Volvo 3.0 GS overheating problems

[wgcdc]

We have a 1996 Regal 258 commodore powered by 2 Volvo 3.0 GS PNCA series. The boat gave us trouble free service until about 5 years ago. Since then we have had several cases of overheating. Over the years and searching through forums I have learned that the raw water pump is the weak link on these engines. The boat is trailered (dry stored) in North Georgia and winterized with anti freeze fed through muffs. The engines have about 450 hours each. The boat gets used only 5 or 6 times a year. The port engine overheated and ingested salt water and seized several years ago. I rebuilt the engine, replaced the manifolds and it is working well. Then STB engine overheated and blew a head gasket. I am in the process of repairing this engine. I take good care of the boat, but it will overheat in a matter of seconds and do its damage. It does not have audible alarms. Through this forum I have learned to inspect the raw water pumps twice a year and replace them every other year whether they need it or not. I have learned to clean out all the little pieces of impeller plugging all the small hoses and fittings on this engine.
I have several questions:

1. Is there a way to install audible alarms for temperature? I purchased the kit from West Marine, but there isn?t room for two sensors. Is there a set up that uses one sensor with gauge and alarm output, if so where I can purchase it? I have looked on the internet without much success.
2. I have installed small raw water strainers on the discharge hose of the raw water pump to catch any impeller pieces. Do you see any issues with this?
3. I am tired of fixing this boat. It is paid for and I would like to get it running reliably. If I put a closed loop cooling system on it would it run more reliably?
4. The tachometers bounce up and down while operating. I can bang them with my hand and sometimes they stop. I read somewhere on the forum that there was a screw on the back that can be adjusted in and out to fix the problem. Is this so?

Thank you for your help!

 

[dubs283]

Re: Volvo 3.0 GS overheating problems

1. you may be able to find a t-stat housing that has two places for sensors, one on either side, one for guage, the other for the warning switch.

2.you need to inspect the water inlet hose for impeller pieces, coolers, hose all the way from the pump outlet to the t-stat housing

3. if your boat is run in salt water, get used to problems

4. sounds like you need new tachs, hook a shop tach to coil and operate the boat and compare values with boat tach

 

[toadwarts]

Re: Volvo 3.0 GS overheating problems

new to the forums. How do i post a new thread ?

 

[wgcdc]

Re: Volvo 3.0 GS overheating problems

Thank you for your reply.

1. I don't believe there is room for two sensors. Does any one make a temperature sensor with 2 outputs one for the gauge and one for the alarm?
2. Do you see any issues with putting a raw water strainer on the discharge of the raw water pump to catch pieces of impeller when it starts to fail? I regularly clean and inspect the pump and cooling hoses.
3. I have constant issues with overheating. Is it worth getting a closed loop system? Will improve reliability?

The details for these questions are in the original post.

 

[captmello]

Re: Volvo 3.0 GS overheating problems

I thought I saw a temp sender with two wire outputs, can't remember where.

I would not add a strainer. Seems like it would be prone to clogging up. Although I know some engines have them.

I think the idea of changing the impeller every 1-2 years, is so you don't have one break into pieces.

I don't see why a closed cooling system would help except that the engines would last a lot longer in salt water.

Also, those manifolds don't last long in salt water. 5-8 years I believe. Less if they are neglected.

Get one of those digital temp guns and point it at the tsat housing by the temp sender and compare temp.

Have you tested your water intake for air leaks?

 

[Bondo]

Re: Volvo 3.0 GS overheating problems

1. I don't believe there is room for two sensors. Does any one make a temperature sensor with 2 outputs one for the gauge and one for the alarm?

Ayuh,... Look Harder,... I'm pretty sure there's 2 ports...

2. Do you see any issues with putting a raw water strainer on the discharge of the raw water pump to catch pieces of impeller when it starts to fail? I regularly clean and inspect the pump and cooling hoses.

Other than just Another problem point,...

3. I have constant issues with overheating. Is it worth getting a closed loop system? Will improve reliability?

Your motor has been in the Salt,.. Way Too Long to go to closed cooling now,...

Change the Exhaust Manifolds,...
I'm bettin' your's are Plugged if you have constant Overheating problems...

 

[wgcdc]

Re: Volvo 3.0 GS overheating problems

Thank you for your reply.

You are correct; there is another port for a second sender. It will need to be drilled and tapped. However, the sender will stick out and the sender wire could get close to a belt. I was hoping to avoid this.

VDO makes a gadget that takes gauge inputs and you can set audible alarms with it. Have you ever heard of this?

I have had the head checked, serviced and resurfaced. I am replacing the head gasket, manifold, riser and bellows. I will also replace the thermostat housing and thermostat. Externally the manifold and riser were in good shape, but many of the passages were corroded and some were plugged with silt, so they will be replaced.