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What else 470 over heating

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bcain724

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Hello all this is my problem.

Hello all this is my problem. I have a 87 165 224 or 470. started over heating on my port engine. I changed the impellers in the drive and it was broken...and also changed the termostat. put back in water and ran. At low rpms under 1500 the engine runs cool about 130 to 140 degrees. at 3000 rpm the engine gets up to about 190ish and levels off there. my other engine runs at about 140ish at the same rpm...I have pulled off the hoses to the exchanger and looks like plenty of raw water passing through.
Soooo where do go from here to get this engine running cooler????
thanks for the help
Bryan
 
Maybe some impeller pieces stu

Maybe some impeller pieces stuck in new thermostat or elsewhere??? ie; too much flow low rpm not enough flow high rpm
 
oh sorry also have just put ne

oh sorry also have just put new head on and manifold and riser were clear. and if I take out of gear and race the rpms the engine cools right down instanty.
bryan
 
Pull the end cap off the heat

Pull the end cap off the heat exchanger and run a cleaning rod/brush thru the tubes to improve heat transfer.
 
that was the next thing i was

that was the next thing i was thinking. do ya have any other sugestions also so i keep moving forward if heat exchager tubes are clear??
 
Merc. PN 99155A 1 is the T&#39

Merc. PN 99155A 1 is the T'stat per merc's parts manual for your engine; it is a 160 deg. F.

No disrespect meant; was the copper pelllet in the down position?

If your gauges are correct both engines should be running about 160-170 F.
 
I did not check the stat. beca

I did not check the stat. because its brand new only put it in last week. it is a 160deg stat. well tomarrow i will check temps with a temp gun. hopefully my gauges are off and i'm running at 170ish rather than 190ish and the other engine hopefully is running warmer than 140ish....kinda funny ones hot ones cool....wanna run the hoses through each other to get happy medium...j/k well i will run a rod through the exchanger and i'll check the new stat. other than that......can it be the gimble bearing or anything mech. in the drive that can cuase it to run a little hot like this? I don't know i'm an elevator man not an engine guy. thx for any and all suggestions....hopefully i can nip this in the but soon....
bryan
 
So I checked my temps with gun

So I checked my temps with gun. the hotest spot i had was at the rear of my exchanger where the raw water exits and i believe the fresh water inlets. and that was about 220ish and much cooler at the front of exchanger. on the manifold above the stat was about 190ish so temps with gun are same as gauges showning.
bryan
 
Bryan:

Compare both heat ex

Bryan:

Compare both heat exchangers by measuring the temps. of the engine coolant hoses going into and out of the exchangers. Check and compare the manifold and riser temps. of each engine. The hotter engine may have a water shutter not functioning which would cause the heat issue.
 
Guy

Guy I did compare the two and the hotter engine is anywhere between 20 and 30 degrees hotter on all spots but the raw water inlet side of the exchanger and that was close to the same temp. and whats the water shutter and where is it???
 
"The site below shows the shut

"The site below shows the shutter at the top of the exhaust downpipe. If it is not there then it fell down into the downpipe and reducing outflow of exhaust and cooling water. If it is working then I would consider cleaning the heat exchanger, exhaust manifold and elbow. Take them to a radiator shop and have them boiled, rodded out and pressure tested.

http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=%2012488&ivar=images/CRUI SER/12488/46.png&inbr=908&bnbr=230&bdesc=EXHAUST+ELBOW"
 
Guy
thanks for the help so

Guy
thanks for the help so far. i opened one end of exchanger and put a rifle cleaning rod and bristletrhough one of the tubes at the bottom and it felt like muck in there so i will take out and clean all tubes tomarrow. hopefully there are a few tubes clogged up. it would make sense to me that i would get this situation with muck build up in bottom tubes.
will let you know if that worked
bryan
 
Guy
ok exchanger clean clean

Guy
ok exchanger clean cleaned it anyway... this water shutter you speak of? I don't think ths is on my engine or if it i don't see it. my exhaust elbow is my riser/resovoir...? then hose to some type other elbow then to more hose? so any other suggestions??

thanks bryan
 
Go back to the picture of the

Go back to the picture of the exhaust system and scroll down to look at the bottom half. You'll see that the shutter is located on the top of the lower iron exhaust pipe that attaches to the inside stern. The bottom of the rubber pipe that connects the down pipe to the exhaust elbow sits on top of the shutter.
 
click on the part number of nu

click on the part number of number 6 in the picture 9 messages above to see a pic of the shutter.
 
"I too am having similar probl

"I too am having similar problems and overheating with my 180HP 3.7LX 470 based engine. I replaced the water pump in the drive a couple weeks ago after experiencing overheating under load at higher rpm's. The old impeller was certainly worn out, but no chunks missing. With the new pump in place, I had a good couple outings and everything was performing great like it should.

OK, so now the other day I go to launch the boat, and the engine overheats within 5mins of just idling at the ramp in neutral. I checked the heat exchanger and water inlet hose and they were both cool/cold to the touch. I checked several coolant hoses on the engine and they were maybe a little warm, but by no means hot.

It's as if the coolant in the block has limited to no circulation. I replaced the t-stat, but made no difference. Also checked the impeller on the front of the engine and it spins when cranked. Any idea's to where to check for blockages? I'm currently dismantling all hoses and checking them.

Just to add, I'm pretty sure my exhaust tube flapper is working b/c I get plenty of water and exhaust flow out the back of the outdrive.

Thanks,

-Jim"
 
"sometimes you can get a air p

"sometimes you can get a air pocket, on the 470's after you have drain the closed side or the antifreeze side of the system. recheck......as the engine is warming up make sure it is full."
 
I took off my manifold and che

I took off my manifold and checked it out all the ports were clean. then i noticed 2 things. 1- was the little fitting for the bypass hose on the riser was clogged. 2- I noticed that there are 2 holes on the manifold that look like bypass holes for the around the stat and the gasket i had in there was blocking those ports...i'll let ya know if these problems were the reason when I get it all back togther
bryan
 
everything is great now My eng

everything is great now My engine is running cool and smooth. I ceaned the water exit ports in the riser and rust and crap came out. and that and the stat gasket thing I think took care of it so thx to all for the help hope this post helps someone else good luck everyone and happy boating
Bryan
 
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