175HP blackmax running too hot?

[jigmister]

1986 black max. 370V ranger bass boat. No jack plate

On the topend it pushes the guage really hot. It runs near hitting the over heat alarm.

5,000 RPM and its fine. 5,200 RPM and that guage is nearly pegged but dose not hit the alarm.
I have done all the usaual things one might do to fix the problem.
New T stats Impeller water pump assembley. new poppet

2 things that come to mind is the trim and running lean?
I have trimmed to differnt postions with the same results.

Again, it dose not hit the alarm. Maybe I am just over concerned. Been this way for a few YEARS. Nothing bad has happened yet.
How can I be sure the temprature is within range?

 

[j_martin]

Re: 175HP blackmax running too hot?

1986 black max. 370V ranger bass boat. No jack plate

On the topend it pushes the guage really hot. It runs near hitting the over heat alarm.

5,000 RPM and its fine. 5,200 RPM and that guage is nearly pegged but dose not hit the alarm.
I have done all the usaual things one might do to fix the problem.
New T stats Impeller water pump assembley. new poppet

2 things that come to mind is the trim and running lean?
I have trimmed to differnt postions with the same results.

Again, it dose not hit the alarm. Maybe I am just over concerned. Been this way for a few YEARS. Nothing bad has happened yet.
How can I be sure the temprature is within range?

If it locks up and tosses you over the helm at WOT, it was too hot.

 

[Faztbullet]

Re: 175HP blackmax running too hot?

Throw the temp guage away and install a water pressure guage. Temp guages cause ghost problems(something that aint there) and get your RPM up as 5200 is low,close to 6000 will be better.

 

[j_martin]

Re: 175HP blackmax running too hot?

Throw the temp guage away and install a water pressure guage. Temp guages cause ghost problems(something that aint there) and get your RPM up as 5200 is low,close to 6000 will be better.

It is normal (and harmful) for them to run warm if they are overloaded. You should set it up and prop it so it runs near, or even slightly over the top of the max rpm spec with half a tank and the driver. (or is that a half tank'd driver) Should stay in the band under all conditions then.

I agree with fast, the pressure gauge gives you the information you need to tell if it is cooling properly.

 

[PrinceValium]

Re: 175HP blackmax running too hot?

If it locks up and tosses you over the helm at WOT, it was too hot.

Ok now THAT made me laugh...LOL

 

[jigmister]

Re: 175HP blackmax running too hot?

installed water pressure gauge year ago. What should it read? I get 8-10 at idle

20-25 when running.

what is the operating temprature range of this engine?
I plan to use temprature rated wax sticks placed on the top of the heads to see if shes over heating.
Anyone know where I could find the wax?

 

[j_martin]

Re: 175HP blackmax running too hot?

believe it or not, that sounds a bit high. You might have some snail shells or something caught in the water exit ports.

I sawed a rotten log in half with the XR4 once. Had to pull the exhaust chest cover and heads to get at all the toothpicks clogging things up.

 

[j_martin]

Re: 175HP blackmax running too hot?

Ok now THAT made me laugh...LOL

You're familiar with the needle, eh.

 

[jigmister]

Re: 175HP blackmax running too hot?

believe it or not, that sounds a bit high. You might have some snail shells or something caught in the water exit ports.

what would be considered normal pressures?

thanks

 

[ufm82]

Re: 175HP blackmax running too hot?

Try This:

Problem Diagnosis
Condition Recommended Range Possible Cause
1) Pressure below specification @ idle 1.0 ? 3.0 PSI (6.8 ? 20.5 kPa)
Poppet valve spring defective
(weak, broken, missing)
Defective poppet valve seal
Thermostat stuck open
Severe internal leak
Low output water pump
Inlet restriction

2) Pressure above 5 psi (34.2kPa) @ idle 1.0 ? 3.0 PSI (6.8 ? 20.5 kPa)
Plugged poppet by-pass passage
or tell-tale

3) Pressure does not drop between 1000 ? 2500 RPM indicating poppet valve has opened 4 ? 9 PSI (27.4 ? 61.6 kPa) between 1000 ? 2200 RPM
Wrong poppet valve spring
Low output water pump
Inlet restriction
Poppet valve vent hole plugged
or restricted
Severe internal leak
Defective poppet valve seal

4) Poppet valve flutter/water pressure drop does not stabilize prior to 2500 RPM 4 ? 9 PSI (27.4 ? 61.6 kPa) between 1000 ? 2200 RPM
Wrong poppet valve spring
Low output water pump
Inlet restriction
Broken diaphragm in poppet
valve
Severe internal leak
Defective poppet valve seal

5) Pressure is below minimum specification @ W.O.T. 12 PSI (54.9 ? 68.5kPa)
Inlet restriction
Engine mounted too high on
transom
Engine trimmed out too far
Configuration of boat bottom interfering
with adequate flow of
water to coolant inlets
Severe internal leak
Low output water pump

6) Pressure higher than normal @ W.O.T., but engine still indicates overheat condition Maximum pressure ? 23 PSI
(157.4 kPa)
Outlet water passages restricted.
Steam pocket has formed at top
of powerhead due to lack of cooling
water

 

[jigmister]

Re: 175HP blackmax running too hot?

what should the maximum operating temprature be?

thanks

 

[Faztbullet]

Re: 175HP blackmax running too hot?

I get 8-10 at idle 20-25 when running.

Your water pressures are pretty close as you have the old style cooling system. Minium is 22psi @5000 rpm and you will see 5 psi or higher at idle. The max temp is around 165? as the overheat sensor trip at 180-200? depending on sensor. Once the engine is at rpm and poppet opens the t-stats are non operational in cooling system and usually temp will temp in the 125-145? range. This is one reason why a factory temp guage is not graduated,just a big space between cold and hot.

 

[jigmister]

Re: 175HP blackmax running too hot?

thanks for the info guys. I will check and see what temp shes running at with a tempilstick or maybe even a fluke thermacouple.

 

[jigmister]

Re: 175HP blackmax running too hot?

well I stuck a chunk of tempilstick on the top of each head. 175 degree melting point.
Ran it hard today. the Temprature gauge was pushing the red line.
Checked the tempilstick chuncks and they did not melt at all.

I think things are ok.

 

[Maxz695]

Re: 175HP blackmax running too hot?

when you do the impeller you should check for water leaking into the midsection with a hose and flashlight. If so the gasket is blown and your water pressure is not enough to coll that thing off properly this can only get worse over time and costly if not repaired soon.

 

[j_martin]

Re: 175HP blackmax running too hot?

when you do the impeller you should check for water leaking into the midsection with a hose and flashlight. If so the gasket is blown and your water pressure is not enough to coll that thing off properly this can only get worse over time and costly if not repaired soon.

Only one problem with this. The engine normally dumps all the water and exhaust into the mid.
Have you actually ever seen an outboard motor?

 

[shankforce]

Re: 175HP blackmax running too hot?

I had this same motor always had cooling issues. Excpecially since it did not like to run in idle to mid speeds only seemed to be happy running 3/4 to near WOT. Some of these get so old they get all kinds of deposits in the cooling channels only way to clean it is to take it all apart. Hope it dont come down to that. Do you run it in salt or fresh.

 

[j_martin]

Re: 175HP blackmax running too hot?

I had this same motor always had cooling issues. Excpecially since it did not like to run in idle to mid speeds only seemed to be happy running 3/4 to near WOT. Some of these get so old they get all kinds of deposits in the cooling channels only way to clean it is to take it all apart. Hope it dont come down to that. Do you run it in salt or fresh.

This thing is managing a 2.5 million BTU fire in a 50 lb. container. Anything out of tune can overpower the cooling system. Fuel mixture, timing, over propped, etc.

 

[Maxz695]

Re: 175HP blackmax running too hot?

Who said anything about return through the exhaust did you not read the reply? It says to look up into the midsection not the exhaust to see if water is leaking at the base. This would be a reason for lack of sufficient pressure and raise water tempature due to lack of water.

 

[jigmister]

Re: 175HP blackmax running too hot?

thanks for all the replies. However I am still trying to determine if the engine is running hot or not.
Dose not hit the over heat alarm.
appears to be running less than 175 degrees.
gauge or sender may be at fault.