Understand, the issue is you either are drawing in air, or not enough pressure. Clear hose to find if air is being drawn in, and pressure gauge to see if there is a restriction
sounds reasonable. But is 115 degrees here in Havasu. Hopefully can get some cooler weather and get some work done. thanks. One last thought. some time ago I hooked up the garden hose directly to the raw water pump intake with the same overheating results.s Seems that would take away leaks from the outdrive to the pump. No oil cooler on the 350 and the power steering cooler is hollow so not sure where blockage might occur. Question do the fittings on the bottom of the exhaust manifolds that are hooked to the fresh water cooling hose flow from the manifold to the hose or the other way around?
Makes sense. So do you think it would be possible that one of the check valves on the bottom of the exhaust manifolds has failed and is draining off pressure to the water mixer?
Makes sense. So do you think it would be possible that one of the check valves on the bottom of the exhaust manifolds has failed and is draining off pressure to the water mixer?
You bring you a very good point. If the check balls are allowing water to pass thru going into the manifold, then there would not be as much water available for the block, which would cause over heat. Pull it apart and see if they move feely
OK so what is the trick to get the check valve apart. Doesn't unscrew and looks like you should pry it apart but can't make that work either. I swear Mercruiser is getting to be more of a bs outfit every day.
Have not tried to take one apart, but after looking on the net I'm wondering if its not glued together. If you search on 22-863786A1 the whole assembly shows up
Don't know if you can put it in a solution or not to clean, to many different materials
OK new year and time to get started again on this POS.
Symptoms:
Normally runs about 175 degrees at idle or under power.
When throttle from idle is applied temperature drops to about 160 degrees.
When at idle for prolonged period of time the temperature tends to climb up over 180 and starts to put out grey/white smoke out the pipes which goes away in a bit. Temperature again drops to about 160 when throttle is applied.
Under power at cruise temperature runs about 180 but when you go back to idle it again puts out grey/white smoke out the pipes which again goes away after time.
Seems to be creating hot spots or cavitation which in turn causes increases in temperature and the gray/white smoke.
Actions Taken:
Replaced raw pump housing/impeller assembly.
Replaced engine thermostat.
Replaced engine water pump.
Examined both sides of gimbal housing water hose for corrosion (Bravoitis) with no corrosion found.
Removed upper and lower outdrive to inspect for issues with nothing found.
Silicone sealed both quick disconnects on water inlet hose between gimbal and the raw water pump.
Removed all hoses on the front of the engine to check for blockage and corrosion.
Checked hose between raw water pump and gimbal housing for leaks.
Checked power steering cooler for blockage (no engine oil cooler).
Put a reducer in the water line to the exhaust manifolds to try to direct more water to the engine with no help.
Blocked off the drain tubes between the exhaust manifold drains and the water inlet hose to eliminate back feed with no help.
So at this point I am at a loss. Sorry to drag this on for so long but definately need some help. Thanks.
Tried several impellers and finally changed the whole raw water assembly so do not believe that is the problem as it was fine for years. Have lots of water from the side exhausts and checked the diverters which were fine. Also tried to isolate the side exhaust versus the outdrive exhaust (Captain's call) which also did not make any difference.
All the water exits the engine thru the 2 hoses that go to the bottom of your exhaust manifolds. How's the flow look when you disconnect them ? Your block may be filled with sand. What's up with the smoke ? Def. not normal.
The IR temp gun would be good to find out where all of the hot spots are.
In post 23 there is the pic of your hoses. Use some clamps of some sort to pinch off all the quick drain hoses. Doesn't need to pinch off 100% but also would have no effect if it does
the 2 hoses coming from the block drains
the 1 hose going up to the tee and the to the top elbows
the 1 each side coming from the very bottom of the check ball on bottom of manifold
Doing this will make all water flow thru the cooling hoses as it should. If this works then it tells us that something is making the flow go thru the drain hoses instead of the engine hoses
Disconnected the hose between the transom and the raw water pump and hooked a hose up and back flowed water out the outdrive which the flow seemed normal. Took the drains from the bottom of the manifolds, hooked up the hose and again the flow seemed normal and the passages were clean. Guess I will get a heat gun and see if anything looks off or just take it to a local mechanic and see if he knows more than I do. Thanks for the help but I am just plain tired of this issue.
So after 2 years it turned out to be the intake hose from the outdrive to the gimbal. Not bravoitis as there was no real corrosion. The hose looked good on the outside but must of had internal damage which caused the hose to collapse under suction. Special thanks to Quality Marine in Lake Havasu who busted their butts to get the job done without pulling the motor as called out by Mercruiser. What a screwed up design by a bunch of pin head engineers who do not care about the end user. I have had an OMC on my first boat, Volvo on the second and now Mercruiser on this one. I thought Mercruiser was suupposed to be the best but it is by far the most screwed up of the bunch.
I've found that both OMC and Volvo used a much simpler cooling system design. Maybe because the older OMCs and Volvos did not have the foolish single point drain which is just a cheapskate way of avoiding making closed cooling standard as it should be.
It's good that the shop kept at it and found the cause.
