running hot, can hoses collapse

I have a new to me boat with twin crusader 8.1's. Starboard engine is running hot. Changed the risers, oil cooler, impeller in water pump and had heat exchanger cleaned. Riser is still very hot hot and engine temp climbs over 190 and then I back it down to keep temp from hitting 200. I ordered an new raw water pump just to eliminate it as a possible issue. The engines are 2002. Is ti possible the hoses can be collapsing like fuel lines and restricting water flow at higher RPM's? I pulled the hoses from the heat exchanger to the risers to see if there is water flow and there is good water flow at idle? Any suggestions?

The only hoses that would collapse are on the suction side of the pumps....and they should have wire in them to keep that from happening....

Are the strainer lids on tight and with good gaskets.....any air leaking in will get mixed with the cooling water and severely reduce the heat it can absorb. Also, are the sea cocks fully open ? all hose clamps tight?

When it comes to assessing the water delivered by a pump, the only consistent way is to measure it....usually with a small bucket and a watch.....15 or 30 seconds, done 3 times will give you reasonable data...

Had a similar problem which turned out to be marine life in the scoop and intake. Old shells lodged in the 90 degree turn before the strainer. An increase in observed vapor at the exhaust is usually an indication of reduced raw water flow.

Thanks guys. I think I may have found the problem. Will find out when the part comes in later today and hopefully get down to the boat to replace. So far I have changed the risers and oil cooler and have had the heat exchanger cleaned. The seacock is fully opened and all of the hoses are clean. The one thing that I had done and did not do myself was have the impellers changed. I was present for the job but had a "Mechanic" there doing the work. I helped him at one point when he asked me to clean up the cover plates for the water pumps with sand paper to get the crud off. I noticed that one of the cover plates, the one on the hot engine, had a lot of scoring on it, fairly deep too. I asked if that was OK and he said yes that is normal. So I thought nothing of it. Well in doing more research the other day I found a few in depth articles about water pumps and read that this is a common cause for over heating as too much water gets through those groves at high RPM when demand is high. I had already ordered a new water pump anyway as it is the last thing in the system that I have not changed. Will let you know after I change it. Does not look like fun either.

So I went for the last thing in the raw water system, the water pump. Changed it last night. Didn't get a chance to take her for a run but in the 10 minutes that she idled at the dock both risers were running at the exact same temp (Which it wasn't doing before) and upon physical inspection of the pump the cover plate had some deep scoring and the back wall of the pump was also scored. Had the impellers changed by a marine mechanic, why would he not be concerned by the scoring? Especially of the cover plate. Anyway, I am confident I have made some progress. And the entire system is new(oil cooler, risers, water pump and cleaned heat exchanger). All of the parts swapped out were 15 years old so it needed to be done anyway. Should get time to tale her out in the next few days.

Thanks for all of the suggestions.

Always hate when you find a good thread with all kinds of information being shared and when you get to the end you never really find out it the issue has been resolved. So here is the conclusion. Generally my issue was just poor maintenance by the previous owner. Port motor has newer risers, new oil cooler, and raw water pump. The starboard motor, the one overheating, was still all original (15 years old). I think it was a combination of all of these maintenance parts being replaced that resolved the issue. The last thing I changed was the raw water pump as the face plate had some heavy scoring and the back wall of the housing as well had some scoring. Ran the boat all weekend and the temps never went above 175 degrees. The tops of the risers still get warm, up to 115-120 degrees but the engine temp stayed right at 175. Should I worry about the riser temps? What is a good temperature for the risers?

Thanks to all for the input on my multiple posts as I am learning more and more on these Crusaders.

The top of the elbows will get 'warm'....and your range is within reason.....the master mechanics I used to work for (before IR guns came out) used to say "You should be able to touch it but you won't want to keep your hand on it."

For closure, now that you have things 'working', now is the perfect time to document "normal" operating temps on both engines....the cooling system diagram in the owners book is a decent point of departure - you can use a red and green marker to record the various temps for each engine.

Great Idea. I will do just that. I think I will make a few copies and document temps at 3100 RPM and at idle. Thanks Mark.