install new impellers, run them a few minutes, you may find the same spaghetti under the cover.
No worries.☺☺

 

[Briankinley2004]

Glad to hear it is OK. Never noticed that before but I might not have been looking. I was hoping I could blame my creeping temp at cruise. I boiled the stats today and they started opening at 160 and were fully open at 185. Going to replace them anyway since I have it apart and save the others for spares. Haven't found a smoking gun yet.

 

[SKYCHENEY]

Replace the seals when you replace the thermostats. My Detroit mechanic said he would only put 170 thermostats in, nothing else. I stuck with that for 20 years and 5000 hours.

 

[Captain Ralph]

my creeping temp at cruise. Haven't found a smoking gun yet.

How old are the raw water hoses from the sea-cock to raw water pump?
I have found fouling and hose delamination to cause issues here.
Had a good bug inside a Groco strainer several weeks ago; In the cast water passage was some fouling that was not visible by eye.
One of my favorite peeve is restricted exhaust dump cans. Usually old zinc parts, silt and grunge clog up the shower heads.

Pending the raw water flow thru oil, fluid, fuel coolers,, then your air coolers, a small restriction could be anywhere.
By hand squeeze the raw hoses. Then while running at cruise; note any hoses getting hard, firm or swelling?

 

[Scarlett]

Undo the fitting where the hose from the intake thru hull attaches to the water pump. Inside mine looked like a fouled toilet hose. Had to dig out a bunch of crude like calcium buildup. After cleaning my temps came way down.

 

[cww]

This is 100% normal. Because of their extremely high compression ratio, diesel engines will often roll backwards at shutdown. You can feel it when you hold the stop button. The pump is cam-driven and will also roll backwards with the engine.

 

[Briankinley2004]

I can attest that from the strainer down the passage as clear as I just hauled out. The hoses were put on by prior owner about 5 years ago and appear to be good. He used the fiberglass fittings to make the turns. I will remove and inspect though just to make sure. I did pull the cover off the freshwater pump and there appears to be some play in the bearings. I don't know if this would cause it not to perform but I am thinking of rebuilding it. Fuel cooler serviced and tested last year and oil cooler looked clean when I pulled heat exchanger. Lost my horoscope in the flood so I ordered a new one and plan to run it in the intercoolers while I have the hoses off checking all the raw water pipes connected to it.

Does anyone know how difficult it is to rebuild the freshwater pump? It appears fairly simple but there always seems to be something to deal with. Unfortunately Boat Diesel closed before I got to downloading the water pump section and all of the online stuff seems to deal with the walking pumps and not standing ones.

 

[Captain Ralph]

Rebuild the coolant (fresh water) pump? Is the rear seal leaking?
It looks and works just like a bronze A/C pump. Mechanical seal and bronze (or stainless) impeller.
If you open the cover and the impeller looks whole, Put the cover back on and keep looking for trouble elsewhere.

 

[Briankinley2004]

Rebuild the coolant (fresh water) pump? Is the rear seal leaking?
It looks and works just like a bronze A/C pump. Mechanical seal and bronze (or stainless) impeller.
If you open the cover and the impeller looks whole, Put the cover back on and keep looking for trouble elsewhere.

Can't see the vanes of the impeller when you open the front cover, just the back side. They face towards the engine. I can move it side to side a bit which makes me think the bearings are bad. I ordered the rebuild kit. I may leave it alone but Im ready to fix this issue

 

[Captain Ralph]

It was 20 years ago I replaced the rear seal on ours, I forgot the impeller faced astern.

 

[Captain Ralph]

I was looking at your pictures again in post #1;
Are the ends of the raw water impellers showing any wear?
How did that contact area look on the cover plate?

 

[Briankinley2004]

Impellers look fine. There is some set in the vanes but the ends look good. The cover plates does not have any grooving. I turned it over when I changed them last time. The cam plate seems to have plenty of metal left.

I did notice when I tap on the freshwater impeller there is a metallic sound like something hitting on the inside. I tried to post the .mov file of the video so it could be heard. It will not let me post those types of files but at least I can post PDF's now. It sounds like a light hammer sounding on a piece of metal like a drive shaft. I wouldn't think that is normal but maybe it is. I have the rebuild kit in hand but not sure I need to tackle that yet. Got a new horoscope today and shined in one intercooler. Didn't see anything growing in there but was hard to see inside the tubes

 

[Captain Ralph]

The raw water pump has a serviceable wear plate on the other end (forward end) of the impeller, how did that look?

The circulating pump shaft is suspended with 2 bearings, a direct drive metal coupling and the floating action is from spring loaded mechanical shaft seal that seems to be NOT leaking.
Don't beat on it to hard in fear of cracking the ceramic seal, pressed into the impeller.
If you must dig into Pandora's box, I recall the impeller screws off the shaft like a big A/C bronze water pump.
You should find 5 metal vanes with no wear and the case behind it without big cavitation pits (lil sand casting dimples are O K).

 

[jmooney]

Last time that replaced a fresh water pump , it cost $275 . You need a dial indicator to set the clearance of the gears .

 

[Briankinley2004]

Wear plat "looked" ok but I need to take it out and check it. Setting gear clearances and Pandora's box makes me think I will put the cover back on the fresh water pump and see if everything else I am working on will fix this. This is why I like this forum. I once took a mechanical fuel pump off an old skytrac I owned and had it rebuilt. I didn't know I had to set the timing and should have marked some stuff when I took it off. I never did get that thing to run and sold it as is.

 

[Briankinley2004]

Last time that replaced a fresh water pump , it cost $275 . You need a dial indicator to set the clearance of the gears .

Depending on rotation they appear to be 1200 to 1600 now. Mine is the standing type which, based on price, must be the marine ones.

 

[Briankinley2004]

Following up on this I decided to forgo the freshwater pump. I may have found my "smoking gun" as nothing else appeared out of order. I decided to check the wear plate and when I removed the cam the teeth on the upper side looked like an inbred hillbillies. I don't know how I didn't see or feel this so I don't trust my old eyes anymore. Anyway I still cant get the wear plate out. I have tried a configuration of picks, tapping on the outside of the pump as well as tapping the plate straight on with a wooden dowel and applying penetrating oil. I also ran an exacto knife around the perimeter of the plate. If anyone has any tricks for removing this thing without taking the pump off it would be appreciated. I have never had difficulty removing one before.