1998 5.7L Bravo 1 seems to be overheating

[string]

Hey all...

Similiar problem to many others....boat is overheating.
Replaced the impellar, circulating pump, t stat, all with OEM parts...still over heating...or seems to run hotter than before.

I can run water from a garden hose a garden hose through the inlet to the tstat housing and it seems to flow freely out the end of the hose near the seawater pump. I can also run water though each hose to the manifolds and it seems to flow freely out each exhaust. If water runs freely out the exhaust would that rule out blockage in the risers?

I pulled the drive and can run water through the drive. Also can run water through the gimball ring inlet and it come out freely the end of the hose near the seawater pump.

Seems like this started when I either replaced the seawater impeller or circulation pump. ( did each items separately)

When you replace the tstat, if you use gasket sealer, can that affect the grounding of the sensors?

Also the starboard riser gets warm ( can place your hand on it ), and the port is cold....

Any other thoughts...thanks

 

[Andys454]

Re: 1998 5.7L Bravo 1 seems to be overheating

I had a similar problem with my 98 454 bravo 1. It turned out to be a sticking t-stat. This was after my sea pump gave out and I replaced it. I also found lots of impeller rubber pieces in the hose and heat exchanger.

 

[wire2]

Re: 1998 5.7L Bravo 1 seems to be overheating

With the boat in the water, undo the supply hose to the thermostat housing, (from the steering heat exchager, along the rocker cover). Idle the engine.
Is there several gallons a minute coming out of it? If not, the impeller in the outdrive is not pumping, or a passage is blocked.

The temp sender is usually in a threaded hole separate from the T-stat housing.

 

[string]

Re: 1998 5.7L Bravo 1 seems to be overheating

thanks wire2, I'll give this a try and post an update

 

[carcraze]

Re: 1998 5.7L Bravo 1 seems to be overheating

The grounding of the Tstat housing depends on the style of housing. Mine is the style which required the copper rivets in the gasket to ground everything. Not sure about yours but if the replacement gashet does not have copper rivets then it should not be an issue.

When mine was not grounded, it had a high resistance reading when I check it, the gauge read cold, would not register the engine temp. Your problem sounds as though it registers hot so I would think it is not related anyhow.

When checking the manifolds and such with a hose I would think putting a pressure gauge on the hose feed into the manifolds and compare the pressure readings. A high pressure should indicate a blockage somewhere worse case it may give you something to compare the 2 manifolds to one another.

just a thought