over heating issues

duane.mosley

i have an 06' 250 ec with the 5.7 volvo penta. what should be the normal operating temperature while running WOT?  at idle? we just bought the boat in april, the first time we took it out we had no issues and while running at idle, we were at around 165-170, full WOT was around 200. the boat ran great and had no issues. last weekend we sucked up some mud at a local boat ramp  that turned out to not be deep enough. now at idle speed we are around 180 but if we try to get up on plane, the temp starts climbing. i am assuming that i have a clog in my system and was curious as to where to start? i pulled the thermostat housing last night and noticed the thermostat was not present so that eliminated it possibly sticking. i just replaced the complete raw water pump assembly last week when i did my tune up.


other issue i had this weekend was with my air conditioner, it would pump water and the fan comes on but it wasn't getting cold. when i bought the boat through the broker, he had the ac running and it seemed like it was working fine. to back up a little bit on my story, i had no idea that the ac needed to be in the water in order to run, so it was on in my driveway for about 10 minutes when i first got the boat. (dumb a** rookie). did my rookie moment fry something? it seemed like the compressor kicked on that day for a minute but shut right off due to no water i assume.

any and all suggestions of help are greatly appreciated in advanced! i am a diy'er and really don't want to pay the 100 bucks an hour if i can avoid it. not too mention, peak season in northern Kentucky so the repair shops are swamped until after the 4th.



i also didn't hear an alarm going off when the temperature was rising.  thanks

MarkB

Has the impeller broken up before. You could have pieces of broken impeller in your block that need to be flushed out.

I don't think you hurt your a/c as the protection should have kicked in. Lots of guys run there aircon without the water pump being primed.

duane.mosley

the existing impeller was in good shape when i removed it. the seal on the bearing housing started leaking that is why i changed it. as to my knowledge the pump hadn't came apart. our first trip out this year went smooth and ran fine. it's only after i think i sucked up some mud last week that we've been having this problem

MarkB

Did you buy the boat new?  I suspect the thermostat was missing due to the same problem.  They took out a restriction.

duane.mosley

no i didn't buy it new, i've put about 6 hours on the boat with out any issues with temperature until i hit mud on the ramp last week. if the pump came apart prior to me owning it, it wasn't disclosed at sale. of course

girls2water

I also had overheating issues, however mine were after having the impleller replaced on my 5.7 mercruiser with a bravo 2 outdrive.  It was sheered clean and I am not sure my motor savvy nephew flushed the parts out properly.  We got a half mile out on plane and the alarm went off.  we slowed down and it went off and the temp guage fluctuated between 150 and 180.  up and down the whole way back at about 6 miles ph.  Is this a symptom of the parts floating around or a thermostat item (or both)..  How do  you flush these parts out of the block?  captiva 232 98.  no overheating issues last year 'even with the sheered  impeller.  Or  have I done more damage to something else?

duane.mosley

x

JC290

Could be one of these.
1. Blocked manifolds or risors due to corrosion. Overheat under load
2. Bad seal in outdrive between pickup and sea water pump allowing it to suck air on plane, but not submerged.
3. The rest of the impeller got stuck in block, manifolds, or risor.

found this info on line 

duane.mosley

turns out my 5'' deep strainer had about 3'' of river silt and muck. i pulled all the hoses and flushed the raw water system and heat exchanger.  haven't had a chance to run it yet to see if my over heating issues are cleared up due to raining tonight. the boat ran fine for about 10 hours this season until i hit some mud on a shallow ramp so hopefully this is all it was. here are a few pics,  the ball of mud sitting on the wall is the size of my fist, and that's just what rolled out on it's own. i sprayed the strainer with the hose and man what a difference. fingers crossed on the over heating. once i know that's good, i will tackle the air con.

Dream_Inn

Yeah, that's a good sign of the problem!  Definitely a good find and should be the source of your issue!

raybo3

I would also take the end caps off the heat exchanger and clean it out with a water hose......

MarkB

Wow, that's more than likely the problem. As Ray says, while you're at it, clean the heat exchanger.

duane.mosley

just got back from my water test and all is good! my  brothers river camp is 10 miles from where i launch the boat, i rode up to his camp and back at WOT and no issues. turns out my sending unit or gauge is definitely off. i checked temp  at the sending unit and at idle it was 145, gauge said 175. at WOT it was 165 gauge said 190 those readings are without a thermostat. (i just bought the boat, i didnt remove it)i will be ordering a sending unit and a thermostat kit as soon as i'm done typing. manifold temps were 106 and 111, no issues holding on to the top of the risers, flow seems to be restored.

when i flushed everything, i pulled the plug from the top of the heat exchanger and the hose off of the raw water pump. started at the plug to blow anything that might be stuck back towards the raw water pump hose, and then reversed the flow. i did that several times as well as pull the hoses from the power steering oil cooler.


once i get a thermostat back in the boat, calls for 170, what should i expect to see at WOT for my normal operating temperature?

Dream_Inn

Really, a 170 thermo?  I would think it'd be a 160.  I know a 160 thermo will give you around 175 at cruise.  The 140 (for antifreeze engines) will give you about 155....oops, you have Volvo, so maybe 170 is what you should have.  I would guess about 15 above that, so 185 for cruising temp?

212rowboat

too many variables to tell you what to expect... water temp, fuel condition/quality, spark advance/retard, flow circulation rate, ect ect ect... 

170?  Strange number... are you closed loop cooling the engine (without looking back to see)?? If not, it should be 160.  

your safe ceiling for temps at WOT and extended period is likely right at 195.  If you're closed loop cooled, you can safely go higher; it can't flash boil because it's pressurized.  If you're raw water, it CAN flash boil, and you'll want to be safely under that point... 212* at sea level, but different (lower) at altitudes... If it's not sea level, I'd not wanna see north of 190* EVER.

you need to be slightly more concerned at 3/4 rather than wide open throttle.  Reason:  the engine opens loop and pumps fuel at the maximum rate at WOT, and will run rich because of such- rich is cooler than lean.  At 3/4 throttle, the engine is managing fuel and trimming it, which means it will be closer to stioch, which is leaner... and leaner is hotter.  If temp spikes, then you aren't circulating enough water, and the circulation pump likely needs to be changed... it's not like a car which has a big heavy clutch fan hanging off the front of it, and seals that will rupture on that shaft giving you a heads up it's checking out of the game, you'll find it first by temps that the impeller/paddle has worn to where it's not pushing enough fluid.  

MarkB

Yeah, when I read 170F I was thinking that's odd. Most stats I know of are 160 stats. But who knows?

duane.mosley

212rowboat, from reading your posts, you certainly know more than me(not being sarcastic). not sure where i read 170, can't seem to find it now. the plan was to put the oem t-stat in it anyway. this might be a rhetorical question, but can i use an automotive temp sending unit or is it marine specific as well?  

212rowboat

're: temp sensor... I don't know... If you're running a pcm (if you're efi you have to) you likely can, as it speaks to the pcm... If you're carb'd, that sendor is married to the gauge and the resistance has to match up for accuracy's sake.  The stat itself you 'can' run a automotive, but the only way I'd do it is if you're in fresh water.  Salt water and raw cooling? Nope.. it's gonna be brass and not steel.  

If you're efi/pcm, you're gonna want to make certain and use the right thermostat.  The engine expects a certain temp and range to trim fuel properly.  Ten degrees makes a difference. 

duane.mosley

my engine has efi/pcm, i can get the oem thermostat locally so what ever the volvo penta store web site  is calling for in my engine model, is what i am putting back in it. none of the marine stores locally have the sending unit, thats why i was asking about the sending unit.

212rowboat

I doubt Volvo engineered their own sensor, and likely use the same ones mass produced for that application for everyone.  I'd run a automotive sensor/sendor and not worry too much about it unless you get a fault.  It WILL fault if its wrong, as that is a pretty important bit of information the computer is looking for.... Again, I just can't see why penta would use something not mass available for many applications for simplicity of production, unless they're looking to make big profits off replacement parts, and that juice just ain't worth the squeeze. 

duane.mosley

Installed my t-stat and sending unit. Verified on the stove that it opened and closed. Started opening in the 150's fully open by 165. Fully closed at 145. 

Temp sending unit, Volvo penta through local dealer- 73 dollars(not in stock) Standard brand through a friend at the local auto store. 11.98 with tax. Thanks 212rowboat. Have to wait for the river to come back down from all this rain before I can test under load. Lake Cumberland trip scheduled for next week so hope all is good. Now time to fix the air con

duane.mosley

temp gauge is still off, showing 160 on the block, 152 at the t-stat housing using an infrared thermometer, but 180 on the dash.  after doing more research,  turns out there are 2 temperature sensors, and a sending unit. it's my understanding that the 2 sensors would be the ones in the manifold risers that communicate with the ecm? the sending unit in the t-stat housing controls the gauge on the dash  right? i have the 4 gauge faria unit that has oil pressure, fuel, volts, and temp. is there a test i can run to make sure the gauge is getting the info that it needs.

duane.mosley

well, i think it is safe to say, that i am all good! after flushing the freshwater system, installing a thermostat, and temperature sender. i was able to spend the entire weekend on lake cumberland with out issue. temperature stayed right at 175 and when on plane at 4000 rpm might have reached 190. thanks