Volvo 5.7 GSI over heating

[ahero4all]

When I remove the thermostat and run the motor it runs at about 180 to 190, when I run the motor with the Thermostat it immediately over heats..Just purchased a new water pump...any input would be appreciated before I remove the circulation pump..

I installed a new impeller and a new temperature sending unit..

 

[shaw520]

Try a new thermostat,

 

[Senior B]

180 to 190 with no thermostat is way to hot to begin with and says you have another problem. Thing shouldn't heat up at all. Water flow is the key. You mention that you just replaced the Raw water pump but how is your flow through the exhaust system? If your Risers or Manifolds are clogged up you'll continue to have problems. Look at the water flow coming from the exhaust at the back of the boat. If that flow is solid with plenty of water and you're able to keep hands on the risers and manifolds then I would look to the circulation pump for the engine. If the exhaust components are hot then you either have a blockage or an impeller/raw water flow issue.

 

[bajaunderground]

Also, to help trouble shoot you should isolate which sensor is sending the alarm. Redneck style is pull one off at a time while running and watch the gauge.

The first culprit is the impeller itself, then the thermostat housing. Make sure all passages are open and not occluded with old impeller fins. Next check risers. If you replaced pump did you replace the whole housing and impeller?

There's a sticky post under the Volvo/Penta portion called "adults only" it has an over-heating trouble shooting process in there...read that as well!

 

[QBhoy]

Agree that 180-190 is much too hot without TS in place. Presumably it feels bloody hot too ?
I'd be checking;
For restrictions Restrictions right from the outdrive and pipe feeding the pump.
Check you have installed impeller correctly. (I'm sure you have, just worth checking)
Perhaps look at exhaust flappers in horns. These being broken up or stuck would cause this.

 

[Thalasso]

When I remove the thermostat and run the motor it runs at about 180 to 190, when I run the motor with the Thermostat it immediately over heats..Just purchased a new water pump...any input would be appreciated before I remove the circulation pump..

I installed a new impeller and a new temperature sending unit..

Out of curiosity was it overheating before the impeller replacement? Temp should be around 165-170

 

[ahero4all]

Out of curiosity was it overheating before the impeller replacement? Temp should be around 165-170

I do not know that answer..The temp guage was non opt when I bought it..I replaced the sensor so I have no idea how hot it was running before I bought it..

I am on the Big Island of Hawaii...To say boats are over priced here is an under statement and I feel I got lucky with this one...This 5.7gsi is in a 23" 1998 Monterey Open Bow with a center console.. 1000 hours on the boat The VP SX cobra outdrive had just been replaced by insurance claim for $10k..I bought the boat for $7k with trailer

 

[ahero4all]

Out of curiosity was it overheating before the impeller replacement? Temp should be around 165-170

I do not know that answer..The temp guage was non opt when I bought it..I replaced the sensor so I have no idea how hot it was running before I bought it..

I am on the Big Island of Hawaii...To say boats are over priced here is an under statement and I feel I got lucky with this one...This 5.7gsi is in a 23" 1998 Monterey Open Bow with a center console.. 1000 hours on the boat The VP SX cobra outdrive had just been replaced by insurance claim for $10k..I bought the boat for $7k with trailer

 

[ahero4all]

Thanks for the all feedback..I am a recovered Paraplegic and am trying to set a world record and free dive to a 100ft..No paraplegic has ever dove to that depth..working towards my dream and a challenge that pushes the limits of my mental and physical abilities..Just need to get this boat up and running..

 

[Thalasso]

Good luck with your en devour.

 

[Scott Danforth]

You have a flow problem

When you replaced the raw water impeller, did the old one have all the vanes, or were some missing? Of some were missing, did you find the pieces?

Did you back flush the system?

How old are the manifolds and risers? You are in salt water and they have a finite life in salt.

Pull the t-stat housing and check for debris. Back flush the lines. Pull the exhaust manifolds and risers and inspect.

Check water flow out of the raw water pump. The raw water pump should fill a 5 gallon bucket with motor at 1000 rpm in about 20 seconds. Very similar going into exhaust.

Make sure the thermostat isn't in backwards

 

[shaw520]

Wow! ,.... good luck on your dive.

 

[ahero4all]

You have a flow problem

When you replaced the raw water impeller, did the old one have all the vanes, or were some missing? Of some were missing, did you find the pieces?

Did you back flush the system?

How old are the manifolds and risers? You are in salt water and they have a finite life in salt.

Pull the t-stat housing and check for debris. Back flush the lines. Pull the exhaust manifolds and risers and inspect.

Check water flow out of the raw water pump. The raw water pump should fill a 5 gallon bucket with motor at 1000 rpm in about 20 seconds. Very similar going into exhaust.

Make sure the thermostat isn't in backwards

The old impeller was missing some pieces and parts..where would they be jammed? I will take the impellar out and check it..

I have not back flushed the system,any links on how to flush a 5.7? The system is a recirculating fresh water..the thermostat goes in spring down..

The block shows some rust and paint flaking, I am seriously considering pulling the motor out of the hull..Thinking in the current condition pulling the manifolds might cause a few bolts to break and trying to make those repairs could be more difficult than just pulling the motor out..feed back please..

It was very well maintained by the 1st owner and a bit neglected by the second..having been operated in sea water is showing signs of corrosion..

On a side note, I regained my mobility after being paralyzed in a motorcycle crash and diagnosed to never walk again..I got out of a wheal chair and taught myself to walk again..through that experience I learned many valuable life lessons..one is there is nothing I can not achieve once I put my mind to it...But this boat is kicking my ass...tired of people who don't have boats telling me to Bust Out Another Thousand!

 

[Scott Danforth]

You need to find the pieces. Just follow the flow

 

[bajaunderground]

Pull thermostat housing...little pieces will likely be stuck in the small cooling passages...

 

[Fishhead-1]

You say the system is a (recirculating fresh water system) do you mean it's a half system with a heat exchanger? Closed system with antifreeze? Then it would run in the 180 range But not much higher. Raw water cooled = no heat exchanger. Good for you not being afraid to take on life problems, we all could learn perseverance from you.

 

[jimmbo]

When my raw water pump packed it in I found many pieces of the vanes plugging up the inlet and outlet holes of the pump itself.

 

[Scott Danforth]

Most of the pieces on a volvo will be wedged in the pump discharge side, however a few may be on the suction side.

On the discharge side, the pieces get pushed to the themostat housing from the force of the new impeller.

Most of the time they get wedged there, however small pieces can get wedged after the t-stat

 

[ahero4all]

Lessons learned...Don't buy a fixer upper..So, if I had to do it all over again with that I have learned about over heating..I would buy a Temperature gun to determine if there is any overheating..Second, I would have installed a manual gauge on the thermostat housing..

I removed the end caps on the heat exchanger and found some calcium build up which cold have been part of the problem..I installed a new water pump, thermostat, heat sensor and a external gauge on the block and the temperature is running around 145 to 151..

The Temp Gauge on the dash is showing 180-190 so although there was some blockage that could have been contributing to the over heating, it appears the main culprit was the gauge reading incorrectly..

I really appreciate the kind and courteous and knowledgeable feedback on this site..

Aloha from the Big Island Hawaii

 

[Fishhead-1]

That's good news but a closed system should be running a 180 degree thermostat and you might want to double check that heat exchanger for a pencil anode. It will look like a 1/4 inch pipe plug on the outside and when you pull it out there won't be anything left on the inside. Should be changed yearly. Good luck with your dive.