overheating issue

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Westie42

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Apr 30, 2013
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21
Hello all,

I recently purchased a 1990 Wellcraft with a 3.0 liter merc engine and a merc outdrive which I believe is an alpha 1. The boat sat for 2 years and was winterized during its time out of the water. When I got it home I decided to change the oil as well as tune it up. It fired up and ran very well after the work was complete, water was pumping in and out without a problem. However I was an idiot and decided to play with the timing some more and fired the boat without the hose on. It ran for about three mins without water, now I am having an overheating issue. My thought is I may have damaged the outdrive water pump, my question is there a good way to test the water pump? Any help would be appreciated.
 
Last edited:
ktbarrentine

ktbarrentine

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Re: overheating issue

Three minutes? No need to test the pump. You fried it, and need to replace the impeller and most likely the pump housing (get the whole kit). May have even melted the water pocket cover where the water pump pumps into the upper drive housing. Take a close look when you get it all apart and keep us posted. You probably want to check the exhaust shudders, too, but you may have gotten lucky with only three minutes of heat there. Best of luck!
 
M

MarkSee

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Re: overheating issue

Westie42 said:
I recently purchased a 1990 Wellcraft with a 3.0 liter merc engine and a merc outdrive which I believe is an alpha 1. My thought is I may have damaged the outdrive water pump, my question is there a good way to test the water pump? Any help would be appreciated.
Click to expand...

Welcome to IBOATS.

Bummer. As indicated above, don't bother testing, just replace.

Based upon the year and info provided, you should need service manual #6 for the drive:
Boatinfo - Mercruiser Service Manual nr. 6 - 1983-1990 - R, MR, Alpha One & Alpha One SS Sterndrives

and service manual #10 for the engine:
Boatinfo - Mercruiser Service Manual nr. 10 - 1985-1989 - GM 4 Cylinders Engines

or #13
http://boatinfo.no/lib/mercruiser/manuals/mercruiser13.html#/0

If you can provide the engine and drive serial number on your next reply or add to your signature, that can help at times as sometimes things change mid-year as your motor could be an 89 or 90.

Mark
 
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dubs283

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Messages
5,322
Re: overheating issue

ktbarrentine said:
replace the impeller and most likely the pump housing
Click to expand...

and the water pump base assy and gasket - most likely the one with the blue bottom for your drive

pressure test before filling with lube
 
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Westie42

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Messages
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Re: overheating issue

Thanks for all the advice guys looks like I will be replacing the pump. Those manuals have been helpful. Is it most likely I smoked the engine pump as well?
 
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littlebookworm

Chief Petty Officer
Joined
Nov 30, 2007
Messages
574
Re: overheating issue

Alpha drives cannot be run at all without water flowing through them. To do so is to fry the water pump. By the way, even if you hadn't fried the pump, you would have had to replace the pump impellor anyway. When a pump has been siting for two years, the impellor takes a 'set', the blades stay bent, and it will not pump properly, particularly at high speed. That would have caused an overheating condition. Follow the manual and replace the pump and related parts. Hy
 
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MarkSee

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Messages
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Re: overheating issue

Westie42 said:
Is it most likely I smoked the engine pump as well?
Click to expand...

You mean the water circulating pump on the front of the engine right?

You mentioned that you did run it at a point with water but then later without the hose so I would think the water circulating pump might still be ok unless you are hearing any strange sounds from it or it is leaking.

Mark
 
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Maclin

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Messages
6,761
Re: overheating issue

The big rubber hose in the exhaust from the riser to the pipe would have been close to the edge of burning at 3 minutes, I would take a close look and feel on that. Also the flapper could have dropped off and down to the bottom of the exhaust pipe. I think you also need to pull the drive and check exhaust passages from the outside.
 
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Westie42

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Apr 30, 2013
Messages
21
Re: overheating issue

MarkSee said:
Welcome to IBOATS.

Bummer. As indicated above, don't bother testing, just replace.

Based upon the year and info provided, you should need service manual #6 for the drive:
Boatinfo - Mercruiser Service Manual nr. 6 - 1983-1990 - R, MR, Alpha One & Alpha One SS Sterndrives

and service manual #10 for the engine:
Boatinfo - Mercruiser Service Manual nr. 10 - 1985-1989 - GM 4 Cylinders Engines

or #13
Boatinfo - Mercruiser Service Manual nr. 13 - 1990-1997 Engines GM 4 Cylinders

If you can provide the engine and drive serial number on your next reply or add to your signature, that can help at times as sometimes things change mid-year as your motor could be an 89 or 90.

Mark
Click to expand...


I am looking at the lower water pump kits online and am not sure which one I am gonna need. Will there be a serial number on the lower unit somewhere? Or do I work off the serial number on the top of the air cleaner on the engine?
 
Don S

Don S

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Messages
62,321
Re: overheating issue

Being a 1990 engine, it could be either an Alpha I or an Alpha I Gen II. Serial numbers of drive and engine can be found shown below.

3.jpg

You earlier stated you were "playing with" the timing. What ignition system do you have? If the EST, did you put it in base timing mode? Did you use the right setting? There was a change to prevent the engine from blowing head gaskets. Again serial number related.

Might want to post your engine and drive serial numbers so you get started off right.
 
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Westie42

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Re: overheating issue

When playing with the timing I was not trying to set the distributor, just after putting new plugs in it I wanted to change the cap, rotor, condenser, and points after a trip to the local marine store I discovered someone put an aftermarket distributor in this thing. It was made by prestolite. The mechanic and salesman we trying to figure out what parts I would need for it I was able to find parts online for it but I was trying to get the points set just right. That is what I was referring to when I said I was playing with the timing. I should have been more specific. I will post the serial numbers of both the out drive and the engine as soon as possible I am sure it is difficult to give assistance without me giving all the necessary info. Thank you for all your help.
 
Don S

Don S

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Re: overheating issue

Prestolite is what Merc used in the 90-94 3.0L engines with conventional ignition. The early models used the Delco distributor.

ign.jpg

You need to get the dwell set first, then the timing.
 
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Westie42

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Apr 30, 2013
Messages
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Re: overheating issue

Ahh I see I have the prestolite, then it was a factory unit the marine place must have been wrong. It seems to run really well now with the exception of me being an idiot and leaving the water off. I am gonna post those serial numbers and try and remove the out drive Thursday night to inspect what I have done to that then will go after fine tuning.
 
Don S

Don S

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Re: overheating issue

Since you don't have the serial numbers, maybe you remember what it looks like. Here is a picture from the stickies.

attachment.php
 
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Westie42

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Re: overheating issue

Ok finally had a chance to look at the serial numbers the outdrive serial number is 0D341550 and the engine serial number is 0c868719. Please let me know if any additional information is needed.
 
Don S

Don S

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Re: overheating issue

You can see what the drive is by looking at the picture I posted and the serial number ranges at the top of the picture.
 
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Westie42

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Messages
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Re: overheating issue

Don S said:
You can see what the drive is by looking at the picture I posted and the serial number ranges at the top of the picture.
Click to expand...

Yes the picture was helpful I have an alpha 1 so I am gonna try and find a kit for that one.
 
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