200 offshore overheat

[rimojop]

I have a 1994 200 offshore 2.5 litre.
Just picked up this engine for my boat.
engine only has about 300 hours total.
I installed a new waterpump including base and upper housing.
Also installed new thermostats.
Engine runs great. Starts within 2 or 3 revolutions.
Will idle and run at lower speeds without any problems.
If i run up to cruise speed, NOT wide open. Temps start to climb.
It will reach 200 pretty quick.
If I slow back to high idle it will cool back down.
Water flow out of "pee hole" is ok, but dosen't seem real strong.
Water pressure gauge shows around 10 psi at speed.
I have pulled lower unit again to make sure everything was right.
All looked perfect.
When I shut engine off it seems to drain water out of the center section for a long time.
Anybody ever heard of a crack in the tranfer tube up to the powerhead?
Sorry for the long post. Kind of grasping at straws!!
Thanks
Rick

 

[tashasdaddy]

Re: 200 offshore overheat

seeing it is a 14 y/o when you had the stats out, did you flush the engine, both ways, thru the stat opening, could be partially clogged with salt deposits.

 

[jdupree]

Re: 200 offshore overheat

I have a 1992 200hp 2.5l. This motor was re-built 2 seasons ago with all cooling components replaced. I think what you are experiencing is the nature of the beast with these engines.

Mine as well will creep up to 180 to 200deg over 1500 rpm's but not at WOT. If I go WOT the temp will come back down to around 160. Mine as well will average around 160deg at idle. My temp only goes up around the above mentioned rpm's.

I would pull your t-stats and run the motor and see if you have good flow out of the t-stat housing. As far as the pee goes, the discharge is controlled by your t-stats so this flow will never be great until the stats open. Have you replaced the poppit valve? If not, I would give that a try but I think that has more to do with higher speeds.

I think these motors are known for running on the warm side anyway. I hope this helps.

 

[Chris1956]

Re: 200 offshore overheat

Rick, Check the water intake grating on the lower unit. Barnacles can get in there and clog 'em up. Check the poppit valve for proper operation, or replace it.

On my old inline six, the salt partially crushed the copper water intake tube. I found it when I had the powerhead off. I do not know if your motor is succeptable to this. You might put a hose on the water intake tube and see if there is a restriction, althought I think it will be difficult to determine.

 

[j_martin]

Re: 200 offshore overheat

To answer your original question, yes there can be a leak in the tube, or more likely a damaged seal where it goes into the base of the motor.

Normally, this motor would have measurable pressure at idle, ramp up to about 12 at about 3000 rpm, step back a bit as the poppit opens, and then go on up to 12 lbs or more, but not over about 20. They tend to run a little warm just before the poppit opens if you run it there a long time.

It is possible to overheat the engine if it's running lean for some reason.

hope it helps,
John

 

[rimojop]

Re: 200 offshore overheat

Thanks for all the replys!
When I had thermostats out the passages looked very clean.
Engine was always stored on lift, so no barnacles in passages.
I started engine with thermostas out and at 2000 rpm it will throw
water 18" out of the thermostat openings.
Is there a way to check the popit valve other than dis-assembly.
Begining to think that I don't really have a problem, just want to be sure.
Thanks Again.
Rick

 

[gss036]

Re: 200 offshore overheat

The poppit is very simple and easy to access. It may never have been replaced and maybe it is time for that now. Not an expensive item for parts. You will need to order each piece seperately as there is no actual kit. Should cost about $35.00 for parts, depending on if you have to pay shipping. Only use OEM Merc parts.

 

[j_martin]

Re: 200 offshore overheat

Thanks for all the replys!
When I had thermostats out the passages looked very clean.
Engine was always stored on lift, so no barnacles in passages.
I started engine with thermostas out and at 2000 rpm it will throw
water 18" out of the thermostat openings.
Is there a way to check the popit valve other than dis-assembly.
Begining to think that I don't really have a problem, just want to be sure.
Thanks Again.
Rick

I agree. If it ain't broke, don't fix it. It helps to know what it's supposed to act like, though.

John