James Lee
Member
Also. There is one of these on the other side of engine also. Same place ? Right below the 2-3 spark plug?
Engine Overheating at Higher Speed/RPM, Helpful Solution
- Thread starter WayneP
- Start date
scoflaw
Well-Known Member
- Aug 10, 2011
- 6,395
- Boat Info
- 1999 Powerquest legend 260 sx 502 mag
2005 Baja 242 islander 496
- Engines
- 502 mpi Bravo 1
496 mag B1
Yes and I blocked off both so I get full flow to the manifolds but I'm not in a freeze zone either so have no use for this feature.
Sounds like you must have opened up/cleaned out something to increase the flow. Removing pipes may have dislodged the blockage and it washed itself out. Temps like that are very good, depending on thermostat that you are using. I am running a 160 marine thermo and my 6.2 MPI now runs between 160 and 170 depending on water temp in river, been around 82 F, and RPM/speed. Sensors are not super accurate so you can expect some difference between them even if both have same thermo. I totally removed my in line anti flow back valve which only had two hoses and a winter drain. I have seen your style on engines but have never touched one.
James Lee
Member
Well my problem still exists. I thought I had it fixed last year. But just put the boat in water last weekend and overheat alarm went off going to dock! How does this anti flow valve come off the engine to clean out. I will take another look at it. Last year. I wasn’t able to get it off I was only able to get 1 hose off
thank you for your replies !!
thank you for your replies !!
James Lee
Member
James Lee
Member
Well my problem still exists. I thought I had it fixed last year. But just put the boat in water last weekend and overheat alarm went off going to dock! How does this anti flow valve come off the engine to clean out. I will take another look at it. Last year. I wasn’t able to get it off I was only able to get 1 hose off
thank you for your replies !!
thank you for your replies !!
Hello: I did more research and discovered that the valve on my engine was actually OEM and not some aftermarket add on.
The Mercury part number is 21-862271A1. It is Blue and Yellow plastic with a blue drain valve on the side. Inside was a one way ball valve totally jammed with crud. I can believe that they could be intermittent as mine surely was. It was located right behind belt tensioner and above the steering pump. Held on by two standard hose clamps. It many be hard to find at first as it hides right behind the belt adjuster bracket. NOTE: I discovered that there are many versions of this valve in different locations. Because of the location on my engine I can agree that the connectors are not easy to access. Leaving the darn thing off as I am not convinced that preventing a quart or two of water to flow back can hurt anything. The only issue is stopping a red hot engine, the water could flow back and prevent static cooling. But the high risk of jamming and compromising flow is not worth this static cooling potential. Others chime in?? Glad to help.
The Mercury part number is 21-862271A1. It is Blue and Yellow plastic with a blue drain valve on the side. Inside was a one way ball valve totally jammed with crud. I can believe that they could be intermittent as mine surely was. It was located right behind belt tensioner and above the steering pump. Held on by two standard hose clamps. It many be hard to find at first as it hides right behind the belt adjuster bracket. NOTE: I discovered that there are many versions of this valve in different locations. Because of the location on my engine I can agree that the connectors are not easy to access. Leaving the darn thing off as I am not convinced that preventing a quart or two of water to flow back can hurt anything. The only issue is stopping a red hot engine, the water could flow back and prevent static cooling. But the high risk of jamming and compromising flow is not worth this static cooling potential. Others chime in?? Glad to help.
James Lee
Member
Thank you Wayne, here is a pic of what I thought you were talking about last season. It is located on port side of motor between the 2nd and 3rd spark plug. Is this what you are referring to?? Last year I was not able to get both hoses off and could not see how this comes out. Is it threaded ? Do u just pull it out. I’m going to try again today. Thanks for reply
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James Lee
Member
Here is a diagram I found of what I think is the check valve on my engine 8 is the fitting that is threaded, 10 is the ball check, 11 is the “fitting” I’m hoping I can just unscrew this after removing the hoses and check for impeller pieces or gunk. I’m also going to get to the power steering cooler and try to back flush. Thanks so much for your input. I’ll let you know how it turns out
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This is what mine looked like. Yours looks like it is a dual valve. Built in anti flow back and diverter valve. Looks like two ports are standard hose clamps like in this picture but the other is a PIPE THREAD that threads into the manifold or block. The valve is most likely plastic so a good chance it will break if you try and un tread it from the engine. Plastic threads in cast iron often break when trying to remove the valve.
NOTE: I have seen several different versions and locations for this valve. I would not try to un tread it from the engine just try and flush it where it is, with water or compressed air. Or if brave, try to remove with only hand power, it may come right out?
NOTE: I have seen several different versions and locations for this valve. I would not try to un tread it from the engine just try and flush it where it is, with water or compressed air. Or if brave, try to remove with only hand power, it may come right out?
James Lee
Member
Got it thanks so much
James Lee
Member
Update:
tonight I just had a few hours but here is what I did:
1. New water pressure sensor - psi went from 0 to 2psi at idle. So I’m thinking the sensor was toast. So this part may be solved I hope
2. New temp sensor - no change and interesting after I started motor after installing it smartcraft gauges said, “no starboard engine” which is weird because this is the port engine. I did a master reset on smart craft and reconfigured everything. Working fine now but temp is still rising over 160 at idle and at high speed over 3k. I took it out for a ride and it got up to 185 but no alarms. This doesn’t seem right. Alarm usually goes off around 175 ??? If I back rpm’s down to 2.5k temp goes down
3. Got back to dock flushed all hoses I could get to. And checked flow as mentioned from some of you earlier. All seems good. For the life of me I cannot get to the cooler behind the engine to disconnect hose and back flush. But with the new psi reading 2. Im thinking there are no obstructions there 1-2 psi at idle is normal so I’ve read
4. Check Valve- was not able to remove it. It is threaded in I could turn it but I didn’t seem to want to come out and I was afraid I’d break it. I was able to flush it and used a bore scope to look inside for impeller pieces. I saw nothing and it looked clean. No rust etc.
5. I pulled the t stat and am going to check it in pot of boiling water. It is a new t stat put in last fall. So I don’t see how it could be bad but maybe it is.
next I’m just going to go ahead and install a new Harin in pump on Sat
we’ll see if that’s it.
thanks for all replies. Keep ya posted
tonight I just had a few hours but here is what I did:
1. New water pressure sensor - psi went from 0 to 2psi at idle. So I’m thinking the sensor was toast. So this part may be solved I hope
2. New temp sensor - no change and interesting after I started motor after installing it smartcraft gauges said, “no starboard engine” which is weird because this is the port engine. I did a master reset on smart craft and reconfigured everything. Working fine now but temp is still rising over 160 at idle and at high speed over 3k. I took it out for a ride and it got up to 185 but no alarms. This doesn’t seem right. Alarm usually goes off around 175 ??? If I back rpm’s down to 2.5k temp goes down
3. Got back to dock flushed all hoses I could get to. And checked flow as mentioned from some of you earlier. All seems good. For the life of me I cannot get to the cooler behind the engine to disconnect hose and back flush. But with the new psi reading 2. Im thinking there are no obstructions there 1-2 psi at idle is normal so I’ve read
4. Check Valve- was not able to remove it. It is threaded in I could turn it but I didn’t seem to want to come out and I was afraid I’d break it. I was able to flush it and used a bore scope to look inside for impeller pieces. I saw nothing and it looked clean. No rust etc.
5. I pulled the t stat and am going to check it in pot of boiling water. It is a new t stat put in last fall. So I don’t see how it could be bad but maybe it is.
next I’m just going to go ahead and install a new Harin in pump on Sat
we’ll see if that’s it.
thanks for all replies. Keep ya posted
Espos4
Well-Known Member
What were your water pressure readings at 3k rpm?
James Lee
Member
Ahh crap! I forgot to look at that when I was out ! I think that should be around 7-10 ?? I’ll have to check next time I get out there. Before I replaced sensor it read 0 all time or never got above 1-2
James Lee
Member
Update - I just installed a mercury tstat to replace the cheap Amazon off brand I installed last fall. Check out the pic of the difference between the 2. Right one in a mercury brand new. Left is cheap one less than 1 month and use.
I’m making progress. I cruised at 3500rpm for solid 25 min. Temp stayed at 163 entire time. Thought I had it. With old stat doing this temp read 180 and alarms went off
I then thought I should open up the throttle. I went full throttle and as soon as I did I got a low pressure alarm and it went in Gaurdian mode and temp went up quickly to 180. Pressure at 3500 rpm was reading 3-4psi with new psi sensor. This seems low to me. Thought it should be around 7-9. Other engine was reading 5psi. Stays cool at 158 doesn’t move
so im left with 2 possibilities. 1. I think. Impeller pieces stuck somewhere and I cannot find them and I cannot get to rear it of engine to back flush cooler or 2. the pump it’s self is scored or damaged and cannot pump adequately at higher rpm’s.
so I’m off to grab a beer and wings then going back to install new Hardin pump. If that doesn’t fix it. I’m gonna have to call in a pro
I’m making progress. I cruised at 3500rpm for solid 25 min. Temp stayed at 163 entire time. Thought I had it. With old stat doing this temp read 180 and alarms went off
I then thought I should open up the throttle. I went full throttle and as soon as I did I got a low pressure alarm and it went in Gaurdian mode and temp went up quickly to 180. Pressure at 3500 rpm was reading 3-4psi with new psi sensor. This seems low to me. Thought it should be around 7-9. Other engine was reading 5psi. Stays cool at 158 doesn’t move
so im left with 2 possibilities. 1. I think. Impeller pieces stuck somewhere and I cannot find them and I cannot get to rear it of engine to back flush cooler or 2. the pump it’s self is scored or damaged and cannot pump adequately at higher rpm’s.
so I’m off to grab a beer and wings then going back to install new Hardin pump. If that doesn’t fix it. I’m gonna have to call in a pro
scoflaw
Well-Known Member
- Aug 10, 2011
- 6,395
- Boat Info
- 1999 Powerquest legend 260 sx 502 mag
2005 Baja 242 islander 496
- Engines
- 502 mpi Bravo 1
496 mag B1
The power steering cooler is a straight through shot that won't trap anything
James Lee
Member
Problem solved folks! I just want to thank everyone for your replies. I think I took a little nugget from everyone to solve this :
Before I dropped this new Hardin pump in I thought I’d take one more crack at the the ps cooler in the back. I was able to get hoses off to backflush. When I did very little water came out. Hello, a clog someplace !! There is a check valve in this side too. I knew there was one on the other side but I did not see this one. I was able to get to it from under the engine. Follow the outlet hose from pump and it goes back to an elbow fitting then up to this check valve. I was able to remove that hose and BINGO! Full of bunch of impeller pieces. It was really packed in there. Had to take some long handle needle nose pliers to grab what I could. Then was able to back flush!
Put it all back together and bam! All fixed. Took her out ran full throttle for solid 20 min. Temp stayed right at 165 didn’t budge and my water psi was 12-13 !!! Much better than the 3 it was getting before.
My current pump is still good and I hope to return the Hardin.
Wow what an adventure. But now I know what to look for. It’s pretty easy to fix. Lol see pic of the culprit that eluded me for a longtime in pic. And thank you all so much for all your comments
Before I dropped this new Hardin pump in I thought I’d take one more crack at the the ps cooler in the back. I was able to get hoses off to backflush. When I did very little water came out. Hello, a clog someplace !! There is a check valve in this side too. I knew there was one on the other side but I did not see this one. I was able to get to it from under the engine. Follow the outlet hose from pump and it goes back to an elbow fitting then up to this check valve. I was able to remove that hose and BINGO! Full of bunch of impeller pieces. It was really packed in there. Had to take some long handle needle nose pliers to grab what I could. Then was able to back flush!
Put it all back together and bam! All fixed. Took her out ran full throttle for solid 20 min. Temp stayed right at 165 didn’t budge and my water psi was 12-13 !!! Much better than the 3 it was getting before.
My current pump is still good and I hope to return the Hardin.
Wow what an adventure. But now I know what to look for. It’s pretty easy to fix. Lol see pic of the culprit that eluded me for a longtime in pic. And thank you all so much for all your comments
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