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Engines heating up AGAIN!!! --SOLVED--


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I purchased this boat in April 2018. In July of 2018 I replaced the manifolds and risers on both engines because they were a little over 5 years old and the engines were overheating. This week while cruising for about 10 min with engines around 3600 RPM the Port engine started overheating. I had to throttle back to cool it off. It's been also 2 years since I replaced the thermostats and raw water impeller, so I just I replaced those, but the overheating continues.

Can the manifolds and/or risers be clogged up only after 2 years?  Keep in mind, I flush these engines every time I pulled out of the water. Usually about 10 min per engine at about 1000 RPMs

Could the recirculating pump be bad?

Also, FYI, In September of 2018 I lost power on the port engine. Turns out it was a couple of valves that failed, we figured due to hotspots on the block due to built up debris. I had the heads rebuilt, and I cleaned out the block water passage ways. I also rebuilt the Starboard engine in Jan 2019.  Used the same manifolds and risers that I installed in July 2018.

So here is what I plan on doing, please let me know if I'm on the right path or just wasting my time...
Going to order new gaskets for the manifolds and risers, and gaskets for the recirculating pumps. Then remove Manifolds, Risers and Recirculation pumps, inspect and maybe use a pressure washer to clear any debris from the manifolds and risers. Inspect the passage ways in the block behind the recirculating pump. Also inspect the exhaust flappers. Then re-install all and see if that makes a difference.

Also, does anyone know the torque specs for the studs and bolts on the Recirculating pump?

Thank you for your help

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I had almost the same problem with a boat I bought that was one year old. It only had 19hrs on it and I could not find the problem. A friend helped me and he looked at the impeller housing. It was all scored from sand! The last owner must have beached her and sucked it sand.  

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Is the boat fresh water cooled or raw water cooled? If fresh has the heat exchanger been checked for corrosion or old pieces of impeller?

No way are the riser/manifolds corroded. That isn't your problem.

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3 hours ago, Iggy said:

I had almost the same problem with a boat I bought that was one year old. It only had 19hrs on it and I could not find the problem. A friend helped me and he looked at the impeller housing. It was all scored from sand! The last owner must have beached her and sucked it sand.  

2 hours ago, drewm3i said:

You could have pieces of old impeller debris lodged in the oil cooler/power steering cooler. A circulating water pump usually only goes bad when the front bearing fails.

I just replaced the impeller, the housing looked smooth, and the old (2 years old) impellor was intact and in very good condition. I actually still have the impellor I replaced in 2018 and there was never a broken impeller...so no impellor debris.

3 hours ago, Dgiles said:

Is the boat fresh water cooled or raw water cooled? If fresh has the heat exchanger been checked for corrosion or old pieces of impeller?

No way are the riser/manifolds corroded. That isn't your problem.

It's RAW water...salt water.

It's a lot of work to pull all those parts out, and go through everything...but what else can I do?? any other suggestions are very welcome

Thank you 

 

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4 minutes ago, Dozer said:

I just replaced the impeller, the housing looked smooth, and the old (2 years old) impellor was intact and in very good condition. I actually still have the impellor I replaced in 2018 and there was never a broken impeller...so no impellor debris.

 

 

You aren't understanding me...the pieces don't get stuck in the housing, they get stuck at the oil/power steering cooler and block flow. I pulled three large pieces out of mine last night. The oil/PS cooler is under the engine on mine, not sure where yours is.

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3 hours ago, drewm3i said:

You aren't understanding me...the pieces don't get stuck in the housing, they get stuck at the oil/power steering cooler and block flow. I pulled three large pieces out of mine last night. The oil/PS cooler is under the engine on mine, not sure where yours is.

We must be talking about two different things. My boat does not have an oil or PS cooler. The impeller and housing I was referring to, is the raw water pump, but the previous two impellors I have replaced, were intact so there would NOT be any pieces lodged anywhere.

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My port engine is over heating as well. New impeller. Old one was great, new thermostat, new water pump. 5.0gxi 2003 280 signature. Doesn’t over heat idling. Only when rpms are increased on plane and off plane at about 2-2500 rpm as well. Does cooL down again but heats again when reving. Can the heat exchanger in the water heater be an issue?  Starboard engine don’t have that connected to it.  Also if I pull the thermostat out I can run it with it barely heating up. I ran it at about 35-4000 rpm for an hour around the lake and it didn’t feel hot at all and the gauge was just over 120.  

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50 minutes ago, Dozer said:

We must be talking about two different things. My boat does not have an oil or PS cooler. The impeller and housing I was referring to, is the raw water pump, but the previous two impellors I have replaced, were intact so there would NOT be any pieces lodged anywhere.

What year, engine, and out drive model? That would help us help you tremendously.

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2 hours ago, Dozer said:

2006, mercruiser 5.0 MPI, Bravo outdrive.

 

You absolutely have a power steering cooler. Use your serial number to look it up here: https://public-mercurymarine.sysonline.com/Default.aspx?sysname=NorthAmericacompany=GuestNA_KEY=NA_KEY_VALUElangIF=englangDB=eng

 

Looks like it may be mounted on the back of your engine behind based on this: https://public-mercurymarine.sysonline.com/Default.aspx?sysname=NorthAmericacompany=GuestNA_KEY=NA_KEY_VALUElangIF=englangDB=eng

 

Take the hose off of the end that comes from the raw water pump and look for debris. That could be your restriction. It could also be the water intake hose which tends to corrode in salt water.

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23 hours ago, drewm3i said:

You're correct, I completely forgot about the power steering, I have to double check for the cooler in the back of the Port engine. The starboard engine is the one that powers the power steering, although both engines have a power steering pump... it's gong to be a PITA to get to it, with both engines in such a tight bay, I can barely reach behind either engine.

Thank you...if anyone has any other suggestions, let me know

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1 hour ago, drewm3i said:

The only other thing it could be is a restricted intake hose at the outdrive.

I was under the impression that piece was upgraded to a plastic connection on mid to late 2000 models....not 100% sure.

Can I check that by just raising the outdrive???

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47 minutes ago, Dozer said:

I was under the impression that piece was upgraded to a plastic connection on mid to late 2000 models....not 100% sure.

Can I check that by just raising the outdrive???

I am not sure if yours is plastic or not, but the drive would have to come off. More likely is a clog in the PS cooler. I hope you get it resolved. Let us know how it goes.

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I found that an after market maintenance book is invaluable. One such as SELOC will show you a diagram of your cooling system and how the water flows. That’s how I found pieces of broken impeller partially blocking the engine oil cooler inlet. Pics below:

1st pic is engine oil cooler inlet. It’s the first thing down stream of impeller. 
 

2nd pic is the pieces I pulled out of engine oil cooler this afternoon. 
 

3rd pic is an example of my water circulation diagram in a maintenance manual. That’s how I knew first place to look!

50D606E5-3A25-4061-BEB0-9EEB344490CF.jpeg

471E958D-6E19-4338-8D43-C72B77972791.jpeg

B41A4E4D-6241-40D9-9317-F99F95021F7D.jpeg

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13 hours ago, mikw said:

I found that an after market maintenance book is invaluable. One such as SELOC will show you a diagram of your cooling system and how the water flows. That’s how I found pieces of broken impeller partially blocking the engine oil cooler inlet. Pics below:

1st pic is engine oil cooler inlet. It’s the first thing down stream of impeller. 
2nd pic is the pieces I pulled out of engine oil cooler this afternoon. 

3rd pic is an example of my water circulation diagram in a maintenance manual. That’s how I knew first place to look!

B41A4E4D-6241-40D9-9317-F99F95021F7D.jpeg

Thanks for the reply, I plan on put her in the water this weekend and doing a flow test to see what is going on. In the mean time I will pull the water hose from the Power Steering cooler and see if there's anything in there... I don't have an oil cooler, 

Any chance you can make that circulation diagram larger???

Thank you

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50 minutes ago, Dozer said:

Thanks for the reply, I plan on put her in the water this weekend and doing a flow test to see what is going on. In the mean time I will pull the water hose from the Power Steering cooler and see if there's anything in there... I don't have an oil cooler, 

Any chance you can make that circulation diagram larger???

Thank you

I sent you a PM

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As you can see from this photo (quality limited by file size) the power steering cooler is upstream from impeller. The diagram doesn’t do it justice. The engine oil cooler is below the port exhaust manifold and the first thing downstream from impeller. 

Edit:

I just noticed you have dual engines and I’m not sure how the power steering cooler applies to your situation.

 

7A65FFE9-A90C-4BBC-AE60-81F221F9893F.jpeg

Edited by mikw
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22 hours ago, mikw said:

As you can see from this photo (quality limited by file size) the power steering cooler is upstream from impeller. The diagram doesn’t do it justice. The engine oil cooler is below the port exhaust manifold and the first thing downstream from impeller. 

Edit:

I just noticed you have dual engines and I’m not sure how the power steering cooler applies to your situation.

 

7A65FFE9-A90C-4BBC-AE60-81F221F9893F.jpeg

Merc Manual shows it in the discharge circuit. https://www.marinepartsplus.com/catalog/mercruiser/serialize(value)/5.0L_MPI_ALPHA-BRAVO/884717005/13884-210

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  • 1 month later...

Just wanted to post an update on this issue. 
drewm3i was right, there's a restriction on the intake hose, and it's the worst case scenario, it's the transom connection. 
I was able to squeeze on top of the batteries to reach the transom wall on the inside, and removed the quick connect for the raw water (red) hose. Once I removed the elbow connector I was able to see how bad this was. Now looking back on previous overheating issues, I can see how this was a culprit to those issues.

So my plan was to replace the bellows during the upcoming season, but now I will have to take care of it now. I have ordered all the parts and tools that I think I will need to replace the bellows and the intake water hose with an upgraded kit. I'm a little hesitant doing this job, as I have never replaced bellows before. I'm comfortable removing/installing the outdrive.

I have been reading the manual and trying to watch various videos online, but I'm still not clear how to replace the shift cable bellow...do I need to pull the cable all the way out, or can I disconnect it from the housing and slide the bellow over it?

Thanks for Wingnut for sending me a bunch of information, once all the parts and tools arrive, I'm going to try and tackle this beast.

If anyone has done this job before, I could use any tips or tricks to avoid any pitfalls. Also what is the best way to clean and repair all that corrosion that is crushing the intake hose?

Here is the photo of the Inside of the Transom after I removed the elbow connector.

Raw-Water_transom03.jpg

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On 8/25/2020 at 1:22 PM, Dozer said:

Just wanted to post an update on this issue. 
drewm3i was right, there's a restriction on the intake hose, and it's the worst case scenario, it's the transom connection. 
I was able to squeeze on top of the batteries to reach the transom wall on the inside, and removed the quick connect for the raw water (red) hose. Once I removed the elbow connector I was able to see how bad this was. Now looking back on previous overheating issues, I can see how this was a culprit to those issues.

So my plan was to replace the bellows during the upcoming season, but now I will have to take care of it now. I have ordered all the parts and tools that I think I will need to replace the bellows and the intake water hose with an upgraded kit. I'm a little hesitant doing this job, as I have never replaced bellows before. I'm comfortable removing/installing the outdrive.

I have been reading the manual and trying to watch various videos online, but I'm still not clear how to replace the shift cable bellow...do I need to pull the cable all the way out, or can I disconnect it from the housing and slide the bellow over it?

Thanks for Wingnut for sending me a bunch of information, once all the parts and tools arrive, I'm going to try and tackle this beast.

If anyone has done this job before, I could use any tips or tricks to avoid any pitfalls. Also what is the best way to clean and repair all that corrosion that is crushing the intake hose?

Here is the photo of the Inside of the Transom after I removed the elbow connector.

Raw-Water_transom03.jpg

You may wish to cap it off and use a through hull raw water pick-up. W

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Get a long round brass or nylon brush from HF and attach to a drill to clean out the inside of the water port. Be careful as there's a rubber donut on the updated hose that seals against that inner surface so you don't want to damage it. Vinegar or a mix of baking soda/water will help clean off the white corrosion.

I installed the updated hose on my boat a few years ago and all has been great. Mine wasn't anywhere near as bad as yours but I could see the "bravoitis" was starting.

For the shift cable bellows, you'll need to remove the inner core wire in order to slide the bellows over the cable. Disconnect the core wire from the shift plate on the exh manifold and it'll slide right out.

One tip I'd recommend is replace the transom drive oil hose connector + new hose while you're in there.  It'll most likely break when you go to remove it, at least mine did and it's inexpensive. Remove the inner c-clip and pull the whole oil hose assembly out as one when you go to remove the bell-housing.  This is 10X easier as access is tight. When time comes to re-install the bell-housing, have the new hose and transom barb fitting all assembled onto the bell-housing.  The manual mentions doing it this way and it really is a lot easier vs trying to attach everything afterwards.

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