Overheating blues

[COOL CROSSBOW]

Hi gang i am new to the boating thing but not to engines in general so i am just learning about how the water cools these engines the hard way, school of hard knocks. I am helping a friend with his 87 z33 crossbow, he bought this DONZI on ebay in Arizona some one here may know this boat it is white with wild graphics . Boat looks grate but little did we know how badly riged up this boat is/was. Sence he got it its been in the water four time no longer than 10 to 15 minits due to one of the 2002 502s keeps running hot. Heres how it began. First time in the water engine runs hot so hot it melts some make shift plastic water line in the exhost manifolds and cracks one head. To the shop for repair.$$$$ Wile there we find out how riged this boat realy is , there is romex house wiring running through the engine bay. We all so found ricpts for new water pump,hoses and thermostat, wich tells us this has been going on before us. After geting it running back to the water it runs hot again. Now we learn about seapumps $$$ oh and the ignition box gose out $$$ new box and dist. Back to the water to day, 10 minites runs hot now we learn about seastraners well it was plug so bad we removed it but it still runs hot.:confused:

[COOL CROSSBOW]

What i dont under stand is with a water hose hooked up it dont run hot but when in the lake it dose. Can someone give me some suggestions, as i am looking at a crossbow my self i realy like these boats and want to learn as much as i can.:boggled:

[zelatore]

Given the way you describe the boat, it sounds like you need to start at the beginning and work your way through the cooling system. Any number of things could be causing the problem, from simple to expensive. Since the previous owner was clearly a brilliant fellow, you could have anything from a hose installed wrong to a blown head gasket.

Is it fresh or raw water cooled?

Do you get any water flow out the exhaust?

Sounds like you've checked/replaced your impellor? Was it running dry? If it was bad, did you find all the parts of it when you removed it?

[COOL CROSSBOW]

Well check the routing of the hoses with the other engine.

Still green on the terms fresh or raw it gets its water at the base of the boat through a small pipe.

The first trip there was only steam and smoke, the smoke was the cheap plastic water line in the manifold melting. Steam was blown headgasket and cracked head.

Wasnt there when the seapump was repaird but i know what you mean i just read a post on how to repair on and it said to check for small pises that could plug the system.

[Lenny]

Could it be the "spellcheck" trying to run in the background that is making it overheat? :kingme:

Just kidding, but ... WOW


grate, riged, Sence, minits, exhost, Wile, riged, romex, ricpts, wich, gose , to day, 10 minites, seastraners, plug, under stand, dose, my self, realy, repaird, pises

Sorry, I had to... :nilly:

[COOL CROSSBOW]

HAHAHAHA i know, i have been dislexit sence 3rd grade and i get tired of trying to type with one hand and use this dictionary with the other. It wood take all night to type any thing. Yall can laugh belive me im use to it after 39 years , at least it doesnt afect my job sence i own the company or my engine building and tuning ability:cool:

I cant keep a good spell checker they keep quiting on me:rolleyes:

[MOP]

If it runs cool on the hose and hot in the water the pumps are not pulling water in, you may have cooked them with the plugged strainers.

[joseph m. hahnl]

Engine's water pump, check riser for correct gaskets and replace.
also there should be water coming out the exhaust pipe. If there isn't any water getting through.More head gaskets in store. Fresh water and raw water?????? what he means is closed cooling" uses a heat exchanger " Half cooler> cools block, Full cooler> exhaust manifold is also cooled with coolant.Raw water > runs out board water through entire system which it sounds like you have seeing is how you never mentioned Anti freeze "AKA coolant" in any case raw water must all ways pass through the exhaust one to cool it down so the rubber hoses don't cook.two to give it a place to get back out of the system.
Also check the thermostat housing for corrosion and blockage.

[gcarter]

Buy yourself a Merc manual for about $25.....you'll find it very helpful.
Everyone here should have one.
They're available at any Merc dealer and most major bookstores.

[harbormaster]

look in your oil cooler for pieces of rubber impellor. Sometimes when go and come apart, they get lodged in the oil cooler on the engine and block water flow causing overheating problems.

Do you have a water pickup or are you picking up water from your Bravo drive? If still using the bravo as water intake make sure you are getting enough water. The Bravo transom assemblies are notorious for corroding up and choking down the plastic hose fitting that the water comes through.

[BigGrizzly]

A cloggedf strainer takes out an impeller in a hurry. You spell Like me so That I don't care about. from what you describe -runs on hose but not in water is a water pump deal, it gotten too hot it can take out the T-stat.

[COOL CROSSBOW]

Thanks guys thats y i joined this site. I have been reading all your helpfull threds. Madpoodle i think your on target. I had thought of an air leak but sence it didnt show up as a leak under presher from the water hose i asumed it wasnt sucking air. I will recheck the seapump from what yall say and what just read. the seapump can be damaged after start up if it doesnt get water soon. And check the pasages to the oil coolers. Thanks agen and i will post what i fine. And i will get a manual.:yes:

[COOL CROSSBOW]

I just talked to my friend he is a little pissed right now, i said whats up. He said i just spent another $$$$ on nothing. He found a hose running under the engine that when in the water it sucks flat like on a car top radator hose when the thermostat opens and theres no water. He says this winter we are going to redo the cool system correctly. I just hope this doesnt deter me from buying the one i want cause its a gorgeous boat just like CAPTWK z33 was but if you cant have any fun with it in the water whats the point.

[COOL CROSSBOW]

I have the boat at my shop now and going to rebuild these 502s. We did fined the problem ill discribe it the best i can. When on the garden hose it gets water just fine but when in the lake it runs hot. Well we found a check valve of some sort that switches from hose water to lake water it was corroded so bad it wouldnt switch thats why it wouldnt get any lake water. Now on to these engines ill be asking questions about them to like cam and intake choises they do have stainless marine manifolds with elbows, but i cant put them back in the boat stock any suggestions.:cool!:

[BigGrizzly]

That is a common problem. I was lucky I saw it and did not like it and took it out before it was a problem and put a T in the place of it. I did this because all my boats have a T with a valve. Just because I do it that way.

[Trueser]

You may want to have a survey done. I would look at the stringers and transom and make sure they are solid.

Why are you not using the stainless marine manifolds?

Welcome to Donzi.net

[COOL CROSSBOW]

Oh i am, i was meaning the engines are stock 2002 502s with the Stainless manifolds and i want to up grade them. I am no expert on boat engines but i do build a lot of blown bbc/sbc NOS and turbo motors and there all camed diffrently. What i have learned so far is that a mairne cams over lap plays with the way water flows through the exh, manifold.

So you think its better to remove those check valves and put Ts in, ill have to check that other one out too.

[chappy]

Just like Griz, I pulled a similar check valve, and replaced it with a T after it corroded. Only took me two months of goofin' around and overheating to find it.:bonk: No issues since.

[BigGrizzly]

Btw Chappy works at a marina so don't feel bad. BTW that valve you have cost between 50 and $120 plus installation. So at this point your ahead of the game.

[COOL CROSSBOW]

Can yall tell me where the original fresh water cleanout was because this is rigged up. That valve was a JP MARINE and has cost as much as $3000 in bills.
Im thinking of putting a T in line after the ball valve after the sea strainer and before the sea pump that way i can hook the garden hose up and switch the valve and run water straight to the sea pump, i dont want to burn up the sea pump. It is amazing how much water they can pump at idle.

[BigGrizzly]

Cross bow that is exactly what I did. Always turn on the water befor starting the engine.