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Joe Culhane

Engine cruising teperature...

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What's the normal engine cruising temperature, depending on RPM ?

 

I have a '94 model 246 with a 5.7 Volvo Penta (350 Chevy engine). At idle, engine temp is 160....at 2200 RPM around 180/190.....at 3000 RPM, 200 degress. Is this normal or am I experiencing a restricted water flow (manifol/riser issue) ?

 

Thanks,

Joe Culhane

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It should stay at about 160 regardless of the RPM. The first thing to check would be the condition of the impeller in the water pump. Put a new one in, and then test again.

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What's the normal engine cruising temperature, depending on RPM ?

 

I have a '94 model 246 with a 5.7 Volvo Penta (350 Chevy engine). At idle, engine temp is 160....at 2200 RPM around 180/190.....at 3000 RPM, 200 degress. Is this normal or am I experiencing a restricted water flow (manifol/riser issue) ?

 

Thanks,

Joe Culhane

 

Look in the Product Support section of the forums and find your owner's manual. The temp should be in there.

 

I have a 2000 242 CR with the 5.7 Volvo engine and my engine temp is usually a constant 150 degrees. It might climb to 155 degrees when running 4000 rpm but I do not run with that high of an rpm. I usually cruise at 3200 to 3400 rpm and I see 150 degrees constant.

 

This is running in both fresh water (Columbia River OR.) and salt water (Puget Sound WA.)

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I changed the impeller before the end of last season. Would be out of shape sitting in same position over the winter ? Do you guys change the impeller every season ?

 

Thanks again,

Joe

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I changed the impeller before the end of last season. Would be out of shape sitting in same position over the winter ? Do you guys change the impeller every season ?

 

Thanks again,

Joe

 

I changed mine before last season began. I ran it all season and I'm going to run it all of this season. I'll change it out to a new one next year. I didn't remove it before I layed the boat up for the season, I should have but just didn't get to it. If my engine temp. went about 155 on my gauge then I would have changed it out this year.

 

Leaving it in you run the risk of the impeller fingers taking a set but I guess I got lucky. I carry a spare replacement kit with me.

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An impeller should last 4-5 years before it needs changing again. Winter would not effect it. Was the impeller you took out still in one peice without any fins broken off? If not did you find all of the broken peices? After you changed the impeller, did the engine ever run without the boat being in the water, or a garden hose connected to the outdrive with ear muffs? 10 seconds will destroy a new impeller, if there was no water going in while the engine was running.

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Thanks, no broken pieces and the last impeller (changed last season) looked fine.

 

Before launching this season, I poured dishsoap down the hose. Saw the soap in the water when i launched.

 

I'm just not familiar with what the norm is. This is a '94 that has had little use. The exhaust manifolds and risers are original.

 

in 2001 I changed the engine water pump and it's not leaking and there's no wobble to the pully. Can the blades on that pump have a buildup of something imparing the proper flow of water ? I never heard of such a thing....

 

I'm more an auto mechanic and not sure what the norm is as these boats age.

 

At the dock, this weekend, I ran it at 1500 rpm and it stayed below 160 degrees. Does that mean I can rule out the manifolds ?

 

Thanks,

Joe

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It also could be the temperture sending unit, or the gauge itself. I would suggest checking the engine block temperature, with a laser temperature gauge to confirm it is running hot, and then go from there.

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Timing is another factor which can affect engine temp.

 

I have to see if the distributor has vacuum advance or just mechanical and go from there.

 

I don't want to simply be a "parts changer", I'd like to diagnose the problem.

 

Thanks,

Joe

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The timing advance in the distributor is electronic. Check the actual temperature of the block and the bottom of the thermostat housing with a laser temperature gauge. It may not really be overheating at all.

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I recently removed the thermostat, ripped the guts out of it and reinstalled it, effectively making it wide open all the time.

 

The engine runs as cool as a cucumber. Is there any issue running the engine too cool ? Someone told me running cooler than the 160 degrees, salt in salt water could calcify in the engine. I'm currently running the boat on the Hudson River, which is brackish where we are and turns fresh North of us.

 

Any thoughts ?

 

Thanks,

Joe

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Running too cool is not good either. I would suggest you install a new 160 degree thermostat, and you should be good to go. :)

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Well, took it out for a good two hour run Sat.....probable is still there. Run it steady at 2600 - 3000 rpm and I'm at 180 degrees. back off and the temp comes down.

 

Late last season I had the lower outdrive rebuilt. Maybe the pickup hose is not connected or broken. That's my latest theory.....

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The problem could be the waterpump itself, the connecting plumping between the upper and lower drive assemblies, the water hose from the bell housing to the gimbal housing, or even a restricted power steering cooler.

 

Having said that, you said it ran quite cool without the thermostat. Was that just at idle on muffs, or is that under load out on the water? Are you running in salt water? The inside of the thermostat housing could have a lot of corrosion build up too, which would restrict water flow at higher RPMs.

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If your at 180 your fine. I've got twin merc 5.0's and one motor is right around 170 at cruise, the other one is closer to 180. Been that way since day 1.

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End result.....Exhaust manifolds and risers have been replaced and it now runs at approx. 150 degrees....

 

Block and oil cooler were also flushed.

 

Thanks to everyone who replied.

 

Happy Boating !

 

Joe

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Hi Joe: Our boat has a pair of 250HP 2 barrel carb 350's and is bone stock. Both engines show 175 degrees of temp When at the 3500 to 3600 RPM cruise speed. Griff

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I have the 5.0L (Chevy Block) with SX VP out drive on a 21' footer, and since day 1, she has always run from 150-175 at cruising speeds, and rarely gets past 200 if ever.

I have never had an issue, and that is with risers and manifolds are being replaced next month due to time and corrosion.

I figure with new R&M I will be at a steady 150-160, which is normal for a V8 small block.

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