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Old 08-23-2012, 05:54 PM   #1
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3208 Cats

We purchased our boat four months ago and have enjoyed the Chesapeake. We are planning to head south in a month. Had the oil and filters changed but am wondering if I should replace the raw water impellers. I have put about 100 hours on the engines and with the log on repairs the impellers are going to have over 200 hours on them before we head south.

Does it sound prudent to have them replaced before we depart?

thanks for all input.

DT
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Old 08-23-2012, 06:05 PM   #2
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We have 3208na cats as well. We don't usually begin to think about them until about 500 hours. We have good sea strainers and travel in mostly clear water. You could pull the cover plates and take a look. Have a set of new gaskets ready after the inspection. Also, for peace of mind, you could install new impellers and keep the current set for spares on your trip South.
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Old 08-23-2012, 06:34 PM   #3
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If it were me, I would open it up and have a look. I trust what I see far more than what I read. I would look for wear on the cover, most can be flipped over. I would look for cam wear, and assuming It all looks good, it should, I would have spares for later. While I am hugging the engine, I would check the alternator belt, the alternator mounting bolts for tightness and carry a spare belt.

Both Items gave me trouble on both engines within 100 hours of bringing my boat home last year. Had they failed on the 900 mile trip home, I would have been a world of hurt. Particularly on the Ohio and Mississippi rivers. I was damn lucky. Now that I have used up my Good Fortune, I know to be far more careful.
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Old 08-23-2012, 07:04 PM   #4
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If it were me, I would open it up and have a look. I trust what I see far more than what I read. I would look for wear on the cover, most can be flipped over. I would look for cam wear, and assuming It all looks good, it should, I would have spares for later. While I am hugging the engine, I would check the alternator belt, the alternator mounting bolts for tightness and carry a spare belt.

Both Items gave me trouble on both engines within 100 hours of bringing my boat home last year. Had they failed on the 900 mile trip home, I would have been a world of hurt. Particularly on the Ohio and Mississippi rivers. I was damn lucky. Now that I have used up my Good Fortune, I know to be far more careful.
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Is excessive pump/impeller wear a specific problem for 3208's or is it because of the river silt/sand?

Here in the PNW the pumps and impellers seem to last a long, long time. Must be the sparkling, clear, clean waters of the Pacific?? As long as you keep your strainers clean and water to the pumps anyway. I'll bet I haven't replaced mine in over 5 years! I need to check my maintenance log, as they've got to be showing some wear by now!!
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Old 08-23-2012, 08:36 PM   #5
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I'll bet I haven't replaced mine in over 5 years! I need to check my maintenance log, as they've got to be showing some wear by now!!
it isn't just wear. The rubber "takes a set" (reducing life), and loses pliability. The real cost is what happens if you lost parts of vanes that can plug downstream coolers.

My club neighbor showed me his 2yo vanes with 250 hours (and seemingly solid pumping) that had lost several vanes.

The reason that PNW boaters go longer is that the cooler water fools them into not noticing reduced cooling capacity.
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Old 08-23-2012, 08:55 PM   #6
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[QUOTE=Capn Craig;100123]If it were me, I would open it up and have a look. I trust what I see far more than what I read. I would look for wear on the cover, most can be flipped over. I would look for cam wear, and assuming It all looks good, it should, I would have spares for later. While I am hugging the engine, I would check the alternator belt, the alternator mounting bolts for tightness and carry a spare belt.

Sounds good to me!

I hope your project has been going well. Are you coming all the way back to LA?
We are keeping a close watch on H.Isaac here.
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Old 08-23-2012, 11:12 PM   #7
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Edelweiss,
I didn't mean to imply pump issues are Cat related. I have 200 hp Perkins. What was more my point, although poorly stated is that I don;t trust that work was done purely because it was in the log. My distrust comes from not knowing how thoroughly it was done. I have seen too many crappy mechanics call themselves professionals. In my case, the first problem was the port engine getting hot. This happened within twenty engine hours of getting home. My on was driving on the flybridge. I was sitting back watching the river go by. I heard a high pitched whine, my son turned around and said What's that? I thought for a second and said 'Oh Shit', engine alarm. I scanned the gauges and saw the port engine was hot, and shut it down immediately. We went home on the starboard engine. I have always been of the belief that if you have two of something, LH and RH, when one side fails you replace both. This comes from years of running snowmobiles, trying to keep the suspensions happy. I decided to rebuild the stbd side first since it was easiest to access. I figured it would be easier to rebuild than the port side which is to the outside and accessible but not easily, after I did the stbd side and learned the tricks and knew exactly what tools I needed, I was amazed to find a third of the vanes missing from the still functioning pump. It didn't have much more life in it. I found the missing rubber on the inlet side of the multicooler. some of it had found its way into the cooling tubes. Not good, but I caught it in time. Extracting rubber bits from the tubes took some doing. I figured out that the easiest way to access the raw water pump was to take off the mounting casting it is attached to. Armed with the experience I gained doing the port side, the starboard side was easier than it would have been had I started there. It too had a bunch of rubber stuck at the inlet side of the multicooler. The PO had told me both pumps were good only a hundred hour before I bought the boat. They didn't have much wear but the impellers grenaded. I wonder if the impellers age due to ozone or warm storage before they are installed, if they have laid around for a long time. I have never experienced this on my old boat. It had a raw water cooled 351 ford that went 10 years running Mississippi water with no ill effects. We don't have too much silt here, but the river coming home was 500 miles of well over flood stage. It looked not unlike a chocolate milk shake.
Refugio has what I believe is a valid point about running in cold water. That said, the river water here has been in the mid 80's this summer. My engines hold a rock steady 170 deg in spite.

My starboard alternator belt was slipping late last season. I went to tighten it up and I found quite a collection of junk hardware holding the alternator on. It had apparently came loose at some point, and the PO didn't have a proper bolt. So substituted was one bolt that was about a inch and a half too long. Making up the extra length and lack of thread length was a stack of various flat and lock washers, two half inch nuts, and two 3/8th's nuts. As an engineer I go absolutely 'nuts' over improper hardware application. So now with proper hardware and torques, and a new belt I have confidence. The starboard alternator tried to fall off about a month ago. The rattle,rattle, thunder, clatter of the alternator fan blades hitting the tensioning bracket got my attention. No damage, I found all the hardware in the bilge. But the belt that turns the alternator also turns the engine water pump. It could have been a disaster. So I have a new, If I didn't do it, I don't trust it attitude.
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Old 08-24-2012, 01:24 AM   #8
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Edelweiss,
I didn't mean to imply pump issues are Cat related. I have 200 hp Perkins. What was more my point, although poorly stated is that I don;t trust that work was done purely because it was in the log. My distrust comes from not knowing how thoroughly it was done. I have seen too many crappy mechanics call themselves professionals.
---------------------------------------------------
Oh sorry, my misunderstanding, OK I thought you were saying you had Cats, I should have remembered you have Perkins. You probably have Sherwood Pumps like mine. Yeah, thank God for the oil cooler screening.

I had the same thing happen when I picked up a plastic bag and blocked the Starboard water intake. Heated up real quick. I found the end of the bag sticking out of the water inlet valve in the strainer, but was able to pull it on through and removed it. Started the engine back up and it was better but was still running too hot. Ran in on the port engine. (Thank God for twins!) Pulled the impeller and found 4 or 5 of the vanes were gone and I took the hose off and found them in the oil cooler screen, like you did. Picked them out, replaced the impeller and we were good to go.

My engines always run just a hair below 180 Deg. according to the gauges. Under normal wear my impellers vanes don't break off, they show wear on the rub side of each vanes rounded tip. Some people turn them around and re-install them. For $25 each, I opt to replace them. I put between 200 - 300 hours per year on the engines. I'm sure its been at least 5 years since I've changed them. So we're talking 1000 to 1500 hours on them. I am going over tomorrow to do some maintenance and I'm going to change them out now. I don't store my spares in the engine room. I had a specific gravity battery tester stored in there once. Went to use it and the rubber bulb turned into powder when I squeezed it. Two alternators and a 7.5 kw gen set running, equals lots of ozone.

I was partners with my brother-in-law on some commercial boats and he fixed things with bailing wire, seine twine, nylon ties and the wrong size nuts and bolts. I appreciate MacGyver skills when that gets the boat back in safely, but just not permanently. He never did get it!!

I'll let you know how they look.

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Old 08-24-2012, 06:09 AM   #9
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Impeller pump parts wear rapidly in silty or sandy water.

Since they are a consumable item like light bulbs or windshield wipers , by a couple of sets.

Change them now to learn how , carry a spare set for the future.

Most important is to log the numbers for the pump , and the impellers.

Sometimes its just easier/faster to carry a spare pump, and swop the pump, and replace the impeller at your leisure.

We replace the stock cover screws with allen head SS cap screws , as there easier to R&R while in a confined space .Get a bunch as they drop easily.

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Old 08-24-2012, 06:10 AM   #10
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Steve, we spent two and a half months at the boat yard? We do not know how far we will get, still might leave it up here for the winter?

Hope to get back to Theriot soon for the fishing.

Stay safe and will see you around Cocodrie.

DT
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Old 08-24-2012, 11:38 AM   #11
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Depending on the raw water pump the impeller is easy to change.

The biggest problem with some covers is the slotted brass screws holding the cover on. They strip easy and since they are brass a magnet can't pick them up out of the bilge. As FF said replace them with another fastener.

I have replaced the stock cover with one of these.
Makes changing a snap. Almost no tools required.

Welcome to Speedseal Safety Covers


www.speedseal.com/speedseal.html

I have no attachment to this. I just think it is a great product.



A small screw driver is useful to pry the old impeller out. there are also tools made just for the job.

In the 3208 there isn't a problem with the rubber bits of a failed impeller doing any damage or finding their way into any thing vital to the engine. The bits will end up in the end cap of the heat exchanger. As the tube bundle is made up of many tubes one or two plugged tubes will really not cause any issues. The fix for a leaking tube is to plug both ends.

Rather than having them replaced you really should learn to do this yourself.

It isn't really a big job.

Carry a spare and know how to replace them. It will save you a bundle if one fails and you are dead in the water. Beats a tow bill any day.

Sd
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Old 08-24-2012, 11:53 AM   #12
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Only takes a few minutes to replace.
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Old 08-24-2012, 11:58 AM   #13
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The raw water pump impeller is the weakest point on a boat engine and high temperatures are engine killers. Some manufacturers state that the impeller must be changed on a yearly basis for the warranty to be effective.
The number of hours on the impeller is only part of the equation. Many times the impellers sit in a hot engine room for years before they are installed, and an engine that sits a lot allows the vanes that are compressed to weaken.
If you are planning a trip south for the winter I would change both before you start.
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Old 08-24-2012, 02:41 PM   #14
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Depending on the raw water pump the impeller is easy to change.

The biggest problem with some covers is the slotted brass screws holding the cover on. They strip easy and since they are brass a magnet can't pick them up out of the bilge. As FF said replace them with another fastener.

I have replaced the stock cover with one of these.
Makes changing a snap. Almost no tools required.

[COLOR=#388222]Welcome to Speedseal Safety Covers


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Wow! Those are very nice. The O-ring and machined slot totally eliminates the gasket. I will have to look into those.

Thanks for the tip!!
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Old 08-24-2012, 03:47 PM   #15
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There is also a sort of bearing built into the cover.

The cover is thicker than the stock one and the center has a machined recess. A small disk of plastic of some sort fit's in the recess the impeller spins on the lubricated disk. The stock impeller just spins against the surface of the cover causing friction and wear.

That is one reason the impeller will last longer.

The company is in the UK I was suprised to talk to the owner of the company when I called to order mine. Be sure to have all the info on the RW pump when ordering.
(Make and model) it seems there are a lot of different kinds of raw waater pumps out there.


SD
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Old 08-26-2012, 10:13 AM   #16
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The OP's original question was similar to one posted on boatdiesel.com. Possibly it was the same poster. The replies there were based upon stated poor records from the previous owner. Bottom line, do the maintenance by the book - and completely service the newly acquired 3208s per the most rigorous Cat interval listing. There are no shortcuts and easy maintenance outs.

To suggest water pump impellers last 5 years is pure folly. This forum and others are littered with "I just saw grey smoke" or "my engine overheated" or "I can't reach max RPM any more" or "I have water in the oil" or "My exhaust elbow is leaking" etc etc as people look for hope and shortcuts on major obvious issues.

Marine diesels require regular by the book servicing and good maintenance checks to insure fun and reliability. Even more so as they approach their 20th birthday. So OP, listening to the pros like Tucker Fallon on this and other Forums cannot lead you astray. Good luck and happy cruising.
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Old 08-26-2012, 12:13 PM   #17
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There is also a sort of bearing built into the cover.

The cover is thicker than the stock one and the center has a machined recess. A small disk of plastic of some sort fit's in the recess the impeller spins on the lubricated disk. The stock impeller just spins against the surface of the cover causing friction and wear.

SD
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Is the plastic disk replaceable or is it pressed in? Sealing that plate on the port engine, its on the hull side, is the worse part of replacing them, just because there is limited room to work.

I spent most of Saturday replacing mine. Starboard was easy and took all of 30 minutes. The port. . . . . . .what can I say. . . 3 hours of love Couldn't get it to seal tight the first two tries. Wish I had had those Speedseal covers. I'll definitely be ordering them after that!!

The old impellers were fine, no missing vanes, just the usual wear on the tips.

Larry B
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Old 08-26-2012, 01:55 PM   #18
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Thanks all, will be ordering the seal kits and will get a Cat Mechanic to assit the impeller check and will have him flush the coolant before we head south.

DT
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Old 08-26-2012, 07:46 PM   #19
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[QUOTE=Edelweiss;100447]Skipperdude
Is the plastic disk replaceable or is it pressed in? Sealing that plate on the port engine, its on the hull side, is the worse part of replacing them, just because there is limited room to work.


It is just a thin plastic disk The center of the inside of the cover is recessed about the thickness of a dime the plastic disk is lubricated and fits flush with the inner surface of the cover. acts as a bearing.

My kit came with a nifty little impeller remover it takes the place of using a thin screw driver to remove the impeller.

It also came with an extra O ring, two extra knurled fasteners and lube.

Once installed checking the impeller can be just routine maintenance.

Loosen four fasteners and the cover slides right off.

Second season on mine and no problems.

Like I said before I have no affiliation with the company.

I think it is just a better idea that seems to work.

Sd
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Old 08-26-2012, 08:03 PM   #20
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That's great. . . I'm sold !!

No . . . For the conspiracy enthusiast, I don't have anything to do with the company either!!

Thanks
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