Running hot on port engine...
 

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

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.

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:D:D 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.

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.:angry-smiley-038:

Well I guess I will spend alot more time in the bilge today than I wanted to. I will keep you guys posted.:ernaehrung004:

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.

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.

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.

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.

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

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??

I put everything back together as it was before I started and now I have nothing. I ran it for about a minute with nothing coming out of the exhaust. I am going to pull it again tomorrow I guess and try again. That sure does suck azz to do it again. It was a major PITA!!!

It shouldn't take more than about 30 seconds to get some water out the exhaust.

The best thing to do after an impeller change is to start it in the water. I've had a brand new one fry itself on the hose.

It makes no difference how the veins are facing when you install the impeller. They will right themselves after a few rotations. Lube the impeller with liquid dishsoap when its installed.

Thanks Griff. I did lube it up with some soap and I don't understand why it's not working. Tomorrow is a new day my brother and I hope I can get it worked out. You were correct about being a contorsionist...my back is gonna be sore as hell tomorrow!!! Thanks bro....:ernaehrung004:
Chuck

Had that problem a few years back & drove me nuts to find it. Crappy design with the plastic wedge/retainer. However it will be the cheapest part you'll ever purchase from Mercruiser.

When replacing the impeller always replace the housing if it is plastic. Make sure you replace the wearplate and "O" ring. AND make sure when you install the pump housing on the shaft you don't disrupt the "O" ring on the impeller body. if you do it will not pump water. GOOD LUCK !!

Does Bam sell a metal housing? If not who is a good vendor to get one from? Thanks for the help.
Chuck

The metal housings are a pain in the a$$ to put on. There are more plates and gaskets and you would need the end part with water fittings. The metal setup is near impossible to change an impeller unless you take off the entire bracket for the seapump. The rebuild kit, not including the actual housing, is almost the same price as the entire plastic housing impeller kit.

I would just replace the plastic/composite housing. WAY easier.

Got everything back together today and took her out for a run. I am still getting about 220-230 degrees on both engines after running hard for 10-15 minutes.
When I was rooting around the engine room I saw the starboard engine has the old style water pump housing that consists of 2 pieces instead of the newer one piece housings.
The previous owner must have changed the port side only to the newer one.
I am starting to get the feeling that he was having a problem with overheating as well due to the fact that the housing and the impeller looked brand new when I removed them and there is a brand new t-stat in the cuddy locker.
Both engines were putting out quite a bit of white steam/smoke but the starboard side was def. worse than the port.
I am also having a problem with the starboard engine dieing when at idle and not wanting to start after it heats up a bit.(20 minutes or so)
I just hope we can get all the bugs worked out before the real season starts down here. I guess we shouldn't expect much out of a boat that sat in south Florida untouched for about 9 months......:(

If both engines are getting hot then I would suspect that there is some salt or corrosion build up in the water inlets as Ed suggested. Those engines should run below 160* during a hard run. Don't let them get over 200* or you are going to hurt them.

Weren't your alarms going off??? They should have been.

I would start with the inlet pieces at the transom assembly that Ed suggested. You can check water flow by disconnecting the hose at the inlet and hooking up muffs. You should get a good flow of water. You could also run some salt-away through and let it break up any salt deposits in the water jackets on the drive. Tape over the intake holes on the drive, fill from the inner hose and let some salt-away sit in the drive for a while. Maybe leave one hole open to let air out while you're filling.

From there, I would change out both TStats. They should have 140* Tstats in them and should run 145* on the guage. Are you sure that your sea pump belts are tight???? Just tossing out ideas.

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[/QUOTE]

The sea trial was run at idle, cruising and wide-open RPMs. The whole thing took about 40 minutes because of the no-wake areas. The wide-open time was only long enough to get readings, so I did not run it long enough heat it up. Most sellers will not run wide-open for more than a few minutes. Gauge readings never got over 155.

check for colapsed hoses. Check the fitting on thye transom assembly.

I will be in town on the 22nd if you have not figured this out yet. :D

where are you kepping the boat?

Thanks for the tips guys. I did check the plastic inlet as well as every hose and connection from the transom all the way to the intake on the front of the engine. Everything looked really good and fresh so I am going to try the t-stat now.

By U Boy I am going back to work Wednesday but I will be coming back in on the 21st if you wanna get together and shoot the sh!t. My number is 504-875-5561. Give me a shout bro. The boat is being stored at a faclity on Fremeau.
Take care,
Chuck

Hey Chuck you could check to make sure you did not swap the suction and discharge hoses on the water pump. They are very close and it would look correct either way. I do know of a problem a friend had with a boat he purchased, the previous owner did not flush it out. It would run fine on the hose and at idle, but under a load it would run hot. The salt had accumulated so much in the water passages that if not on the hoses it was not getting water. Pulled the drive, cleaned the drive-no problem!

hey chuck
sorry to hear you are having problems ....the only thing i can say is check for any blockages ......does it look like there is enough water comming out of the exhaust ????....

saw you the other night in the canal.....i am not sure you heard me but that was me standing on the end of the boat house dock ........ that boat looks real nice love the paint.........i really hope you get this problem fixed and can be on the water with us soon!!!!!

Ran today again and both engines are running hot. A buddy of mine said that it may be blockage in the manifolds. I am thinking of pulling the drives and checking from start to finish on the cooling system.
I am going to try the saltaway trick first though Griff because that will be alot easier than pulling the drives.:D I wish I had a shop to do all of this in but for now I will do it when I can. Thanks for all the input guys. I will keep you posted.

Salt Away will not cure the problem nor will it prevent the "S" shaped water inlet hose located in the transom assembly from failing. Salt water corrosion builds up around these hoses and causes the hose to close up from corrosion on the outside of the hose. Running at WOT (wide open throttle) will usually cause the Bravo water pump impeller to fail when corrosion reaches a certain point and hose restriction lessens volumn of water going to engine water pump. Engine temps sometimes climb slowly at WOT to indicate this problem and other times do not increase until water pump impeller fails. Water pressure gauges will always give a heads up on this problem when water pressure drops at WOT. This is a very common problem with Bravo outdrives in salt water. Remove the outdrives and renew the hoses and plastic inserts.

I think this is probably the issue as well. The salt away may only act as temporary fix.

Chuck, I'm digging this one up so as not to hijack your rebuild thread. Which t-stat housing do your motors have? Is it the big black hunk of iron?

I had a problem with my motors running hot, checked everything, tried everything. At first I realized I put the wrong upper gasket in. Changed 'em to the correct gasket and that fixed one motor. But I had to change the whole t-stat housing on the other engine before it would run the correct temp.

I'm actually running two different housings now, the stock one and the stainless sierra piece. I drilled a few holes in the t-stat under the Sierra housing, but otherwise they both run identical, and proper temps.