Boat running hot on plane PLEASE HELP

[captmello]

Re: Boat running hot on plane PLEASE HELP

Remember, the water going through the manifolds and risers is not necessarily passing through the block. When the thermo is closed water is still pumping in and through the exhaust. Riser temps can fluctuate quite a bit as they are not thermostatically controlled, in fact many run hotter on one side than the other. If you can hold your hand on them, you're good.

 

[Robertpel9]

Re: Boat running hot on plane PLEASE HELP

Sometimes i do note that one riser is hotter than the other

Can you answer me this. Is it normal when you sut the engine down if you have the compartment cover off that you may hear some shutdown noises like the sound of water moving or something?? The mechanic said that was a sign of a hot engine.

I know engines can withstand temps well into the 200's as many car engines are designed to run in the 210 -220 range. The mechanic said the risk is the exhaustr and all of the rubber parts mated up to it that will melt and eventually overheat and ruin the engine. If i can rest my hands on the risers doesnt that mean they are not even seeing this heat

The whole thing is so damn irritating as i do not want to be watching a temp guage while boating all the time.

I am sold on the fact that it is running hot as when i come off of plane is settles right down to 175 and stays there so i know it is running right where it should. On plan moving it goes right up to 210 in a matter of minutes. I am still trying to understand what exactly the ramifications of that are as it has been driven like this for 6 years

AARRGGHH

 

[captmello]

Re: Boat running hot on plane PLEASE HELP

Just do the test with the temp gun. then we'll figure it out.

It seems like engines make noise when they are cooling down. How much is acceptable I don't know.

The fact that the risers are cool only means water is pumping. But does not confirm if your getting air infiltration or not. Your clog could be it the block causing the flow to be restriced in there but no restriction in the exhaust. the clear hose test will show bubbles in the water. Take it out with the clear hose and temp gun.

 

[Robertpel9]

Re: Boat running hot on plane PLEASE HELP

Armed with my new info the mechanic said nothing he did not already know and that the blockage is in the block and could be anything from rust to sand to impeller fragments.

I am going to do as you said tonight and see what happens. If it is in fact in the block how the heck to you clean it out without incurring major costs

 

[Robertpel9]

Re: Boat running hot on plane PLEASE HELP

OK 2 hours later i have a lot of data - hopefully this helps

I installed the impeller again and replaced all 4 screws and ensured everything was tight. She started right up and was not leaking anywhere etc, i was off to a good night and if anything else i will never pay anyone to replace my impellar again as it is easy

Let her run at a high idle (2200 rpm) for about 7 minutes and she never got over about 130 on the gauge (this is where my last boat always ran) thought i might be in luck

got out and put her on plane was going straight with the trim all the way down and it stayed right at 175. I thought SWEET but it was not to be. I turned right and it started heating a little right away. got back to straight and it cooled off a bit. I then stayed straight and was back at 175 then i trimmed up / out a little staying straight without turning at all and as soon as i did that it started climbing and went right where it always does to exactly between the 200 and 250 marker and stayed there. It climbs from 175 to this position damn near instantly under both scenarios ( when i turned and when i stayed straight and just trimmed up a little). Also as before if i dropped the hammer and got up to 48 mph and 4400 RPM it came down from 225 to 200 on the gauge

I then spent an hour taking temps with a IR gun. Here is the deal looking at this photo

Looking at it from this angle the right riser is always about 20 degrees higher than the left riser but the right valve cover is always about 20 degrees cooler than the left valve cover. Right riser at max temp on gauge is 170-180 and left riser is 150 - 160

When gauge is reading about 225 the place i have shown in the pic (The base of where all the hose comes together) is right at 200. As soon as i am idling it comes down quick. when the guage is right in the middle at 175 this spot is reading on the gun about 165. If i shoot the engine block just below and to the right i get a similar reading to the spot i am showing in the pic

So at this point i think it is safe to say it is running hot and replacing the missing screw, etc made no difference. So i need help with three things

Why was it fine at 3000 rpm and 30 mph when in a straight line and with the trim all the way down / in. What causes it to go up really fast with either of just a little turn or just a little trim. I have no way short of the marina coming to get it and take it back to their shop to do anything drive related and i am hoping that is not it but it seems to me i must have an issue with sucking water into the boat vs getting water thru the engine

what does it mean that one riser is 20 deg hotter than the other and the opposite valve cover is 20 deg cooler? and at the temps i gave is it ok to use the boat. It run perfect and i just am hoping for this PITA to be over with

Anyway that is all i have. I hope this info is useful in helping to diagnose it. Please let me know your thoughts

Thanks,
Robert

 

[Gary H NC]

Re: Boat running hot on plane PLEASE HELP

This is getting harder than it should be.

So you are saying the temp stayed at 175 at full throttle until you trimmed out or turned?
Get a piece of clear hose at lowes or Home Depot the size of the inlet hose.
Go through the same test again and watch that hose as soon as the temp starts rising above normal.
See if its full of air bubbles or trying to suck flat..

Don suggested this way back in the thread but i did not see where you tried it or not

 

[Bifflefan]

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

When you "PEG" any gauge it needs to be replaced. most (99%) of the time they wont read accuratly any more. (probably gonna get decenting opinoins on this). I would get a couple of those melting sticks, and try them on the engine to let you know if it really is running hot. You can also get a cheap gauge from an auto parts store just to put in and read the temp (mechanical gauge). this will tell you alot.
As i used to race cars alot, we always changed a gauge if it got pegged. We learned that lesson the hard way.

 

[Robertpel9]

Re: Boat running hot on plane PLEASE HELP

This is getting harder than it should be.

So you are saying the temp stayed at 175 at full throttle until you trimmed out or turned?
Get a piece of clear hose at lowes or Home Depot the size of the inlet hose.
Go through the same test again and watch that hose as soon as the temp starts rising above normal.
See if its full of air bubbles or trying to suck flat..

Don suggested this way back in the thread but i did not see where you tried it or not

When i read the tstat housing it is never above 160 degrees. It is hot (200-205) right where the housing meets the engine. Am i reading the right place. The housing itself is never over 160 degrees?????????????

Gary,
i have not had a chance to get the clear hose yet but difinitely will be by weeks end

Yes it was fine at 3000 RPM and straight trimmed all the way in. As soon as i turned or trimmed out it shot up fast

I know i need to get the clear hose but in the time i had today this is all i could do. There must be something that can be deciphered from the data i got tonight??

If i put the clear hoses on it i assume one of two things happen. What will bubbles mean??

Bifflefan - as you can see in the pic I was able to shoot it with an IR gun - isn't that pretty much what you are suggesting. It looks like the gauge is pretty accurate as when it read 225 on the dash i was getting readings of 200-205 on the IR gun

 

[Gary H NC]

Re: Boat running hot on plane PLEASE HELP

Air bubbles will tell you if its sucking air in somewhere between the water pickup on the lower to the engine.
The fact that when you turn or trim up it gets hot is an indicator that something is going on with the transom hose or drive.
Just a guess at this point.
I always aim the IR gun at the brass base of the water temp sender.

 

[Robertpel9]

Re: Boat running hot on plane PLEASE HELP

I am going to Lowes today to get the clear hose and pipe.

Since It looks like i will be spending my night down at the boat dock again without internet access please tell me the next step of action for :

1) if i see bubbles what do i do next

2) If i do not see bubbles what do i do next

I am hoping to at least get to the end of the diagnosing part tonight. Please let me know

Robert

 

[markotah]

Re: Boat running hot on plane PLEASE HELP

I know this sounds crazy but it is a cheap test. I don't know Volvos but it is a Chevy engine. I have a friend is having overheating issues with a 95 mercruiser. Older mercruisers had ball checks in the lines feeding the risers. He had no ball checks but to test tried a couple of lugs nuts inserted in the hoses and it seemed to make a big difference. He has ordered the ball checks and will try them his weekend.
The theoroy is the housing is corroded and allowing water to bypass and not flow equally. Water will take the least pass of resistance which seems to be the risers. The smaller hole in the lug nut acts as a flow resticter. While running have someone use the infared thermometer and check temps at the risers and lower manifold for extreme differences. Then try again with the lug nuts and see if you note any changes. If it works get a new thermostat housing or ball checks if available.
Before anything make sure the water pump housing is sealed and all screws are installed and all piping has no leaks. Leaks = loss of suction.
Good Luck

 

[BLDFW]

Re: Boat running hot on plane PLEASE HELP

If you see air in the clear hoses coming from the pump, it means you have a leak somewhere between the impeller and the water.

If it runs solid water, then you're problem is going to be somewhere PAST the point where the clear hoses discharge into the engine.

Also, when you shut down, you will eventually see the hoses drain out and likely steam up a bit. That's normal as the water will seek the lowest point and that will be back through the impeller housing downward. The steam will just be heated water from the risers or the block.

 

[Robertpel9]

Re: Boat running hot on plane PLEASE HELP

I talked to three marinas today and they all were not much help at all.

I am going to run a clear hose to the intake of the water pump tonight. I guess where i will be at a loss is what to do next. I think i am going to see bubbles but i do not have the tools or experience to take it further and my boat is kept on a lift in the water

I am almost thinking at this point i ned to let a marina just take care of it but at $99 an hour that scares the crap out of me

I just talked to the orginal maintenance shop and gave them all the info i have given here. They said it is definitely sucking air (We will see tonight with the clear hose). They were pretty articulate about how to find it and gave me the three place from the drive to the pump where that happens. They cant get me in until early next week but they are going to go ahead and fix it i think

 

[BLDFW]

Re: Boat running hot on plane PLEASE HELP

I talked to three marinas today and they all were not much help at all.

I am going to run a clear hose to the intake of the water pump tonight. I guess where i will be at a loss is what to do next. I think i am going to see bubbles but i do not have the tools or experience to take it further and my boat is kept on a lift in the water

I am almost thinking at this point i ned to let a marina just take care of it but at $99 an hour that scares the crap out of me

It's painful a painful reality if you don't have the ability to do the work yourself. At that point it's unavoidable with only two choices; Throw the towel in and sell the boat and take the SAME financial loss by reducing the asking price of the boat....or...pay the money and continue to enjoy the boat. We've all experienced unwanted expenses in one way or another.

You can possibly minimize the financial hit by not taking it to a marina repair shop which tend to be more expensive and taking it to a qualified marine repair shop elsewhere.

Back to the problem at hand.....if the water in the clear hose is running solid with no bubbles, as suggested the problem is in the block somewhere. Something is impeding the water's free flow OUT of the engine block. Where that occurs, you will likely find the block to be hotter.

You should be pointing that heat gun to the heavy metal parts of the block in various locations above and below the risers. The differences in riser temps suggest possibly focusing your temp shots on that side but you will need to get below the risers to do temp shots as well.

Before you start climbing around though, I would definitely aim that gun directly at the temp sensor to validate the heat levels there. It could very well be the sensor is bad. If it is, replace it and retest everything. I also like the idea of replacing (even if temporarily) the temp gauge on the dash. It's a very cheap step you can take yourself.

 

[Robertpel9]

Re: Boat running hot on plane PLEASE HELP

I am the bun right at the bottom plate of the engine where the T-stat housing is and it is very close to the gauge on the dash (it is ready 200-216) when the gauge is between the 200 and 250 markers so i think the gauge is good

While the risers are always 20 degrees apart it seems and the opposite from the riser valve covers are 20 degrees apart the block itself is right about the same all over and it nearly identical to the t stat housing reading. One side of th block is the same as the other

The place i have it serviced is a used boat seller and service shop. I just talked to the owner he said he noticed too t spiked when they went around the sharp bend to get to my house and thinks it is sucking air. I think from what i have read here that i should know tonight definitively if it is or not when i run a clear house to the impeller intake. At that point i think at the very least i have done a lot of the diagnosing for them so it at least will reduce labor costs as if it is juscking air they can avoid looking for contamination in the risers , etc correct and focus on the water flow from the intake in the lower unit of the drive thru to the impellar and if it is not sucking air then they can rule all of that out and just focus on issues from the engine to the exhaust

is this correct??

 

[BLDFW]

Re: Boat running hot on plane PLEASE HELP

Interesting...... You've said it twice now about it spiking in a turn. Is that a highspeed turn? It sounds more like an outdrive seal issue as the outdrive is up and out of the water at higher speeds.

I think I mentioned it before, I had the same experience wherein 3900rpms I was fine but at 4000 rpms, the temp gauge would climb fast up to 220-250. Turns out it was a seal somewhere in the lower unit. It was fine at slower speeds because the drive was still down in the water.

Put the clear hoses on and go through the slow and the high speed tests again. You really can't determine anything more at this stage until you do that.

 

[BLDFW]

Re: Boat running hot on plane PLEASE HELP

Oh yeah....sorry if I missed in the 52 previous posts, but note exactly at what RPM's you start to see the increase in temps. Start slow and inch your way up and see if there's a magical number where the temp starts it's upward surge.

Just another piece of the puzzle.

 

[Robertpel9]

Re: Boat running hot on plane PLEASE HELP

I HAVE NEVER BEEN SO HAPPY TO SEE BUBBLES

My wife and i went down to the boat and hooked up the clear hose to the top hose on the impeller housing. At idle and puttering out at low speeds no bubbles, as soon as we got on plane and the drive started coming out of the water there were a ton of bubbles to the effect that it appeared the hose was only half full of water. As soon as we came off plane no bubbles again and within a couple of minutes it was right back down to 170 degrees

So - now that i FINALLY have gotten to this point what is next? I do not trust my local cheaper mechanic as i showed him my clear hose on the way home and he told me i was wasting my time and that he never heard of that issue and they just had the drive off to replace the bellows and everything looked great and he laughed at me. The manager said after that they would not have seen the lower unit, etc and it was worth doing but how can i trust this mechanic now.

One of my goals here was to fix it myself - that is not possible although i have learned a ton as my boat is on a lift in my slip in my neighborhood but i have no trailer or way to remove the drive, align it, etc. So my goal now is to minimize cost at a waterside dealer. I know i am armed with diagnostic data but how do i specifically go about getting this fixed and any ideas now on the exact cause??

Thanks so much for all of your help and patience. I really took a risk shelling out for the boat, selling my old one, buying a lift, etc and i looked for this specific boat for a LONG time so i have just had a lot of anxiety about this issue. Now that i went thru exactly what you guys told me, can you shed some more light on what i have and what to tell the repair shop

 

[MERCrazy]

Re: Boat running hot on plane PLEASE HELP

did you get an infrared thermometer??
what are the temps??

 

[Robertpel9]

Re: Boat running hot on plane PLEASE HELP

yes, i worte them in the posts from yesterday, the t-stat housing reading right about what the gauge says and the engine block on both sides is about the same (200-205 degrees) risers are 150-170.