1991 200 hp Mariner running hot

JLowe59 · #1 September 22nd, 2007, 03:08 PM

Hello and thanks for any help

My 1991 Proline 230 w/a 200hp Mariner starts up great and in gear all through the no wake zone is good. As soon as I give it gas to get up on plane the temp goes up just to the point that sets off the alarm.( about 180 I think) alarm goes on and stays on for a few seconds. It then goes off and temp falls back down to 140. After cruising on plane I come down to a crawl and the alarm goes off again. temp rises just to that point again but then comes off the high point and is okay.

I just bought this boat. The PO told me he has not changed the impellor in two years so thats my first clue.

Could it be that the impellor isnt pushing enough water to cool when the engine starts to get hot (Soon as I put it under load) but then the high rpms make it push enough water too cool it down. And when I come off plane the water flow cant cool the hot engine but soon the engine cools and the water flow is enough?

The t stats are new the old ones were covered with sand and gunk.

The compression check was fine and it runs great under load or at idle.

Any suggestions would be appreciated

gss036 · #2 September 22nd, 2007, 07:24 PM

It could be the impeller, but I would bet on the poppet valve sticking or full of junk.
I think the over heat is set for about 220 degrees.(?)

JLowe59 · #3 September 23rd, 2007, 01:12 AM

poppet valve?? what does that do??

JLowe59 · #4 September 23rd, 2007, 05:55 PM

Does anybody know if this boat even has a poppet valve?

gss036 · #5 September 23rd, 2007, 08:21 PM

Yes! You have a poppet valve. It is on the lower starboard side of the block, look for a plate that looks like a figure "8", with 4 small bolts holding it on. The poppet valve will (should) open at about 3000 rpm and relaese excess water into the exhaust. Pretty easy fix, remove the starboard side lower cowling for easier access, just four small cap screws to remove, nothing to disconnect.

JLowe59 · #6 September 23rd, 2007, 11:39 PM

Thanks for the reply... I dont want to start changing parts just before I lay her up if I dont have to.
The engine runs slow fine and runs under load fine. Its when it runs at about 2800 rpm that the temp starts to climb. If I open her up the temp drops or if I power down to a crawl she cools down as well.

Poppit or impeller????

What do you think