Volvo Penta 5.7Gi Closed Cooling Question

[MalibuMike]

Just purchased my first boat and trying to make is safe for the family. Did one test run of 60 miles total and the boat ran great. It stalled when I pulled back quickly on the throttle and it looks like my trouble might be the IAC valve since the fuel pump (oem Volvo) is new . The boat is a 25 foot Parker pilot house and I ran it between 3100 and 3200 rpm. I was being pushed along between 21 and 25 mph. At idle the boat temp was around 165 and 168 when motoring out of the harbor but at 3200 it sat right at 180. This is above the manual which states that normal temps are 155 to 175. Is this something to be concerned about? Should I start looking at the conditions of the risers or get a infrared gun to verify temps? Appreciate any advice since I just cant tell if 5 degrees is a big deal or not!

 

[Scott Danforth]

first, welcome aboard

second. you still need to service your raw water impeller every few years and I suggest since this is a new to you boat to pull the drive and do a bellows job as well as an alignment and do all the maintenance the prior owner didnt do prior to you buying it.

 

[Horigan]

In addition to what Scott said, get an IR gun to confirm the temperature at the thermostat housing matches the gauge and to ensure the risers aren't too warm. I would plan on cleaning the heat exchanger to ensure it's operating at max efficiency. That could explain the 180 deg temp. Also consider backflushing the raw water system to ensure there is no debris blocking passages.

 

[MalibuMike]

Thank you for your input. I posted the results of the laser thermometer here. I did the bellow and gimbal service recently. https://forums.iboats.com/threads/temp-gauge-vs-laser-thermometer-at-thermostat-housing.741492/

 

[jerryjerry05]

I'm guessing it's a used boat? Salt water/fresh water?
The 5.7GI (any more #s) could be anywhere from 1995 to 2021
Always add the year and the rest of the model#.
Is it a factory cooling system? Manifolds cooled? or just the block?

If the boats a 95 then I'd pull the big hose off the riser and check for blockage.
Pull all the connectors and clean the contacts.
Pull the temp sender and clean the probe.
3200 and 180d Check/clean the contacts on the gauge.
It sounds like the risers are clogged.

 

[Lou C]

I don't think Volvo offered full closed cooling in that year range because of the design of manifolds, there are only 2 low mounted ports for fittings on the manifold front and rear, not a low mounted one and a high mounted one like on a Merc manifold. You need a high and a low mounted port to allow antifreeze to circulate without air locks and hot spots. This engine likely has raw water cooled exhaust manifolds & elbows.
It depends on the water the boat was used in but if in salt water these exhaust systems have to be checked and possibly replaced every 5-7 years or sooner if you see water leaking from the joint between the elbows and manifolds. Volvo had trouble with their original gaskets and updated them some years back.

 

[MalibuMike]

Thank you all. The boat is a 1997 with a 5.7Gi-f. The risers are cooled with sea water. The boat has been run its whole life in salt water. I did see a tiny bit of water leaking in the area you described. I tightened down the four bolts on the riser and it stoped the leak. I just been a little bit timid about cracking open the riser to check the condition but it’s on my list of things to do. I think in terms of just trying to figure out the temperature, I first was trying to understand what normal is and if the gauge or sending unit could be giving a false reading. I completely understand the process for replacing the exhaust manifolds and risers, Ive just been a little bit worried about breaking a bolt. I recently had the boat serviced getting all the outdrive maintenance taken care of, and the mechanic did mentioned that the exhaust risers gaskets needed to be replaced. The good news is that the previous owner provided a bunch of parts that were all very nicely labeled and in a box was a brand new Volvo Penta exhaust riser.
If the risers are showing restrictions, does that always mean that the manifolds get replaced along with them?

 

[Lou C]

You can wind up ruining the engine if you let this go too long. Take a look at the spark plugs and see if the electrodes are getting a bit of rust on them. Salt water will trash the engine and then you'll be in for a long block replacement. After running on plane the Volvo style exhaust on my engine tops out at about 135*. Now a closed system might run a bit hotter since the water feeding the manifolds and elbows has to cool the heat exchanger first. See how hot they get after coming off plane. I would still check them on a new to me saltwater boat. Neglected raw water cooled exhaust is the #1 cause of inboard engine failure.

My boat being in salt water approx 20 years, has had the exhaust changed 3 times since I've owned it. That's a nice boat, it's worth the investment. Don't put it off .

 

[MalibuMike]

You can wind up ruining the engine if you let this go too long. Take a look at the spark plugs and see if the electrodes are getting a bit of rust on them. Salt water will trash the engine and then you'll be in for a long block replacement. After running on plane the Volvo style exhaust on my engine tops out at about 135*. Now a closed system might run a bit hotter since the water feeding the manifolds and elbows has to cool the heat exchanger first. See how hot they get after coming off plane. I would still check them on a new to me saltwater boat. Neglected raw water cooled exhaust is the #1 cause of inboard engine failure.

My boat being in salt water approx 20 years, has had the exhaust changed 3 times since I've owned it. That's a nice boat, it's worth the investment. Don't put it off .

Thank you. I did take some readings of the exhaust manifolds and never really got too hot. Well I am a new boater, I do you have a good understanding of the weakness of a neglected cooling system and that’s why I’m trying to figure out what direction to start with since I don’t really know the boats history.

 

[Lou C]

If Those temps are taken at idle they are fine, the true test is take it up on plane for a while then let the boat drop off plane and let it idle and take readings then. Mine will usually be 135-140 max. Any hot spots suggests clogging. And what’s clogging the cooling passages (rust) used to be part of the manifold/elbow bringing it closer to catastrophic rust through dumping salt water in a cylinder. Salt water boaters should keep track of how many seasons they were used and figure on replacing by 5-7 years. Barr marine makes nice exhaust for Volvo much better price than Volvo OE.

 

[bruceb58]

Those numbers are lower than mine are with a 7.4L engine. You do need to see what they are after running under load.

BTW, with an IR thermometer, you want to be really close to the thing you are measuring the temp of. They have quite a wide angle so if you are too far away, you are getting an average of a large area. The red LED is just a pointer. It is not used to measure the temp.

 

[jerryjerry05]

Take it for a ride, have someone drive the boat,
get it on plane and 2/3 speed.
Then go back and hold your hand on the riser and
if it's too hot to hold?? Then replace the risers.

 

[Lou C]

If you are going to check them throughly you need to take off the elbows and manifolds. Prop up the manifolds level and carefully fill with acetone (careful very flammable) let them sit and then see if you see any leakage in the poets that match up with the cyl head. And you have to check the mating surfaces to make sure they are not pitted. They can be resurfaced but if they were full of flaking rust that rust used to be part of the manifolds, they are getting thinner closer to failure...

 

[Scott Danforth]

If it only gets warm when on plane, look at the fitting on the drive where the raw water hose connects to.

 

[Lou C]

just an example of what you'd be looking for...the elbows on the left are Merc dry joint ones but you can see how when installed they would look fine from the outside but are bad on the inside, the other pic shows how the sealing surfaces get eroded and will not seal.

 

[MalibuMike]

If it only gets warm when on plane, look at the fitting on the drive where the raw water hose connects to.

Can you clarify which fitting and Im not sure what the drive is.

 

[MalibuMike]

View attachment 331843View attachment 331842

just an example of what you'd be looking for...the elbows on the left are Merc dry joint ones but you can see how when installed they would look fine from the outside but are bad on the inside, the other pic shows how the sealing surfaces get eroded and will not seal.

So I just want to make sure I understand the procedure. Since the riser might be good, I will first go buy some gaskets. When I take the riser off, Ill inspect that passages ways and surfaces. If they look good, and I deem then still usable, I will stuff a rag in the exhaust manifold and proceed to clean both surfaces to prepare them for the new gaskets. Reassemble and tighten to specs with a torque wrench. Sound right?

 

[jerryjerry05]

Yes.
You can try to remove the hose on the end of the riser
the passages might be closed off??
Looks can be deceiving
Called to work on a 86 Volvo 4cyl. over heating.
I started checking things out, the manifold looked
brand new, all shiny and new.
The first touch poked a hole in the top of the manifold.
Under the shiny paint the inside of the manifold was
rotted away.

The "drive" is the unit that has the propeller on it.

 

[Scott Danforth]

Can you clarify which fitting and Im not sure what the drive is.

the outdrive

the raw water fitting under the upper transmission where the raw water hose is.

look at the manual.

item #9 in the image below

 

[Lou C]

So I just want to make sure I understand the procedure. Since the riser might be good, I will first go buy some gaskets. When I take the riser off, Ill inspect that passages ways and surfaces. If they look good, and I deem then still usable, I will stuff a rag in the exhaust manifold and proceed to clean both surfaces to prepare them for the new gaskets. Reassemble and tighten to specs with a torque wrench. Sound right?

I prefer to remove the manifold due to risk of rusty bits falling into a cylinder even though it’s a bit more work. I changed the exhaust on my OMC 3 times in my salt water use.
first pic is what the sealing surfaces look like when new on this style of exhaust...
second pic shows my old OMC one piece batwings after 5.5 seasons in salt vs new, note how one cooling passage is rusted shut...
third pic shows the OMC method of using studs and nuts to retain the manifolds, actually this makes for very easy changes because the nuts and studs were rust resistant never rusted manifolds came right off. I had to switch to bolts with the new system because the old studs were not the right length, but if I replace them again I might look for correct size studs.