496 ho over heating
 

temp gage going to 180-200 alarms going off shut boat down.I checked the raw water pump ok I even swapped the heat exchangers new thermostat Still alarm no antifreeze in the oil.What else could it be?blown head gasket but no signs.















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I'm working through a similar issue with one of my HO's. My water temp would slowly rise at cruise, but cool right down at idle. In my case I drove through a debris field on the river and sucked up wood chips. I flushed the raw water cooling system with a garden hose that was duct-taped to the heat exchanger inlet hose and got some of the wood chips out. However, a test drive proved there were still more. I came up with this flush tool made from 1" pipe, a 1.25" OD joint, a garden hose fitting, and a on/off valve. This gave me much more pressure and I blew out even more wood chips. I used a washing machine lint filter on the end of the seawater pump outlet hose to catch stuff. One chip was about 3" long and 1/4" wide. I can't believe it made it through the drive. I think sea strainers are going to be a project next winter.

http://img.photobucket.com/albums/v2...nic/flush1.jpg

http://img.photobucket.com/albums/v2...nic/flush2.jpg

How many years/seasons on your antifreeze? It silts up after about 6 years and needs flushed and replaced.

Also, is the antifreeze on one engine darker than the other? Dark/metallic antifreeze is indicative of a circulation pump going south.

ok This is the story.the local dealer had the people check the port motor out reversed flush put on the computer and the alarms are going off and the temp is rising.the computer show no faults risers good and cool heat exchanger new new impeller but it didn't make a diffrence.what else!!!!!!!!! please help

Your English is tough to understand. Start from the beginning and work your way through it.

Just because you replaced the impeller does not mean the water pump is good. Are the ends scored causing it to loose prime/pressure? Did you verify the condition of the circ pump? Do you have excess water in the bilge? Have you totally covered the intake holes on the drive while on the hose (hence side and low water pickups if you have them)? Is the engine completely stock? Stock pulley? Are the air actuated drains stuck open? Does it only heat up at idle or all speeds? Do you have a known full coolant tank/system?

Do you have good pressure from the water hose while flushing? You have not really given much info.

Mine would overheat on the hose at dead idle eventually.

It can only be so many things. If your people can't figure it out go elsewhere.

Pull off all the 1 1/4" raw water hoses and verify that there is no debris in any of the coolers regardless of backflush.

SD you are correct.I just rambled on because I was pissed.SORRY It was the circulator pump.

No worries. My dog typed out all those questions after stealing my password.

Frickin' Yorkster.

Glad they found your problem. I found mine, too. All this was stuck in the inlet to the oil cooler. :eek:

http://img.photobucket.com/albums/v2...onic/chips.jpg

Can you Spell Strainer Installation?

Regards,
Ray @ Raylar

check the heat exchanger,,also,,,it gets past the oil cooler to