Cooling system 165 Mercruiser.

[SabineStalker]

Ok guys, I have twin 165's which are straight 6's. I have ran them 3 times and the first 2 were excellent. However, the other day, I had a water hose blow and when it blew, it blew hard, there was a lot of pressure built up from somewhere but the temp never registered hot by the guage. I have an open loop system. I replaced the hose and tried it out, the hose gets tight pretty fast, the other motor's water hose stays soft enough to squeeze a little, so there is definitely something wrong with the other. I have checked all the hoses on the motor, checked the manifold for restrictions, and found none. I rigged the water hose from my house to check the internal water ports, but seem clear. Im at a loss, have any of you experienced anything like this. Id appreciate any help you can give. Thanks in advance.

 

[Bondo]

Re: Cooling system 165 Mercruiser.

Which Hose ????????

 

[SabineStalker]

Re: Cooling system 165 Mercruiser.

It it the "U" shaped hose. The one that leaves the water pump and heads to the block..

 

[thunderchikken2020]

Re: Cooling system 165 Mercruiser.

Theres a possibility that there may be a blockage in your exhaust riser elbow. since this is where the water makes it's exit from the engine and mixes with the exhaust. if there were excess pressure, it should be released at this point. it may be possible that your engine needs a full flush job. it is possible that some corrosion or scale broke loose and plugged your water jackets. also it is cheap insurance to take your exhaust riser elbow off and make sure the water passage in the down spout is clear. on mine it has a piece of stainless tubing in the passage and when i took mine off, there was a lot of scale in this passage and since you're this far in, may as well remove your rubber boot from the lower exhaust j pipe and check your water shutter. good luck and let us know how it all went.

 

[Bondo]

Re: Cooling system 165 Mercruiser.

Theres a possibility that there may be a blockage in your exhaust riser elbow. since this is where the water makes it's exit from the engine and mixes with the exhaust. if there were excess pressure, it should be released at this point. it may be possible that your engine needs a full flush job. it is possible that some corrosion or scale broke loose and plugged your water jackets. also it is cheap insurance to take your exhaust riser elbow off and make sure the water passage in the down spout is clear. on mine it has a piece of stainless tubing in the passage and when i took mine off, there was a lot of scale in this passage and since you're this far in, may as well remove your rubber boot from the lower exhaust j pipe and check your water shutter. good luck and let us know how it all went.

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