5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

[markindaytona]

ok, two months ago bought a 1990 Sunbird Cuddy with a 5.7 OMC,had some over heat problems, dealer replaced: water pump, impeller,still ran hot installed new manifolds and risers today, water tested it ready to have some fun... WRONG ,,still running hot, port side more than starboard, and water being discharged from starboard exhast at back of boat is huge jet of water, while nothing but steam from port side, Im ready to call it quits with the %#@( thing can anyone offer advice what to check or ever heard of this situation before......thanks mark

 

[P.V.]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

Have your dealer recheck the impellor housing on the outdrive. Often the stainless cup, inside the plastic housing, will "spin" slightly and block off some of the water passsages. That's what I'd do first! Also, have him run the motor in the water, and remove the incoming water hose(located at the thermostat housing), hold it up and you should have about an inch "head" of water at idle, at least! More at higher rpms. Then start checking manifolds/elbows for blockage, ie: rust, scale...

 

[flashback]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

I don't know what the plumbing looks like on an omc, but on a merc there is a slew of hoses for cooling the manifolds and risers, and if anyone of those is plugged up it could cause what you are experiencing.

 

[markindaytona]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

thanks for comments will pass em on to dealer today, as for removing hose at t-stat, that is exactly what i did last night on the river, checked both sides for comparison, wondering if it isnt a blown head gasket???? cant figure why i gat water blow out on one side not the other, shot both sides with a temp gun, only a 6-8 degree variance, nuch better than the old 40 degree before new manifolds wer installed

 

[llerrad]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

Check plugs to see if they have been steam cleaned which could mean blown head gasket.

 

[markindaytona]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

# 2 UPDATE: DEALER STROKING ME...EVERYTHING IS NEXT WEEK....PULLED FLUSH VALVES OFF GOOD SIDE HAD GOOD STREAM OF WATER, BAD SIDE NO FLOW, RAN WIRE UP IT GOT FLOW GOING RAN HOSE STRAIGHT INTO T STAT HOUSING FLUSHED GOOD, WE WILL SEE, IM WONDERING IF I TAKE IT OUT TO RIVER RUN IT AND OPEN FLUSH VALVE AND RUN IT 1/2 THROTTLE WOULD WATER FLOW CLEAN REST OF JUNK OUT OR WOULD IT HURT THE ENGINE ????? OTHER IDEA IS TO DRIVE BOAT THROUGH WINDOW OF BOAT DEALERS SHOP.....HMMMMMM

 

[markindaytona]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

PLUGS ARE OK. PULLED T STAT TODAY FLUSHED BLOCK, SOME SAND SLUDGE IN BAD SIDE CLEAR H2O ON GOOD SIDE, ANY OTHER IDEAS ON ASSURING I FLUSHED EVERYTHING OUT? IF I WERE TO TAKE IT TO RIVER AND RUN AND UNDO ONE FLUSH VALVE TO FORCE MORE WATER THROUGH WOULD IT HURT ENGINE?

 

[Stanp]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

test

 

[Ralph 123]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

When you say he installed new risers and manifolds do you know for sure they were brand new? Were the elbows replaced as well? That sound an awful lot like a messed up manifold/riser/elbow<br /><br />I'd appreciate it if you would keep us up to date on what the outcome is.

 

[markindaytona]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

ralph, manifolds are new osco's i opened the box myself risers are oscos, elbows have not been replaced you think thats the problem...monkeyed around with it tonite some more in the yard( seems it spends a lot of time there ) water ears dont really tell the tale, i undid the hose coming from the lower unit to the oil cooler, wasnt a great deal of flow, was running abut1000-1200 rpms, still had some but temp was decent, after reading some prior posts on overheating im wondering if the impeller is shot even though it was the first thing replaced,water pump is new, im beyond baffled, if weather would cooperate ill water test tomorrow in river...will keep you posted, thanks

 

[Ralph 123]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

Could be. Elbows last approximatly 2 years. Manifolds tend to fail at about 4 years<br /><br />Check this out:<br /><br /> Mercruiser Exhaust

 

[GodsBeast]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

I hope I don't live to regret that Boat through the window of the boat dealer comment! <br /><br />GodsBeast

 

[Bondo]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

Check the inbound side of the oil cooler.....<br />Many times a broken/ lost impeller vane will lodge there....

 

[markindaytona]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

end result. after all this they found two stuck valves, did head job on engine, are "rebuilding/puuting it all back together" all parts now, mech. said stbd side ( problem side ) was full of sand almost to top of freeze plugs, so now i have new manifolds risers,pump impeller, heads, gaskets, starter, u name it its new.....hopefully will hit the water the 1st of next week, will keep you posted , THANKS to all who replied to my questions, and all advice given it is appreciated. this site is pretty cool, allows mechanical morons like me to know what to ask and look for so shady dealers dont try to take me or my wallet to the cleaner !!!!

 

[doubleDs]

Re: 5.7 OMC Running Hot and Steaming,CAN ANYONE HELP ME FIGURE THIS OUT ??

how do you check to see if the valves are stuck i'm having the same problem. did you have to pull the whole thing out? thanks