Suzuki DT-4 overheat

[Sylva-Ranger]

Suzuki 4 hp 2 strokes 1985 DT-4 00402-505089

Cold the engine run well, water pump pump normaly ............After few mins the water stop pumping water and overheat.

​I change the impeller and gaskets, the pump,s cup is good.

​All the seals and groomet from the pump to behind the powerhead are ok

​I removed the powerhead to inspect and change the gasket,

the pipe beetwin the pump and the powerdhead is good to.

​i also removed the head gasket to blow and clean the water passage and everyting seem to be good. In fact is not a realy cylinder head, is more a water passages cover gasket (like certain Merc).

​is like when the engine reach a certain degres of temperature, the water stop circulate. when you stay the engine cool down and restart,the water begin to circulate again.

​More you go faster, more the water sudently stop to circulate .

​Any ideas ?

 

[raczekp1]

look into water pump housing if there is bleeding hole. it should be not be blocked.
i think there is a problem

 

[Sylva-Ranger]

All in the water-pump seem to be good, and that pump perfectly until the engine is warm............I saw different old thread here in I-Boat and some others that have exactly the same problem on DT-4 , and anyones seem to find the real trouble.

​Is like if a cracked block begin to leak a certain temperature, making exaust pressure going into cooling system, and making normal water circulation bad.

 

[robert graham]

Does the motor have a thermostat that may be faulty?

 

[Sylva-Ranger]

Does the motor have a thermostat that may be faulty?

No thermostat on that engine.

 

[River Explorer]

Take the exhaust cover off too. It maybe a fin off the impeller. Cold it may not flex enough to plug it but warm it may move into blocking it. I think k there's a narrow water way that goes beside the exhaust.

 

[Sylva-Ranger]

I find this thread and maybe 10 others aroud the world that have exactly the same problems whit similar DT-4 engines......

http://forums.iboats.com/forum/engi...oard-brands/438847-suzuki-dt4-cooling-problem

​But no ones seems to find exactly where is the problem .........Many tell that removing the rubber plug ( opening to disconect the shif-rod) help a bit by reducing the pressure build in the exhaust housing.........Some people things thar may be a crack in the block escaping ex pressure into the cooling system.......One ( link) tell that more pressure in the water pump solve the problem...........

 

[Sylva-Ranger]

Take the exhaust cover off too. It maybe a fin off the impeller. Cold it may not flex enough to plug it but warm it may move into blocking it. I think k there's a narrow water way that goes beside the exhaust.[/QUOTe

​I removed all cover that i can and see nothing anormal...........theyre no large exhaust cover (that we usualy found in may engine) in that Suzuki......May be something inside the block that i can't see ?