HELP-Volvo penta experts

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nimrod69

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Feb 11, 2008
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I have a 2000, 5.7 duoprop with sporratic overheating problems.
I replaced the thermostat - no difference.
I suspect the raw water pump is bad but I replaced the impeller and seal last month. As an experiment, I disconnected the hose that goes from the pump to the thermostat housing and started the engine. (the boat was lowered on the lift just enough to cover the intake grate on the outdrive). No water came out of the hose. Suspecting I might have an air leak I pulled the hose from the pump suction side and sucked on it and was able to pull water from the hose. Should the pump be able to draw water under this condition?. I know when the boat is floating that the suction for the pump is probably submerged which makes it easier for it to get suction. Any suggestions?
 
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Maclin

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Re: HELP-Volvo penta experts

It should be able to draw water that way no problem, when it works properly it will suck much better than a human could.

Sounds like to me you have isolated the problem as the pump. Have you looked at the impeller since your tests?

Could be improper impeller and/or seal installation or wrong impeller. Could be the impeller is not turning inside the housing with the crankshaft. Could be a broken or scored or otherwise leaky housing. Could be leaky inlet hose fitting at the pump.
 
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nimrod69

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Re: HELP-Volvo penta experts

I replaced the impeller last month and everything was fine for a month.
I pulled the pump to inspect and everything looks fine. There is some scoring in the pump housing on the face but it doesnt look that bad.
The problem comes and goes. I can tell when it is going to overheat because it makes a gurgling/cavitation like noise coming from the outdrive when it overheats, like it is sucking air. After I let it cool and start again the sound and the overheat problem goes away.
 
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Maclin

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Re: HELP-Volvo penta experts

There is a hose connection fitting on the intermediate drive that a molded hose connects to then goes thru the transom and feeds the raw water pump. The fitting on the drive can be corroded away or the parts the fitting connects to inside the drive could be compromised somehow, or even the hose could have a problem. Any of those conditions would allow it to suck air and not water.

This part of the drive is all underwater at idle so the symptoms you describe should only happen at speeds high enough to raise this part above the water.

Go to this site for some drawings to see what is what, look up year 2000 then your engine then intermediate housing then part#9....


http://www.dougrussell.com/partscatalog/volvo_omc/index.cfm?fuseaction=group&type=volvo&group=
 
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Maclin

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Re: HELP-Volvo penta experts

I re-read your post that describes your boat up on a lift during your tests. If the top part of the drive is not underwater then that may be the same condition you are experiencing out on the water. When you slow down and stop on the water it cannot suck air (if that is what is happening) and you get good cooling water flow. Then when you are running at or close to planing that part of the drive is in air so the problem can show up. On the lift that part of the drive is up in the air and it could suck air.

I am not sure why you got water and the pump did not, but the pump is way more powerful and maybe once the water tension breaks all it gets is air.
 
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Maclin

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Re: HELP-Volvo penta experts

Maybe you could find the right size and length of hose to fit the inlet side of the raw water pump and put it into a bucket of water in the boat and see if it draws that water out ok.
 
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nimrod69

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Re: HELP-Volvo penta experts

When I had the boat raised on the lift so that the intake only was submerged, I was able to get plenty of water by sucking on the hose. I would think that if there was an air leak where you described I would have sucked air.
 
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Maclin

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Re: HELP-Volvo penta experts

Pretty slick there slick!. That last test (taping off the drive inlet then putting the water to the inlet hose) would definitely show any problems with leaking at the drive connections.
 
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Maclin

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Re: HELP-Volvo penta experts

Nimrod69,

That area may not be your problem, hard to know. Then again the position of the drive can flex those components to where it may block off the air leak, who knows. If you can get the entire drive underwater then try your tests again that may show some differences.
 
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nimrod69

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Re: HELP-Volvo penta experts

Don, thanks for the troubleshooting guide, I did the duct tape test and found no leaks, that is before the tape blew out.
Looks like im ok up to the pump, that only leaves the pump as the culprit.
Guess it could have excess clearance or be leaking air by the seal. At any rate I suppose I'll just have to buy a new pump- sure they're not cheap.
On a related note, there is a sticker on the engine that mentions 120 db warning alarm, but nothing sounded. There are two temperature sensors, one on the intake manifold right by the thermostat housing( for the gauge), and one on the thermostat housing which I assume is for the alarm. I tried grounding it but no alarm sounded. Does anyone know where the alarm is.
Maybe its malfunctioning.
 
Don S

Don S

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Re: HELP-Volvo penta experts

What is the full Volvo model number or SN of your engine?

And by any chance is the owners manual that you have #7797286, if not, what is the number on yours?
 
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Bill S.

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Re: HELP-Volvo penta experts

nimrod69 said:
Don, thanks for the troubleshooting guide, I did the duct tape test and found no leaks, that is before the tape blew out.
Looks like im ok up to the pump, that only leaves the pump as the culprit.
Guess it could have excess clearance or be leaking air by the seal. At any rate I suppose I'll just have to buy a new pump- sure they're not cheap.
On a related note, there is a sticker on the engine that mentions 120 db warning alarm, but nothing sounded. There are two temperature sensors, one on the intake manifold right by the thermostat housing( for the gauge), and one on the thermostat housing which I assume is for the alarm. I tried grounding it but no alarm sounded. Does anyone know where the alarm is.
Maybe its malfunctioning.
Click to expand...

The one on the intake manifold with one wire is the sender for the gauge and the sensor on the T-Stat housing (with 2 wires) is for the fuel injection system. There should be a buzzer and it should sound at key on as a horn check to let you know that it is working. It should be mounted on the enigne and be round and black with 2 wires.
 
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nimrod69

Seaman
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Re: HELP-Volvo penta experts

Don, the engine info from the sticker is:
5,7GS PEFS
4012001861
3869058

Bill,
The sensor on the tstat only has one wire. The engine is carbuerated.
The dash beeps when you turn on the key, but I have yet to hear an alarm.
 
Don S

Don S

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Re: HELP-Volvo penta experts

The dash beeps when you turn on the key, but I have yet to hear an alarm.
Click to expand...

When it beeps when you turn the key on, that means the alarm is working. Not necessarily the sensors that indicate a problem. It may also mean the engine hasn't overheated enough to trigger the alarm, or that sensor could be faulty. There should also be a horn back on the engine (Stbd side) just next to the main electrical connector.
 
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Bill S.

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Re: HELP-Volvo penta experts

Don S said:
When it beeps when you turn the key on, that means the alarm is working. Not necessarily the sensors that indicate a problem. It may also mean the engine hasn't overheated enough to trigger the alarm, or that sensor could be faulty. There should also be a horn back on the engine (Stbd side) just next to the main electrical connector.
Click to expand...

As Don said, it probably hasn't overheated long enough to set an alarm and I missed that it was a carbed engine somewhere in the thread :( Sorry about that. If you put a clear hose on the inlet side of the pump the hose should be full the entire time the engine is running. If the pump isnt pumping because of an internal leak inside the pump (worn housing) the only real way you will find it is in pressure readings on the outlet side of the pump but the hoses (inlet and outlet) will probably stay full.
 
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nimrod69

Seaman
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Feb 11, 2008
Messages
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Re: HELP-Volvo penta experts

The thing that baffles me is that the problem is occasional.
A bad pump would be bad all the time wouldnt it?
 
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Bill S.

Recruit
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May 29, 2008
Messages
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Re: HELP-Volvo penta experts

I have provided Don an updated copy of the overheat diagnosis pamphlet. You need to clear hose test this engine to determine where the problem is originating. This procedure is explained in the pamphlet.
If you read it and have any questions about the procedure let me know.
 
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