88' 7.4 Mercruiser Bravo Overheating

[RepoMan207]

Re: 88' 7.4 Mercruiser Bravo Overheating

Jax,
definitely enough amps in the battery.

As far as getting the starter wet, I really flushed the heck out of it. I took the petcock housing out as well to get a better flow. I actually had the thought of "oh sh*t I got the starter wet" but then countered that thought with "well they did design them to get a little wet, even in the auto world".

I do see your point on wiring getting wet. In fact I have the "Thunderbolt Ignition System" in my boat and had it off the bracket when examining the risers and manifolds. Not sure what to do about that other then let it dry out a bit.

I did give it another try in the drive on muffs. It started after a quick grind. Of coarse it overheated again so I am on the war path of replacing the risers and manifolds against my better judgment (over $1000 in parts)

Once I get the risers and Mani's on I will replace the starter.

I had another thought on the starter issue. Occasionally I have an issue engaging into gear. on occasion it is quite difficult moving the throttle into forward gear initially. When it occurs I simply go neutral forward(correct term?) then back to stationary, then it goes into forward with ease. I also had an issue just after the whole overheating thing began of it not starting due to it (the ignition system / boat) thinking that the boat was in gear. I would move the throttle forward to reverse, then back to stationary and it would allow me to turn it over. Obviously this wouldn't be related to the overheating (I would think anyway) but it maybe playing a roll in the starter issue (maybe the gears might be engaging on the drive well the starter is engaged??? I hope not but if anyone has any insight, please speak up.

 

[RepoMan207]

Re: 88' 7.4 Mercruiser Bravo Overheating

 

[RepoMan207]

Re: 88' 7.4 Mercruiser Bravo Overheating

I can't figure out photobucket as of yet, so here is a link to the related pics.

Century Pic's http://s799.photobucket.com/albums/yy277/repoman207/Risers/

 

[jaxnjil]

Re: 88' 7.4 Mercruiser Bravo Overheating

repo; any thing new in the last few days?

 

[RepoMan207]

Re: 88' 7.4 Mercruiser Bravo Overheating

you mean other then the crappy weather....

The UPS man was kind enough to drop of my Risers about an hour ago though. Manifolds will be here Tuesday. I should have more updates by Wed. of next week if the weather cooperates with us.

 

[jaxnjil]

Re: 88' 7.4 Mercruiser Bravo Overheating

as you have the same motor i have i am very interested in your out come.

it seems to be a tough one to trouble shoot.

best of luck in changing the manifolds

 

[RepoMan207]

Re: 88' 7.4 Mercruiser Bravo Overheating

Thanks......I may need it, there probably the originals! They look in great shape on the exterior.....but of coarse that always can be deceiving.

I am constantly trouble shooting, & thinking scenerios in my mind. I will be happy once this is over with. I dropped a new mooring in my cove last weekend and am looking forward to putting the trailer up for a month or two.

I'll keep you posted.

 

[flargin]

Re: 88' 7.4 Mercruiser Bravo Overheating

Repo,
I have been away for a while, hope your coming to the end.

Looking at the pictures of the risers, there is a hole on the top (bottom) of your pictures which should be flowing out water as well, so you likely needed the new risers/exhaust.

 

[RepoMan207]

Re: 88' 7.4 Mercruiser Bravo Overheating

Hello all! Sorry for the delay in updates. We have been at camp 90% of the season with no Internet.

I changed out the Manifolds and risers (Elbows), doubled checked everything from the transom inlet to the Y Pipe and back to the bellows. Headed for the ramp for a test.

Busy day at the ramp so I moved directly to the nearby sandbar to clear the ramp for my test. 8 minutes at idle and she overheated.

I neighbor advised he had the same problem on his Four Winns. His solution was to pull the T Stat and balls & springs from the T stat housing. Apparently it worked really well for him. Normally I wouldn't take that route or advise....but after throwing so much time and money at this I said "why not". 5 minutes later I had her at idle with my fingers crossed. 30 minutes later and still at idle, I took her out through the channel to the big bay.....all was well so I headed for the cove (where my camp is.) at headway speed....the temp started to climb quickly now with the dreaded buzzer nearing I pushed her onto plane and got to WOT. Temp quickly descended with pleasing reaction. Hmmmmmm WTF is going on here????

Kept it at WOT till I got to my cove (5-8 minutes) still cool as a cucumber. Went for a longer cruise that night to determine that so long as I break just above head way speed I everything is 100%... I am thinking the impeller may need to be replaced. I had the lines (inlet / outlet) reversed the very first test. I will do this AGAIN the next time I have her out of the water.

We took an all day trip out through the crooked river this Saturday, through the locks, Bandy pond and to the end of Long Lake and back. Everything went well other then the locks. Alot of sitting in a very narrow & shallow river waiting for the bridge and locks operator. She started to climb over 160 degrees quickly so I responded with a high idle to get her cooled down.

No overheating....so long as I am moving. The quest is not over yet. Any with advice to running with out the T Stat..please speak up. Thanks in advance.