Sucked up mud, now overheating above idle !! FIXED- Update!!

[supermottl]

Hey Folks<br />First bonehead boating manuever: Dropped a friend off at an unknown dock and stirred up a helluva lot o'mud, then temp spiked hard to 210. I shut er down, let cool, and at idle she's runnin' normal at 140, but temp rises quickly with rpms.<br /><br />Back home on the muffs, definetly not as much flowing through as before.<br /><br />Where should I start looking?<br />1994 Seaswirl Striper, Ford 302, OMC Cobra O/D<br /><br />I was gonna pull all coolant hoses and start checking things, then the risers, then replace H2O pump..... the list goes on<br />Thanks

 

[Lou C]

Re: Sucked up mud, now overheating above idle !! FIXED- Update!!

Probably the first thing to check is the raw water impeller. The original series Cobras impeller is behind a plastic panel at the rear of the upper gear housing, the newer ones have it on the engine like a Volvo. You also want to make sure you don't have debris or pieces of the old impeller in the hose that goes from the transom shield to the thermo housing.

 

[supermottl]

Re: Sucked up mud, now overheating above idle !! FIXED- Update!!

Well, <br />I pulled the water pump (the one on the side of the engine) and sure as hell, it's done for. Seized up, and when you do get it to turn, it's sounding like grit. So, off the the parts house... I loosened all other belts and gave the water pump on the block a spin... All sounds good there...<br />That was an expensive mistake...<br />live and learn

 

[Bondo]

Re: Sucked up mud, now overheating above idle !! FIXED- Update!!

Back-Flush the System, While you have it apart.....

 

[supermottl]

Re: Sucked up mud, now overheating above idle !! FIXED- Update!!

Well, <br />No dice on the water pump (side of engine). Took it apart and the impeller is good, all bearings spin freely. I didn't realize how tight it was to turn, so all is good there.<br /><br />Where should I look next?<br /><br />Bomdo, How does one back-flush? Is it a kit you buy?<br />thanks

 

[Lou C]

Re: Sucked up mud, now overheating above idle !! FIXED- Update!!

I know with the OMC's there is a test you can do to see if it is pumping enough water. but you have to do it fast and be careful. What you do is start it, let it warm up, and then shut it off. Next disconnect the hose that goes from the raw water pump to the thermo housing at the thermo housing. Now you need a helper to hold up that hose while you start the engine. Water should shoot up out of the hose about 2-4 inches. If it does you have enough raw water coming in, so you have to check for blockages in the rest of the system. You can try running the motor (on the hose) with the block drain plugs removed to flush the block out, and if you still have heating problems, you may have to start checking the risers and manifolds to see if they are clogging. How hot do they get while running?<br />I am not familiar with the Volvo style pump on the later OMCs but I know that on the original Cobras the housing has to be sealed to keep it from pulling in air, and you have to check all the wear plates and other parts that can get worn from grit being pulled in the cooling system.

 

[supermottl]

Re: Sucked up mud, now overheating above idle !! FIXED- Update!!

OK, sounds like an easy test. That test will let me know if there's a clog in the lower unit, or the block.<br />Risers run hot enough that you can still touch them, but not forever, and feel consistent with a 140 degree thermostat.<br /><br />Thanks for your help

 

[Lou C]

Re: Sucked up mud, now overheating above idle !! FIXED- Update!!

The manifold/riser on my 4.3 (the oddball ones OMC cast out of one piece) is cool enough that you can keep your hand on it as long as you want even after running on plane, although these are new, just installed this year.<br />Even if your flow is good, you may want to flush out the line that goes from the transom shield (back of the motor) up to the impeller, and then the one from the impeller to the thermo housing. I'd take that off too and check out the thermo to make sure it opens at the right temp (usually OMCs start to open at 160 and are fully open by about 175 or so).<br />Good luck!<br />You have a good one, that is the later Cobra with the cone clutch which is the same as a Volvo SX.

 

[supermottl]

Re: Sucked up mud, now overheating above idle !! FIXED- Update!!

Thanks again Lou<br />I will definetly do that tonight. lucky, I trailer it, so it's way easy for me to work on.<br /><br />As for the later Cobra - Yeah, I heard it's a decent unit. Looking at exploded diagrams, there are so much fewer parts than earlier models. Much better - K.I.S.S = keep it simple, stupid!<br />LOL, thanks again

 

[supermottl]

Re: Sucked up mud, now overheating above idle !! FIXED- Update!!

Update and 95% sure what happened:<br />Started ripping off hoses and worked my way back from the raw water pump. That was good, so I went back from there, folowing the hoses. Found out I have a power steering cooler. Pulled both ends and the intake side of the cooler has a screen in it which was clogged ot hell. I found leaves, seagrass, barnacle pieces and most oddly a clam shell about 1/2" around!!! So, that makes perfect sense why I was getting enough water to cool at idle, but no higher.<br />I backflushed the outdrive with the hose, and only tiny black particles came out. Did the same with the manifolds and all was clean.<br />So, I think I have found my problem. Thanks to those who helped.<br />Now, on to my low RPMs issue....

 

[Lou C]

Re: Sucked up mud, now overheating above idle !! FIXED- Update!!

Hey sorry I did not mention that but it is a known place for clogs to occur, esp on the old style Cobra with the impeller in the upper gearcase of the drive like mine.<br />Mine usually runs at 160 degrees while running and maybe just a tiny bit above that 165~170 at idle.<br />As far as the low rpms issue some things to check:<br />Make sure you are gettting full dist advance at 3000 rpm as per their spec<br />If you have a 4 bbl carb are the secondaries opening?<br />On mine I had an acceleration problem, it turned out to be a bad anti siphon valve on the gas tank, it runs great now, planes out in about 3 sec at 3000 rpms and takes off like a rocket when the secondaries open up.

 

[supermottl]

Re: Sucked up mud, now overheating above idle !! FIXED- Update!!

Lou, <br />The low RPMs just started this past weekend. When I went to start it up, it sounded a bit funny, like 1 cyl. wasn't firing off, but seemed to go away. tonight, I'm going to check each plug buy hooking up my induction timing light, and make sure that the gun lights up on each plug. If I find one plug not firing, that's great. If I find all are firing, then it's prolly the points (I should put in a Petronics ign.), advance, or ???<br />Thanks again