Overheating AQ131

I have changed most of the com

I have changed most of the components that cool the engine. I have also boiled the exhaust manifold out. I have had a cooling issue for awhile you have helped me in the past. It has all worked to help the problem but I still have a small heating problem at about 3000to3500 and above it likes to climb abit if I run at this rpm for about 7to8min. the temp starts to climb. My question is that if i had cut some of the spacer out of the heat exchanger could that be part of the problem as when i took the exchanger apart to clean it part of the spacer was bad. Thanks for your help

Which spacer?

Which spacer?

The spacer between the heat ex

The spacer between the heat exchanger at the cover of it (inside) the exchanger itself.

"What RPM is the engine reachi

"What RPM is the engine reaching at WOT? If below 4500, the engine may be overloaded.

Have you checked inside the lower drive unit grids for marine growth? Also, consider installing a clear plastic hose in the raw water suction line to connect the copper pipe to the pipe in the transom shield; this way you can see if air bubbles are present, which would be an indication that the problem is not in the engine but rather the raw water pump sucking air."

Yes I have put a clear hose on

Yes I have put a clear hose on the inlet pipe and it is completely full all the time when in the water. as for rpm I try not to run it much more then 3500 what is good running rpm for that motor? Also I had the o-ring and pipe in the outdrive changed.

"Try to run the boat with the

"Try to run the boat with the engine at WOT for a one or two minutes. You should be getting 4700-5000 RPM. If lower (say below 4500), the engine may be overloaded (possibly the propeller is too large for your boat).

How high is the exhaust manifold and the exhaust pipe temperature when you are running the engine at 3500 RPM? You should be able to touch it with your hand and feeling it warm but not too hot (i.e. you should not burn your hand). If you have a laser thermometer, that will give you an accurate reading. Also, at the same RPM, how cold (or hot) is the raw water leaving the heat exchanger? You can touch the copper pipe between the heat exchanger and the exhaust manifold to have an idea."

I would still like to know if

I would still like to know if that spacer inside the heat exchanger ( the rubber one ) should be there or could that make a difference? Thanks again

"I have not taken apart that t

"I have not taken apart that type of heat exchanger and tank, but judging by the schematic I think that spacer is there to keep the heat exchanger in place sandwiched between the tank housing and the cover. I don't see how this spacer could affect the heat transfer between coolant and raw water."

"If You are talking about spac

"If You are talking about spacer 9/10 on below pick, that part is essential and must NOT be damaged. If not sealing properly, water will by-pass the element and You will have a cooling problem.
Have the element 'boiled out' at a radiator shop, install with a new spacer if needed.
"

I would like to thank you for

I would like to thank you for your help with the overheating problem which appears to be solved to the degree that we can now use the boat. I have put in the spacers and we can run the boat all day long at about 3800rpm's. I still have a little issue when I try to run the boat over that for about 4 to 5 min's. but like I say atleast we can use the boat.

Thanks again
Vern Blair