Buggered Impeller.

Gee. Maybe this is why the engine always ran a little hot?
New to me 1980 CHB PT-38 With a single Ford Lehman,so i decided to do all the preventative maintence I could not do last season.
This certainly doesnt look good to me .
Going to check with American Diesel to see if the pump itself should be replaced but welcome advise from here as well.

AD has an upgraded water pump for the 120s. I would ask Brian.

Craig_b said:

Gee. Maybe this is why the engine always ran a little hot?
New to me 1980 CHB PT-38 With a single Ford Lehman,so i decided to do all the preventative maintence I could not do last season.
This certainly doesnt look good to me .
Going to check with American Diesel to see if the pump itself should be replaced but welcome advise from here as well.

Click to expand...

The pump body and cam look good to me! It looks like someone installed the last cover with silicone sealer, not a paper gasket. The paper gasket is an important part. It is what spaces the cover out properly from the body to make the clearance at the ends of the impeller correct.

If the cover plate is not scored or worn excessively I would reassemble with the proper impeller and paper gasket.

Bill

Looks like you got it just in time. All the pieces look to be there. If no scouring just replace the impellor.

I disagree about the cam plate.
The photo is not great but it looks like several of the fingers of the cam plate are worn to the point of being sharp. THey will begin to cut the impeller reducing its pumping ability.

In addition the wear will have reduced the thickness of the cam plate itself which means the pump cannot move as much water as intended.
Get a new cam plate.
I suggest that the back wear plate also be closely examined for excessive wear as it to will reduce water pumping ability if worn to far.

As far as the replacement pump from A.D. that has proven from all accounts to be a good move. More reliable drive and by the time you get into cam plate replacement and maybe the rear wear plate you may have run the cost up enough to help make the Johnson a whole lot less of a shock.

C lectric said:

I disagree about the cam plate.
The photo is not great but it looks like several of the fingers of the cam plate are worn to the point of being sharp. THey will begin to cut the impeller reducing its pumping ability.

In addition the wear will have reduced the thickness of the cam plate itself which means the pump cannot move as much water as intended.
Get a new cam plate.
I suggest that the back wear plate also be closely examined for excessive wear as it to will reduce water pumping ability if worn to far.

As far as the replacement pump from A.D. that has proven from all accounts to be a good move. More reliable drive and by the time you get into cam plate replacement and maybe the rear wear plate you may have run the cost up enough to help make the Johnson a whole lot less of a shock.

Click to expand...

The plate on the back has Johnson stamped into it. Does that mean this is already the upgraded pump?

I would ask Brian, he will know. If it is the newer style pump that is very good.

Also, check that the shaft turns smooth, no rough spots.
If rough, bearing and seal will need replacement.

C lectric said:

I disagree about the cam plate.
The photo is not great but it looks like several of the fingers of the cam plate are worn to the point of being sharp. THey will begin to cut the impeller reducing its pumping ability.

In addition the wear will have reduced the thickness of the cam plate itself which means the pump cannot move as much water as intended.
Get a new cam plate.
I suggest that the back wear plate also be closely examined for excessive wear as it to will reduce water pumping ability if worn to far.

As far as the replacement pump from A.D. that has proven from all accounts to be a good move. More reliable drive and by the time you get into cam plate replacement and maybe the rear wear plate you may have run the cost up enough to help make the Johnson a whole lot less of a shock.

Click to expand...

where are you seeing sharp edges? would there not be cut marks on the impeller blades from the fingers?

Can anyone tell me where i could get just the impelller just in case thats the route i go?

I usually get them online, google the part number. Get it from a place that you think sells a lot of them so they haven’t been sitting on the shelf for a couple of years. I got my last ones from Defender I think.

Comodave said:

I usually get them online, google the part number. Get it from a place that you think sells a lot of them so they haven’t been sitting on the shelf for a couple of years. I got my last ones from Defender I think.

Click to expand...

Any idea what the part # would be?

Craig_b said:

Any idea what the part # would be?

Click to expand...

Craig, it is in the picture of post 1.
Johnson 1028

Soo-Valley said:

Craig, it is in the picture of post 1.
Johnson 1028

Click to expand...

Is there another way to determine it just in case it was the wrong part installed last time?

I have no faith in whoever has done previous work on this boat.

Call Brian at American Diesel. He will know. Usually Mondays are not a great day to call though.

Craig_b said:

Is there another way to determine it just in case it was the wrong part installed last time?

I have no faith in whoever has done previous work on this boat.

Click to expand...

Fred Warner website
Product Description
New Jabsco Profile Y impeller kit. Part number 17937-0001-P. Used by many major engine builders. See table for part number cross reference.

Cross Reference Part Number
Yanmar 127610-42200
Perkins 0460024, 24880031
Volvo 801277, 877061-2, 825941
CAT 7C-3286
Johnson 09-1028B
Sherwood 18200
Oberdorfer 7441

I have a different engine with a different pump. But I had to do exactly those replacements about 5 or 6 yrs ago and it made me VERY watchfull of wear in those areas. It took a lot of years to get to that point but get to it it did.

I also replaced the drive shaft this last winter due to wear of the splines that drive the impeller.

I always do a complete pump re/re including the rotary seal and bearing, all seals and gaskets but every 4-5 yrs for those.

That cam plate may be OK. The centre finger is the first to give trouble as the impeller fingers can bend in. As mentioned it is also a sign of the plate wearing. As thickness is lost pumping can be affected.

Cannot really tell from the photo but it is something to check which is why I brought it up.

If you talk to A.D., Brian , he should be able to give you the plate thickness and the wear point that it needs to be changed. Same for the back wear plate.

If the pump is the Johnson upgrade then maybe there is less to do as it will be much newer.
Just take your time and examine, examine and questionable bits replace.

This is what I used on mine this year. Also replaced the cover plate because it was worn enough to feel and see the ridge.
Jabsco Wearplate & Cam Kit 7884-0000, Wearplate & Cam Kit https://www.amazon.com/dp/B00H8SSDQ...abc_3S6QV9W43WN82DAM45SP?_encoding=UTF8&psc=1
The cover plate you took off hopefully was the original with the pump name and number on it. If it's the Jabsco then I recommend this kit. You'll have to remove the pump to get at the cam screw. Easy, two bolts and a nut holding it to the engine. Best to order a gasket in advance. The only hassle is cleaning the mating surfaces of the old gasket material.
Your hoses into and out of the pump need to be inspected for impeller bits. There may have been prior impellers that broke up.
My engine runs a steady 10 degrees cooler than before since replacing the cam, cover, and wear plate.

Just ordered this impeller for my pump. It's a replacement for a 1027B , but that's the part number my old one had. I don't know what the difference might be between it and a 1027B.

I found getting at the little cover screws and keeping them from falling in the bilge to be a bit of a pain. So I ordered these stainless "cabinet screws" to replace the originals. Only fingers required to remove the cover.

My cover plate was worn a little, but I just milled it down on a diamond whet stone.

A worn cover plate with a ridge can be easily corrected with a bit of 320-grit wet and dry sand paper, a FLAT surface and enough water to keep things wet while you rub it around on the sand paper. Never had a problem with doing it on both the original pump bodies and the Johnsons after I updated on my Lehamn 120s. The I switched to the wonderful o-ring sealed Speed Seal cover plate which unfortunately went out of business.

I also put Speedseal covers on our last boat, they were great. Too bad they went out of business.

Soo-Valley said:

Fred Warner website
Product Description
New Jabsco Profile Y impeller kit. Part number 17937-0001-P. Used by many major engine builders. See table for part number cross reference.

Cross Reference Part Number
Yanmar 127610-42200
Perkins 0460024, 24880031
Volvo 801277, 877061-2, 825941
CAT 7C-3286
Johnson 09-1028B
Sherwood 18200
Oberdorfer 7441

Click to expand...

Thanks for the part #'s.
I was able to source one and got it installed today.

Thank you everyone else who responded as well.

I do about 900 engine hours per year (Lehman 120's) and change the impellers regularly.
Last year on the move my port engine overheated - lost prime - no raw water cooling!
The impeller was perfect but there was some wear on the back plate - not much but presumably enough.
I replaced the pump but could have installed a repair kit.
Pay attention to the back plate and slipper for any wear.
I have Borel raw water alarms which give the earliest warning of over-heating. They prevented any engine damage, head gasket etc..

mickand said:

I do about 900 engine hours per year (Lehman 120's) and change the impellers regularly.
Last year on the move my port engine overheated - lost prime - no raw water cooling!
The impeller was perfect but there was some wear on the back plate - not much but presumably enough.
I replaced the pump but could have installed a repair kit.
Pay attention to the back plate and slipper for any wear.
I have Borel raw water alarms which give the earliest warning of over-heating. They prevented any engine damage, head gasket etc..

Click to expand...

Gotta love the Borel alarms. I am going to be putting them in our new boat this winter.

Something I found out a little while ago on this great forum, is that impellers have a shelf life of about 3 years and a use life of about 300 hrs. As I was getting less than half the use life out of mine, I decided that they were beyond the 3 year shelf life span. I had a brand new water pump, but it was still recommended I check the cam very carefully as it could still be the issue. I am about 2000 miles away from the boat right now, so I will order new impellers and check the cam before putting it back in service.

Marco Flamingo said:

Just ordered this impeller for my pump. It's a replacement for a 1027B , but that's the part number my old one had. I don't know what the difference might be between it and a 1027B.

I found getting at the little cover screws and keeping them from falling in the bilge to be a bit of a pain. So I ordered these stainless "cabinet screws" to replace the originals. Only fingers required to remove the cover.

My cover plate was worn a little, but I just milled it down on a diamond whet stone.

Click to expand...

When I opened my pump on my "new to me" boat, the impeller was as battered as yours

I also found one screw was completely rotted away at the threads and a couple of the others were flat head types, probably original that had the screw-heads buggered up such that the screwdriver would slip either unscrewing or screwing-on depending on how the screwdriver was mishandled

I managed to use a hacksaw to renew the screw-heads as best as I could, but I was thinking of replacing them with Allen-head cap screws. I never thought of thumb screws. I would be concerned of not being able to compress the screw tight enough to prevent any water-pump leaks from the cover. Or worse, the plastic part of those thumb-screws breaking off leaving the cover loose.
So let us know how those thumbscrews work out for you. I would be willing to try it but I am still leaning toward socket heads.

I put Speedseals on our last boat. They came with thumb screws but they didn’t have any plastic on them. I found that I couldn’t tighten them tight enough by hand so I used channel locks to tighten them up without any problems. I would be reluctant to use plastic thumb screws.

May be an optical delusion but, in your first photo it appears to me that the shaft is not fully engaged into the impellor. Not even sure if that is possible if the impellor is fully inserted to the pump housing.

Tator

I just did this on mine, jabsco just the impeller, paper gasket and 6 new brass screws to finish her. Bought spare impeller and gasket too. Remember to prime the pump before starting again.

Xlshrimp said:

I just did this on mine, jabsco just the impeller, paper gasket and 6 new brass screws to finish her. Bought spare impeller and gasket too. Remember to prime the pump before starting again.

Click to expand...

If you cannot find thumbscrews, plastic-headed or metal, a better replacement would be allen-heads rather than slotted head screws. Those slotted-head screws are easily forever lost in a bilge when working on a pump in a difficult location.