Water temp zero until shutdown?!

[chrisvr6]

Having a crazy problem. Changed water impeller and thermostat +gasket with brass grommets. Not getting the needle on gauge to come up at all until the motor is shut down. It then goes up to 180°. I can not figure this out. Ran it on the lake all weekend like this. It does smell kinda rich like not atomizing properly maybe? Its a 93 mercruiser 454 magnum. Help!!

 

[Bondo]

Ayuh,..... Which T-stat housin' ya got,..??

Are All it's parts assembled in order,..??

Check the housin', when runnin' with a point, 'n shoot thermometer,...

Ground out the sender wire, when runnin' to see if the gauge pegs out Hot,....

 

[chrisvr6]

No idea which housing. Its a mag motor is all i know. The plastic sleeve is really the only part in there and it only goes one way. The housing is cool to touch This is driving me crazy.

 

[Fun Times]

No idea which housing. Its a mag motor is all i know.

Does it look more like this one
http://www.mercruiserparts.com/Show...+HOUSING(STANDARD+COOLING)+S/N:+0F305000+&+UP

or this one, http://www.mercruiserparts.com/Show...SING(STANDARD+COOLING)+S/N:+0F3519999+&+BELOW

 

[chrisvr6]

The second one.

 

[chrisvr6]

So, what was the outcome? My 454mag is doing the exact thing now after an impeller and tstat change.

 

[Watermann]

Uh oh over 90 day reply to the OP. Sorry didn't notice.

We have the same motor although mines a 1988 and I noticed a similar condition but something I learned along time ago is that heat kills so I haven't worried about it since the motor runs so well. I have a new temp gauge, a 140 degree T stat and an IR gun as well. Our temps are nearly identical and I only see my temp gauge move up to 140 at 4k or better RPMs the rest of the time it's under. I say just be happy your not like 90% of the guys posting here about their dying motors that are overheating!

 

[chrisvr6]

Welp, new season and my 454 is still overcooling. Its so cold that it bogs after i put it into gear while backing out of slip. Not helping that lake michigan is still like 50?.

 

[GA_Boater]

Chris - Moved these posts from the hijacked thread. The best way to solve your problems is to keep your thread active or start a new thread. Look at the Help Tip on top of the page. Thanks.

 

[Fun Times]

So, what was the outcome? My 454mag is doing the exact thing now after an impeller and tstat change.

One thought would to check the condition of the thermostat housing and nylon check ball valves to make sure there opening and seating properly or the housing hasn't corroded away in the ball seating area.

If they're flowing to much water to fast then the engine may not have enough time to warm up like it should.

Also check your spark plugs for being fouled out due to low engine temps.

Also just to be sure, you may want to check that the choke setting on carb is working properly and the area is clean.

 

[chrisvr6]

Changed the balls thinking the same. Has to be something with that plastic sleeve and oring in there since i changed those originally before the problems started.