Boat running hot on plane PLEASE HELP

Robertpel9

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I bought a 1999 Chris Craft 230 Sport Deck with a Volvo Penta 5.7GS / SX Drive last week with 42 hours on it

I noticed that the boat runs according to the gauge at 210 degrees when on plane and moving. When in a no wake zone she runs at 175 and at WOT it cools down to right at 200. I took it into to be service right after i bought it to have the bellows replaced along with the gimbal. They noticed the motor running hot too so they replaced the impeller and the T-stat as when and ran it on a hose and checked the exhaust for blockages etc and could find nothing

500 dollars later the boat is still running hot even with these new parts. The weird thing is that it will run up to 210 degrees very quick but then never get any hotter. I drove 20 miles tonight straight between 30-50 moh and it stayed right at 210 then whole way and runs great

I tlaked to the previous owner (A 70 year old from italy who is very meticulous and honest (I have known him for a while) and is the original owner. He said in 2003 the boat pegged the temp gauge and the mechanic replaced the impeller and it was shot (Missing small pieces) since then over the last six years he said he watched it very close whenever he used the boat (With a little over 40 hours on it when i bought it obviously he did not use it much) but he said it ran right at 210 for him for the last 6 years

Before i throw a whole bunch more money at this do i need to be worried. The boat works like new and looks like new and I want to keep it that way. The marina said there is likely a blockage somewhere but no way to know till they start tearing things apart and no way to know how much they will need to tear apart till they get into it. The master mechanic said since i am not a moron mechanically if it was his boat he would just watch the gauge and since it has run at 210 for 6 years it is probably fine but play at your own risk. The compression was perfect, there is solid flow fromt he exhaust and he said everything appear to be working perfect outside of it running warm

At this point what do you all think should be done. I want to just enjoy the summer but i dont want to be ignorant of a real problem if it is one. I have owned 6 corvettes and i rememeber my 90's corvettes witht eh 5.7 350 were designed to run at ~230 degrees, what am i exposed to here??
 

rbh

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Re: Boat running hot on plane PLEASE HELP

happy friday night-
could you have those chunks of impellors stuck some where in the system impeding flow? If the motor overheated really good once before, could that possibly have screwed up the sender or the tstat?
(you are running a 140 deg tstat?)
are any of the hoses pinched or colapsed?
rob
 

Robertpel9

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Re: Boat running hot on plane PLEASE HELP

Brand new T stat today and impeller also, the hoses feel fine.

To be honest it runs so good at 210 degrees i almost want to ignore it but if i come off plane and shut her off right away and open the engine compartmet i can hear the sounds of a hot engine (like a sizzle as exhaust water hits hot metal).

I am thinking there is a piece of the impeller (this is three impeller ago now) fom 2003 (That is when it overheated and he replaced it and said it has run fine like this since) another impeller was put in during 2006 as PM and i just put on in today at the marina as a PM. The last two inmpeller came out looking fine, the one when it overheated was pissing piece. No one an find them though and i cant ether

I dont want to be an idiot as p*ss away a perfect 50 hours Volvo drivetrain and i also dont want to be paranoid and ruin my summer over something that has worked fine for the last 6 years at 210

Thoughts????
 

HT32BSX115

Supreme Mariner
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Dec 8, 2005
Messages
10,083
Re: Boat running hot on plane PLEASE HELP

Howdy,

#1, get yourself an infrared temp "gun" like below. $29 at Harbor Freight.
96451E.gif


#2, measure the temp at the T-stat housing. If the temp is MARKEDLY different then change your gage or sender.

If it's the same, then go hunting for blockage.

Impeller fragments love to congregate in the oil/PS coolers and T-stat housings.


Regards,


Rick
 

Robertpel9

Petty Officer 1st Class
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Messages
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Re: Boat running hot on plane PLEASE HELP

I can grab one of those guns at work on monday and will tyr that

considering my mechanic just rplaced my t-stat wouldnt he have seen an issue there is there was one


Is it safe provided i am confident it levels off at 205-210 to drive the boat short term or am i going to ruin it?? It is SOOOO nice this weekend i dont care to be landlocked and it runs smooth as silk at 210 but i dont want to toast the engine
 

captmello

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Jun 30, 2008
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3,848
Re: Boat running hot on plane PLEASE HELP

He said in 2003 the boat pegged the temp gauge and the mechanic replaced the impeller and it was shot (Missing small pieces) since then over the last six years he said he watched it very close whenever he used the boat (With a little over 40 hours on it when i bought it obviously he did not use it much) but he said it ran right at 210 for him for the last 6 years

He does sound honest but I don't know about meticulous.

He's been running it that way for 6 years.

Start by checking the gauge against one of those guns.

Are you boating in salt water?
 

Bondo

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Re: Boat running hot on plane PLEASE HELP

Is it safe provided i am confident it levels off at 205-210 to drive the boat short term or am i going to ruin it?? It is SOOOO nice this weekend i dont care to be landlocked and it runs smooth as silk at 210 but i dont want to toast the engine

Ayuh,... Water Boils,+ turns to Steam at 212?,....

If it's a faulty Gauge,... No Problem,....
But,...
At this point,.. You Don't know that...

I guess you can just Roll the Dice,+ Cross your fingers....
 

Robertpel9

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Re: Boat running hot on plane PLEASE HELP

It is used and has been used exclusively in fresh water

I will have access to a heat gun on Monday, where on the engine am i looking to measure temp?? I may go out and buy one today just to have it vs borrowing one from work. Where is the T-stat housing located??

Is it normal to hear that noise i described at shutdown (I hear it with the compartment open looking at the engine when it is off.

It is definitely at least on the guage at 210-215 as it sits right between the 200-225 markers on plane and smack dab right on 175 when idling. What i do not understand is that it runs absolutely perfect, no misses, strong as could be no signs of anything but then again some cars run at 210 degrees all the time too by design.


What can happen if it really is (and i think it is) at 210??

When i touch it the risers are warm (Not hot but warm - i can leave my hand on them though) and the valve covers are very hot (But aren't they supposed to be??)
 

Bondo

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Re: Boat running hot on plane PLEASE HELP

where on the engine am i looking to measure temp??

Ayuh,... The T-Stat Housing,.... It's front,+ Center just ahead of the carb,...
The thing with all the Hoses attached to it...

but then again some cars run at 210 degrees all the time too by design.

And,... Cars run a Pressurized system,....
Raw water cooled boat motors Don't....
 

Robertpel9

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Re: Boat running hot on plane PLEASE HELP

Ahhh i see - you just cleared up my main confusion - water boils at a higher temp under pressure and a boat is not under pressure

So if we assume my boat is really running where the gauge says it is (in the 210-215) range wouldnt the engine have boiled over many times over by now??
 

Bondo

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Re: Boat running hot on plane PLEASE HELP

Ayuh,... Water Boils,+ turns to Steam at 212?,....

If it's a faulty Gauge,... No Problem,....
But,...
At this point,.. You Don't know that...

I guess you can just Roll the Dice,+ Cross your fingers
....

Ayuh,... Like I said,... We're Guessing,+ You're shooting in the Dark....
 

Robertpel9

Petty Officer 1st Class
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Messages
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Re: Boat running hot on plane PLEASE HELP

I understand and am going to put a gun on it Monday at the latest I guess all i am wondering is IF we assume the gauge is right just for arguments sake at these temps what would happen (boil over, etc??)
 

Bondo

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Re: Boat running hot on plane PLEASE HELP

IF we assume the gauge is right just for arguments sake at these temps what would happen (boil over, etc??)

Ayuh,... I'm not here to Argue,....

You're the 1 with the Bet on the table,.... Go Run It....
If it Blows,... She's Your Baby...:rolleyes:

There's nowhere for it to Boil Over....
If it's causing Steam Pockets in the heads or block,.... You'll be possibly Replacing the Whole Thing....
 

rbh

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Re: Boat running hot on plane PLEASE HELP

mornin robert-
you said you have touched it with your hands and its not that hot.
if it was 210 deg you would have burned yourself good, I would look into replacing the gauge and/or sender(remember to replace with a matched set as the resistance is different, mfg to mfg)
on that thought could the sender have been replaced with the wrong one?
rob
 

Robertpel9

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Re: Boat running hot on plane PLEASE HELP

I drove it all day yesterday and same situation under light load / idle sits at 175 on the guage, when running goes up ti 210-215 and then when off pf plane prettly quickly comes back to 15 (just a couple of minutes.

When it is reading 210 i can rest my hands on the exhaust and it is pretty warm but does not burn my hand or anything. When i touch the stat housing it is too warm to leave my hand on but it does not burn me it is just hot to touch

I really am pissed about all of this, the boat runs absolutely perfect - no misses, starts right up regardless of temp etc. I wont have a temp gauge till tomorrow but i am pretty sure it is not the gauge as i talked to the mechanic who worked on it and he said he can tell it is running hot by listening to it after shut down. He said he backflushed it after installing the new impeller and that he cleaned out the t stat housing, etc before installing a new t-stat. He said there is something restricting flow but it is deeper inside the engine. He said if it were his boat he would keep an eye on it if i dont want to lse the boat ofr a week this summer and then let them see if they can get whatever is stuck in the engine out later in the year. He said the engine will not be damaged by these temps but the rubber in the enhaust system will be

Does all of that make sense?? I know i am taking a gamble here but everything seems to run fine. If it was this hot would i be able to touch the metal on the top of the exhaust (I think you al clal them risers) or would that sizzle my skin??
 

captmello

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Re: Boat running hot on plane PLEASE HELP

With a raw water cooled engine, the tstat housing distributes water to the block, through the thermostat and to the manifolds all the time. Check the actual temp with the gun to be sure, Its possible you have blockage in the engine, with no blockage in the exhaust, giving you your difference in temps.
 

Don S

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Re: Boat running hot on plane PLEASE HELP

You should NEVER see temps over 175? with a raw water cooled engine. If you do, then something is wrong.
Might want to read this Overheat Diagnosis.
http://www.4shared.com/account/file..._Overheat_Diagnosis.html?sId=pyiNkWSS5xzgplMJ

I have also seen the tube between the upper and lower unit of the outdrive, corrode through with small holes. The rubber gromet it sets in could cause a problem too. When at slow speeds, the tube is underwater and the pump will pull water through the pickup and the holes in the tube . When on plane, that part of the drive is above the water line and will suck air, causing an overheat.
 

Robertpel9

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Re: Boat running hot on plane PLEASE HELP

Thanks - That download is very helpful in giving me some pointer on some testing and flushing i can do myself I will likely try some of that later today. I don't see how to use a scan tool as i just have a carbed engine (1999 Volvo 5.7GS) am i missing something there and where is the blue flush cap they reference, i do not see it

My mechanic is telling me i am wasting my time and he is sure it is actually in the engine block. He said they flushed everything out and there is no easily removed debris. I want to beleive him but maybe they just want more service cash.

Knowing that in 2003 the impeller was shot and pieces were missing and that the previous owner said it has run exactly a si have described here ever since then (he said he never watched the gauge before then but has kept a close eye on it since and it always ran 3/4 up the gauge) I am thinking strongly that a piece of impeller is sitting somewhere in the system. The drive was pulled off last week to do the bellows and gimbal / u joint service and they said it literally looks brand new inside.

I am really frustrated, the things runs so well i wan to just let it be but I know it is not supposed to be like this and i am the type that gets driven nuts when something is not working as intended.

What is my next step after i drain the manifolds, backflush the system again they already did it so i am assuming none of this will help but i am going to try anyway).

When the service shop says it is "in" the engine - what does not mean as far as trying to fix it??
 

Don S

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62,321
Re: Boat running hot on plane PLEASE HELP

When the service shop says it is "in" the engine - what does not mean as far as trying to fix it??

Got me, it's their story, ask them what they mean.

If you follow that overheat guide, you WILL find the problem, no matter what it is.
 
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