200hp efi overheating

[workboot]

2002 0t556519, in 2023 I replaced head gaskets on starboard side because of water in the 2 lower cylinders, ever since then the temp. gauge goes up above 2000 rpm. it's only on the starboard side that gets hot, I've changed water pump, poppit, rydelimed it but it still gets hot, looking at my factory manual it says there are rubber water dams between the pistons on the block. Quote "rubber water dams -if missing may result in uneven cooling of cylinders and scuffed pistons" but looking at online retailer's diagrams I cannot find them. I'm not sure that they were there when I did head gaskets. I found out about them looking through my service manual at a picture called water flow diagram. Does anybody know about these or any other reason it might be overheating. Also it does it with or without thermostats

 

[Dukedog]

those are usually called "diverters".. we would put 'em our hot rods years ago before merc ever thought 'bout 'em.. never seen 'em on any Parts charts except later model Hi Perf. 2 stroke stuff ie: 260, 280 etc... they should not be a problem.. earlier production mercs have ran for years without 'em.. when you replaced tha head gaskets did you have tha head checked for being totally flat?

i did find a dia. that shows their location but file is to big to put in a post.. can email it ya want?.. all they are is a piece of 5/16 fuel hose cut ta length.....

 

[Dukedog]

if you cut and install yourself tha length will be estimate.. it needs about 1/4" gap at both ends when installed.... these don't need ta be exact measurements......

are you getting any type of overheat alarm??? if not, i wouldn't think twice about it....

 

[workboot]

if you cut and install yourself tha length will be estimate.. it needs about 1/4" gap at both ends when installed.... these don't need ta be exact measurements......

are you getting any type of overheat alarm??? if not, i wouldn't think twice about it....

thanks for the reply, I did not check for flatness, I have a diagram in my service manual for where they go, I did get an overheat alarm once but as soon as i throttled back it stopped. On a youtube video I watched on overheating someone replied that his water pump housing had a little seepage at the base and he used a gasket sealer to stop it, his thought was that exhaust gas was getting into the water pump. I saw a little water coming out of my pump when I did the rydelime clean by didn't think much about it. I'm going to try that this Monday and see if that resolves it, thanks again Dukedog

 

[Dukedog]

when you replaced tha water pump did you install a "kit" or jus tha impeller?.. need ta replace all of it...

 

[Dukedog]

" his thought was that exhaust gas was getting into the water pump "

this is almost impossible.. water pump is in a separated part of tha motor..

 

[workboot]

I replaced the whole kit, and I do it every 3 years. As for the exhaust gas, doesn't it surround the water pump as it goes out through the prop. and wouldn't it build up pressure the faster I go. The temp gauge goes up after about 2000 rpm. Thanks again

 

[Chris1956]

Compression leaks causes overheating. Are you sure the head gasket you replaced is not leaking? Did you check the head and block for flatness?

 

[Dukedog]

I replaced the whole kit, and I do it every 3 years. As for the exhaust gas, doesn't it surround the water pump as it goes out through the prop. and wouldn't it build up pressure the faster I go. The temp gauge goes up after about 2000 rpm. Thanks again

it goes thru tha front side of tha can thru an exhaust tube thats suppose ta be sealed both top and bottom.. its completely separate from exhaust...

without it (like our hot rods) will sometimes completely destroy (melt) tha water pump....

tha tube also prevents tha discoloring of tha down housing paint from heat...

 

[Dukedog]

Compression leaks causes overheating. Are you sure the head gasket you replaced is not leaking? Did you check the head and block for flatness?

he did not!

 

[workboot]

thanks for the replies guys. so I guess I should do a compression check , would that be my next step ?

 

[Chris1956]

Unfortunately, a compression check doesn't always find head gasket leaks. However, do the compression check and maybe it will be obvious. Check the torque on the head bolts as well. Those V6 motors had a habit of the head bolts loosening up.

 

[workboot]

ok I'll check the head bolts, but do you know the torque? the book says 30 lbs. then tighten another 90 degrees but I used a number I got on the web back when I did the job but can't remember what it was. Or I'll just find a tight one and use that number

 

[Chris1956]

Some stuff from a Merc 150HP service manual. It covers 200XRI model.


Cylinder Heads and Exhaust Divider Plate 1. Inspect internal surface of cylinder heads for possible damage (as a result of piston or foreign material striking cylinder heads). IMPORTANT: Cylinder head warpage should not exceed 0.004 in. (0.1 mm) over the ENTIRE length of the cylinder head. If measured warpage, as determined on a surface block, exceeds 0.004 in. (0.1 mm) or a discontinuity of up to 0.004 in. (0.1 mm) exists in a narrow portion of the cylinder head’s surface length, then the cylinder head may be re-surfaced up to 0.010 in. (0.25 mm). 2. Replace cylinder head(s) as necessary. 3. Thoroughly clean gasket surfaces of exhaust divider plate. 4. Inspect exhaust divider plate for deep grooves, cracks or distortion that could cause leakage. Replace parts as necessary

CYLINDER HEAD INSTALLATION 1. Install each cylinder head to engine block with thermostat pocket “UP”. Apply light oil to cylinder head bolt threads and torque bolts to 30 Ib. ft. (40.7 N·m) and rotate 90°. 10 6 2 3 7 11 8 4 1 5 9 12 2. Install thermostat washer into each cylinder head. 3. Install overheat temperature sensor into STARBOARD cylinder head below #1 spark plug. d e f h c i b g j a a-Washer b-Thermostat Cover c-Hose d-Clamp e-Bolt (Torque to 200 Lb. in. - 22.6 N·m) f-90° Elbow g-Temperature Sensor h-Bolt (Torque to 200 Lb. in. - 22.6 N m) i-Retainer j-Bolt [Apply Light Oil to Threads - Torque to 30 lb. ft. (40.7 N·m) and rotate 90°