trapezeartist
Well-Known Member
I recently had to rebuild the raw water pump on my Volvo D1-20 after 250 hours of use 
. it was not the easiest of jobs and I wish I had known at the beginning what I know now. So for the benefit of anyone else undertaking the task on a D1-20 (or any similar engine, I imagine), here are the salient points.
The pump is driven by a gear running on the camshaft drive. It is mounted to the engine by two nuts and bolts (fairly accessible) and two bolts threaded into the casing ( incredibly inaccessible).
It would be nice to start by slightly loosening all four fixings but that's pretty impractical. So first remove the two easy nuts and bolts. They are NW and SW as you look at the front of the engine. Next remove the bolt in the NE corner. Use a small 10mm combination spanner. You may be able to start loosening with the ring end but will probably do most of it with the open-end end, 1/12 turn at a time. Finally turn your attention to the SE corner. You may be lucky enough to manage 1/12 turn at a time on this one too, but it will be a lot easier (well, less difficult) if you have a cranked spanner. You can only get the spanner onto the bolt head if the head is against the mounting face, so the pump will have to be pulled forward gradually as the bolt is undone.
On stripping my pump I found that the water-side seal was shot and the shaft had a nasty groove worn in it. This is the result of pumping the dilute grinding paste that we amusingly refer to as "sea water" in the Bristol Channel. As the shaft isn't available as a single item and a repair kit is about £160-180, I chose to repair the pump using a SKF Speedi-sleeve from my local bearing supply company. Only time will tell if this was a good idea, but I'm hopeful.
When re-fitting the pump, leave the impeller and cover plate off. Fit the four fixings in the reverse order of removal ie start with the little swine under the engine. As you start to pull the pump in towards the engine, you may find the drive gears go tooth-to-tooth. If so, stop tightening and use a very large screwdriver in the shaft slot to rotate the pump slightly until the teeth pop into mesh. Fully tighten the first bolt, then move on to the second, then finally do the two easy ones. Phew! Fit the impeller, put on the hoses and award yourself a very large drink. You've earned it. Remember all the bolts have their head facing the back of the engine so tightening rotation appears reversed. If you have very small and agile hands you will be just about able to touch the bolt heads with the tip of your finger but you won't have much luck with rotating the bolts with your fingers. Just plod away 1/12 turn at a time.
. it was not the easiest of jobs and I wish I had known at the beginning what I know now. So for the benefit of anyone else undertaking the task on a D1-20 (or any similar engine, I imagine), here are the salient points.The pump is driven by a gear running on the camshaft drive. It is mounted to the engine by two nuts and bolts (fairly accessible) and two bolts threaded into the casing ( incredibly inaccessible).
It would be nice to start by slightly loosening all four fixings but that's pretty impractical. So first remove the two easy nuts and bolts. They are NW and SW as you look at the front of the engine. Next remove the bolt in the NE corner. Use a small 10mm combination spanner. You may be able to start loosening with the ring end but will probably do most of it with the open-end end, 1/12 turn at a time. Finally turn your attention to the SE corner. You may be lucky enough to manage 1/12 turn at a time on this one too, but it will be a lot easier (well, less difficult) if you have a cranked spanner. You can only get the spanner onto the bolt head if the head is against the mounting face, so the pump will have to be pulled forward gradually as the bolt is undone.
On stripping my pump I found that the water-side seal was shot and the shaft had a nasty groove worn in it. This is the result of pumping the dilute grinding paste that we amusingly refer to as "sea water" in the Bristol Channel. As the shaft isn't available as a single item and a repair kit is about £160-180, I chose to repair the pump using a SKF Speedi-sleeve from my local bearing supply company. Only time will tell if this was a good idea, but I'm hopeful.
When re-fitting the pump, leave the impeller and cover plate off. Fit the four fixings in the reverse order of removal ie start with the little swine under the engine. As you start to pull the pump in towards the engine, you may find the drive gears go tooth-to-tooth. If so, stop tightening and use a very large screwdriver in the shaft slot to rotate the pump slightly until the teeth pop into mesh. Fully tighten the first bolt, then move on to the second, then finally do the two easy ones. Phew! Fit the impeller, put on the hoses and award yourself a very large drink. You've earned it. Remember all the bolts have their head facing the back of the engine so tightening rotation appears reversed. If you have very small and agile hands you will be just about able to touch the bolt heads with the tip of your finger but you won't have much luck with rotating the bolts with your fingers. Just plod away 1/12 turn at a time.
