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It' that a high temperature ?

A

Alister Cara

New member
I rebuild two 4.3 TBI alfa one mercruiser 1998 last year
One its running fine But the last one swallowed in the first hours at 3000 rpm with normal oil pressure and temperature (180 F)
We rebuild the engine and we found signs of swelling on 5 of the pistons. (picture)
Now it s running with the same temperature but I can't hold my hand at the starboard elbow
Everything it s new: manifold, elbow, waterpump (6 months) and thermostat
It's the engine temperature 180F normal? and How can I be sure that's its not responsible for the problem that I have had
Thanks
 

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Could be a few things. Temp is too hot to begin with if raw water cooled. wrong thermostat or installed incorrectly.
You want a 140 stat if raw water cooled
piston to wall clearance too tight.wrong type of pistons (cast/forged). Wrong head gasket, reversed gasket.
Too much timing advance.
we found signs of swelling on 5 of the pistons ,elaborate,
 
There are several factors.

Based on a 1998 V6 the specification is 160 degree thermostat for both raw and closed cooling. (Closed = heat exchanger and antifreeze)

how is the water supplied to the engine (s)? thru the outdrives or a thru hull pick up?

If outdrives then water pump impeller would be suspect or water path

If thru hull pick up then clogged pick up or strainer if one is used.

A engine with a 160 degree thermostat will run ~ 10 degrees hotter then thermostat set point so if you are running ~ 170 degrees F then that is OK.

If the temperature goes above 180 under normal operation or at idle speeds then you may have an issue.

V6 engines have a history of heat related issues and are very susceptible to over heating.
 
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I agree are both engines pulling from the same water pickup (sea chest) if so start there. A real common restriction is a oil cooler if you dont know how old just replace them it is part of preventive maint. Start from the water intake and clean all the fittings and replace the hoses. If the pistoms are getting cooked that could also be a over lean fuel condition or the spark advance (progressive timing advance is out of spec) Map out the advance curve detonation is the most common cause of pistons getting cooked.
 
..........................

Bt Doctur said:
You want a 140 stat if raw water cooled
140* stat if RWC and if operating in salt water. (has to do with salt crystalization at temps above this)
160* stat if RWC and if operating in River/Lake water.
160* stat if fitted with a Closed Cooling System and while operating in either salt or fresh water.

piston to wall clearance too tight.
Possibly.

wrong type of pistons (cast/forged).
As in wrong profile for the combustion chamber volume.

Wrong head gasket, reversed gasket.

Too much timing advance.
Possibly...... this would raise cylinder temperatures caused by detonation.


we found signs of swelling on 5 of the pistons ,elaborate,
Yes...... please elaborate on this!
Click to expand...
 
IMHO.... if the spec says
" Based on a 1998 V6 the specification is 160 degree thermostat for both raw and closed cooling. (Closed = heat exchanger and antifreeze)"
for sea water, then I'd ignore it if I was running raw water cooled in sea water and use a 140 degree 'stat. Running a 160 degree with raw water/sea water would result in an engine might likely last thru the warranty period just fine, but.....!!!

( Overheard in the bowels of the M*******er product planning room...
Cost Control Guru: "We would save $0.1380 on each engine on average if we only offered one t'stat".
Engineer: "But then the engine would eventually overheat in sea water"
Cost Control Guru: " Would it last thru the warranty period?"
Engineer: "Probably"....
Cost Control Guru: " DONE!!!! just one t'stat it IS!!!! " )
 
The water supplied is thru the outdrive alpha one and the flow seems normal
The engine are running at 170 degree and I checked the timing advance it s 8 degree at idol
But I can't keep my hand at the starboard elbow It's that a issue ?
Thanks a lot

e
 
Alister Cara said:
The water supplied is thru the outdrive alpha one and the flow seems normal
The engine are running at 170 degree and I checked the timing advance it s 8 degree at idol
But I can't keep my hand at the starboard elbow It's that a issue ?
Thanks a lot

e
Click to expand...

How do you know if the water flow is "Normal"? What are you basing it on?

If you cannot keep your hand on the Elbow, something is wrong.

Like I posted earlier,


High temp and one waffled hole....I would start at the lower unit and inspect the water dam. Is it rotted? Is the filler block and filler wall installed?
 
Did you confirm true TDC on the harmonic balancer with a piston stop tool? There are videos on how to check for true TDC you need to find out why the pistons got torched first it was not because the engine was running at 180 degrees. The only thing that cools the valves and pistons is fuel. Start from the beginning and confirm everything before you get to fuel. True TDC is critical when setting up any engine.
 
Just for reference, do you have or can you get your hands on a IR hand held temperature gun?

To see exactly what the elbows are running.

I agree with Chris.

Start with the water pump impeller area and impeller. confirm all is as it should be and then work your way towards the engine.

You will have a power steering cooler in line with the incoming water hose, make sure it is clear of debris.

If all the incoming components are as they should be then the elbows themselves would be suspect. If water is not getting out it will get hot!!

YOu still have not answered whether or not you are getting raw water from out drives or from a hull pick up with a engine mounted water pump impeller?????
 
Alister Cara said:
But I can't keep my hand at the starboard elbow. It's that a issue ?
Click to expand...
It is most likely an issue in that it may be a sympton of a potentially greater problem.
Make sure that all of the seawater transfer ports (between the Manifold and Elbow) are clear and open.
If they are restricted due to rust or corrosion, you will see an issue.

kimcrwbr1 said:
Did you confirm true TDC on the harmonic balancer with a piston stop tool? There are videos on how to check for true TDC you need to find out why the pistons got torched first it was not because the engine was running at 180 degrees. The only thing that cools the valves and pistons is fuel. Start from the beginning and confirm everything before you get to fuel. True TDC is critical when setting up any engine.
Click to expand...
Well said!


kghost said:
Just for reference, do you have or can you get your hands on a IR hand held temperature gun to see exactly what the elbows are running?
While I fully agree.............. if it is HOT to the touch something is wrong.
The IR temp sensor will show you how warm/hot they are.


Start with the water pump impeller area and impeller. confirm all is as it should be and then work your way towards the engine.
Ditto!
Just foward of the gimbal bell you will find a hose that makes an S curve.
This hose will sometimes become pinched or fractured.

You will have a power steering cooler in line with the incoming water hose, make sure it is clear of debris.
Ditto again.

If all the incoming components are as they should be then the elbows themselves would be suspect. If water is not getting out it will get hot!!
Or....... the point at which the "spent" seawater is being divided (seawater to each exhaust side), is not being divided equally.

YOu still have not answered whether or not you are getting raw water from out drives or from a hull pick up with a engine mounted water pump impeller?????
Click to expand...


********************************************

Off topic and running with Bob's anology (just for fun) : :D

(Overheard in most all Marine manufacturer's product planning room)

Cost Control Guru (bean counters): "On average we can save $20.37 on each engine if we continue to use the GM Full Dished piston profile".
Engineers: "But then we risk overheating from detonation and detonation damage caused by a poor combustion chamber design!"
Cost Control Guru: " Would it last thru the warranty period?"
Engineers: "If we hold back ignition advance, possibly!"
Cost Control Guru: " DONE!!!! GM Full Dished pistons it IS!!!! " :eek:


.
 
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Docksidemarineservices said:
How do you know if the water flow is "Normal"? What are you basing it on?

If you cannot keep your hand on the Elbow, something is wrong.

Like I posted earlier,


High temp and one waffled hole....I would start at the lower unit and inspect the water dam. Is it rotted? Is the filler block and filler wall installed?
Click to expand...


Just so you understand why,

If any of the parts I listed are damaged or missing it will allow exhaust gasses(bubbles) to pass into the water pump and those bubbles will find a single spot in your engine block and cook that area.
 
After the measurement of the temperature with IR gun of the elbows I noticed that on the starboard side is 156 F against 96 on the Port side .
According to your orientation I continued the investigation of the problem starting adjusting the ignition time and checking the incoming hoses and the power steering cooler. Changed the engine circulating water pump and the impeller at the drive and the temperature at the stb elbow still high
So I decided to change the manifold on the starboard side and the temp drops down to 112 F at 1000 rpm and gets 118 F after 10 min of running
So I would like to thank you very much for all the guidance and instructions
 
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