Need Help With 470, Engine Overheating

[alex3012red]

I just rebuilt the engine, went thru everything, got it on the water and temp above 180. removed thermostat samething, replace thermostat, and replaced impeller. same thing, checked engine water pump o.k, no corrosion on any of the parts (manifold,head,intake). checked 4" heat exchanger looks clean. anybody have an Idea. I also replaced coolant sensor. I checked for raw water and it circulates very good. I have not overheated the engine above 190. Dont want to risk it. The engine seems to have less power than before, but I've only ran it for like 10min, before the temp goes up.
Any help would be appreciated.

 

[Todd Peterson]

Re: Need Help With 470, Engine Overheating

Why did you rebuild the engine in the first place?
I overheated last fall and tomorrow will be the first day in the water for the summer. Had a local marina screw things up for me during the rebuild.
I also put in new stringers and floor. When I got done the carb was plugged and had to rebuild that. Did the impeller go bad and block the heat exchanger? I took pieces of the impeller out of my exchanger. What a mess.

 

[Rocky_Road]

Re: Need Help With 470, Engine Overheating

I am new to the 470, myself (just bought one)...but have done a great deal of searching on this forum, for 470 issues.

I remember someone having this issue on a newly rebuilt engine...and his answer was the engine timing. Once he set it to specs...he had no problems.

I am assuming that your closed loop cooling system is full...and not losing any coolant.

 

[achris]

Re: Need Help With 470, Engine Overheating

Rebuilt engine...

Wrong valve timing
Wrong ignition timing
Leaking head gasket

lack of coolant. Sometimes the engine doesn't fill up properly...

HTH

Chris......

 

[Big Boat Bay Buster]

Re: Need Help With 470, Engine Overheating

Is the riser passages clear??
How about the gauge. That was part of the problem I had on my 470. There was a plug next to the sending unit that I removed and added a mechanical temp gauge to compare to the original 25 year old set-up. Mechanical temp gauges are very accurate and confirmed the original electric gauge was reading too high.
Also, those new lazer temp guns might help to pinpoint where the problem might be. Food for thought
Chris

 

[chiefalen]

Re: Need Help With 470, Engine Overheating

Why these guys rebuilding the 470?

Cris gave you everything to check.

If it all checks out, than re-adjust the valve springs, if they are to tight can give you the symptoms you describe.

 

[Don S]

Re: Need Help With 470, Engine Overheating

Those valves aren't adjustable except by changing pushrod length. Did you get the pushrods in the same place they were in originally.

Also, did you align the oil pump with the special tool when you reinstalled it. If it's out of alignment, it will break off the distributor shaft and the oil pump will not be running. Then you have no oil pressure.

 

[alex3012red]

Re: Need Help With 470, Engine Overheating

Thanks for all your reply's. I'll start by why I rebuilt the engine. I bought the boat was leaking water, yes from the seals, fixed, went to try out kept on losing water (did not get hot while coolant in engine). replaced coolant recovery tank, went for another ride and spun a rod bearing #1.Found out it was a head gasket. took the engine apart, decided to fix, bought parts, took rods and crankshaft to get cut .020 on crank. measured everything else checked o.k. Head was also rebuilt new valves and seats.Honed cylinders and assembled.Cleaned or replaced every bolt on engine. Checked 4" heat exchange looked clean.Replaced lifters, left push rods. Put everything together timed at 4 deg. Started quickly went to try out and temp. issue.
So i guess I did not check the valve clearance. I had no idea i needed to do that. I just torqued with valve closed to spec. Where should I start. My temp climed close to 200 deg. should I check the head.

 

[alex3012red]

Re: Need Help With 470, Engine Overheating

Finally had the time to try to figure the overheating problem. Checked comp. 180 psi in all 4, checked valve clearance they were all o.k. Iam down to re-timing a 4 deg., re-checking 4" cooler for being clogged.
Does anybody know the air screw position.
I will post tomorrow after i play with timing and heat exchange unit.

 

[jerryjerry05]

Re: Need Help With 470, Engine Overheating

How old is the riser? Even though it might look like it's getting enough water it could be clogged.The heat exchanger could be clogged.You cant see in the closed cooling passages.Take it to a radiator shop.Jerry

 

[alex3012red]

Re: Need Help With 470, Engine Overheating

Thanks to all of your replys, I gone thru all of them at least once.

the riser and heat exchanger, where inspected today along with the complete exhaust, everything is fine no rust, no clogs. timed the engine at 4 deg. seems to help. tested with water hose temp at 180
Now the bad news got worse, the engine is making a noise from 1500 rpm and on, sounds like a rod or something inside. when you hit the throtle you can hear it and get a little louder as the rpms go higher. the engine was rebuilt 2 hours ago. when you started it sounds perfect after it warms a little and rev it you hear the noise. I really can't tell if the noise is on the bottom,top or behind the engine. sound starts like a vibration and then sounds like a rod or main noise. oil is at 80 and drops to 50 when you rev the engine. I'am ready to give up on engine. Any Ideas would be appreciated
should i tear it apart, or any more test I should do?

 

[CAPTKEV85]

Re: Need Help With 470, Engine Overheating

I have the same engine and had that problem all year. did another leak down test yesterday. oh yeah i have a blown head gasket. compression was pushing into the water jacket causing the engine to overheat. might want to do a leakdown test.