Carver Owners Forum

I figured it was time to change my impellers as it has been 8 years since I put new ones in and about 450hrs. When I purchased Midnight Sun I replaced everything just to be safe. The original impellers were still in place after 9 years and 1000 hrs. To my surprise they still looked great. The Impeller design is obviously rather stout as normally after so much time they should have failed then again boating in pristine fresh water with no sand/silt must also help quite a bit.

Point is most impellers need to be changed much more frequently depending on the brand and water conditions. I usually go by a 5 year rule however I have seen as little as every year and everything in between.

Here is a little tip to help insertion of the new. Before inserting coat with some kind of lubricant. Personally I have a little container of 100% pure silicone lube that gets used for a bunch of things on board.

I get enough slack in the drive belt to be able to slide it off the water pump pulley as in my case you are not going to get the impeller out without turning the pump drive wheel by hand and pulling with long nose pliers at the same time which works really well by the way. The Volvo ones on the diesels are supposed to use a puller because they are so difficult to remove however I figured this rotation thing out myself last time when I was at loss first time around trying to pull it out. It has been a breeze using this drive pulley rotation while pulling and also for insertion.

After lubing up the impeller I place a tie wrap around the end about 3/4 of an inch in and bend the impeller ends in the correct direction which allows me to easily insert the impeller partially in and then I cut the tie wrap off. After I simply push on the end of the impeller while turning the pump belt drive wheel by hand and she slides right in.

At the same time you get a good visual on the belt and in my case I can verify if there is any slop in the idler belt wheels that may need to be addressed. It is also requires you to tension back the belt which does stretch with time so you end up killing 2 birds with one stone.

As can bee seen below, the old impeller was in great shape, no cracks or worn rubber. Obviously there is a set because of it being inside the pump housing but this is normal and even the new one will look similar if remove it in the next month or so.

The other picture shows the temporary tie wrap to facilitate installation of the new.

Nice write up.

Clean water helps indeed, also regular use helps.

Do you take them out over winter?

Additional tip: make a picture of it while still inserted so you can see how the vanes are bent. So you can copy that with your tie-wrap. If you take it out without noting that and flip it when putting it down you can't tell which side was in or out.

No, I have never removed them for the winter on any boat I have ever had. I do know some do however I have never found the need to do this.

Good tip on the picture by the way. I just made a mental note of having the vanes bent in a counter clockwise fashion which worked for me.

While it's a good practice to set the fins in the right direct when inserting the impeller, it's not critical. Lubricating the pump housing and the impeller which should always be done with an impeller change, provides the lubricant needed to prevent any damage to the impeller as the fins flip over to the correct position when they clear the cam which happens in less than one complete rotation.

FWIW Hans, you gotta know that 8 years is too long between impeller changes. Diesel application impellers tend to be beefier/bigger because of cooling requirements, operating rpm, etc., hence can seemingly take more of a beating before showing signs of wear compared to their gasoline counterparts. Having said that, one shouldn't think this is license to run them years longer than you normally should in gasoline applications which is typically two years to be safe. Sure you can go longer but I wouldn't go more than 4 years on any impeller. I mean look at the impeller that was pulled out, it hasn't disintegrated but it stopped being efficient years ago. The drop in volume may not have been enough to affect cooling as they're always over rated but it definitely wasn't pumping to spec which may have been noticeable under certain conditions.

Remember guys, these are your engines we're talking about here, and your ability to get back to safe harbour, impellers are cheep insurance.

BTW, for the larger impellers, I prefer to use a cylindrical type piston ring compressor tool to fold the impeller evenly along its entire length. This prevents pinching every fin in one spot that can lead to damage. Lubricate the impeller, pump housing, and the tool, insert the impeller in the tool, tighten the tool to fold the fins, place over the pump, slightly push the impeller through the tool and align the spines, once aligned, push the impeller all the way through the tool. Use one similar to this ratcheting type.....

https://www.amazon.ca/dp/B088FY484Y/ref=sspa_dk_detail_6?pd_rd_i=B088FY484Y&pd_rd_w=qsXuD&content-id=amzn1.sym.c7dca932-da6a-44fc-af09-cc68d2449b34&pf_rd_p=c7dca932-da6a-44fc-af09-cc68d2449b34&pf_rd_r=70267X1XKTNBBMRC39YD&pd_rd_wg=BqtWn&pd_rd_r=ab96a1c7-7bfd-4783-9a26-70e6b3ff6b52&s=automotive&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExMUZOMllWVlA3MlZBJmVuY3J5cHRlZElkPUEwNzQ4OTgyM05UNUZRSUtYUVdRMCZlbmNyeXB0ZWRBZElkPUEwNjI0NTMyMjcwM0hNVzlHVVJGWiZ3aWRnZXROYW1lPXNwX2RldGFpbCZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU&th=1

As a mechanic who works on those all the time, I can see the necessity of the ring compressor tool however as a boater and not wanting to have everything but the kitchen sink on board and in an emergency, tie wraps work well and is usually something we have on the boat.

I know, 8 years was pushing my luck big time however most of the hours were at hull speed. Just trying to make up an excuse for my lack of maintenance.

Thanks for acknowledging the impeller will flip to the correct direction when operated if installed wrong. Though so, but was not sure.

The first time I replaced my impellers it was a bit of a challenge to get the starboard side out, but the port side was a bitch due to lack of space and my arms got beat up pretty bad. I have never heard of rotating the pump pulley method and I will give that a try for sure. Thanks for the tip Hans.

I was trying to locate the proper gear puller to extract the impeller. If anyone can point me in the right direction for the right puller for the VP D6’s. I like the tool that viper pointed out for inserting the impeller into the housing, may be a great addition to the tool box for $20. I was lubing the impeller up and just twisting it in as I insert it by hand.

Thanks

Greg

Another tip for a fellow D6 owner is you should have a 1/2" socket wrench or better yet a 24", 1/2" breaker bar to tension up the belt . Also if the belt does fail and you are on the water you will need this to replace the belt assuming you have spares on board.

Below the 2 bolts locking the tensioner in place, there is a square hole meant for a 1/2" drive breaker bar where you insert it, pull tight and then tighten the 2 screws to lock it in place.

One advantage for the impellers on diesels is that lower RPM they run. They probably spend their life at HALF the RPM a lot of gas engines run at.

Another lube that I've seen folks used is glycerin, but any lube is good.

There is a thing called "the impeller tool" that is basically a made-to-fit device like the ring compressor tool. Pretty cool, but kind of expensive. You could probably do something similar just with a small section of large-diameter stainless tubing (or really any metal tubing that's the right size). http://impellertool.com/

Just my opinion, but you should **always** carry a spare set of impellers on board, even if you can't change it yourself. If you're on a trip and one fails (could be due to blockage upstream for some reason), you'll save a LOT of wasted time trying to track one down, if the stores are even open when you get back to a dock. A fellow boater is likely to have the tools and knowledge to change one, but not very likely to have impellers that fit YOUR boat.

Good item to have as a spare, rotate (add a new, insert the now old) so you keep a fresh one at hand.

The impeller insertion tool: stainless steel is the best of course but the plastic of a coke bottle plus a tie-wrap does the trick too to bend the vanes over their full length

Midnsun......Thanks for the post.....seems to me that the GPH requirements at a certain rpm of a pump will be based on heat exchanger needs and can be achieved by pulley sizes not necessarily engine rpm, don't really see why an impeller on a diesel water pump would be any different than any other than maybe the size if the engine cooling systems require more water flow.

Years ago I used to pull impellers every fall and reinstall in the spring, also gives you the chance to inspect closely a critical part of your engine systems.....always got a good clean start up using dish soap as a lube.....