A few questions rpm, speed, and temp

[lil buggy]

i recently purchased a 25 ft cruiser with a 5.7 mercruiser
first time out yesterday
first thing i did was load the boat down with fuel and water!
25 extra gal gas and about 30 gal water!

even playing around with the trim settings and trim tabs
i couldent get the engine over 3000 rpm
at 31mph on gps
after cruising around at that speed 1 hr the engine temp started to climb
when i pull back to just on a plane (21mph gps)temp would come back down.
repeating the process with the same result

i get that adding all the fuel and water weight certainly would change the
speed characteristics of the boat
but i assume i should be running around 4500 rpm wide open throttle

any thoughts out there on speed, rpms, and most importantly engine temp?
the waterpump was replaced and the heads redone before i purchased.

we will be out after lunch to burn some more fuel off LOL
and i can always dump most of the fresh water if need be.
the boat ran much better at test drive on a plane easier etc...
but i attribute that to all that weight i added.

any thoughts?

[www.stvowners.com]

What temp does the engine run at, and what was the max? What's the pitch/dia/material( AL or SS) on the prop.

[lil buggy]

engine temp 160 or less
when i am on it after planing out it climbs steadily up and i gotta back off (climbing over 200).
stays on a plane all day without overheating 160 to 170
as long as i dont open her up all is good.

no idea on the prop i bought the boat wet

talked with the previous (previous 2 ago) owner yesterday took him for a ride
he said it seemed like normal speed and rpms

i am quite happy with the boat even if i dont have the upper end speed

on a plane is nice at 22 mph gps no HOLY ROLLERS
headed out to shake up other docks/boats

i am thinking that the rpm guage is off
and the thermostat needs replaced

any advice/suggestions would be greatly appretiated
thanks in advance for the replies

[Cableguy Greg]

160 to 170 should be normal. It is probably a 160 thermostat. If you are getting above 175, then I would be concerned.

[lil buggy]

thanks cableguy Greg,
and yes i am concerned
a buddy of mine said to put a new thermostat in and see if that does it.
at the local auto parts store?
i see if you get them from a marine dealer they are almost twice as expensive.
whats the deal with that? are marine ones different?
thermostat reaches temp and opens, right? what can a marine one do different?

thermostat sounds plausable to me what do you think?
i guess thats the job for today

[lil buggy]

so to review, this temp issue could be

thermostat
water pump
chunks of the old waterpump wedged somewhere
pickup tube on the outdrive

any ideas

[Cableguy Greg]

Since you bought a Rinker, check out this site: www.rinkerboatowners.com
It has a ton of useful information from fellow Rinker owners like myself.

I would start with the thermostat, then move to the impeller on the fresh water intake. If it is an alpha drive, it is located in the drive itself. If it is a bravo drive, it is on the front of the engine.

[lil buggy]

thanks and also for the link

[galleyslave]

I read somewhere online (it's been a few years), the difference between marine and automotive thermostats is because marine units are designed for a lower temperature to run in salt water. Salt separate from the water at high temperatures, and it will deposit salt residue in your engine. If you are running in fresh water only, the automotive thermostat should work fine. Actually, the higher running temp on the engine increases fuel efficiency.

[lil buggy]

thanks all,
that makes sense galleyslave
heading out to change after lunch i am looking for a 160 degree thermostat correct?

[Cableguy Greg]

Yes, that is correct.

[lil buggy]

thanks again to all,
i changed the thermostat today
when changeing i saw no debris, in fact there was signs of being wet but not full of water like i expected
(i expected the water to be up to the thermostat)((is this correct?))
a lil rusty in there
it had a 140 degree in it,(glad they are all stamped).
i put a new 160 in
was by myself,
under a half tank of gas, 3qrtrs water, and got about 4200 rpm after plane and was whippen along(no gps) dat bugger was a haulin!
that would account for the difference in the test drive.(i think i'll go with a lower pitch! to handle the load).

however a minute or so of wot broght back a temp climb again steadily towards the danger zone.
backed off to around 3000rpm and the temp dropped back to around 180degrees and stayed there,
didnt budge at all.

yes that sound is me scratching my head

my common sense says something is blocking the water at wot
but my common sense doesent include the knowledge of the i/o's

so back to the drawing board

i guess that leaves,

the impellor
pieces of and old impellor stuck somewhere hoses engine etc...
the pickup tube ive been hearing about on the other blog(thanks cableguy greg)


when i removed the fitting to get to the thermostat, i didnt have to take off the hoses,
previous owner was saying something about balls in the end of the hoses on the fitting?
to prevent backwash.
what is that about?
i have to take apart again to at least put some gasket sealer on(had a lil bit of water leaking) and i think i will switch back to the 140degree thermostat for more headroom? any suggestions on that?

any other suggestions before i have to put it on the trailer to investigate further?

i have to be missing something here.

mr obvious says i am not thinking of something relatively basic
thanks in advance for the replies!

[FlapJaw]

First Replace water pump in out-drive - $55 for everything housing, tube, impeller, etc...... you tube has how to's very easy (needs replaced anyways)

Also make sure that the Water hose from out-drive is not kinked.

Then if I where you I would get my hands on an infrared temp gauge. Run the boat and when it starts to heat up check over the whole engine to find your hot spot.

* If the whole engine is the same temp that's good. (including manifolds and hoses)
* If you find one spot hotter than the rest, your problem starts there.
* If your can't find a hot spot Good you have eliminated the engine being clogged with debris and other problems (as long as timing is in check VERY IMPORTANT)

* There is an oil cooler, could be clogged
* Someone might have replaced the circulation pump with an automotive one (water pump on block) Big no no marine is brass auto WILL rust and be useless



Your problem is Not your thermostat someone has all ready tried to jerry rig the boat with a 140* (didn't work) (as long as where it's stamped faced down)

It really could be a many things or maybe just one component.

Good luck, I went though hell with mine.

[FlapJaw]

I just read your post again, and yes there should have been water all the way to the top of the thermostat.

[lil buggy]

thanks flapjaw,
laundry list is good.
it is what i needed to proceed.

yes the thermostat was number side stamp down

when you are saying the water hose from outdrive not kinked i assume you mean within the outdrive?
also the previos owner said the hose (from outdrive ) goes to the power steering first
and he was advised that pieces would likely get stuck there, he found none.
is this the correct path of the outdrive to the engine?

i will get an infrared temp gun and do as you say.

oil cooler where is it at? i am sure i can find that.

as far as the waterpump on the block. is it loacated under the center pulley? under the thermostat?

i talked with the previos owner and he said that there was pieces of rubber fins up against the thermostat upper side when he was rebuilding but the impeller was not damadged

i also talked with a block rebuilding company this morning
they suggested that i take the freezeplugs (i thought freezeplugs were just diesel)
out of the engine lower center each side
to see if i get more impeller pieces or other junk in there
they say if there is junk than i must flush the block to get the rest out
i havent got my face down under yet to see if i can see what hes talkin about


i got alot of homework here to do.
and i am trying all the steps myself even though i trust the previous owner.
so my own eyes believe and i have a better understanding.

i am trying to get everything done that i can while in the water before i pull to check the rest ( i dont wana keep pulling and putting in unnecessarily)

i appretiate all the help and suggestions
i will let you all know as i go through it what i find

thanks flapjaw for your continued time and effort
and as always thanks for the replies

[FlapJaw]

Oil cooler is for power steering can't miss it.

Yes "most" of the rubber would stop there but..... depending on your oil cooler size there could be size-able pieces in your engine very bad. The owner already said there was rubber in there. This means one thing almost 80% sure...... it was overheated at some point, cracked warped heads, head gasket, exhaust burned, out-drive damage........

Freeze plugs are glued in and are brass (last thing I would try)

Below the freeze plugs on either side a the block there will be a drain plug you could some what flush there as well.

I/O's are very involved I suggest getting books on everything and read read read.

One thing I CAN guarantee, you will know ALOT about your boat very soon

Maybe someone can advise a good mechanic, I have never used one so can't help there.

Good luck

[lil buggy]

flapjaw,

i didnt realize the oil cooler was for the power steering. makes sense though

and it was overheated( i dont know to what degree) and was told to me that it was rebuilt.
heads replaced, outdrive gone thru and ok ,and also new starter.

apparently something was missed! just gotta figure out what.

i got a good mechanic who hasnt minded helping me along when stuck in the last few outboard boats i owned. as well as you guys on here.
by the time this is over ill owe you all a few

i will look for those drain plugs tomorrow (have a few hours to play round)
do you think i should leave the 160 thermostat in?
my mechanic advised to put the 140 back in. however, more than alot of folks say 160
in any event i have till tomorrow afternoon to decide.

you are right i gotta get a good shop manual. the ones i have gotten in the past for outboards are usually a little vague but they do help

ill see what i can also get into without pulling the boat.
we have a little time before i pull her for the year
and it runs fine as long as i dont push it
(for now anyways)thats what i am worried about!!

in any event ill post as i go, and we'll see what we find

thanks for the continued support
and as always thanks for all the replies

[lil buggy]

update,
i did end up putting the 140 back in.
no issues with that.

we had a little time so me and the misses
took her out for a short cruise
in any event the water in the ohio was a mess.
i was carefull and didnt run anything over. no noises etc...
than out of nowhere bad noise clicking loud imediately stopped.
forward again same noise, reverse same noise
nuetral, revved great
back in gerar clicking again.
stopped engine raised the outdrive and inspected propeller no debris no scratches, dents, nosecone ok
skeg looked a little eroded(no annode) ((good to know)) but not cracked no leaking anything
turned the prop forward in forward gear click click
and reverse in reverse gear click click
one or two clicks per revolution
limped back to the dock clicken the whole way took forever at 800rpm about 2 or 3 miles current was swift
felt like it wouldent go into gear and stay just kinda bounce in and out

pulled out tonite
allready dark couldent see much
for another day i guess
gonna check the lower unit oil first
from there not sure.

dont have too much time for the next week but ill see what i get into.
its an alpha one outdrive

now that i am typing i did not check the gear shift cable
i wish it were that simple i guess we will see i will check tomorrow

i kinda wish i was just worried about overheating when pegged.seems like a very small problem now(given the heat stays on wot anyway).
any ideas?
now that its out i will have a chance to go thru the outdrive in any event.

(THANKS FOR THE CONTINUED SUPPORT)
(AND ALWAYS THANKS IN ADVANCE FOR THE REPLIES)
almost forgot that

[lil buggy]

i got a little info on the outdrive isue and maybe more!
thanks to boatpittsburgh family

pull outdrive complete with the driveshaft,

on the outdrive away from the boat
turn shift dog under driveshaft side, to 12 oclock and hold,
turn prop forward, positive force (no clicking) means shift cable needs replaced.

clicking,no positive force,= lower unit issues clutchdog etc...


likewise turn shiftdog to 9 oclock and hold,
turn prop backwards, positive force(no clicking) means shift cable needs replaced.

clicking, no positive force,= lower unit issues clutchdog etc...



sounds pretty simple, at least the next direction anyways!

now this is all theory at this point it will be tested later.

and yes flapjaw i am learning lots about my new boat quickly,
thanks for the continued support

and as always thanks for the replies

[lil buggy]

hi again all thanks for the support,
i pulled the outdrive and followed above (check)
lets just say it wasnt the shiftcable!

i got a line on an alpha one gen 1 outdrive the other day
thanks boat pittsburgh!
it was run for three seasons,
brandy new looking, new impeller all the annodes, small doelphin(two piece) and a stainless prop to boot
needless to say we put it in tonite.

woooooooo
the beast is back, nice!
took out for a test drive
half tank of gas 2 people, no cooler
long time to plane (like loaded boat) i gotta get comfortable with the trim tabs.
however rolled right up with a little trim to 3900rpm trimmed out at 4400rpm
movin real good
no noises, infact that temp only rolled to about 180 and stayed there
ran about 15-20 min all out! no issues!
thats a first.

the prop i took off other drive was a 14.5 x (ground out couldn't see) aluminum
the stainless is a 3 blade 14.5 x 17p the edges are a little burred but not bent
upper outdrive gears 1:1.5

so my next prop should be? 15p? to handle the load?
or would a 4 blade 17 pitch or even a four blade 15pitch get that up quicker with load whadya think
i know that if i am lightboat i could over rev a smaller pitch prop

i guess i really gotta get used to those tabs and start using

any thoughts
thanks all for the continued support
the boat pittsburgh family rocks!
and as always thanks for the replies