1986 470 overheating

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wmike

Recruit
Joined
Aug 2, 2011
Messages
3
help I have a 470 closed sys that is running about 220 -230 .I have put in a new impeller,flushed coolent sys pulled the cover off the water pump and the impeller looks good and is turning with motor is turned over,cleaned out the heat exchanger,back flushed lake water side of coolent, compession tested the cyl at 125 psi,pressured tested the coolent sys to 25psi for one hour,no leak ,replaced the stat and it is still running hot,took the exhaust elbow off it is clear checked the flapper and it was ok.
running out of things to look at . dose anyone have a clue to what is going on.i am at a loss
 
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dn010

Petty Officer 1st Class
Joined
Oct 16, 2010
Messages
301
Re: 1986 470 overheating

Hows the flow of water out of the exhaust?

Start at the screens in the outdrive and work your way through the rest of the cooling system until you reach the exhaust. Kinked hoses, plugged passages, things of that nature you're looking for. Also, did you replace the riser gasket? Check the exhaust manifold for issues?

Are you sure your gauge isn't faulty-do you have a backup method of checking your engine temp? Can you hold your hand on the riser when it is running that hot?
 
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wmike

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Messages
3
Re: 1986 470 overheating

the water flow out of the ehaust seems to be good. I have not tried to touch the riser. i have a i/r thermometer i am going to use to see the temp.have never had the riser off. do the gaskets go bad on them? it is a one piecse riser. the inlet sceens are open. used hose and muffes to flush sys. then took a hose off and back flushed
 
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stonyloam

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Mar 13, 2009
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5,827
Re: 1986 470 overheating

That is pretty hot! I suspect your gauge may be incorrect. Measure the temp at the reservoir. If it is running hot you may want to pull the endcaps off of the exchanger to make sure the tubes are clear. The endcaps are on the seawater side, so no antifreeze should come out when you take them off. Good luck.
 
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stonyloam

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Re: 1986 470 overheating

That is pretty hot! I suspect your gauge may be incorrect. Measure the temp at the reservoir. If it is running hot you may want to pull the endcaps off of the exchanger to make sure the tubes are clear. The endcaps are on the seawater side, so no antifreeze should come out when you take them off. BTW what year? Good luck.
 
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wmike

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Re: 1986 470 overheating

stonyloam said:
That is pretty hot! I suspect your gauge may be incorrect. Measure the temp at the reservoir. If it is running hot you may want to pull the endcaps off of the exchanger to make sure the tubes are clear. The endcaps are on the seawater side, so no antifreeze should come out when you take them off. BTW what year? Good luck.
Click to expand...

took all hoses off the heat exchanger , both end capes off clean wather came out cleaned all tubes with a doll rod and coth. blow hpa thought them, pored a flush in the coolent side let it set for 1/2 hour and cleaned out with a hose and air
 
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stufferron

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Joined
Jul 23, 2011
Messages
11
Re: 1986 470 overheating

I may have the same problem, 1985 Merc 170 engine is very hot to the touch, can't even touch the rocker arm cover. While at the lake this morning I was concerned that something was wrong, removed engine cowel and could not believe how hot the engine was, the temp gauge was reading normal, 160 to 170, oil presure was normal. Came home and will check the engine when it cools down. Still is too hot to touch. I did check the timing at the lake and set it to 4 degrees btdc. Engine was running rough all morning. I can remember being able to touch the rocker arm cover without burning my fingers. I really need help on this problem, I am not sure where to start.
 
Eric 3.7LX Alpha 1

Eric 3.7LX Alpha 1

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Joined
Mar 27, 2010
Messages
3,008
Re: 1986 470 overheating

stufferron said:
I may have the same problem, 1985 Merc 170 engine is very hot to the touch, can't even touch the rocker arm cover. While at the lake this morning I was concerned that something was wrong, removed engine cowel and could not believe how hot the engine was, the temp gauge was reading normal, 160 to 170, oil presure was normal. Came home and will check the engine when it cools down. Still is too hot to touch. I did check the timing at the lake and set it to 4 degrees btdc. Engine was running rough all morning. I can remember being able to touch the rocker arm cover without burning my fingers. I really need help on this problem, I am not sure where to start.
Click to expand...

Announcement: -------------Please DO NOT reply to old threads or hijack existing threads.

Welcome to Iboats!! We are happy to try help you with your problem, but it is not polite or proper to ask your question on someone else's, even if you have the same engine.

Just imagine, tips are given to the Original Poster to help him out, and you respond that you have done it already and what else to try. While he hasn't responded yet.

It can get confusing as heck helping out two on the same thread. Please start a thread of you own.
 
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stufferron

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Jul 23, 2011
Messages
11
Re: 1986 470 overheating

OOPS, Sorry about that, I am still leaning to use this forum. I will start a new post.
 
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