CAPTAIN CHUCK

My port engine (1996 500 HP carbed) is running hot. I pulled the water pump and checked the impeller and it looks brand new.

I have know idea what prior work has been done to the engines because the previous owner passed away before I got to speak to him.

I checked the sea strainer and it looks good. My next thing will be the thermostat. Am I moving in the right direction?

I also would like to change the plugs on both engines. Is there any easy way to do this? They have the factory Gil exhaust which is a major PITA to work around. Should I just pull the manifolds to get to the plugs?

Thanks in advance guys,
Chuck

Edward R. Cozzi

Chuck:
I would back-flush the oil cooler before I pulled the thermostat. If a previous impeller came apart and the mechanic did not get the pieces out, they could be causing your elevated temperature.

As far as changing the spark plugs with the Gil Offshores: You need Snap-On's spark plug socket with the swivel and a 6" extension. You will find the alternator, the hatch lift cylinder and the fuel separator in the way of getting to the inboard plugs. Remove one of the things for access and take your time. Be patient and you'll get through it. Best done on a cold engine.

Griff

How hot compared to the other engine??? Is this new or has it been doing it since you got it??? Does it just run hotter and hold temp or does it keep climbing???

They should run around 140-150* on the gauge.
I would also verify that the sensor and gauge are working properly. You can just run a jumper wire from the engine temp sensor to the sender wire for the other engine.

If you change the TStat, make sure to get the merc gastkets and don't use sealer on them. They have a crush rivet that makes a metal to metal contact so your sensors ground and work properly.

As far as changing spark plugs with the Gil's........Hire a contortionist Find all the different length extensions you can a have a couple of swivels. Then make sure you have a good magnet extension wand to pick up all the chit that falls in the bilge.

CAPTAIN CHUCK

Thanks for the info guys. The temp has been high since we picked up the boat. It was running around 210 and then started getting in the 230-235 range before we shut it down.

It took about 30 minutes to at pretty close to WOT to get this high. One thing That made me think it was the impeller is the water press. On that engine it was only about 6 or 7 a WOT where as the other engine was 15-20.

As far as the plugs are concerned Griff you are absolutely correct about a contorsionist!!! I don't undertand why the hell they put those engines in like that. If you need to change one thing you have to take 6 or 7 other things off to get to the first.

Well I guess I will spend alot more time in the bilge today than I wanted to. I will keep you guys posted.

Griff

I doubt its the tstat. Most of the time a tstat will either stick intermitently or it will not open till a higher temp.

I think you have a flow problem based on water psi. The impeller might be fine, but the actual housing might be worn. Do you have the plastic housings???? Either that or you have an obstruction. I would change the housing and then run some salt-away through it.

CAPTAIN CHUCK

It does have the plastic housing on the pump. I am going to try a reverse flush and see if anything comes out but everything I pull looks really good so I don't think it would have anything blocking the flow. The guy definately took care of these engines but something isn't right....I will keep on it.

Thanks guys.

Griff

You should be able to just pull off the end cap on the oil cooler and look for pieces as long as its like the one that was on my 1996 525SC. Pieces really can't get past the inlet side of the oil cooler unless they are very small.

I would check that, and if there is nothing, then replace the impeller and housing.

Edward R. Cozzi

Just thought of the Bravo syndrome! The water inlet at the inner transom plate closes-up due to salt build-up. Go behind the engine and remove the inlet hose from the plastic gooseneck on the inner transom plate. Then carefully remove the two small bolts that hold it on. See if the hole is restricted.

CAPTAIN CHUCK

Well I spent all day putting the water pump back together. I did flush the whole cooling system and I managed to change all the plugs but one on the inboard port engine.
I just couldn't get to it so oh well. I started the port engine on the hose and ran for about a minute but never did get any water coming out the exhaust. I shut it own and checked all connections and everything looked good.
I was wondering if it may take a couple of minutes to come out since I emptied the whole cooling system? I made sure to put the new impeller in and connect the hoses exactly how they were before but now I don't know what to do next.....Any help will be greatly appreciated.

Ed, if you read this I was wondering how long you ran the boat on the sea trial because we ran it for about 30 minutes and it started getting hot. Did it not do that on sea trial? I'm just curious.

Chuck

jez350

When you put the impellers in you set them up for proper rotation?? I found when I replaced the impellers in mine a few months back it takes anywhere up to 10-15 secs for water to come through. Otherwise there might be a blockage??