Alpha one gen 2: diagnosing overheating

[ShoalSurvivor]

Re: Alpha one gen 2: diagnosing overheating

Bondo, thanks for your feedback. After further deliberation,
a) the motor is 10 years old,
b) it was running great, but it overheated suddenly, and I heard a backfire, which was unusual (I always knew that I would have to replace these, but I didn't know when or how I would know),
c) remembering that when I got this last fall, I initially saw signs of rust when flushing,
d) it's used in salt frequently... and
e) I don't want to ruin the engine,
f) I like working on it, preferably in a preventive maintenance form.... and
gee) I don't think I need any more reasons...

I think I'm clogged, so, off with the batwings!

 

[pjumper]

Re: Alpha one gen 2: diagnosing overheating

10 years in salt. you are overdue for manifolds.

 

[ShoalSurvivor]

Re: Alpha one gen 2: diagnosing overheating

She only met salt for the first time about 4 months ago, but will see a lot of it.

drained water was rusty. Here's what the right side looks like:







Comments and suggestions are welcomed. Thanks!

 

[ShoalSurvivor]

Re: Alpha one gen 2: diagnosing overheating

And this is what the flapper looks like:


It appears that the flaps are missing. I wonder where they are..... blockage?

 

[ShoalSurvivor]

Re: Alpha one gen 2: diagnosing overheating

I found 1/2... it was wedged down the Y and I was able to retrieve it. I'm going after the other one with a long-flexy-spring-grabber (assuming I can get a visual on the path).

The port side batwing is now removed as well. It shows more corrosion/scale than the starboard, and the outflow from the drain port and the hose was very rusty. The flapper on this side is cracked and about to break off, so I'm glad I've got this all apart.

any suggestions on how to get to the other 1/2 of the flapper? I saw a thread that someone else lost one, and I'll go search that out.

 

[ShoalSurvivor]

Re: Alpha one gen 2: diagnosing overheating

Found the other 1/2. It's stuck in the pipe. I pulled the outdrive and can see it, push it, pull it, but can't get it out either way .

if only my arm was a little thinner, I might be able to reach all the way down. hmmm... "OH Honey....., can you help me for a second?"

 

[Fun Times]

Re: Alpha one gen 2: diagnosing overheating

I'm going to replace the t-stat, just to be safe. Should I use a 140 or 160?
Please help with correct replacement parts. (does the tstat come with housing gaskets, or is there a kit?)

Engine is a 2004 Repower 4.3 Alpha I Gen II with 4bbl carb.
drive SN: 0L102679 1.63R is stamped in, but 1.81R is hand written next to it.
Engine S/N: 90004747

Thanks!!!

Besides the one piece manifolds you have, here is your engine parts catalog you need to use. http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=879150157. They now show you the two piece manifolds.

You need a 160 degree thermostat mercruiser kit part number 807252Q5. If you go with an aftermarket kit on this then you will still need to buy an oem gasket that goes between the thermostat housing and intake. You need OEM part number 27-530451.

Here is your drive parts catalog,
http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=809759+98

To get the rest of flapper out, try using a shop vacuum to see it will hold on to it while you pull out the hose. Good luck.

 

[ShoalSurvivor]

Re: Alpha one gen 2: diagnosing overheating

OK. I've got the 2-piece manifold conversion kit, thermostat, impeller w/housing, outdrive gasket kit on the way.

Wife was able to reach in and feel the flapper, but could not force it through. One way or another, that sucker is coming out!

In conclusion (until I put it all back together), the source of the overheating has been solved:
- 2 wedged flappers in the pipe
- 1 spent impeller
- 2 questionable 1-piece manifolds with unknown status

Now that explains it! Thanks, again, for all the tips and advice!

 

[ShoalSurvivor]

Re: Alpha one gen 2: diagnosing overheating

I have the Mercruiser Outdrive Mounting Gaskets kit(Mallory Marine Part # 9-62601).
I have a drive oil monitor.

Do I need to do anything to the drive oil valve between the upper unit and bell housing? Remove/clean? I do not have replacement seals or O-rings for it.... I'm just hoping that once the water o-ring, larger sealing ring in the bell housing, and the gasket are in place... that seal for the monitor will be ok as is.

I was not having issues with it before, but I just wanted to make sure I wasn't skipping an obvious step here when reinstalling.

Thanks.

 

[ShoalSurvivor]

Re: Alpha one gen 2: diagnosing overheating

I finally got the right flappers and exhaust assembled, drive lubed and ready to go.....

Ran on muffs for 15 minutes:
The right side reached as high as 160.
Left side, 130.
T-stat housing - never over 130.
Engine block at temp sender: 160-170.

Everything ran very nicely, but....
my gauge showed 185.

NOWHERE could I get a reading that high... anywhere on the block, exhaust, outflow.... nada.
Even worse, I replaced this sender and gauge last fall, and as far as I could tell, it was aligned with engine readings before all of this started.

I'll go test the gauge and temp sender, but:

If my readings all over the manifolds, risers, t-stat housing, engine block, etc... stay under 160.... can I assume everything is AOK? or is the temp at the sender location (inside where I cant read it with an IR gun) hotter than the surface?