What is your engine operating temp? 5.7Gi Volvo

[USA591]

Hi Fleet,

Ok, so I had in interesting incident the other night and I'd love your opinion. First, the facts: I have a Denali 2460 with a Volvo Penta 5.7Gi, raw water cooled. Our ocean temps here in Southern California are around 58' F. The engine has about 120 hours on it and the leg is the original unit. I keep the boat moored in salt water, year around.

Ok, so the other night I was running at about 3000-3200 RPM's for about ten minutes. I slowed down, went into idle and about two minutes later the engine alarm sounded. Oil pressure looked good, but my engine temp was at 85' C--I'm using celsius as my reference because there are more tics on the gauge in that scale, thus way more accurate. My first reaction was to turn the engine off because I remember that an alarm will sound during an overheat or oil under-pressure scenario.

It was off for about thirty seconds and I said, "oh crap! I should really have water running though the system!" and started it again. I engaged the gear and went up to 2500-3000 RPM's for the return trip. No alarm, no issues--the temp gauge read 80' C the rest of the way home. Looking back, I seem to remember the operating range being about 70' to 80' C over the past several months.

I looked at the manual, and it says that my operating range should be between 68'-78' C (155-175' F). Soooo...no matter what, I'm at the top of my range. hock:

Does anyone have any ideas on what might be going on? I flush my engine with fresh water (via the in-compartment attachement) after every cruise, but could growth inside the raw water intake be restricting my cooling flow?

I'd love to hear what temps other 2460's are operating at.


Cheers,

Pierson

[MarkT]

My first question is what year is it? Have you changed the water pump impeller? Have you checked your exhaust manifolds and risers? They rust up inside and restrict cooling water flow. Simplest thing first though, is the raw water pickup clean? How is the thermostat?

[hnt]

I have a 1996 2460 with a raw water cooled Mercruiser 5.7Lx Efi Bravo III. I just replaced the themostat and the impeller. I also removed the risers and checked the mating surface of the risers and the manifolds and installed new OEM gaskets. My temps before and after the preventative maintenance run between 160 and 175 on the gauge. The starboard riser is warmer to the touch than the port but I can hold my hand on both. I am told this is normal.

[MarkT]

Next time you have it running check a few spots on the risers and see if you have any hot spots. 16 years on the original risers? If that is true I bet they need to be replaced. And any variation that you can see on the gauges could just be calibration. At the very least keep your eye on them and if it happens again dig deeper to see what it is.

[USA591]

Hey Guys,

Thanks for the responses. To answer a few questions:

• The engine & risers were installed, new, in March of 2011 by the previous owner who was un-aware that they should be fresh-water flushing after each use. Ooopps. That went on for seven months, then I got the boat and I've always done a flush.
• Haven't checked the impeller...dumb question, but where is it?
•The raw water pickup was clean.
• The thermostat has a March 2011 install date, as well.

I have an infrared thermometer--I'll check for hotspots on the Risers next time I go out.

Also--does anyone have a link for a detailed engine schematic or shop manual for the 5.7Gi? I have a line drawing of the engine with a bunch of arrows, but it's not super detailed.

HNT: thanks for the operating info.
MarkT: thanks for the checklist of items.

I'll report back as I discover more... "Learning by Doing...the only way to Learn!"[img]../images/emoticons/thumbsup.gif[/img]

[hnt]

The impeller is in the raw water pump (on my Mercruiser its on the starboard side of the engine and its driven by a belt). I think the Volvo has a similar setup. These pumps cannot run without water for more than a few seconds without damage. When the boat is run on land it must have water through the muffs. I would plan on replacing the impeller as it is fairly inexpensive. If you remove the old one and it is missing vanes you will want to remove hoses and check the thermostat housing and back-flush the cooling system to account for all the peices. If not they can get lodged in the system and restrict cooling flow.

If your manifolds and risers are only a year old they should be fine.

While it can never hurt to flush the system with fresh water after each use you should know that lots of raw water cooled boats kept in salt water never get flushed with fresh water. Even in those cases manifolds and risers can last 5 years or more and the engine blocks can go for decades.

Good luck and let us know what you find.

[MarkT]

I have to agree with HNT. Most people never flush out engines with little noticeable change if any in the life of the engine. I believe the Volvo impeller is at the front of the engine. I guess the impeller is a year old now. Check that and see if any of the vanes are missing. If so you need to find the pieces so they don't cause a blockage. Impellers can also get a "set" to them and have reduced capacity. Most people change them every year at the start of the season.

[USA591]

hnt - 4/26/2012 11:20 AM

While it can never hurt to flush the system with fresh water after each use you should know that lots of raw water cooled boats kept in salt water never get flushed with fresh water. Even in those cases manifolds and risers can last 5 years or more and the engine blocks can go for decades.

Good confidence booster, thanks!

I will let you know what I find out.

[Wicked Good]

I have a 2460, 5.7 Gi, Fresh/raw cooled, and my norm temp. is at 174 F . If your a do it yourself kind. "SELOC" has an on-line subscription which I have, and has a lot of info / repair guides. Also Volvo Penta web site has a lot of info.. Was this the 1st time in the water after the thermostat install? I agree with the possible impeller problem, also check the wires on the thermostat for connection/corroision. The impeller is located on the front bottom of the engine, follow the serpintine/fan belt to the lowest pully. The pully has two pipes coming off of it connected with an intake and exhaust line. Check to see if water is leaking around the pully. I changed my impeller prior to my first test run, then later the whole pump started leaking. It was a slow leak but enuff to replace. There are weep holes on the pump, when the seals break down water will drip in to the bilge and spray fan belt dust and sea water. A mess. I replace the whole pump/impeller, no leak, ops. check good. Gool luck, I know this is a late posting but I just signed on.