1988 Mercury 45hp Pro Fifty Overheating issues - Pictures, story and videos included.

on_ice

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Starting a new thread because my other one has an unclear title and someone's posts were lost (which seemed very valuable).

Lets start from the start. I bought a 1976 Boston Whaler with a 1988 Mercury 45hp, Pro Fifty model, 2 stroke and 4 cylinders. It didn't start right away but after a little tinkering it started and ran great. I took it out on the lake for a test and it idled great, started fine, and was pretty quick! After 40 seconds of running though I got a overheat alarm. As soon as you slow down and get the boat off a plane the alarm goes away. I then brought the boat home and put in a new thermostat, wear plate and the 2 gaskets that go above/below the plate. Then I took the boat out for another test but unfortunately I had the same overheat alarm.

Fast forward to today. I did a compression test and had (from top to bottom) 123, 128, 128 and 120. Then I took the videos you see below which may show my issue. I removed the lower unit and back flushed the engine with water from the hose from the top of the block through the water tube. After doing that a little I plugged the water tube, and tried to fill the block with vinegar in hopes of breaking up any salt deposits that might be in there. Most of it came out the exhaust and im not sure how effective it actually was. Then I back flushed again, then flushed from the water tube back out the tell tale hole. I will do this again tomorrow with an air compressor after I buy one.

It looks like the issue may have been with my impeller install as I dont remember water shooting out the top of the LU like that and it looks like I have some sort of exhaust leak. I posted pictures of most of the seals and I was hoping you guys could point out which ones are wrong.

Video 1:

Might be the source of my issue. I didn't notice this before because I was running the boat in a barrel and then in the ocean. Water flowing out from where the lower unit mates up to the mid section. How does this even happen? Where is it leaking from/pressurizing the midsection?

201305221804312_zps3f5e2a23.mp4 Video by blueovalstanggt | Photobucket

Video 2:

Shows the stream building when the engine revs, then a close up of spray leak #1 which I am assuming is fuel because of the way it pulses. Maybe this explains why it doesn't seem to idle as well as it used to and stalls. Then, I go to the other side where you can see fuel (i assume) leaking from the carbs. Can't tell where it is coming from. When I prime the fuel bulb fuel will shoot out of the bottom carb once I build pressure. Maybe related? Then the engine dies at idle.

201305221811032_zps6722a697.mp4 Video by blueovalstanggt | Photobucket

Video 3:
Looks like I have an exhaust leak or something as this gunk is leaking out of the area where the lower unit meets up with the mid section. Short video but if you pause it you can see what I am talking about. What's the deal here?

201305221812512_zpsb0b47210.mp4 Video by blueovalstanggt | Photobucket




Random stream out the side which I don't believe is normal

P1040234_zps6ab02f8f.jpg


Goo leaking out the side
P1040237_zps1af72df3.jpg


This little piece was on the inside of the exhaust...I'm hoping it came from the cooling system

P1040244_zpsadc45a21.jpg


Is this seal in the right place(question 1)?
P1040245_zpsd3aff999.jpg


How about these (question 2)?
P1040246_zps8fb0b8ab.jpg


Running vinegar through the block
P1040250_zps693fcfc5.jpg


Original thread:

http://forums.iboats.com/mercury-ma...r-1988-mercury-45hp-pro-fifty-how-605104.html

Thank you in advance for all the help. Once thing I really enjoy about this motor is I am learning a lot. My previous experience was limited to automotive engines. Thanks again.
 

on_ice

Petty Officer 3rd Class
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Messages
92
Re: 1988 Mercury 45hp Pro Fifty Overheating issues - Pictures, story and videos inclu

I assume this is for the oil mix
P1040251_zpsb68faee0.jpg


Found this in the bottom of the cowling
P1040254_zps4eb279aa.jpg


?? Interesting work
P1040255_zps660098c0.jpg


More random wires to no where
P1040256_zps3bc79612.jpg


Pointer finger on yet another wire to nothing
P1040257_zpsc76178c5.jpg


What is this thing tapping into cyl #1(question 3)?
P1040258_zpsd512f327.jpg
 

bgc

Ensign
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Jul 13, 2011
Messages
980
Re: 1988 Mercury 45hp Pro Fifty Overheating issues - Pictures, story and videos inclu

"Random stream going out the side" Is there a screw hole?

"Goo leaking out the side" There is a gasket between the two parts to seal this, probably needs checked.

"Is this seal in the right place(question 1)?" Its a slinger to help keep crud out of the pump, move up a bit, shouldn't contact pump.

"Found this in the bottom of the cowlin" Looks like a carburetor gasket.

Someone got creative with the repairs to this motor.
 

on_ice

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Re: 1988 Mercury 45hp Pro Fifty Overheating issues - Pictures, story and videos inclu

#1 - No screw hole but it does look like there is some sort of relief or something there to possibly pry the lower unit off the midsection with a screw driver.

#2 - Hmmm, definitely wasn't a gasket there before... I'll check the schematics

#3 - Thanks, will do

#4 - I'm not too worried with the wiring stuff, it works and I'm not going to ask questions. I just need to get this cooling thing figured out.
 

Chinewalker

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Messages
8,902
Re: 1988 Mercury 45hp Pro Fifty Overheating issues - Pictures, story and videos inclu

You've got a pretty good stream, localized, coming out the side of the unit. NOT normal. Some water pump housing bases have a hole in the side for a flush attachment. Not sure all lower unit housings have the spot for the flush, so if you've got the wrong pump base with your housing, you'll have a leak. Check the base gasket for the impeller housing, too. Gotta be something obvious on that count.
 

on_ice

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Re: 1988 Mercury 45hp Pro Fifty Overheating issues - Pictures, story and videos inclu

I didn't change the housing so that shouldn't be the issue. I'll shoot water in the top of the waterpump housing and see if there are any obvious leaks. Could it be an exhaust leak which is pressurizing the area and forcing the water/unburned oil out the side? I noticed it doesn't look like much water coming out the back of the propeller.
 

on_ice

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Re: 1988 Mercury 45hp Pro Fifty Overheating issues - Pictures, story and videos inclu

No obvious leaks when shooting water from top of the housing. There is a stream shooting out of some sort of pee hole in the water pump base, but this appears normal?
 

on_ice

Petty Officer 3rd Class
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Re: 1988 Mercury 45hp Pro Fifty Overheating issues - Pictures, story and videos inclu

What temperature should this engine operate at?
 

on_ice

Petty Officer 3rd Class
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Messages
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Re: 1988 Mercury 45hp Pro Fifty Overheating issues - Pictures, story and videos inclu

Well...the power head is off! What a grand ol time that was. No obvious cracks/holes and it's hard to tell by looking at the gasket. Maybe you guys will notice something.

One question, how does this come off?

P1040301_zpsd9590a28.jpg


More pictures:

P1040302_zpsbe6d33d2.jpg


P1040300_zps66a78c28.jpg


P1040298_zpsc8ce819f.jpg


P1040295_zpsa5088979.jpg


P1040294_zps933e200d.jpg
 

on_ice

Petty Officer 3rd Class
Joined
May 11, 2008
Messages
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Re: 1988 Mercury 45hp Pro Fifty Overheating issues - Pictures, story and videos inclu

Anyone?
 
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