98 dt 140 cooling issues?????

[Eshaw150]

I have a 98 dt140 fuel injected when we gut up to 3000 plus rpm and are on a plane the over heat warning comes on and horn goes off and drops the rpm for a split second it does it about every 5 minutes and only at high rpms it has a good pee streem on it and has a new thermo i am currently in the process of replacing the water pump which happens to be backordered and have found many peixes of decayed rubber but not off the impeller
it is fine if im under 3k rpm but sounds the alarm every five minutes if over 3k
the water pump impeller is tight and pumps good i think this could be a senser
i need help checking them thanks
and this motor is a saltwater motor

thanks

 

[Marion Moore]

Re: 98 dt 140 cooling issues?????

Explain the pieces of rubber. Could they be from an old impeller that broke apart and clogged the passages?

Another thought is the impeller could be old enough to not have the rigidity to pump the water the top cylinder of the engine needs when you get up the RPM's.

I had a similar problem but I shot gunned so many things that I may never know which one fixed the problem. I changed from a 3 blade back to my 4 blade prop, installed a new water pump, swapped water pump bases, sealed under the water pump base where it touches the exhaust rubber seal I think that did the most help), and retorqued the head bolts where a few were actually a little loose.

One thing to not overlook is the exhaust rubber seal under the water pump base. If it gets cracked and breaks off it can suck in exhaust gas and cause the pump to loose prime or draw in exhaust gas.

 

[Eshaw150]

Re: 98 dt 140 cooling issues?????

the exhaust rubber seals are decaed and i tuched it with a screwdriver and it fell apart and im thinking thats what caused the problem but im going to change all that and take the lower unit in to a machine shop and tru to bet the two polts that proke off

 

[Eshaw150]

Re: 98 dt 140 cooling issues?????

are u referring to the little rubber that the sub watger tube goes through

 

[Marion Moore]

Re: 98 dt 140 cooling issues?????

http://store.brownspoint.com/dt115/fig045-1158601.asp
Number 13, exhaust seal rubber. If that is not whole it can certainly suck in air.

 

[Eshaw150]

Re: 98 dt 140 cooling issues?????

yep that was in many peices so that is probably my colprit im gonna order all of it right know