Uneven riser temperature after pump replacement

[dsiekman]

Hey guys, I am reposting this in its own post instead of as a follow up to my previous issue - Over the weekend I replaced the raw water pump on the stbd VP 5.0Gi PWTR. I also replaced both port and stbd temp gauges with new Faria gauges to match the existing (Long story covered in another post:facepalm. The stbd riser is running consistently 10 degrees hotter than the port riser(128 vs 118). The temp gauge is registering about 170 which is about 10 degrees hotter than the port engine. My first thought is a blockage in the thermostat housing before the stbd line out but I have not had time to check into it. Hoping to tonight. Thoughts?

BTW - This is a new bronze VP raw water pump. I ran the boat for about an hour Monday night and the stbd engine held steady at 170 while the port engine held steady at 160. I've only had the boat a year and do not know if the manifolds/risers were done by the PO. Then engines have about 190 hrs on them and I boat in brackish though mainly fresh water. My marina is near the headwaters of a tidal river off the Chesapeake Bay.

 

[dsiekman]

Re: Uneven riser temperature after pump replacement

Okay, so I just got back from the boat. Didn't find anything out of sorts. I pulled all the hoses off the manifolds and tstat housing. All were relatively clean. Stuck a finger in the inlets on the manifolds. They felt nice and smooth, as did the inside of the block. Not sure if that means anything, but it was different than the inside of the tstat housing. The housing was VERY rough and pitted. The tstat was pretty cruddy too. Not sure if that has anything to do with my issue or not.

Is it possible that this new VP pump just doesn't put out quite as much water as the old one? The impeller came installed in the pump - don't know how long it has been sitting on the shelf - could it be bad? Am I making too much of a 10 degree difference? HELP!

 

[Don S]

Re: Uneven riser temperature after pump replacement

If this is happening on the muffs, it's normal for risers to vary in temp. I's usually more than just 10 degrees. Even at idle when in the water it may vary. But when on plane and running under load, they will even out.

 

[dsiekman]

Re: Uneven riser temperature after pump replacement

Thanks, Don. I'm already into the expensive stuff pretty heavy this season (drives rebuilt, props tuned, sea water pump, trim cylinders, etc.) and I'm hoping it is all squared away for the summer. I was planning to do manifolds and circ pumps next year. I will probably replace the port sea water pump later this season. I'd rather be safe than sorry, just can't do it right now.

This was in the water that the two manifolds were running different temps. It wouldn't concern me quite as much if the two engines were both at 160. Since I have the housing off I am going to replace the tstat. Don't really think it will help, but since I'm already in there...

What temp should the manifolds be reading?

 

[Don S]

Re: Uneven riser temperature after pump replacement

Should be about the same as the engine.

 

[dsiekman]

Re: Uneven riser temperature after pump replacement

Sorry, I meant risers.