engine wouldn't start ...now overheating

[PMC]

Oh... You can't tell visually if you are getting enough flow...

Agreed. Doesn't the 320 have underwater exhaust?

The first time happened on plane .. Shut the engine down pretty quick and returned to the dock on the starboard... Started again during docking and by that time it cooled....

Ran it again on idle just to check to see if it was a thermometer issue and it gradually overheated after around 10-15 minutes up to 190 (turned it off before alarming )

just checked the the oil again today and no water

what's the best place to out the laser thermometer to get a good reading of the temp? Risers ? Thermostat ? Manifolds ?

Also so after reinstalling the impeller do I have to add water back in the engine before I start her up ?

If your overheating at idle, you have very little (to no) water flowing through the engine to cool it. Start scanning all the areas and post them. Risers, Thermostat, Manifolds, Elbows. Post some pictures of the specific locations. You have a lot of variables to eliminate before finding the problem. Could be a collapsing hose, could be a clogged cooler (oil, fuel ?? ), could be a lot of things. Is this a V drive or Outdrive boat (I may have missed it)?

 

[Woody]

I reviewed your previous posts and see this is a continuation of last years overheat problem. Did you get your seacocks to open and close properly? Did you 'make sure' that water flow is not restricted through the seacocks and the thru hull fitting and the water pickup grate itself?

 

[CliffA]

ok so I finally got around to checking the impeller.. It was in good condition .... Then I changed out the thermometer and cleaned the t stat housing .. Had a little gunk but not to bad ....
still having the same issue .. Slow and steady overheat... The engine continues to start fine ...
any other ideas ?

did you check to ensure the impeller was actually spinning while turning the pulley on the pump?.....i have heard that sometimes the impeller appears to be in good condition but in reality the rubber blades were slipping around the center hub as the pulley was turning the shaft and the rubber blades were not turning at all or turning at a reduced speed thus causing overheating issues....

cliff

 

[ballinsncbirth]

ok guys thanks for ll the helpful posts,, ill answer each one I can remember

so the sea strainer is clean, seacock is open (I got the stuck seacock open last summer with some pb blaster)(other overheat issue was related to a loose hose)

the boat is in the water so inspecting the water inlets and the seacock isn't feasible.. (might have to pull the boat if I don't get anywhere)

the hoses seem to be in shape however ill have to look at them carefully both with engine running to see if I get any collapsing

the impeller is in good shape and turns normally (no blades missing looks brand new)

changed the thermostat and cleaned the housing (yes used correct thermostat from the engine parts manual )

the boat does not have a heat exchanger

I have a v drive boat, and the exhaust is not underwater




so whats weird to me is that the engine just slowly overheats at idle, takes about 15minutes ...slow and steadily increasing temp gauge
... when giving power it just overheats faster...

when looking at both exhausts with both engines running there seems to be equal water out of both exhausts .. for the engine to overheat even at idle should one expect to tell the different if it was a water cooling issue... this along with the fact this all started after the engine wouldn't start for a days.. and now starts normally.. is somewhat perplexing

so the next step wil be going over the hoses and connections through the entire cooling system, tightening all the clamps, and observing them with the engine running.. then going thru the engine with a temp gun

 

[julietbravomike]

Just FYI, you can't see a hard wall hose collapse - these hoses have an internal lining and it can separate from the external portion and get sucked closed. It will look fine from the outside. Again, not saying that's your issue, but just wanted you to know.

 

[Xplicitlnck]

Not sure what thermostat setup u have but a friend of mine had similar symptoms abd he has sine kind of setup that has a threaded rod with springs abd balls. Something stuck open or closed and he would slowly overheat. Just a thought

 

[CliffA]

i am starting to suspect a failing water circulation pump.....when i first bought my 215EC several years ago the engine was running a little hotter than normal....since i did not know the service history of the engine i decided to basically replace all of the components in the cooling system so that i would have a base line of when they were replaced....i started with the normal items such as water pump impeller, thermostat, etc and moved through the system....after each item i replaced i tested the engine to see which component stopped the overheating.....i saved the water circulation pump for last.....it was not until i changed out this pump that the temp came down to normal....there were no visible signs of anything wrong with the pump and the bearings seemed to be tight....i just assumed that the pump vanes had worn to the point they were not moving enough water through the pump....never had an issue with overheating for the 5 years i had that boat.....

cliff

 

[dwna1a]

One last thing. If it is a hose issue, the inner lining will fail and act like a valve closeting as the water flows.

When end you replaced the impeller did you replace the wear plate?

Back flush the the hose from the pump to the strainer and do it till you see water and air bubbles coming from under the boat.

 

[ballinsncbirth]

i am starting to suspect a failing water circulation pump.....when i first bought my 215EC several years ago the engine was running a little hotter than normal....since i did not know the service history of the engine i decided to basically replace all of the components in the cooling system so that i would have a base line of when they were replaced....i started with the normal items such as water pump impeller, thermostat, etc and moved through the system....after each item i replaced i tested the engine to see which component stopped the overheating.....i saved the water circulation pump for last.....it was not until i changed out this pump that the temp came down to normal....there were no visible signs of anything wrong with the pump and the bearings seemed to be tight....i just assumed that the pump vanes had worn to the point they were not moving enough water through the pump....never had an issue with overheating for the 5 years i had that boat.....

cliff

I will ill check the pump after I check all the hoses

I have always wondered about how the water circulating pump and the sea water pump interact ?
I've which one does the bulk of the pumping ?

Does the sea water pump function to pump water up to the circulating pump and then the circulating pump takes over?

Or or does the circulating pump just pump water through the engine and it is the sea water pump power that pumps water out the exhaust ?

For or example if the circulating pump completely failed would water still come out the exhaust ? Just wouldn't circulate through the engine? Thus giving the impression water is circulating but leading to engine overheating ?

 

[sdleo26]

Your circulator pump circulates coolant through the block, while your sea water pump brings in cool seawater to dissipate the heat from the coolant via the heat exchanger. The seawater pump also cools your manifolds/exhaust lines , otherwise hot exhaust burns your boat down

 

[ballinsncbirth]

Your circulator pump circulates coolant through the block, while your sea water pump brings in cool seawater to dissipate the heat from the coolant via the heat exchanger. The seawater pump also cools your manifolds/exhaust lines , otherwise hot exhaust burns your boat down

I dont have have a closed cooling system . I don't have coolant or heat exchanger . Engine is sea water cooled . Which is in part why I am confused about how the sea water pump and circulator pump interact. Which one does the bulk of the pumping. If the circulating pump failed would the sea water pump still have water coming out the exhaust ?

 

[sdleo26]

If you have the serial numbers of your motors you can look up the flow diagrams online. Apologies , I didn't realize this was the same thread where you already made me aware that it was open cooling

http://www.boatinghowto.com/content/how-boat-cooling-systems-work-240/

 

[CliffA]

I will ill check the pump after I check all the hoses

I have always wondered about how the water circulating pump and the sea water pump interact ?
I've which one does the bulk of the pumping ?

Does the sea water pump function to pump water up to the circulating pump and then the circulating pump takes over?

Or or does the circulating pump just pump water through the engine and it is the sea water pump power that pumps water out the exhaust ?

For or example if the circulating pump completely failed would water still come out the exhaust ? Just wouldn't circulate through the engine? Thus giving the impression water is circulating but leading to engine overheating ?

the sea water pump is responsible for pulling the cooling water in from the sea/lake.....the circulation pump then takes the water and circulates it through the engine and exhaust.....they work in tandem with each other....if either one fails you will have overheating issues...if either pump could handle the cooling requirements on its own the Mercruiser Engineers would have designed the cooling system to have only one pump....

cliff

 

[ballinsncbirth]

the sea water pump is responsible for pulling the cooling water in from the sea/lake.....the circulation pump then takes the water and circulates it through the engine and exhaust.....they work in tandem with each other....if either one fails you will have overheating issues...if either pump could handle the cooling requirements on its own the Mercruiser Engineers would have designed the cooling system to have only one pump....

cliff

Well I guess my question is ..since it seems the same amount of water is coming up the exhaust on both engines (let's just assume it's true) .... And the impeller and sea water pump is in good condition ... If the water circulation pump failed or was weak.... Would the sea water pump be enough to still allow the same amount of water out the exhaust ? Ie water is pumping through the cooling system and out the exhaust at equal rate ... Just not through the engine thus not cooling the engine ?

I also went went out today and took some temp reading with laser temp gun
I started the engine at the same time and compared at idle


the starboard engine temp stopped increasing at 154 (port was at that time 152) :
tstat both engines =154
manifolds both engines =170-180
risers both engines = 70-74

i let let the port engine get up to 167 and took another set of reading (starboard still 154 )
tstat port =170 star=154
manifolds port =200/195 starboard =190/185
risers both engines =70-74

so so it seems the port manifolds were a little hotter but not significantly so.(could be a manifold or a cooling issue ?) . And the risers were cool throughout ... Not sure if this helps diagnose the issue but wanted everyone's thoughts ..

Again thanks so much for all the responses .. You guys are extremely helpful

 

[mwph]

What do you think about switching the T stats from one engine to the other as a quick way to rule that out?

 

[CliffA]

Well I guess my question is ..since it seems the same amount of water is coming up the exhaust on both engines (let's just assume it's true) .... And the impeller and sea water pump is in good condition ... If the water circulation pump failed or was weak.... Would the sea water pump be enough to still allow the same amount of water out the exhaust ? Ie water is pumping through the cooling system and out the exhaust at equal rate ... Just not through the engine thus not cooling the engine ?

since i am not familiar enough with the cooling water flow through your engines i am not qualified to answer that.....my 'GUESS' is that the water pumps could be pulling in the same amount of water each and pushing the same amount of water through the exhaust on both engines....this would give the 'appearance' that both engines are receiving the same amount of water flow through each one....but in reality if one engine had a weak circulation pump that could still cause an overheating situation because there is not enough heat transfer between the engine block and the circulating cooling water....this would not be evident by just looking at the engine and observing the exhaust water flow....

cliff

 

[Bob & Sue]

I also went went out today and took some temp reading with laser temp gun
I started the engine at the same time and compared at idle


the starboard engine temp stopped increasing at 154 (port was at that time 152) :
tstat both engines =154
manifolds both engines =170
i let let the port engine get up to 167 and took another set of reading (starboard still 154 )
tstat port =170 star=154
manifolds =port =200/195 starboard 190/185
risers both engines =70-74

so so it seems the port manifolds were a little hotter but not significantly so.(could be a manifold or a cooling issue ?)

Your manifolds are very hot, mine run around 90*-110* on a FWC system running on muffs or in the water.

I would pull the risers off and inspect them, if they look good pull the manifolds & plugs. If all is good you will at least eliminated that as a problem & have new gaskets.

You may need to do a compression & leak down test to eliminate a blown head gasket or crack somewhere, I would do this now before going any farther.

Best of luck

Edit: I wouldn't rule out a circulation pump except both engines are running hot, but I wouldn't start throwing money at it yet till you've eliminated all you can.

 

[CliffA]

You may need to do a compression & leak down test to eliminate a blown head gasket or crack somewhere, I would do this now before going any farter.

Best of luck

+1...:thumbsup:.....at this point i would do a compression test to rule out a blown head gasket....

cliff

 

[Bob & Sue]

One more thing if it were me I wouldn't run these engines till you've found the problem, you could hydroloc the engine, at the least you're over heating the oil causing it to break down which can cause things like sludge to develop, poor lubrication on the cam, lifters, bearings etc.

 

[ballinsncbirth]

+1...:thumbsup:.....at this point i would do a compression test to rule out a blown head gasket....

cliff

Yea definetly not running the engine except to check the temp and shut it down at 170... I was wondering how hot the manifolds could get... I just checked the records and the manifolds and riser were replaced in 2011 ...what would a blown head gasket look like ? Could that be the reason. My engine wouldn't start when this all started ? What happens if it is a gasket ?