View Full Version : 5.7 Overheat

10-08-2011, 09:20 PM
OK here is the situation... I have a 25 Luhrs with twin FWC 5.7's. STBD engine is running hot I have changed the manifolds, risers, sea water pump, thermostat, gauge temp sender, and radiator cap. As soon as I fire it up at the dock it runs right up to 175 and holds there. If underway it runs up to 190 at about 2800 RPM(not gonna push it any further). I swapped the leads for the gauges so its not the gauge. I checked the cooler while it was running for bubbles and I'm not losing any coolant.So the next step is to pull both coolers and have them cleaned...Looking for ideas...Maybe the fresh water pump might be worth doing without the cooler on?

10-11-2011, 03:04 PM
half system or full man and eng fresh cooled?just risers saltwater? buy a heat gun there cheep and great harbor frieght has them 39$ ck all the hose con on the good eng with heat gun write them down and mans thermo housing see what you got also the salt water hoses that go from the tank to the risers take them off one the good eng start it and see how much flow you have? you may want to add on the hose after you take them off so it will just flow away from eng then do the same on bad eng see if they look the same?i wouldnt change anythig utill i see the flow

10-12-2011, 08:18 PM
Turns out the cylinder head is cracked.

I'm going to tackle this on my own and was wondering if anyone would share some tech advice and tell me the torque sequence and spec for this head.


11-04-2011, 04:56 PM
Baxter go to marineengine.com and get the correct manual for your engine, you're going to need it sooner or later , so you might as well get it now.

11-04-2011, 11:30 PM
Check the original cylinder head casting number against SBC Cylinder Head Casting numbers that you can find when doing a web search.
There were some light cylinder head castings that slipped through the cracks over the years.
You'll want to avoid these castings.
Also make sure that the combustion chamber volume is correct.