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5.0 228 to 5.7 overheating.

I

I can’t think of a name

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I converted my 305, 228 to a 350, 228 in a 22.5 Bayliner model 2250SK, (I can’t find any information about this model).
Bought a long block from Tristar, moved all auxiliary equipment to the 350. New coupler, new starboard and port logs.
Broke it in, on the trailer, that was backed into the river @ 2000 to 3000 rpm for about 2 hours. The temperature read on the gauge was about 195 degrees to 180, depending on rpm, (too hot), but I was committed to the process.
Brought it home, changed oil and on the following week went for a ride. With 7 persons aboard, it would stay at about 195 not on plane nor pushing water just idling. With a one minute of 3/4 throttle in gear down the 75 degree lake.
Two weeks later just myself on board 50 degree water, I idled up to temperature then got it on plane for 2 minutes and the temperature was just over 195, backed it back down to just off idle and it would not come off of 200 degrees.
Thermostat is a 140 and opens at a 138 indicated on a digital thermometer.
I’m 95% sure where the timing is at because the light decided to pack it in.

What should I check first, second, third, fourth……? Power steering cooler is clear of all obstructions.
 
I can’t think of a name said:
I converted my 305, 228 to a 350, 228 in a 22.5 Bayliner model 2250SK, (I can’t find any information about this model).
Bought a long block from Tristar, moved all auxiliary equipment to the 350. New coupler, new starboard and port logs.
Broke it in, on the trailer, that was backed into the river @ 2000 to 3000 rpm for about 2 hours. The temperature read on the gauge was about 195 degrees to 180, depending on rpm, (too hot), but I was committed to the process.
Brought it home, changed oil and on the following week went for a ride. With 7 persons aboard, it would stay at about 195 not on plane nor pushing water just idling. With a one minute of 3/4 throttle in gear down the 75 degree lake.
Two weeks later just myself on board 50 degree water, I idled up to temperature then got it on plane for 2 minutes and the temperature was just over 195, backed it back down to just off idle and it would not come off of 200 degrees.
Thermostat is a 140 and opens at a 138 indicated on a digital thermometer.
I’m 95% sure where the timing is at because the light decided to pack it in.

What should I check first, second, third, fourth……? Power steering cooler is clear of all obstructions.
Click to expand...
Verify the timing , late timing can cause elevated temps. Check how much water is coming up from drive to thermostat housing should be 3-4 qts in 15 seconds. If you have enough water then look at elbows if they are clogged not enough water can get out of the engine.

Is the engine using a marine circ pump?
 
Clean exhaust elbows are essential...if the cooling water is restricted, so will the heat removal ...

on the water pump volume test, it should be at least 4.0 quarts in 15 seconds...

Have you verified the temp gauge with the IR temp gun?
 
Some people call the elbows risers but what I’m referring to is the piece bolted to the manifold where the exhaust gases & cooling water mix….those passages must be open. For a raw water cooling system to work you have to have a high volume of cool water in and high volume of warm to hot water out. Anything that interrupts this flow will cause overheating…..
 
Dieter said:
Verify the timing , late timing can cause elevated temps. Check how much water is coming up from drive to thermostat housing should be 3-4 qts in 15 seconds. If you have enough water then look at elbows if they are clogged not enough water can get out of the engine.

Is the engine using a marine circ pump?
Click to expand...
My Seloc Mercruiser stern drive 1964-1992 Manual, states 8* BTDC, I’ll set it at that when I get a new timing light. I’ll pull the hose off and put a clear one from the power steering cooler to the engine pump and look for bubbles, after I see 3-4 qts in 15 seconds.
When I converted to the 350, I assumed it was a marine pump because the plate on the backside is stainless steel and so are the eight or so bolts holding it in place, could I be wrong?
 
I can’t think of a name said:
I converted my 305, 228 to a 350, 228 in a 22.5 Bayliner model 2250SK, (I can’t find any information about this model).
Bought a long block from Tristar, moved all auxiliary equipment to the 350. New coupler, new starboard and port logs.
Broke it in, on the trailer, that was backed into the river @ 2000 to 3000 rpm for about 2 hours. The temperature read on the gauge was about 195 degrees to 180, depending on rpm, (too hot), but I was committed to the process.
Brought it home, changed oil and on the following week went for a ride. With 7 persons aboard, it would stay at about 195 not on plane nor pushing water just idling. With a one minute of 3/4 throttle in gear down the 75 degree lake.
Two weeks later just myself on board 50 degree water, I idled up to temperature then got it on plane for 2 minutes and the temperature was just over 195, backed it back down to just off idle and it would not come off of 200 degrees.
Thermostat is a 140 and opens at a 138 indicated on a digital thermometer.
I’m 95% sure where the timing is at because the light decided to pack it in.

What should I check first, second, third, fourth……? Power steering cooler is clear of all obstructions.
Click to expand...
What year of production? If you need info for that model, try contacting Bayliner and make sure to provide the hull ID- without that, they can't help yopu because ALL boat manufacturers had variations for each build and the only way to find info that's specific to a particular boat is by using the hull ID.

When was the raw water impeller changed last? The fact that it was running hot tells me it may not be getting much water for cooling.

From experience with a boat I bought that was said to have 'had a bit of an overheat", DO NOT RUN IT FOR LONG IF IT'S RUNNING HOT!

I can provide a list of the parts that were replaced due to the idiot who decided to redefine 'overheat', if you want- they were in the engine, exhaust and throughout the upper and lower gearcases and it's not just the raw water pump's impeller that will needed.
 
makomark said:
Clean exhaust elbows are essential...if the cooling water is restricted, so will the heat removal ...

on the water pump volume test, it should be at least 4.0 quarts in 15 seconds...

Have you verified the temp gauge with the IR temp gun?
Click to expand...
I don’t have an IR gun, but when I can really feel the heat rising off of it and a smell of overheating engine…
 
I can’t think of a name said:
At the time of 350 conversion I put a new impeller in and new “log” style exhaust manifolds in.
Are the elbows that critical?
Click to expand...
If the water passages are clogged, they may as well be solid and not have any way for the water to pass through. That causes the water to be bl;ocked from moving AND it kills everything I mentioned in my previous post.
 
jimn said:
What year of production? If you need info for that model, try contacting Bayliner and make sure to provide the hull ID- without that, they can't help yopu because ALL boat manufacturers had variations for each build and the only way to find info that's specific to a particular boat is by using the hull ID.

When was the raw water impeller changed last? The fact that it was running hot tells me it may not be getting much water for cooling.

From experience with a boat I bought that was said to have 'had a bit of an overheat", DO NOT RUN IT FOR LONG IF IT'S RUNNING HOT!

I can provide a list of the parts that were replaced due to the idiot who decided to redefine 'overheat', if you want- they were in the engine, exhaust and throughout the upper and lower gearcases and it's not just the raw water pump's impeller that will needed.
Click to expand...
I replaced the pump with the new 350
 
louc said:
Some people call the elbows risers but what I’m referring to is the piece bolted to the manifold where the exhaust gases & cooling water mix….those passages must be open. For a raw water cooling system to work you have to have a high volume of cool water in and high volume of warm to hot water out. Anything that interrupts this flow will cause overheating…..
Click to expand...
I understand.
I need to search deeper.
 
I can’t think of a name said:
I replaced the pump with the new 350
Click to expand...
I saw that after posting but you didn't mention the impeller's condition WRT intact vanes, which style of impeller (has to do with vintage), which drive (Alpha and which version or Bravo), how long you have owned it, etc. If you aren't the original owner and especially if you bought it not long before replacing the engine, it's possible that a piece of the impeller is clogging a hole in the thermostat housing.

Because of the potential for damage from overheating, I would recommend inspecting everything in the passage where exhaust exits the engine, including the raw water pump cover, water pocket, driveshaft seal, shift shaft seal (upper) and the plastic tube on the raw water pump, assuming it's an Alpha drive. If the raw water pump cover is metal, it indicates the vintage. Mine was at the point where two of the nuts were covered by the melted plastic and the plastic tube had 'tulipped' (turned inside out).

I hope yours hasn't been badly damaged.
 
I can’t think of a name said:
I replaced the pump with the new 350
Click to expand...
That’s why the flow test , if less than 3-4 qts in 15 seconds look at impeller and supply issues. I have found them used on oem impellers last a long time and are worth the money.
I can’t think of a name said:
Well it looks like I need to do more than I was hoping to do. Elbows off.
Click to expand...
Do flow test first .
I can’t think of a name said:
When I converted to the 350, I assumed it was a marine pump because the plate on the backside is stainless steel and so are the eight or so bolts holding it in place, could I be wrong?
Click to expand...
If you got a marine long block would assume it is.
 
A non marine on engine water pump will work fine for circulating water in the engine for now. If it was used in salt water for a period of time it may be an issue but if its new (er) and only used a couple times. It should work fine for now.


Auto type typically use a stamped steel one directional impeller.
A marine circulating pump uses a bronze bidirectional impeller
 
I’d start by double-checking the raw water pump and impeller since that’s often the culprit with high temps. Next I’d look at flow restrictions in the manifolds/risers, then verify timing once you get a working light. If all that checks out, I’d inspect hoses and the circulation pump for hidden issues.

 
Last edited:
The hose that runs from the power steering cooler to the from the water inlet, (from stern drive) was the culprit.
The power steering cooler takes a 1 1/2 inch od hose, the pipe that comes out of the stern drive is 3/4 inch od. There was a pice of hose on the stern drive piping 2 inches long that brought the od from 3/4 to 1 1/2
So now a 1 1/2 hose could connect the power steering cooler to the stern drive pipe. That little hose on the stern drive pipe was all cracked and was allowing air to be sucked into the engine by the engine water pump causing the over heating problem.
I once had a 2.0 4 cylinder OHV Volvo that had a 270 out drive on it. It too had overheating issues that I diagnosed to be an air infiltration issue. It would run nice up to about 3500 RPM then I could hear it change in pitch and overheat. I tightened the clamps up and bingo, all fixed.
 
It's always the simple things. I can't tell you how many hours I have spent in confusion looking at wonky engines with the problem staring me in the face, but I'm sure it adds up to a nice vacation in Bali.
 
kghost said:
A non marine on engine water pump will work fine for circulating water in the engine for now. If it was used in salt water for a period of time it may be an issue but if its new (er) and only used a couple times. It should work fine for now.


Auto type typically use a stamped steel one directional impeller.
A marine circulating pump uses a bronze bidirectional impeller
Click to expand...
Non-marine circulating pump seals are made to be used with coolant- when I worked for a MasterCraft dealer, we saw several seals fail because the supplier couldn't source marinized pumps, so they sent what was available and they all failed, due to the lack of lubrication from the coolant. Some bodies of water (salt or brackish) are far more damaging than clean water withextremely high or low pH.
 
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