Water Pump - Mercruiser or GM?
John Schneider
slow but steady water leak. I traced it down to the engine water
circulating pump. This is a 1994 Mercruiser 7.4L (GM 454). With all
the dealerships closed for the holiday weekend, last night I went to
Google and did some searching. I found the prices for Mercruiser pumps
ranging from $110 for a rebuilt all the way up to $290 for a new one,
with lots of prices in between, most in the low $100's.
I have always used "genuine Mercruiser parts" when working on my
engine. When it comes to items in the fuel, electrical, and ignition
systems, I would NEVER even consider using a non-marinized part.
However, in this case, I find myself wondering if I could substitute a
GM pump (the GM part number is stamped on the front of the pump) instead
of paying the premium for a "marinized" version. My only concern is
that possibly the marinized version may be more stout, since it is
expected to run at or near full-throtle for long periods of time, and an
automotive one runs at a much lower rpm.
Does anyone know if Merc marinizes these circulating pumps with heavier
duty bearings? Or is this the exact same pump I could get from a GM
dealership, or even an auto parts store?
Thanks!
John Schneider
HLAviation
>duty bearings? Or is this the exact same pump I could get from a GM
>dealership, or even an auto parts store?
Merc does nothing, they get them from the same supplier that GM does, that is,
the lowest bidder. As long as the lengths are the same and the outlets are the
same you can use either. This is providing you are fresh water cooled. If
they are raw water cooled, I believe, not sure, that Merc specs them out with
some different materials to prevent corroding through. The back plates of the
pumps were always the problem is salt water with an RWC engine. If the backing
plate of the old one is a different material than the new auto parts store one
you might consider swapping the covers. You might also check at a NAPA store,
the handle, I believe, Sierra brand of aftermarket marine parts which I have
found to be acceptable and see what they say.
http://hometown.aol.com/hlaviation/
John Schneider
Thanks for the reply. It is raw water cooled and I mostly run in fresh water,
going to salt once or twice a year. I just checked the NAPA website, and found the
exact water pump I need under their "marine" items. According to the listing on
their website, it is new and manufactured by Chevrolet. Their price is $139. I'm
calling a couple marine dealers in the morning just for laughs. I'll bet their
price is at least $175.
Thanks again for the info!
John Schneider
John Schneider
John Schneider wrote:
One interesting thing I found out. In calling a few local dealers (metro Atlanta area)
pricing a replacement pump, one of them (an old salt that struck me as very
experienced) told me that he has seen this numerous times over the years. He said
that he has seen instances where, upon cranking the engine for the first time after a
winter layover, a small amount of water may leak through the lower weep hole. He said
to let it run for a few minutes and the leak will stop. He said this is especially
true for engines where the block has been drained for the winter. Since the leak was
relatively minor, I cranked it up again and let it run for about 10 minutes. The leak
stopped!
However, I did pull the pump and noticed some rust spots in and below the weep hole.
Being that this engine is now 8 years old, I went ahead and replaced the pump. Just
my luck, we would be out on the lake and the old one would give way.
Based on a few posts in here in rec.boats, I found out that NAPA has a marine catalog
and a very impressive line of replacement parts for Mercruiser and most major engine
manufacturers. Their pump was about $60 cheaper than one from a Merc dealer, but it
would take 2-3 days to ship. And, of course, I had to get out on the water that day,
so I paid the premium. I got a copy of their marine catalog when I went to a local
NAPA to get a new set of fan belts. BTW, the 3 belts for my engine were about $30 at
NAPA. Had I bought them from a Merc dealer, the power steering pump belt ALONE would
have been $40!
Live and learn...
John Schneider