in-line 6 overheating problem

[moneyhole]

I posted some pics of my boat-only had 1 of the motor. How expensive is it to have the lower unit water pump replaced if that is my problem? I have the in-line 6 with the heat exchanger and I'm not sure of which outdrive I have as it was painted over-completely with black paint. I had the muffs on -fired the boat and after 5 mins she climbed to 160, 180 200 then I shut it down @220 degrees or so. I let it cool off and placed a tub of water covering the intake lower unit holes and it bubbled some but temp still climbed. I didn't let it get anywhere near as hot and called it a day. I really want to fix her- it's been re-wired bow to stern, engine swapped in 'o8 with a known good running engine, but I did go thru the parts today and realized they used the old engine t'stat. That was cheesy. After it cooled down, I opened the drain ports & it had no water what so ever in the heat exchanger & I'm sure the manifold as well. What are ya'lls thoughts? Greatly appreicate them.

[Destroyer]

Originally Posted by moneyhole

I posted some pics of my boat-only had 1 of the motor. How expensive is it to have the lower unit water pump replaced if that is my problem? I have the in-line 6 with the heat exchanger and I'm not sure of which outdrive I have as it was painted over-completely with black paint. I had the muffs on -fired the boat and after 5 mins she climbed to 160, 180 200 then I shut it down @220 degrees or so. I let it cool off and placed a tub of water covering the intake lower unit holes and it bubbled some but temp still climbed. I didn't let it get anywhere near as hot and called it a day. I really want to fix her- it's been re-wired bow to stern, engine swapped in 'o8 with a known good running engine, but I did go thru the parts today and realized they used the old engine t'stat. That was cheesy. After it cooled down, I opened the drain ports & it had no water what so ever in the heat exchanger & I'm sure the manifold as well. What are ya'lls thoughts? Greatly appreicate them.

Price depends on if you do the labor yourself and what the condition is of the inside of your outdrive. I don't know exactly what the cost is for your unit, but from experience I can tell you that most impellers run around $20 and full impeller kits run about $50. Do a search on iboats.com. for your model.

On your heat exchanger comment, are you saying that the raw water side had no water in it, or are you saying that the fresh water side was empty? If it's the fresh water side did you fill it before you tested it? That part of your cooling system is a sealed system and should not have gone dry. If you didn't fill it, fill it and test again. If it's the raw water side, I'd suspect a blockage somewhere. My thinking being that even if your impeller was gone, the force of the water pressure coming through the muffs would have been enough to at least wet everything. Only a blockage would prevent the water from reaching the heat exchanger. Understand that this is pure speculation since I don't know what type of system you have, and you haven't posted any pics. At the very least you should change your impeller. (It's just good practice to change the impeller and the lower unit oil at the start of every boating season.)

[moneyhole]

Destroyer ,
I did post pics ..they are under my profile or something of that nature. I think I posted 5 or 6 pics but only one I have of the motor.
The boat's cooling system has water/ antifreeze mixture in the pressure tank, but was low on the overflow jug. After running the boat, there was no water at all on the two drain plugs the fellow I bought it from told me to drain down - one one the manifold & one on the heat exchanger. I thought with thelow. unit muffs have filled up at least one side of the system.
What do you recommend I do in sequence to perform checks, but not too cause any engine damage.

[spareparts]

2 hours labor as a stand alone job, 1 hour labor when combined with an annual service. Impelelr runs around $30, I susually use the kit that cost around $50, If it needs an upepr housing, add another 20 to teh kit

[moneyhole]

sparepats... are you thing , like you posted yesterday, that it is the stern pump. I have a lot on motorcycle experience, but no much at all on boat wet systems. Thanks for all advise

[spareparts]

the water pump in those drives is a weak point, they only have to run dry for about 20 sec before they are damaged, they will also get brittle and break the blades off if they sit for long periods of time. Go ahead and drop the lower unit. Do a search on utube, there are probaly several videos of people doing a water pump on a mercruiser(I'm going to make a video of it one day), i'll give you two hints, drain the fluid out first, and put the gear shift in fwd gear before you drop the lower. Between Ferm, Skools and myself, we've probably explained it 30 times on here, do a search for water pump replacement

[moneyhole]

Thanks....been looking at all the video feeds I can find on the internet. The manual's pictures are very hard too make out. Wish thet were in color instead of B/W.

[moneyhole]

Spareparts, what are the most important things I need to pay special attention to when dropping the lower unit and making the repairs to correct my water intake flow problem? Any special tricks/tips I should be aware of?
Thank you for your help.
Do you & Destroyer feel this is most likey my problem?
** Note - My boat pics are on my profile page

[moneyhole]

I see now why my water pump is bad, as I was taking off the lower unit I noticed some areas that had been epoxied and painted over. Guess what, the whole trim tab casting on the upper half of the motor broke off. I traded the boat with a horse trader. Can this type of "pot metal" be welded or am I just up the creek wihout a paddle. I'm going to post a pic of it in my album. If any one has any ideas, suggestions, solutions or other ideas than sinking her, let me know. I've contacted the fellow I got the boat from asking to reverse our trade...doubt I get far with that one. Live & learn.

[spareparts]

they weld on those lower units all teh time, just find someone whos familure with the repairs, try a prop shop