2005 320 DA port engine (rebuilt 2 years ago) running warmer

pineknollj

pineknollj

Member
Jun 23, 2009
34
Pine Knoll Shores, NC
Boat Info
320 Sundancer 2005
Engines
twin 350's
Prodigal Summer LQ.jpgThe port engine on my 2005 320 (5.7L) is running on average 15-20 (175-180[SUP]o[/SUP]) warmer than the starboard. I am going to flush it with Barnacle Buster using a Sea Flush device too. My Thermostat was replaced during an engine rebuild in early 2013. Raw water cooled and we are at the coast (Atlantic Beach NC). Starboard motor is running at 160 or so.

An "old salt" here recommended not going back with a 160 thermostat but going with a 145...any thoughts on that? His thinking is that the higher temperature allows more of the salt to adhere to the internal parts of the motor speeding corrosion.

Thank you for any ideas or feedback!

Pineknollj
 
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You need to stick with the right thermostat. The fuel injection is designed to work at the warmer temps.
 
I would swap you two thermostats and see what happens... The gauges sometime read off... You could also swap you gauges...
 
My belt is loose and cannot be tightened further. I am going to buy a new one...could that contribute by not sending enough water through the system under load (if it is slipping any)? Belt is not squealing like it would if it was really loose. Also, is there an oil cooler that has circulation of water through it on this model? I had another boat that had heating issues once underway and it was little bits of rubber from the impeller that was plugging up the coolant flow. Any thoughts appreciated.
 
Is this a new issue? Everything spot on in 2013? New manifolds and risers in 2013 ? Impellors?
 
Do you have gauges that tell you your water pressure? You might have a bad impeller that is not pushing enough water through to keep that engine cool under load.
 
All new from the exhaust manifolds, spacer, and risers replaced. New impellers on both motors and a new raw water pump on the port as well.

New water pressure switch added about 2 months back and pressure is actually a bit better on the port motor. My belt is definitely loose and another old time boater/mechanic thinks that could cause the issue. I am unable to cross match the Mercruiser part number with a Gates belt at my local auto/boat parts dealer (Carquest). Tried one and too big and got another that is smaller and may have to get an even smaller one. Does anyone have exactly the circumference of that Mercruiser belt?

I am on the verge of giving up on my mechanic and resharpening my own motor repair skills with the help of the forum. I was in the motorcycle business for about 4 years in the early mid 70's so a bit rusty but all coming back quickly including bleeding knuckles. Getting a pair of mechanic gloves next trip out!

863876 5 Is number off of the Mercruiser parts site.

Thanks for the feedback!
JC :smt100
 
The higher water pressure could be an indicator of blockage downstream. New engine but old power steering cooler? Maybe you should look at that impeller
 
pineknollj said:
All new from the exhaust manifolds, spacer, and risers replaced. New impellers on both motors and a new raw water pump on the port as well.

New water pressure switch added about 2 months back and pressure is actually a bit better on the port motor. My belt is definitely loose and another old time boater/mechanic thinks that could cause the issue. I am unable to cross match the Mercruiser part number with a Gates belt at my local auto/boat parts dealer (Carquest). Tried one and too big and got another that is smaller and may have to get an even smaller one. Does anyone have exactly the circumference of that Mercruiser belt?

I am on the verge of giving up on my mechanic and resharpening my own motor repair skills with the help of the forum. I was in the motorcycle business for about 4 years in the early mid 70's so a bit rusty but all coming back quickly including bleeding knuckles. Getting a pair of mechanic gloves next trip out!

863876 5 Is number off of the Mercruiser parts site.

Thanks for the feedback!
JC :smt100
Click to expand...
There are many configurations of belt on the 320 350 MPI horizon engine based on raw water cooled, closed cooled etc. here are mine.
Napa store:-
- Two serpentine belts in picture equivalent to part # 57-865615-006

image.jpg
 
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First, I would confirm the temperature differences by measuring temp at the exhaust port on either side of the boat. Second, an increase in water pressure doesn't mean more flow. It could mean there's a blockage of some type. Definitely get the right belt tension, measure your temps, swap thermostats, look for obstruction, and see if you're sucking air anywhere before the water pump.
 
All looks good and my diver's report from last week did indicate strong marine growth on all intakes, but he said he got them all cleaned as well as possible.

Nothing in the strainers either and I did pump a gallon of barnacle buster through this motor and let it sit over night last week.

My neighbor also owned a 280 and he fully suspects the impeller is just not able to get the job done. We did test run it today and it heated up at idle then cooled down, then heated up again under pressure. Used an infra-red thermometer to confirm gauges and we were running hot and accurate gauges. Do I need to pull the entire pump or can the front be pulled and new impeller popped in?
 
It is going to be such a joy to pull that pump out! Thanks and will get started. Of course it is a gorgeous day here in NC and boat stuck at the dock.
 
Are these Horizon motors or raw water cooled?
Before you start taking out and replacing unnecessary parts I would confirm the engine temp with either mercruiser software or an infrared temp tool.
Gauges at most times are not accurate.
If you have V Drives i would pop the raw water hose off the transmission cooler and see if theres impeller parts stuck in the cooler before you tackle the raw water pump.
 
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2005 V-Drives and raw water cooled. My neighbor and I did a infrared temp test to day and the gauges are almost dead on accurate.

I pulled the hose off the oil cooler (mounted on the "bow side" of the motor) and was hoping that was going to be the issue, but a little rust and nothing else was in there.

I do not think it is the thermostat because it is fine at idle which means it is opening and closing properly.

I messed around for about 30 minutes assessing the situation and tools needed and decided to stop to watch some football. The port side gas filter is right in the way so I am going to pull that off and maybe the hose in front of the bracket. I am able to turn the pump by hand in clockwise direction and not in counterclockwise direction. Assuming that I should not be able to turn it very easily?? Any other ideas for tackling those hose clamps at the pump? It might be easier to manage getting the pump out by leaving the hose on at the pump and removing from the other end.

Thoughts?
 
I just mentioned the cooler because i just replaced both of my coolers and they both had impeller parts in them.
You can still have a bad impeller.
Use a 1/4 inch ratchet set with a swivel and different extensions.
Use electrical tape and tape the socket to the swivel and extension in case you drop it in the bilge.

Will make the job a lot easier.
 
Thanks for the feedback...I still might yank the gas filter but the 1/4 drive is a good idea with the swivel too. Like the tape idea also. Great investment in a magnet that I tied to a length of line and can pull it across the bilge too instead of losing them to some obscure corner.

Previous boat had a huge over heating issue and that was it...impeller parts in the oil cooler.

JC
 
What is the best way to remove that pump assembly to replace the impeller on the 350 mag motor? It looks like I am going to be working in the blind here as I can barely see the bolts or I will have to feel for them. I think that there are only 3, but want to be sure.

Does anyone recommend removing the fuel-water separator and fuel pump to improve access? Is it easier to remove the hoses from the opposite end and then pull them out with the pump assembly?

Thanks for any feedback! Finally got several days of dry weather after 2 weeks of rain here in NC.
JC
 
I have the 6.2 motors that I can only assume would be close to what you have. I could not access the back side of the pump to remove hose so I split the pump using a rachet wrench. I have to remove the exhaust hoses and muffler just to get enough room to work in there. Then remove the belt and remove the bolts that hold the pump in place on the motor. Once the pump is hanging, I split the pump and remove the front side with the impeller. Yes, removing the bolts to split the pump is by feel but it's doable.

While you have that pump off take a good look at the bearings in the pump to see if they are bad or leaking. My boat is a 2005 and I've had to replace both pumps. Good luck!
 
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