Not warming up to temp??

[further]

Hey guys, so finally splashed today after months of cleanup and maintenance work. She ran pretty much flawlessly. Got up on plane very quick. Noticed however that it's not reaching the operating temp I thought it would...around 160?? Stayed at around 120 the whole time and I shot the risers and manifolds with and ir gun. Risers/manifolds, Tstat and housing are all new. Waterpump and impeller is brand new. All hoses are new. Any ideas??? Thanks in advance.

 

[bruceb58]

So what does the IR gun say when you measure next to the temp sender?

 

[further]

Not sure where the temp sender is. Ir gun measured between 115-120 on the risers and manifolds both sides and 120 on the Tstat housing. Shot a couple spots on the block and that was a bit warmer at 130ish.

 

[further]

Maybe the Tstat is stuck open??? It's brand new but maybe defective. Possible I guess?

 

[dypcdiver]

Remove the thermostat housing and check the bypass port does not have any debris blocking it. A flexible piece of wire will do it. I had the same problem for 2 seasons until I was advised on here to check the bypass, I got 2 vanes from the raw water pump out of it, I could not see them but the wire got them out. Seemingly the extra pressure due to the blockage opens the thermostat.

 

[further]

It's all new so don't think anything is stuck in the ports of the housing. Still leaning towards a defective Tstat. Either way looks like I need to open it up and test it. Just want to confirm that a stuck open Tstat would cause this??

 

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So got the tstat housing off today and tstat seems fine. Tested it in a pot of water along with a new one that I picked up just in case and both opened at 160 and fully open at around 170 then closed fully when I took them out. So I turned my attention to the housing. The housing is brand new as is mostly everything else. This is what came out after running a abraded wire through the bypass port and through the manifold ports....



It's like sand?? At first I thought maybe the old impeller disintegrated before i got into the housing but that's not possible because before I replaced the water pump with a new pump and impeller, I put a new impeller into the old pump before I ran it. Maybe this is just leftover gunk that was in the out drive, oil cooler and hoses I didn't replace, before the water pump and plumbing up tot he tstat housing? Anyway, all ports are cleaned out and there's nothing that is blocked so hopefully this will do the trick and get her up to normal operating temp.

Bruce,
I found the sender.... It's on the intake manifold right under the tstat housing and was covered up by one of the hoses going to the tstat housing. At least I know where it is now
I was measuring near its vicinity with the IR gun when I was getting the 120-130 readings.

 

[BRICH1260]

I had the same problem with my last boat. Found out I had a clogged bypass port in the tstat housing, clogged with small piecies of an impeller.

 

[further]

Yep that seems to be the common culprit...

 

[BRICH1260]

That sand could be left over from the casting that was never removed during manufacturing.

 

[further]

So finally go around to re-installing the tstat housing (moved to new place and have been spending most of the summer with home improvements instead of at the lake :facepalm after cleaning it out. Fired her up an she warmed up beautifully to about 160 and stayed there. Mani's and risers felt cool to the touch and all good. Now just gotta find the time to get on the lake again.
Thanks all for the advise as usual!