Cooling system 2000 1800 sr with 4.3merc - Maxum Boat Owners Club

grantnicol543 · 08-13-2008, 10:47 PM

Hi i am now the proud owner of a 2000 maxum 1800sr with a 4.3l v6 mercruiser engine,i havent got a manual yet and trying to get to grips with some stuff!! Was wondering if there is a seperate cooling reservoir on this engine, i cant find any pressure caps etc only thing i can see is a metal threaded plug on top of the water pump behind the pulley??? Is the engine cooled only by the water it takes in thru the vents a the bottom of the leg??? I have noticed some blue twist caps around the engine and when i remove them water comes out, should i drain these after every use??? I am a complete novice on this kind of set up as i have only owned small outboard engines before, any help will be hugely appreciated.

thanks
grant

seapuppy · 08-13-2008, 11:09 PM

welcome to the zoo...that's a nice boat for sure...you can contact maxum for an owners manual up in arlington wa.
as for your cooling system...if you don't have a plastic bottle on or near the engine...and a big tank across the front of the engine..then yes..your raw water cooled....meaning the water is pulled up from the leg or outdrive...pushed thru the engine and exhaust manifolds...and then out the bottom of the transome mount where the drive penetrates the transome bulkhead......
the first thing you want to do besides change all the oils....is to pull the lower unit off and replace the impeller on the outdrive...if you don't feel comfortable with that...take it to a service ctr and have a mechanic do it..it only takes about a half hr to an hr to pull the drive..replace the impeller and replace the drive along with the drive oil.....

so..hope this helps....
keep comin here!!...we're a good bunch for maxum to have around...

SP

grantnicol543 · 08-14-2008, 10:10 AM

Thank you, thats a great help. Ive got a mechanical background so those jobs wont be too much of a problem.

Should i drain the water from those blue taps after each use?? :?

seapuppy · 08-14-2008, 03:56 PM

if salt water ...no..just run it on the muffs after each use...use the blue plugs to remove water in the winter...pull all of them..there might be 5 on your model....then you can either winterize with antifreeze and a huge bucket..stick the drive down in the bucket after the thermostat has opened...or...use a rig with a jug of antifreeze (non poluting kind we call rv antifreeze...it's the pink stuff) attached to your garden hose and a valve..when the thermostat opens....divert the water to the jug with the pink stuff...after you get pink coming out of the drive exhaust...shut it down and your done..

sp

grantnicol543 · 08-14-2008, 04:59 PM

brilliant, thank u very much, i will be back here a lot for advice probably!!! Going out for my 1st run in it on sunday, cant wait, thanks again.

grant

seapuppy · 08-14-2008, 05:03 PM

one big piece of advice....never approach the dock faster than your willing to crash into it.....

SP

zt260 · 08-14-2008, 10:14 PM

I would recomend you buy the engine manual and outdrive manual for your set up then any minor probs and fault finding should be a bit easier
have fun

ash

grantnicol543 · 08-15-2008, 10:48 PM

Thanks for the advice guys, dont think i'll be out on sunday, discovered a problem, not sure how big or small when changing the engine oil, i checked the dipstick and i loked ok, quite fresh but was going to change it anyway, when i drained it it came out very creamy, looked alot like beige paint! I replaced the filter and oil and put a engine flush thru it, ran the engine for 30mins at idle then drained the oil again and it was a lot lighter, just off white. i am going to do that another few times an hopefully it will clear!! I bought the boat as a non starter and it lay off the water for a year without being drained or even flushed.

Any ideas guys????

seapuppy · 08-17-2008, 10:01 PM

yeah..do a compression check on all cylinders...you may find a blown head gasket or something like that....water has gotten into your oil somewhere.....that's a start...

let us know how it goes...

SP

grantnicol543 · 08-17-2008, 11:19 PM

Hi guys, well i had my first outing in the new boat........few different concerns!
I flushed the engine yesterday got the oil looking lovely and clear which was all good.
I got underway today....... boat only revving to 3000rpm when pulling away with throttle wide open.... finally got on the plane and the engine revs began to pick up to around 4000rpm but fluctuated between 3900-4100rpm without me moving the throttle from the full postition and only achieving a max speed of 32-35mph on relatively calm water, i was expecting a bit more from the 4.3 v6???????? I noticed during the day that the oil pressure was getting lower and lower to finally being at 15psi (ish) which is way too low. i checked the oil and it was mixing with water again.
I bought the boat knowing there was engine problems so was expecting to have to do some work or replace it, just wondered if any1 has any ideas what could be wrong? im sure it is more than one thing not right!!!!
there is also some back pressure in the engine, notice it when i take the oil cap off when it idling. :?

Gazjen · 08-18-2008, 12:47 AM

Sounds like Head gasket(s)

Compression check all cylinders but try not to turn it over for long to get your reading these large capacity engines are very good at masking low pressure if you keep cranking

It's easy to get the heads off as there is no cam belt etc. Take the plugs out and have a look at them. That may give you an idea which side to start on

I've just rebuilt my 4.3 its not the end of the world to do it. but you may get away with head gaskets

Lack of revs could be plugs, timing, bad fuel or a blocked jet in the carb. Is your flame arrestor clean, fuel starvation etc Get yourself the mercruiser manual its more than worth its money PM me and I'll let you know where to get it