Rodbolt, please help!

wjob

Petty Officer 2nd Class
Joined
Jan 24, 2005
Messages
100
Need some more help with the overheat problem I described in thread: “’88 Suzuki 150hp Overheating”

As I explained I just replaced water pump impeller and now I’m getting an intermittent beep, beep, which prompted me to check with a laser gun and when it showed about 175/180 degrees on one c-head plus an extremely hot pee stream I turned it off. Other head was holding at about 115/120.

It’s been at least one year since I had run the engine and as I remember the pee stream then was almost non existent. After I did the new impeller and restarted at idle the pee stream was coming but not with a lot of force, then about a minute later it started coming with a lot of force for about 30 seconds, then reverted back to
the lesser (but steady) flow.

I had some trouble getting it to fire the other day so I disconnected the oil injection wiring that goes to the top of the oil tank in order to move tank out of way so I could check that fuel pumps were sending fuel to the carbs which they were and eventually I got it to run (I had cleaned the carbs). Now I’m wondering whether the beep, beep I was getting was an oil system warning rather than an overheat warning (I was running on fuel that I had premixed so as not to take chances). Nevertheless the laser gun produced the above heat readings and when the pee stream became too hot to feel I quickly turned off the engine. I then pulled the thermostat on the hot side which has since checked out ok on the stove. This prompts the following questions:

1 I‘m assuming I would have overheat on both heads if I had re-installed lower gear case incorrectly? During the re-installation at one point I kind of cocked the lower unit slightly as I pushed upward. Also, when torqueing the water pump housing down over the new impeller I wasn’t sure of the exact mm size of bolt in order to determine the correct foot pounds but I think it’s probably pretty close.

2. should I have let the temp build beyond that 180 degree (pee stream was real hot too), hoping it might drop down, before turning it off? It had run 3/5 minutes before I turned it off.

3. What should be my next steps? I’m not anxious to pull the entire power head unless I absolutely have to. Will removing the cylinder head cover help me or will I need to remove the entire head? What’s best process to clean a “caked” head?

4. A flushing solution has been suggested so as not to have to remove components? If this makes sense, do you know of any? Could I do it through thermostat hole or somewhere else? Do I need to drop the lower unit again to do a flush? Can I run the engine without causing damage for a short time, leaving the thermostat hole open, if it makes sense? Should I blow compressed air in through thermostat hole or somewhere else, hoping to blow out any obstruction?

Will appreciate your thoughts
Bill
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: Rodbolt, please help!

I cant remember how the cooling flow is but you have a restriction on the hot side. the t-stats are also the ressure valves so they have to be inplace and working. if the water pump is doing its thing its time to go find the restriction.
 

wjob

Petty Officer 2nd Class
Joined
Jan 24, 2005
Messages
100
Re: Rodbolt, please help!

Thanks for your reply Rodbolt!

I've done some checking locally and have been told the following:

1. Run the engine again and don't get concerned about overheat damage until the temperature gets up to about 205 degrees. Told overheat alarm shouldn't come on
until about 200 degrees, so beep, beep must have been the oil warning, not temperature.

2. Run it with open thermostat hole on hot c-head side to see if getting flow of water out of it. If necessary pull thermostat on cool side in order to compare flow from each side.

3. Feeling was that as long as I have pee stream coming and one side stays cool, probably no problem with way I re-installed lower gear case after replacing impeller

Your comments please.

Bill
 
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