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37 4 cyl what Should the running temp be

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fchris

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"I have a 1987 regal with a 16

"I have a 1987 regal with a 165 3.7 4 cyl engine, closed cooling system.. I was experiencing what i thought was over heating the engine would get up to 190-5 when running.. and then it would seem to go into some reduce power mode??? (not sure if that was what was happening) I replace the lower unit pump. i checked all hoses for tightness and replaced a few, changed the thermostate, took off the resevour and checked for clogs, along with the exchanger. all looks good.

I reciently tuned it up, sparks plugs, and wires, distributer, points (set to specs) and cap and condencer, adjusted timing. Engine was running great at the slip.

When i run the boat at the dock at idle the temp goes up to 180, when i rev the engine the temp starts to come back down around 170. Next I take it out for a drive and in the harbor at 6mphs the temp stays about 180 then when i excelerate the temp climbs to about 190 and stays there. but then when i de-excelerated the motor kept wanting to stall.. i had to keep in high idle to keep it running.

Whats going on??? is the temp running right?? or is that hot??

Any help guys????"
 
i went the the merc parts stor

i went the the merc parts store with the specs and the thermastate is the one that was called for 160.

I don't see any leaking around the engine circ pump.. as i said i just replaced the lower unit pump.
 
yes i replaced it when it when

yes i replaced it when it when i had the system apart.. there was actually nothing there except the metal bar that streches across..
 
"Did you find the rest of it,

"Did you find the rest of it, it's probably piled up in the bottom restricting your exhaust."
 
no i didn't... where??? ho

no i didn't... where??? how?? would i find that?? just stick my hands down inside and feel around??? at the point were the flapper is there was water at that level.. would that be causing the temp and loss of power... the boat ran great for about 20 mins at full speed then when i de excelerated that was when the problem started.
 
Look very closely at the radia

Look very closely at the radiator cap on the tank that you put in your 50/50 antifreese and water.

Do you see any dried water/antifreese trails running down the side of the housing towards the spark plugs??????

If so replace the radiator cap! Spark plugs could be getting grounded out if this occurring. You wont see this if you are not looking for it.

As far as the temp issue I would replace the sending unit and make sure you have NOTHING on the threads and the threaded hole it screws into is clean as well for a good ground.

Hope this helps.
 
"Try sticking a long magnet in

"Try sticking a long magnet in it, it might grab it if is not jammed, but usually you have to remove the outdrive to see if the exhaust is plugged. The water level should be the same height as the water level outside your boat if it,s still in the water. If it's on the trailer, there should be no water in it."
 
"Kg... that was one onf the fi

"Kg... that was one onf the first things i checked when i bought the boat.. the temp guage didn't work. first i replaced the guage, that didn't work so i replace the sending unit next. the guage all seems to be working now...

I am trying to figure out if the engine running at 190-5 is hot or is that normal?????"
 
"I'm no expert on these en

"I'm no expert on these engines, but I have to agree with Jeff that 190+ is a little hot.

If you have a 160 stat in it, that is about what the engine should run at, assuming that there is adequate raw water flowing thru the exchanger and enough heat transfer across the exchanger to remove the required heat.

With the temps you describe it is safe to assume the stat is wide open and not controlling anything. The fluctuating temps you are seeing result from changes in water flow with RPm, changing heat output from the engine etc.

My take is that you have some restriction in the raw water side, or the exchanger is dirty. And this will only get worse. You should get the exchanger professionlly cleaned and flushed first in my opinion. Exchanger efficiency drops dramatically when they get dirty. It may "look" clean, but have you looked at the insides of the tiny tubes?

Rod"
 
rod thanks for the insight.. i

rod thanks for the insight.. i took the exchanger off and looked through all the little holes and i could see the other side through each one.. when you talk about "dirty" could the tubes still be seen through but still be dirty???? I have never dealt with a heat exchanger before. how can i guage the water intake from the lower pump???
 
The tube walls can have a thin

The tube walls can have a thin layer of scale and sludge buildup on them which acts as an insulator. There is a tube brush made for cleaning them yourself.
 
"Guy is right.
If you can&#39

"Guy is right.
If you can't find the correct brush, a brass rifle cleaning brush for a 22 will work quite well.

Note that the inside of the tubes is where the raw (read "dirty") water flows and is the most prone to fouling.

Rod"
 
2 things
1. Absolutley confi

2 things
1. Absolutley confirm that there is no water/antifreese getting to the spark plugs from the radiator cap!!! If so replace!!
Believe me when I say this! This will make the engine act exactly as you describe!
There is NO reduced power mode. This is a simple point ingition not electronic!

2. 190 degrees is to hot under normal operation (expect at prolonged full speed running)

Remove the RAW water hose where it conncets from the voltage regulator and the manifold and replace with a clear piece of hose.

Put boat in water (not on hose) and run. see what the water looks like coming into the manifold.

If it is full of air bubbles than you have a incomming water supply isuue. You will need to look at the impeller and assosiated hardware in the lower unit.

One more thing. If this power loss in immediate and it never gets above 2000-2500 rpms then remove the distibutor cap and make sure your MECHANICAL ADVANCE WIEGHTS ARE MOVING FREELY.
If they are not this will inhibit your ability to get beyond 2000 rpms or so.
 
I thought of one more thing to

I thought of one more thing to check.

When at full wide open throttle check to see if you are activating your interuptor switch intermitenly. Your cables may be out of adjustment a bit and at wide open throttle you may be making contact with the switch.

Just a thought. May not be happening but it is worth checking.
 
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