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Perhaps, Gasket between the drive and the intermediary?
1994 volvo penta 570 no raw water flow
- Thread starter palermo
- Start date
Can you "rod it out" using a coat hanger, small drain snake, or the like, starting backwards from the fitting you changed? I just tried to look your drive up on marinepartsexpress. Does the fitting you replaced look like a miniature of the water outlet/thermostat housing on a car?
If so, it seems to mate up with a vertical tube. I was looking at the Intermediate Housing, and that tube also seems to be the axis it steers around. Given that's true, and that tube is steel, it could be badly rusted and the rust is plugging its interior. Which would be your water passage. Or, rusted through so the pump doesn't get a good suction...
If so, it seems to mate up with a vertical tube. I was looking at the Intermediate Housing, and that tube also seems to be the axis it steers around. Given that's true, and that tube is steel, it could be badly rusted and the rust is plugging its interior. Which would be your water passage. Or, rusted through so the pump doesn't get a good suction...
Let me start from the beginning. I purchased this boat used at the end of the season last year. I only water tested it for about 30 minutes at different speeds and it did not overheat so the water must have been circulating in the engine. The boat is on a trailer in my yard where I am working on it.
Yes the part looks like the thermostat housing on a car. Just to summarize again what I have tried.
If I take the hose off of the raw water pump and run a garden hose into it the water runs out the inlet of the out drive freely. There is no restriction. I have also removed the power steering cooler and inspected the inside and it is clear. If I take the s shaped hose off of that new connector fitting I changed and then attache a hose to that end and place it in a bucket of water and place the bucket of water on the ground beside the out drive it sucks the water out and up into the engine with no problem. I have to keep the garden hose running in the bucket to keep the water level up. That tells me that the raw water system is fine from the raw water pump, all the hoses that run down to the through hull fitting, the thru hull fitting, the S hose. After the S hose you then go into that new connector and then down that steel pipe into the bottom of the drive. There must be a leak someplace where the bottom of the drive mates to the upper portion and when I water tested it last year this entire portion is submerged in the water so the suction would work and cool the engine. I guess now I have 2 choices to either take apart the drive or just leave it as is and use it.
I have owned Mercruisers in the past and have no experience with the Volvo Penta so I am reluctant to take this thing apart.
Ed
Yes the part looks like the thermostat housing on a car. Just to summarize again what I have tried.
If I take the hose off of the raw water pump and run a garden hose into it the water runs out the inlet of the out drive freely. There is no restriction. I have also removed the power steering cooler and inspected the inside and it is clear. If I take the s shaped hose off of that new connector fitting I changed and then attache a hose to that end and place it in a bucket of water and place the bucket of water on the ground beside the out drive it sucks the water out and up into the engine with no problem. I have to keep the garden hose running in the bucket to keep the water level up. That tells me that the raw water system is fine from the raw water pump, all the hoses that run down to the through hull fitting, the thru hull fitting, the S hose. After the S hose you then go into that new connector and then down that steel pipe into the bottom of the drive. There must be a leak someplace where the bottom of the drive mates to the upper portion and when I water tested it last year this entire portion is submerged in the water so the suction would work and cool the engine. I guess now I have 2 choices to either take apart the drive or just leave it as is and use it.
I have owned Mercruisers in the past and have no experience with the Volvo Penta so I am reluctant to take this thing apart.
Ed
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I have to agree with Charlie on the back flushing idea. If you back flush and have a leak some where that would normally be sucking air, you will find it. If there is no leak then you likely have a hose that is collapsing under suction.
I doubt this will help but just in case: my last boat, a 2005 four winns, had a Volvo penta. It had an engine flush connection that I used regularly. The first year I winterized it I did so through the engine flash connection. The next year the first time out the engine temp started climbing higher than normal. I shut it off in the middle of the lake and opened the engine hatch. Found out I had forgotten to replace the hose connection cap on that flush hose. It was sucking very little water.
If you don't already have one, I would get a service manual with an exploded parts diagram. I have figured out a lot of things mechanical with an exploded parts view.
I doubt this will help but just in case: my last boat, a 2005 four winns, had a Volvo penta. It had an engine flush connection that I used regularly. The first year I winterized it I did so through the engine flash connection. The next year the first time out the engine temp started climbing higher than normal. I shut it off in the middle of the lake and opened the engine hatch. Found out I had forgotten to replace the hose connection cap on that flush hose. It was sucking very little water.
If you don't already have one, I would get a service manual with an exploded parts diagram. I have figured out a lot of things mechanical with an exploded parts view.
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No need to back flush from the inlets. They would not be collapsing as they are under pressure from the output of the water pump. You just need to connect from that outlet. You already know the pump is working with the bucket test. Connect to the outlet of the pump with you hose and turn the water on. Then look for your leak.
John,
I am confused. Not sure what you mean. Are you talking about checking for a leak in the engine water system or looking for a leak in the raw water system that draws up through the outdrive?
I did check for leaks the other day by disconnecting the hose that goes to the inlet of the raw water pump. I then connected my garden hose to that hose and ran the water down thorough the entire system out of the outdrive and saw no place that the water was leaking out.
I am confused. Not sure what you mean. Are you talking about checking for a leak in the engine water system or looking for a leak in the raw water system that draws up through the outdrive?
I did check for leaks the other day by disconnecting the hose that goes to the inlet of the raw water pump. I then connected my garden hose to that hose and ran the water down thorough the entire system out of the outdrive and saw no place that the water was leaking out.
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Agreed Charlie. That is why I am suggesting back flushing from the output side of the RAW water pump. That should show where the leak is. If there is no leak then your raw water intake hose is collapsing under suction from the pump.
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Lets go back to the very beginning. You submerged the outdrive in a tub and I assume that you were able to submerge the water outlets on the drive. Here is the problem. Your impeller is way up on the engine. When the engine is off and the drive is down the water drains out of the drive and most of that long hose that goes up to the impeller housing on the engine is full of air.
There is no way a Volvo impeller or for that matter a Bravo impeller (same issue engine mounted pump) will prime in a tub. That only works on outboards and a Merc Alpha drive (even then the water has to be above the level of the water intakes, above the joint between the lower and upper unit)because on those models the impeller is in the lower unit.
To run your Volvo on the water hose you must either use muffs that fit very tightly with good water pressure, or fab up a flush adaptor and hook up the water hose to the raw water intake hose just before the impeller.
It will NEVER prime in a tub. You are forcing a water impeller to suck air for about 6 feet before it can suck water. They don't work that way....
The way Volvo designed it, you put the boat in the water, the water pressure forces water up in the drive, through the transom fitting and then starts to fill the hose that goes from the transom to the thermostat housing. If you took that hose off to change the 'stat with the boat in the water, and held it down, water would come out of the hose. The normal static water pressure fills the hose. That's how it primes the impeller.
Even sometimes with muffs, if they don't fit right the water pressure is too low it may not prime. If I had a Volvo or Bravo I'd use a flush adaptor right before the impeller to avoid burning up the impeller.
Using a tub with accomplish nothing but burning up impellers and overheating the engine....
There is no way a Volvo impeller or for that matter a Bravo impeller (same issue engine mounted pump) will prime in a tub. That only works on outboards and a Merc Alpha drive (even then the water has to be above the level of the water intakes, above the joint between the lower and upper unit)because on those models the impeller is in the lower unit.
To run your Volvo on the water hose you must either use muffs that fit very tightly with good water pressure, or fab up a flush adaptor and hook up the water hose to the raw water intake hose just before the impeller.
It will NEVER prime in a tub. You are forcing a water impeller to suck air for about 6 feet before it can suck water. They don't work that way....
The way Volvo designed it, you put the boat in the water, the water pressure forces water up in the drive, through the transom fitting and then starts to fill the hose that goes from the transom to the thermostat housing. If you took that hose off to change the 'stat with the boat in the water, and held it down, water would come out of the hose. The normal static water pressure fills the hose. That's how it primes the impeller.
Even sometimes with muffs, if they don't fit right the water pressure is too low it may not prime. If I had a Volvo or Bravo I'd use a flush adaptor right before the impeller to avoid burning up the impeller.
Using a tub with accomplish nothing but burning up impellers and overheating the engine....
Lou,
Thank you for the great explanation. Maybe I have been chasing a ghost all this time. But just to clear, yes the problem I am having is with the boat on a trailer and theoutdrive trimmed down I have placed a tub under the outdrive that allows me to fill it and get the water level just about the inlets of the outdrive. not more than about a couple of inches above the inlets but they are fully covered and I guess what you are saying is even if there is no leak the pump will just not have enough pull to draw the water up into the engine and circulate it. The reason I am doing it this way is that I have always had alph one mercrusiers and I have always tested them on the muffs or in a tub with no problem.
Ed
Thank you for the great explanation. Maybe I have been chasing a ghost all this time. But just to clear, yes the problem I am having is with the boat on a trailer and theoutdrive trimmed down I have placed a tub under the outdrive that allows me to fill it and get the water level just about the inlets of the outdrive. not more than about a couple of inches above the inlets but they are fully covered and I guess what you are saying is even if there is no leak the pump will just not have enough pull to draw the water up into the engine and circulate it. The reason I am doing it this way is that I have always had alph one mercrusiers and I have always tested them on the muffs or in a tub with no problem.
Ed
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Yep you may not actually have a problem at all. There is no way a rubber impeller mounted on the engine will suck water from the lower unit like that. Like I said it will only work on OBs and Alphas. Even my OMC Cobra won't prime in a tub because the impeller is in the upper gear housing. The water has to be up to the top of the outdrive for those to prime. When I launch the boat I trim the drive down, to allow the impeller to fill up with water, start the engine so its primed, then trim up about half way and back off the trailer. If I started with the drive half way down, it might not prime because of the angle of the boat on the trailer and the fact that the impeller is out of the water and full of air. Water doesn't travel up hill LOL....
Impellers pump water, they do not move air, they don't create suction against air.
Either get good fitting muffs, or, make a flush port in the hose that goes to your impeller (later model Volvos use a fitting there)....I think the flush port is a safer way to run it on the water hose...no chance of burning the impeller that way....
This is similar to what happens when you replace your water separating fuel filter and don't fill it with gas. It will take a LONG time to start the engine because fuel pumps don't pump air they pump liquid fuel. So I always fill it as full as I can get it....still takes 3 crank overs to get it to fire after changing the filter.
Impellers pump water, they do not move air, they don't create suction against air.
Either get good fitting muffs, or, make a flush port in the hose that goes to your impeller (later model Volvos use a fitting there)....I think the flush port is a safer way to run it on the water hose...no chance of burning the impeller that way....
This is similar to what happens when you replace your water separating fuel filter and don't fill it with gas. It will take a LONG time to start the engine because fuel pumps don't pump air they pump liquid fuel. So I always fill it as full as I can get it....still takes 3 crank overs to get it to fire after changing the filter.
Mercs bravo and volvo pumps are self priming just like the alpha...but they have to have good seal in the pump body. It just takes longer if there's more vertical distance to raise the water. In these circumstances, the slightest air leak will make it more difficult to pull water instead of air. One problem,if there's maybe 24" or more from water level to the pump, it will create more vacuum in the intake side of the pump which will collapse any old or weak hose. Try getting the water level as high as possible...maybe one of those plastic 30 gal trash cans.
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Here is an experiment that I did that proves what I am saying...
A few years ago I had trouble with barnacles growing on the water intake screen in the lower unit of the Cobra (very similar to the lower units on older Evinrudes and Johnsons). So I removed the impeller housing and hooked up to the muffs and hose to test it. What I found was that there was some blockage but unless the muffs fit really tightly, hardly any water was getting up to the impeller on the water hose. I have since removed that screen since here its really not needed and as I said if you keep the boat in the water stuff grows in there. Cleaned out the water passage in the lower unit re-assembled with new water tube gaskets. When I put in a new impeller I test the flow first. I had to slightly bend the spring clamp for the dual inlet muffs for them to fit tight enough to get enough water to come out the passage that feeds the impeller in the upper unit. And this is only requiring the water to go from the water intakes to the impeller mount the upper unit, which on the Cobra is about 15" . The Bravo/Volvo design is much more demanding in terms of no restrictions or air leaks. You have to raise the water the same height but also have to push it forward about 3'. If I had a boat with one of these I might also try adjusting the trailer jack so the boat is bow down, to help the water flow up to the impeller.
Last tip...those screw-type hose clamps...loosen over time...you can get them tighter...using a 5/32nds box end or socket if you have a small socket set...
Every year before launching...I go over ever hose clamp to make sure its tight...esp...the hose from the transom mount to the P/S cooler that you can hardly see...
A few years ago I had trouble with barnacles growing on the water intake screen in the lower unit of the Cobra (very similar to the lower units on older Evinrudes and Johnsons). So I removed the impeller housing and hooked up to the muffs and hose to test it. What I found was that there was some blockage but unless the muffs fit really tightly, hardly any water was getting up to the impeller on the water hose. I have since removed that screen since here its really not needed and as I said if you keep the boat in the water stuff grows in there. Cleaned out the water passage in the lower unit re-assembled with new water tube gaskets. When I put in a new impeller I test the flow first. I had to slightly bend the spring clamp for the dual inlet muffs for them to fit tight enough to get enough water to come out the passage that feeds the impeller in the upper unit. And this is only requiring the water to go from the water intakes to the impeller mount the upper unit, which on the Cobra is about 15" . The Bravo/Volvo design is much more demanding in terms of no restrictions or air leaks. You have to raise the water the same height but also have to push it forward about 3'. If I had a boat with one of these I might also try adjusting the trailer jack so the boat is bow down, to help the water flow up to the impeller.
Last tip...those screw-type hose clamps...loosen over time...you can get them tighter...using a 5/32nds box end or socket if you have a small socket set...
Every year before launching...I go over ever hose clamp to make sure its tight...esp...the hose from the transom mount to the P/S cooler that you can hardly see...
We can close the book on this thread. After reading all the good information and advice I realized that my driveway is sloped down and with the boat backed down the driveway, the tongue raised all the way up that I was asking this pump to pull the water up hill quite a bit. I lowered the tongue of the trailer all the way down and then I primed the hose by removing the hose from the inlet of the raw water pump and filling it with water from a bucket I then started the engine with the outdrive in the tub of water and it pumps like crazy. The water pours out of the exhaust as it should.
Thanks again to everyone for the great ideas and advice.
Ed
Thanks again to everyone for the great ideas and advice.
Ed