Help!! Over heating only in water

[Aaronjr]

Hello glad to finally be a part of a good boat forum so I'll jump right into it my 77 Ray sv 220 with a 5.7 350 engine only overheats when I put it in the river when I run it on the muffs it stays cool I've ran on the muffs for an hour temperature never budged I've even ran it at different rpms and it still says cool on the muffs
I'm a master automotive tech but this got me baffled boat had been sitting before I got it years
Not sure how long but since I have been trying to get it in the water nothing has been going right so where should I look 1st now?

 

[Lazy Daze]

Classic symptoms of a worn impeller. It's impossible to duplicate the load a boat engine sees on the water, when only on a hose. The load a boat engine sees, on the water, is kinda like a pickup truck engine going uphill, towing a trailer, all day long. It's easy enough to check the impeller and housing, I'd start with that. Also look at t-stat and housing - maybe check water flow at housing on the intake hose. Could also be a crudded up block and/or manifolds. But start with the easy stuff.

 

[OldEngineer]

Dennis,

I agree, and I suspect most of the rest of the cooling circuit components are ok, since the engine ran cool for an hour on muffs. To me that rules out bad thermostat, bad cooling channels in the block, or manifolds.

Aaron, when using the muffs and water hose, you are literally forcing water through the cooling system on your boat, your boat's engine does not have to suck up (via the water pump impeller in your outdrive) its own cooling water as it would when the boat is in the water.

Dennis, help me out here, I am assuming Aaron's sv 220 has an outdrive and impeller, not a straight inboard with an on-board water pump.

Regards,

Al

 

[Aaronjr]

thanx for the reply didn't expect it to be so fast ok so i pulled the impeller twice
the housing looked a lil shaby impeller looked fine i just backed the boat down in the water
no load and it runs hot after a bit ill change the impeller again what the heck i did pull the t stat housing off while in the lake and its getting water up and out i did put a automotive raw water circulation pump on it could that be it heard somthin about reverse rotation but when i pull the hose off the pump water is really gushing out so id say its moving hopfully in the right direction:grin:

 

[Aaronjr]

you guys are great!! wow hey dennis that makes alot of sense when you say it like that
im going to try that impeller again what way is the fins are to face maybe i put them in wrong? thanx for all the help

 

[Aaronjr]

Dennis,

I agree, and I suspect most of the rest of the cooling circuit components are ok, since the engine ran cool for an hour on muffs. To me that rules out bad thermostat, bad cooling channels in the block, or manifolds.

Aaron, when using the muffs and water hose, you are literally forcing water through the cooling system on your boat, your boat's engine does not have to suck up (via the water pump impeller in your outdrive) its own cooling water as it would when the boat is in the water.

Dennis, help me out here, I am assuming Aaron's sv 220 has an outdrive and impeller, not a straight inboard with an on-board water pump.

Regards,

Al

i dont recall seeing nothing but the impeller in the lower unit and the
pump mounted the the engine correct me if im wrong thats just the circulation pump right

 

[OldEngineer]

Aaron,

I am not familiar with your boat, so unless Dennis chimes in again, I need a little "level-setting". Do you have a Mercruiser outdrive? I am familiar with your engine, a Chevy small block 350 marinized. What I don't know is if you have a raw-water cooling system, or a fresh-water (actually, antifreeze) cooling system. If fresh-water, that would explain the water pump you have next to (attached to?) the engine itself.

What I am sure of is your impeller. The rubber fingers take a "set" in the direction of impeller rotation, so if you remove it and then inadvertently replace it upside down, the impeller with prematurely fail (into little bitty pieces that will clog your cooling system in nasty ways you don't want to think about).

Regards, and hope that Dennis chimes back in here.

Al

 

[Lazy Daze]

Really, any restriction - whether intake or exhaust side of engine - can cause an overheat. Once the engine is under load it's a huge difference compared to idling.

It doesn't take much in regards to the impeller housing/plate (nicks, gouges, etc... basically, if you can catch your fingernail in it - replace it) to limit the amount of cooling water going to the engine.

As far as the amount of water flow on a hose compared to in the water, the water hose actually flows a lot LESS than when in the water. So much so that it's not advisable to run an engine on the muffs at more than a 1,200-ish RPM's for any length of time. It "seems" like the hose would force water in, but it really doesn't - the impeller is still only going to pump what it can. And when the drive is in the water, it has access to a lot more water for pumping than what comes through a hose.

Yes, it would have an outdrive. Although I'm not sure which version - I just don't have much experience with them from the pre-80's stuff. It could be a Stringer. And, yes, there would be an impeller and a circulation pump (what we refer to as a water pump on a car) -- regardless of fresh-water or raw-water cooling. As far as I know, the only difference between an automotive and marine circ pump is that the marine has an SS backing plate. I don't "think" that engine was a reverse rotation engine - but again, I'm bowing out on that one due to lack of experience.

 

[Aaronjr]

Really, any restriction - whether intake or exhaust side of engine - can cause an overheat. Once the engine is under load it's a huge difference compared to idling.

It doesn't take much in regards to the impeller housing/plate (nicks, gouges, etc... basically, if you can catch your fingernail in it - replace it) to limit the amount of cooling water going to the engine.

As far as the amount of water flow on a hose compared to in the water, the water hose actually flows a lot LESS than when in the water. So much so that it's not advisable to run an engine on the muffs at more than a 1,200-ish RPM's for any length of time. It "seems" like the hose would force water in, but it really doesn't - the impeller is still only going to pump what it can. And when the drive is in the water, it has access to a lot more water for pumping than what comes through a hose.

Yes, it would have an outdrive. Although I'm not sure which version - I just don't have much experience with them from the pre-80's stuff. It could be a Stringer. And, yes, there would be an impeller and a circulation pump (what we refer to as a water pump on a car) -- regardless of fresh-water or raw-water cooling. As far as I know, the only difference between an automotive and marine circ pump is that the marine has an SS backing plate. I don't "think" that engine was a reverse rotation engine - but again, I'm bowing out on that one due to lack of experience.

can you maybe answer this? if when i had the boat in the lake and i pulled of the intake water hose from the lower unit alpha one drive by the way and i even took the t stat housing off and sure enough i have water coming up from the intake manifold and the pump out put side so wouldnt that mean the impeller is working in the lake? im just throwing bones here..

 

[Aaronjr]

no antifreeze ... im pretty sure i didnt put in the impeller upside down al' but im not sure if i put the fins in curled the right way and if that even matters

Aaron,

I am not familiar with your boat, so unless Dennis chimes in again, I need a little "level-setting". Do you have a Mercruiser outdrive? I am familiar with your engine, a Chevy small block 350 marinized. What I don't know is if you have a raw-water cooling system, or a fresh-water (actually, antifreeze) cooling system. If fresh-water, that would explain the water pump you have next to (attached to?) the engine itself.

What I am sure of is your impeller. The rubber fingers take a "set" in the direction of impeller rotation, so if you remove it and then inadvertently replace it upside down, the impeller with prematurely fail (into little bitty pieces that will clog your cooling system in nasty ways you don't want to think about).

Regards, and hope that Dennis chimes back in here.

Al

 

[OldEngineer]

Aaron,

I'm gonna get silly here for a sec', but bear with me, hopefully it will help us troubleshoot this problem accurately, and not go off on rabbit trails. Your cooling system has a "gozinta" and a "comesouta". So far, you have demonstrated that at several points in the gozinta part, you have water flowing. However, you had to "break the circuit" to do so. Sooo, maybe we should look at the "comezouta" part, where the water exits the cooling system. If the water exiting from your prop exhaust (I'm assuming that it does) is weak or non-existant, that would be a sure indicator that you have some sort of blockage in your manifolds or engine block cooling channels. I'm trying to visualize all this while pounding on my keyboard at work, so perhaps the only way you could check for water output at the end of your cooling system is while the engine is on the muffs and water hose. Think hard, and try to think of all the points along your cooling system that you can check for proper water flow. If all of that checks out, then we'll have to look at other engine sub-systems that could contribute to overheating when under load.

Regards,

Al

 

[Aaronjr]

Aaron,

I'm gonna get silly here for a sec', but bear with me, hopefully it will help us troubleshoot this problem accurately, and not go off on rabbit trails. Your cooling system has a "gozinta" and a "comesouta". So far, you have demonstrated that at several points in the gozinta part, you have water flowing. However, you had to "break the circuit" to do so. Sooo, maybe we should look at the "comezouta" part, where the water exits the cooling system. If the water exiting from your prop exhaust (I'm assuming that it does) is weak or non-existant, that would be a sure indicator that you have some sort of blockage in your manifolds or engine block cooling channels. I'm trying to visualize all this while pounding on my keyboard at work, so perhaps the only way you could check for water output at the end of your cooling system is while the engine is on the muffs and water hose. Think hard, and try to think of all the points along your cooling system that you can check for proper water flow. If all of that checks out, then we'll have to look at other engine sub-systems that could contribute to overheating when under load.

Regards,

Al

I have attached videos and photos..OK so I went out and crank it up again just for the hell of it and I'm getting water out of the prop however I do notice that the left side standing behind the boat the left exhaust port seems to have very little water coming out the right side has a very good stream of water coming out I and I don't want to go off track but I don't now it seems as it's running a little warmer than normal now with the muffs on as well

https://vimeo.com/185719023

 

[Aaronjr]

you have to click on the video link under the last photo al thanks..

Aaron,

I'm gonna get silly here for a sec', but bear with me, hopefully it will help us troubleshoot this problem accurately, and not go off on rabbit trails. Your cooling system has a "gozinta" and a "comesouta". So far, you have demonstrated that at several points in the gozinta part, you have water flowing. However, you had to "break the circuit" to do so. Sooo, maybe we should look at the "comezouta" part, where the water exits the cooling system. If the water exiting from your prop exhaust (I'm assuming that it does) is weak or non-existant, that would be a sure indicator that you have some sort of blockage in your manifolds or engine block cooling channels. I'm trying to visualize all this while pounding on my keyboard at work, so perhaps the only way you could check for water output at the end of your cooling system is while the engine is on the muffs and water hose. Think hard, and try to think of all the points along your cooling system that you can check for proper water flow. If all of that checks out, then we'll have to look at other engine sub-systems that could contribute to overheating when under load.

Regards,

Al

 

[Aaronjr]

Hello glad to finally be a part of a good boat forum so I'll jump right into it my 77 Ray sv 220 with a 5.7 350 engine only overheats when I put it in the river when I run it on the muffs it stays cool I've ran on the muffs for an hour temperature never budged I've even ran it at different rpms and it still says cool on the muffs
I'm a master automotive tech but this got me baffled boat had been sitting before I got it years
Not sure how long but since I have been trying to get it in the water nothing has been going right so where should I look 1st now?

Here is another photo and a video of water comin out from outside of t stat to pump

https://vimeo.com/185720314


Sent from my iPhone using Tapatalk

 

[Aaronjr]

Here is another photo and a video of water comin out from outside of t stat to pump

https://vimeo.com/185720314


Sent from my iPhone using Tapatalk

better photo



Sent from my iPhone using Tapatalk

 

[LiquidWrench]

Just wondering, when you checked the impeller in the lower unit, did you just put the old one back in or put in a new one? As others have said, the set that the vanes take will affect the pumping action and yes it DOES matter which way they are pointing. Also in that video did you have the muffs centered over the pickups? With it running there shouldn't be any water spraying out like that, the impeller in the drive should suck the muffs right in. If there is ANY grooves in the stainless cup or anything resembling a wear mark on the base plate replace them. New impellers are not that expensive and should be either a yearly job or at least every other year. It's just not worth the hassle to save a few bucks. Also regarding the automotive circulation pump. As long as you are in fresh water you probably won't have an issue but keep an eye on it to be safe.

 

[scoflaw]

You have to start somewhere when doing the same thing concludes with the same results. I would suggest you start by replacing your shabby raw water pump with a new complete pump.

 

[OldEngineer]

Aaron,
I apologize! I did not read your original post completely. You are a Master Auto Mech! I had a thought ... (they still happen occasionally *grin*) if you have one of those new-fangled infrared heat sensors, try aiming it at each side of the engine. From what you described about the uneven exhaust water flows, perhaps one side of the engine is hotter than the other, which would point to a possible partial blockage of the water channels in that side of the engine. It's a start at least. Wadda ya think?

Regards,

Al

 

[Aaronjr]

Just wondering, when you checked the impeller in the lower unit, did you just put the old one back in or put in a new one? As others have said, the set that the vanes take will affect the pumping action and yes it DOES matter which way they are pointing. Also in that video did you have the muffs centered over the pickups? With it running there shouldn't be any water spraying out like that, the impeller in the drive should suck the muffs right in. If there is ANY grooves in the stainless cup or anything resembling a wear mark on the base plate replace them. New impellers are not that expensive and should be either a yearly job or at least every other year. It's just not worth the hassle to save a few bucks. Also regarding the automotive circulation pump. As long as you are in fresh water you probably won't have an issue but keep an eye on it to be safe.

I just took out the old one and put it back old meaning the second one I tried but I my have still put it in the wrong way as far as the fins face? As far as the muffs I thought I had them center hummmm.... Now I have to go out and do it again


Sent from my iPhone using Tapatalk

 

[Aaronjr]

You have to start somewhere when doing the same thing concludes with the same results. I would suggest you start by replacing your shabby raw water pump with a new complete pump.

I did replace it its new!! It's not even 4 months old I have not had it in the water a hr since I got the boat


Sent from my iPhone using Tapatalk