H180 Volvo Penta 3.0 cooling - How much water flow to expect

Smoky123 · **Joined:** Sat Feb 07, 2015 6:41 pm **Posts:** 8

Hello,

I have a H180 with a Volvo Penta 3.0. I took the boat out last weekend and it had an overheat problem.
At home I inspected the Impeller and one fin almost sheared off so I took it off … a new part will arrive tomorrow. I put the unit back together and continued testing. I used the hose connection and later also the ear muffs…
On idle the engine is getting to hot… next I took the thermostat out… the new part will arrive tomorrow.
Without the thermostat the temperature is steady around 175.
I’m wondering now how much water flow I should expect out of the engine?
If the hose will deliver 100% water flow my judgment is that I get about 60-70% out of the engine. Is this OK?
I checked:
Intake to raw water pump – OK
Raw water pump – new impeller on order
Thermostat… unknown – I ordered a new one just to be sure
What could be my next issue?

deafwish · **Posted:** Tue Mar 10, 2015 8:59 pm

Raw water cooled engines actually flow very little water through the system.
Heat dissipation is actually better at slower speeds...
Have you inspected the water jackets around the exhaust manifold?

ric · **Posted:** Tue Mar 10, 2015 10:23 pm

Having owned a VP 3.0 it shouldn't be 175 without a thermostat. It should run about 120 without a stat.

Sounds like your manifold is rusted/clogged.

signalstan · **Posted:** Tue Mar 10, 2015 10:35 pm

if your engine has a power steering or oil cooler check it for rubber impeller junk it may be plugged

TX H210SS · **Joined:** Thu May 27, 2010 9:10 am **Posts:** 1488

Did I read it wrong? You haven't replaced impellor and tested it after plucking that bad fin. I assume this since you said part coming in tomorrow.

If that's the case.....STOP. don't run it until you install new impellor. If one fin busted your impellor is shot and likely the prob. Inspect it to make sure no busted pieces are missing. They will clog the water jackets.

TX H210SS · **Joined:** Thu May 27, 2010 9:10 am **Posts:** 1488

Also, use the thermostat. From what I understand the water needs to absorb the heat from block before being evacuated by the opening of thermostat.

Running with no therm just rushes water thru. Water stays cool but not engine components.

NiagaraChillin · **Posted:** Wed Mar 11, 2015 7:10 am

Yes to all the above. Testing with a busted impeller and no T-Stat is not going to give you any usable data.

Smoky123 · **Joined:** Sat Feb 07, 2015 6:41 pm **Posts:** 8

Thank you for your answers and support.
The boat is a 2008 and touched water the first time in 2009… as what I have seen inside the engine and the little buildup inside the rubber hoses I think the manifold shouldn’t be rusted and clogged.

How do I test the flow of the manifold? The water is coming out at the prop… For me the unknown is if the motor has a bypass flow for water which is not used and an internal for the hot water? I think so since the thermostat is shielding some of the cold water.
Where do I connect the hose so I only run water through the manifold and out? Is this even possible?

rpengr · **Posted:** Wed Mar 11, 2015 12:11 pm

After getting the new impeller in:
With the engine idling and running on the hose (or in water), squeeze the big water hose (going from the circulating water pump to the thermostat housing. It should squeeze fairly easily without much water pressure indicated. If it is very firm (like a tennis ball) at idle, then your exhaust manifolds (and/or your thermostat housing) must be rusted and clogged, and water is not able to get out of the engine.

All the water pumped into the engine must go out (thanks Mr. obvious). And it all goes out through the exhaust manifolds regardless of whether the thermostat is open or closed.

Hopefully, just the new impeller and thermostat will fix the problem.

ric · **Posted:** Wed Mar 11, 2015 1:32 pm

The awesome thing about the 3.0 is the exhaust manifold is also the intake manifold. It's 'spensive

fi.na.tine · **Posted:** Wed Mar 11, 2015 2:09 pm

http://www.ebay.com/itm/Volvo-Penta-3-0-Exhaust-Intake-Manifold-1992-09-3858870-BARR-1-3858870-/371251973349?pt=Boat_Parts_Accessories_Gear&hash=item5670578ce5&vxp=mtr

$420 shipped. I don't consider it that expensive in the realm of boats...

TX H210SS · **Joined:** Thu May 27, 2010 9:10 am **Posts:** 1488

Don't make it complicated when it don't gotta be. Install new impellor and new thermostat...buy a $ 20 in fared thermometer. Start her up on muffs or in water and let run. Check the temps of manifold, therm housing and see if you have any real hot spots. You can have clogged areas in system and water will flow out other jackets so trying to measure water flow is like pissing up a rope.

Not being ugly, but I'm trying to understand why you would replace a broken impellor with same broken impellor and be looking elsewhere for water flow issue. Seems kinda like looking past a shitty diaper in search of why the baby stinks, don't it?

Smoky123 · **Joined:** Sat Feb 07, 2015 6:41 pm **Posts:** 8

Hello, the impeller and the thermostat arrived today and everything got installed.
I will try to run the engine tomorrow or on Friday.

Smoky123 · **Joined:** Sat Feb 07, 2015 6:41 pm **Posts:** 8

Hello,
I tested the engine at home today with no issues… so we went to the lake.
If I stay at 3,000 rpm the boat will get up to 175F and will hold the temperature.
If I increase the rpm to 3,500 the temperature will increase to 195F and will stay steady as long I hold the rpm. If I reduce to 3,000 rpm the temperature will quickly go back to 175F and if I go faster it will exceed 197F were we stopped it.
Any idea?

LouC · **Posted:** Sat Mar 14, 2015 3:36 pm

I'd say that's still too hot, the 175 is fine, but keep in mind that most engines that have a overheat buzzer will set the alarm at 200* so you're almost at borderline overheating. With raw water cooling systems, usually your overheating issues are caused by low raw water flow in, or restrictions to the water flow exiting the engine. These systems are low pressure but high volume, they are not pressurized like a motor vehicle system or a closed cooling marine system. Because of that, you can have localized boiling in the hotter parts of the engine when the temp gauge reads 200* that is why the warning system is set to alarm at 200*.

So you basically have a few things to check. Did you replace the impeller housing and wear plate when you replaced the impeller? If not and the housing or the wear plate was worn, then it won't pump as well as it should even if the impeller itself is new. The best way to trouble shoot these problems is to put the boat in the water and then disconnect the hose that goes from the impeller housing to the thermo housing. Find out what Volvo's spec is for how much water should be pumped out at idle. Start the engine BRIEFLY and see how much water is pumped out according to their spec. Check that first, that will tell you if the impeller is OK and if there are no restrictions from the outdrive water intakes up to the impeller. If that's good, then you need to make sure there are no obstructions or clogging in the thermo housing and the exhaust manifold. In salt water these are common problems. We usually have to rod out the thermo housing water passages that feed the exhaust manifolds/risers and also make sure the exhaust ports in the risers are open.
The other thing that can cause this problem is air getting sucked into the raw water intake hose, that causes the cooling water to get aireated and that reduces cooling capacity. There is a way to check for this using clear re-inforced hose of the right size but you need a helper to watch the hose while running the boat at speed. There is a Volvo Penta document in PDF form called "Overheat Diagnosis" or something like that, that details the steps you should follow. See if you can find that on the web.
Lastly engine mechanical problems such as a blown head gasket or cracked cylinder head can cause overheating, but you'd be seeing other problems such as water in the oil, or water in cylinders if that were the case.

Wait a min...were you running it at 3500 rpm on the water hose? If so usually the water hose will fliw enough water at idle and a bit above, but not at 3500 rpm. Re test in the water...

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H180 Volvo Penta 3.0 cooling - How much water flow to expect

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